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Qi Zhang

Publications and source records attributed to Qi Zhang.

At least 109 records · Page 6Linked to original sources
PubMed2005

Deconvolution and quantification of hydrocarbon-like and oxygenated organic aerosols based on aerosol mass spectrometry.

A new technique has been developed to deconvolve and quantify the mass concentrations of hydrocarbon-like and oxygenated organic aerosols (HOA and OOA) using highly time-resolved organic mass spectra obtained with an Aerodyne Aerosol Mass Spectrometer (AMS). This technique involves a series of multivariate linear regressions that use mass-to-charge ratios (ml/s) 57 (mostly C4H9+) and 44 (mostly CO2+)-the identified AMS mass spectral tracers for HOA and OOA, respectively-as the initial principal components. Two algorithms have been developed: algorithm 1 is based solely on m/z 44 and m/z 57, and algorithm 2 is an iterative procedure expanded from algorithm 1. This technique was applied to the AMS organic aerosol data acquired at the EPA Pittsburgh Supersite during September 2002. The reconstructed organic concentrations (= HOA + OOA) agree well with the measured values (r2 = 0.997, slope = 0.998), and the reconstructed organic data matrix (size = 3199 time steps x 300 m/z's) explains 99% of the variance in the measured time series. In addition, the extracted mass spectrum of HOA shows high similarity to those of diesel exhaust, lubricating oil, and freshly emitted traffic aerosols observed in urban areas, while the spectrum of OOA closely resembles those of aged organic aerosols sampled in rural areas and also shows similarity with the spectrum of fulvic acid- a humic-like substance that is ubiquitous in the environment and has previously been used as an analogue to represent polyacid components found in highly processed and oxidized atmospheric organic aerosols. There is evidence for the presence of a third component, although its contribution to the total organic signal appears to be small in this study. The most important result is that m/z 44 and m/z 57 are reliable AMS mass spectral "markers" that provide the "first guess" for algorithm 2 which allows the quantitative description of the organic aerosol concentration and mass spectra over a period of 16 days in a major urban area and allows the extraction of mass spectra of OOA and HOA that can be interpreted chemically. These findings indicate the potential of performing organic source apportionment on the basis of total particle mass, rather than on the basis of organic tracer compounds that contribute a small fraction of this mass.

Aerosols↗
PubMed2005

Oxidative stress and left ventricular function with chronic intermittent hypoxia in rats.

RATIONALE AND OBJECTIVES: Obstructive sleep apnea (OSA) is associated with oxidative stress and myocardial dysfunction. We hypothesized that the chronic intermittent hypoxia (CIH) component of OSA is sufficient to lead to these adverse effects. METHODS AND RESULTS: Rats were exposed to CIH (nadir O2, 4-5%) for 8 hours/day, 5 days/week, for 5 weeks. Results were compared with similarly handled controls (HC). Outcomes included blood pressure (tail cuff plethysmograph), echocardiographic and invasive measures of left-ventricular (LV) function, and indices of oxidative stress that included levels of myocardial lipid peroxides and Cu/Zn superoxide dismutase. Blood pressure was greater in CIH (n=22) than in HC (n=22) after 2 weeks of exposure (136+/-12 vs. 128+/-8 mm Hg; p<0.05). However, the difference disappeared by 5 weeks (127+/-13 vs. 127+/-13 mm Hg). LV weight/heart weight was greater with CIH (CIH, 0.52+/-0.05; HC, 0.47+/-0.06; p<0.005). Echocardiograms revealed LV dilation, as well as decreased LV fractional shortening (CIH, 29.7+/-9.8%; HC, 37.4+/-7.1%; p<0.001). LV end-diastolic pressure was increased with CIH (CIH, 13.7+/-5.5; HC, 8.0+/-2.9 mm Hg; p<0.001), decreased LV dp/dtmax (CIH, 5072+/-2191; HC, 6596+/-720 mm Hg/second; p<0.039), and decreased cardiac output (CIH, 48.2+/-10.5; HC, 64.1+/-10.9 ml/minute; p<0.001). LV myocardial lipid peroxides were greater (CIH, 1,258+/-703; HC 715+/-240 microm/mg protein; p<0.05) and LV myocardial superoxide dismutase levels were lower (CIH, 10.3+/-4.9; HC, 18.6+/-8.2 U/mg protein; p<0.05) with CIH. CONCLUSIONS: CIH leads to oxidative stress and LV myocardial dysfunction.

