Biomedical subjects

Bing Zhang

Publications and source records attributed to Bing Zhang.

At least 55 records · Page 3Linked to original sources

PubMed2005

One-color two-photon mass-analyzed threshold ionization spectroscopy of ethyl bromide through a dissociative intermediate state.

Mass-analyzed threshold ionization (MATI) spectra of ethyl bromide were obtained using one-color two-photon ionization through a dissociative intermediate state. Accurate values for the adiabatic ionization energy have been obtained, 83099+/-5 and 85454+/-5 cm(-1) for the X1 2E and X2 2E states of the ethyl bromide cation, respectively, giving a splitting of 2355+/-10 cm(-1). Compared with conventional photoelectron data, the two-photon MATI spectrum exhibited a more extensive vibrational structure with a higher resolution, mainly containing the modes involving the dissociation coordinate. The observed modes were analyzed and discussed in terms of wave packet evolving on the potential-energy surface of the dissociative state.

Journal Article↗

PubMed2005

Photodissociation study of ethyl bromide in the ultraviolet range by the ion-velocity imaging technique.

The photodissociation of ethyl bromide has been studied in the wavelength range of 231-267 nm by means of the ion velocity imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme. The velocity distributions for the Br ((2)P(1/2)) (denoted Br*) and Br ((2)P(3/2)) (denoted Br) fragments are determined, and each can be well-fitted by a narrow single-peaked Gaussian curve, which suggests that the bromine fragments are generated as a result of direct dissociation via repulsive potential-energy surfaces (PES). The recoil anisotropy results show that beta(Br) and beta(Br*) decrease with the wavelength, and the angular distributions of Br* suggest a typical parallel transition. The product relative quantum yields at two different wavelengths are Phi(234nm)(Br*)=0.17 and Phi(267nm)(Br*)=0.31. The relative fractions of each potential surface for the bromine fragments' production at 234 and 267 nm reveal the existence of a curve crossing between the (3)Q(0) and (1)Q(1) potential surfaces, and the probability of curve crossing decreases with the laser wavelength. The symmetry reduction of C(2)H(5)Br from C(3v) to C(s) invokes a nonadiabatic coupling between the (3)Q(0) and (1)Q(1) states, and with higher energy photons, the probability that crossing will take place increases.

Journal Article↗

PubMed2005

Dechlorination of hexachlorobenzene using ultrafine Ca-Fe composite oxides.

Ca-Fe composite oxides with different Ca/Fe atomic ratios were synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy with elemental X-ray analysis (SEM-EDX) and inductively coupled plasma optical emission spectrometer (ICP-OES). Their dechlorination activities were evaluated using hexachlorobenzene (HCB) as a model compound. The results indicate that the dechlorination activity is related to the composition of metal oxides. Different compositions lead to the formation of different phases of Ca-Fe composite oxides. When Ca/Fe atomic ratio was 3.4, the dechlorination activity reached 97%, which was the highest in the dechlorination of HCB at 300 degrees C for 0.5 h. This may be related to the formation of Ca(2)Fe(2)O(5) phase and small agglomerate size of oxide crystal of about 1 microm. The effect of reaction time on HCB dechlorination and the pathway of dechlorination were investigated using the Ca-Fe composite oxide with the highest activity. It was found that hydrodechlorination took place in the destruction of HCB, the dechlorination efficiency is almost 100% after 2 h reaction. After reaction, quantitative measurement of chloride ion and qualitative analysis of CaCO(3) indicate besides hydrodechlorination, other degradation routes may be present. The mechanism of synergic dechlorination using Ca-Fe composite oxides was discussed.

Adsorption↗

PubMed2005

WebGestalt: an integrated system for exploring gene sets in various biological contexts.

High-throughput technologies have led to the rapid generation of large-scale datasets about genes and gene products. These technologies have also shifted our research focus from 'single genes' to 'gene sets'. We have developed a web-based integrated data mining system, WebGestalt (http://genereg.ornl.gov/webgestalt/), to help biologists in exploring large sets of genes. WebGestalt is composed of four modules: gene set management, information retrieval, organization/visualization, and statistics. The management module uploads, saves, retrieves and deletes gene sets, as well as performs Boolean operations to generate the unions, intersections or differences between different gene sets. The information retrieval module currently retrieves information for up to 20 attributes for all genes in a gene set. The organization/visualization module organizes and visualizes gene sets in various biological contexts, including Gene Ontology, tissue expression pattern, chromosome distribution, metabolic and signaling pathways, protein domain information and publications. The statistics module recommends and performs statistical tests to suggest biological areas that are important to a gene set and warrant further investigation. In order to demonstrate the use of WebGestalt, we have generated 48 gene sets with genes over-represented in various human tissue types. Exploration of all the 48 gene sets using WebGestalt is available for the public at http://genereg.ornl.gov/webgestalt/wg_enrich.php.

Computer Graphics↗

PubMed2005

Computational, integrative, and comparative methods for the elucidation of genetic coexpression networks.

Gene expression microarray data can be used for the assembly of genetic coexpression network graphs. Using mRNA samples obtained from recombinant inbred Mus musculus strains, it is possible to integrate allelic variation with molecular and higher-order phenotypes. The depth of quantitative genetic analysis of microarray data can be vastly enhanced utilizing this mouse resource in combination with powerful computational algorithms, platforms, and data repositories. The resulting network graphs transect many levels of biological scale. This approach is illustrated with the extraction of cliques of putatively co-regulated genes and their annotation using gene ontology analysis and cis-regulatory element discovery. The causal basis for co-regulation is detected through the use of quantitative trait locus mapping.

Journal Article↗

PubMed2005

AP180 maintains the distribution of synaptic and vesicle proteins in the nerve terminal and indirectly regulates the efficacy of Ca2+-triggered exocytosis.

AP180 plays an important role in clathrin-mediated endocytosis of synaptic vesicles (SVs) and has also been implicated in retrieving SV proteins. In Drosophila, deletion of its homologue, Like-AP180 (LAP), has been shown to increase the size