Animals↗
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

Chitosan-DNA microparticles as mucosal delivery system: synthesis, characterization and release in vitro.

BACKGROUND: Mucosal immunity is important to defense against dental caries. To enhance mucosal immunity, a DNA vaccine mucosal delivery system was prepared by encapsulating anticaries DNA vaccine (plasmid pGJA-P/VAX) in chitosan under optimal conditions and the characteristics of the microparticles was investigated. Furthermore, the release properties and protective action of microparticles for plasmid were studied in vitro. METHODS: Plasmid loaded chitosan microparticles were prepared by complex coacervation. Three factors, concentration of DNA, sodium sulfate, and the chitosan/DNA ratios in complexes [better expressed as N/P ratio: the number of poly nitrogen (N) per DNA phosphate (P)] influencing preparation were optimized by orthogonal test. The characteristics of microparticles were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). DNA release rate of microparticles in similar gastro fluid (SGF) or similar intestinal fluid (SIF) at 37 degrees C was determined by ultraviolet spectrophotometry. RESULTS: High encapsulation efficiency (96.8%) was obtained with chitosan microparticles made under optimal conditions of 50 mmol/L Na2SO4, 200 microg/ml DNA and N/P ratio of 4. The size of particles was about 4 to 6 microm. The encapsulation process did not destroy the integrity of DNA. When incubated with SIL, after a release of about 10% in the first 60 minutes, no further DNA was released during the following 180 minutes. When incubated with SGL, the microparticles released a small burst (about 11%) in the first 60 minutes, and then slowly released at a constant, but different rate. CONCLUSIONS: These chitosan microparticles showed suitable characteristics in vitro for mucosal vaccination and are therefore a promising carrier system for DNA vaccine mucosal delivery.

Animals↗
PubMed2005

On the susceptibility of organic peroxy bonds to hydride reduction.

Reduction of organic molecules that contain a peroxy bond is broadly considered as a "risky" and uncertain operation when cleavage of the peroxy linkage is not desired. For this reason, such reduction steps are normally avoided at the planning stage of the synthesis when possible. As a natural consequence, the information in the literature about the susceptibility of organic peroxy bonds to reducing species is scant. In this work the tolerance of organic peroxy bonds to some common hydride reductants was examined systematically for the first time. Using reduction of ester group to alcohol as a probe, LiAlH(4), LiAlH(O(t)()Bu)(3), LiBHEt(3), and LiBH(4) were found to be significantly better than other reductants examined when taking into consideration both the completeness of the reduction of ester groups and the peroxy bond survival rate. LiBH(4) appeared to be the most suitable reductant for the reduction under discussion, not only because of the high reduction yields/excellent compatibility with peroxy bonds, but also because of the advantages in practical aspects. The results disclosed herein may (hopefully) provide a handy reference for dealing with reduction of other peroxy bond-containing molecules in the future.

Journal Article↗
PubMed2005

Solution structure of BmP08, a novel short-chain scorpion toxin from Buthus martensi Karsch.

A novel short-chain scorpion toxin BmP08 was purified from the venom of the Chinese scorpion Buthus martensi Karsch by a combination of gel-filtration, ion exchange, and reversed-phase chromatography. The primary sequence of BmP08 was determined using the tandem MS/MS technique and Edman degradation, as well as results of NMR sequential assignments. It is composed of 31 amino acid residues including six cysteine residues and shares less than 25% sequence identity with the known alpha-KTx toxins. BmP08 shows no inhibitory activity on all tested voltage-dependent and Ca(2+)-activated potassium channels. The 3D-structure of BmP08 has been determined by 2D-NMR spectroscopy and molecular modeling techniques. This toxin adopts a common alpha/beta-motif, but shows a distinctive local conformation and features a 3(10)-helix and a shorter beta-sheet. The unique structure is closely related to the distinct primary sequence of the toxin, especially to the novel arrangement of S-S linkages in the molecule, in which two disulfide bridges (C(i)-C(j) and C(i+3)-C(j+3)) link covalently the 3(10)-helix with one strand of the beta-sheet structure. The electrostatic potential surface analysis of the toxin reveals salt bridges and hydrogen bonds between the basic residues and negatively charged residues nearby in BmP08, which may be unfavorable for its binding with the known voltage-dependent and Ca(2+)-activated potassium channels. Thus, finding the target for this toxin should be an interesting task in the future.

Amino Acid Sequence↗
PubMed2005

Semi-industrial isolation of salicin and amygdalin from plant extracts using slow rotary counter-current chromatography.

Salicin in the bark extract of Salix alba and amygdalin in the fruit extract of Semen armeniacae were each separated by slow rotary counter-current chromatography (SRCCC). The apparatus was equipped with a 40-L column made of 17 mm i.d. convoluted Teflon tubing. A 500g amount of crude extract containing salicin at 13.5% was separated yielding 63.5 g of salicin at 95.3% purity in 20h using methyl tert-butyl ether-l-butanol (1:3) saturated by methanol-water (1:5) as a stationary phase and methanol-water (1:5) saturated by methyl tert-butyl ether-1-butanol (1:3) as a mobile phase. A 400g amount of crude extract containing amygdalin at 55.3% was isolated to yield 221.2g of amygdalin at 94.1% purity in 19h using ethyl acetate-1-butanol (1:2) saturated by water as a stationary phase and water saturated by ethyl acetate-1-butanol (1:2) as a mobile phase. The flow rate of the mobile phase was 50 ml/min. The results show that industrial SRCCC separation of salicin and amygdalin is feasible using a larger column at a higher flow rate of the mobile phase.

Amygdalin↗
PubMed2005

Different regions of the mouse nestin enhancer may function differentially in nestin expression in an NSC-like cell line and astrocytes.

Nestin is a characteristic intermediate filament protein expressed in neural stem cells (NSCs). Evidence has shown that it is also found in reactive astrocytes. Previous studies have demonstrated that the second intron of the human and rat nestin genes harbors the central nervous system (CNS) enhancer and the midbrain enhancer, which regulate nestin expression in different regions of CNS during development. In this study, using an NSC-like cell line C17.2 and primarily cultured astrocytes, we show that both C17.2 cells and astrocytes express nestin. To characterize the nestin enhancer in further detail, we cloned the second intron of the mouse nestin gene, which is homologous to the human and rat counterparts as shown by DNA sequencing. Reporter assay indicated that the full-length nestin enhancer was active in both C17.2 cells and astrocytes, consistent with the immunocytochemistry results. However, in C17.2 cells, the enhancer activity was attributed to the highly conserved 3' part, and the 5' part of the enhancer was suppressive to the transcription activation activity of the full-length enhancer. While in astrocytes, both 3' and 5' parts were able to enhance the reporter gene expression. Our data suggested that different regions of the nestin enhancer might have different functions in C17.2 cells and astrocytes: while the 3' region activates transcription in both cell types, the 5' region suppresses in C17.2 cells but activates in astrocytes nestin expression.

Animals↗
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

Effect of Sinai san decoction on the development of non-alcoholic steatohepatitis in rats.

AIM: To explore the effect of Sinai san decoction on the development of non-alcoholic steatohepatitis induced by CCL4 combined with a fat-rich diet in rats. METHODS: Twenty-seven Sprague-Dawley rats were divided into three groups randomly: control group (n = 9), model group (n = 9) and treatment group (n = 9). The rats of model group and treatment group were given small dosage of CCL4 combined with a fat-rich diet, and those of control group were given normal diet. After four weeks of fat-rich diet feeding, the rats of treatment group were given Sinai san decoction. The serum levels of aminotransferase and lipid were measured, and the pathology of livers was observed by HE staining after the rats were sacrificed at eight weeks. RESULTS: The rats' livers presented the pathology of steatosis and inflammation with higher serum levels of ALT and AST in the model group. In the treatment group the serum ALT and AST levels decreased significantly and were close to the control group. The hepatic inflammation scores also decreased markedly, but were still higher than those of control group. And the degree of hepatocyte steatosis was similar to that of model group. CONCLUSION: Sinai san decoction may ameliorate the hepatic inflammation of rats with steatohepatitis induced by small dosage of CCL4 combined with a fat-rich diet, but does not prevent the development of hepatocyte steatosis.

Alanine Transaminase↗
PubMed2005

[hTERT promoter regulated replication-selective adenovirus CNHK300 in treatment of hepatocellular carcinoma].

OBJECTIVE: To evaluate the therapeutic efficiency of replicative adenovirus CNHK300 targeted at telomerase-positive hepatocellular carcinoma. METHODS: Human liver cancer cell line HepGII and Hep3B, human embryonic kidney cell line 293, and normal human fibroblasts of the line BJ were cultured and added with adenoviruses CNHK300, ONYX-015 (55 000 protein deleted adenovirus), or wtAd5 (wild type 5) with different multiplicity of infection (MOI) for 7 days. 293 cells were used to measure the titer of the filial generation virus from different cells. The cell survival rate was calculated by MTT method 2, 4, 6, and 8 days after. Different cells were added with CNHK300 virus and then the E1A protein in the cytoplasm was measured by western blotting. Fluorescence microscopy was used to observe the CNHK300-EGFP proliferation after the cells were cultured and added with the virus for 1.5 hours. RESULTS: The replicative viruses CNHK300 and wtAd5 proliferated rapidly in HepGII and Hep3B cells since 24 hours after inoculation and proliferated 40625 and 65326 times respectively with a proliferation potential similar to that of the wild-type adenovirus and much higher than that of the ONYX-015 virus. CNHK300 of the MOI of 0.0002 killed half of the cancer cells, especially those of the line Hep3B, within 5 approximately 6 days, and CNHK300 virus of the MOI of 0.5 pfu/cell killed almost all the HepGII cells in the 8th day, with a killing power lower than that of the wild-type virus and higher than that of the ONYX-015 cells. The IC(50) was as low as MOI of 0.002 pfu/cell for the Hep3B cell and was as high as MOI of 100 pfu/cell for the BJ cell. CNHK300 was a less powerful killer of fibroblasts than wild-type virus. E1A expression was shown by western blotting in 293 cells and CNHK300-infected liver cancer cells, but not in the CNHK300-infected normal human fibroblasts. Fluorescence microscopy showed only isolated fluorescence-positive fibroblasts till the 10th day of infection, but obvious proliferation of CNHK300-EGFP virus since the 3rd day and fluorescence-positive cells in sheets by the 7th day, however, the fluorescent intensity was weakened since the 10th day. CONCLUSION: Tumor-selective adenovirus CNHK300 replicates in telomerase-positive liver cancer cells efficiently as well as wtAd5 and causes oncolysis, but has severely attenuated proliferation and cytolysis in normal cells.

Adenoviridae↗
PubMed2005

Potent antitumor efficacy of an E1B 55kDa-deficient adenovirus carrying murine endostatin in hepatocellular carcinoma.

Data from clinical trails have shown that the antitumoral effect of ONYX-015, an E1B 55kDa-deficient adenovirus, as monotherapy is insufficient. To enhance its efficiency, CNHK200-mE, another E1B 55kDa-deficient adenovirus armed with a mouse endostatin gene was constructed and its antitumoral activities against hepatocellular carcinoma (HCC) in vitro and in vivo were investigated. The selective replication and cytotoxicity of CNHK200-mE in Hep3B and HepGII cells independent of p53 status were confirmed via TCID50 and 3-(4,5dimetylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assays. Potent tumor growth suppression on SMMC-7721 xenografts in nude mice was observed and a synergistic effect of the carrier virus and the therapeutic gene was suggested. Moreover, in comparison with the nonreplicative adenovirus carrying the same therapeutic gene, amplified transgene expression of mouse endostatin in vitro and in vivo were confirmed by Western blotting and ELISA assay. The effective angiogenesis inhibition and replication of CNHK200-mE in nude mice xenografts were demonstrated by immunohistochemistry. In conclusion, the recombinant adenovirus CNHK200-mE is a replication-competent oncolytic virus mediating high expression of therapeutic gene. Because CNHK200-mE is capable of replicating in and lysing HCC cells selectively with effective tumor growth suppression and antiangiogenic activity on HCC xenografts in nude mice, it holds good potential for the treatment of HCC.

Adenoviridae↗
PubMed2005

Age-progressing cognitive impairments and neuropathology in transgenic CRND8 mice.

Patients with Alzheimer's disease suffer from progressive cognitive impairments and show distinct post-mortem neuropathology, including beta-amyloid plaques. Transgenic (Tg) CRND8 mice carry a mutated human amyloid precursor protein gene and show age-related increases in beta-amyloid production and plaque deposition. It was previously reported that during the early stages of plaque deposition, Tg CRND8 mice demonstrated Morris maze impairments. However, it is unknown if Tg mice would be impaired at an earlier age prior to plaque deposition or more impaired at a later age with more extensive plaque deposition. In the current study, we describe Tg CRND8 age-progressing beta-amyloid neuropathology and cognitive abilities in greater detail. At all ages, Tg mice showed normal short-term memory in the Y-maze. Pre-plaque Tg and age-matched Non-Tg mice did not differ in learning the spatial Morris water maze. However, both early and late plaque Tg mice showed impairments during acquisition. In addition, although early plaque Tg mice performed well in the probe trial, late plaque Tg mice demonstrated impaired probe trial performance. Therefore compared to their Non-Tg littermates, Tg CRND8 mice demonstrate cognitive impairments that progressed with age and seemed to coincide with the onset of beta-amyloid plaque deposition.

Age Factors↗
PubMed2005

Oxidative stress in heroin administered mice and natural antioxidants protection.

The oxidative stress of heroin administered mice via intraperitoneal injection, and the therapeutic effects of exogenous antioxidants on the restrain of the oxidative damage of biomolecules and withdrawal syndrome were studied. After administered with heroin, mice showed decrease of total antioxidant capacity in blood, increase of reactive oxygen species production in white blood cells, and increase of oxidative damages of protein and lipid in brain and liver, but not in heart. On the other hand, exogenous antioxidants could restrain the oxidative stress, even alleviate withdrawal syndrome.

Animals↗
PubMed2005

Apoptin induces chromatin condensation in normal cells.

Apoptin, a chicken anemia virus protein, was reported to induce tumor specific apoptosis, which was correlated with the nuclear localization of the protein in tumor cells. While in normal human cells, Apoptin was detected mainly in the cytoplasm and did not induce apoptosis. Using a recombinant adenovirus expressing Apoptin, we have found that Apoptin induced G(2)-M cell cycle arrest and chromatin condensation in cancer cells. Here we report that adenovirus mediated Apoptin expression also induces G(2)-M arrest in normal cells. In normal cells Apoptin is localized mainly in the cytoplasm but is also found in the nucleus of a subset of cells. Apoptin induces chromatin condensation not only when it is expressed in the nucleus but also when it is expressed in the cytoplasm. Our results indicate that Apoptin-induced chromatin condensation in the normal cells may not correlate with its nuclear localization and the mechanism of regulating the G(2)-M transition might be a target for Apoptin.

Capsid Proteins↗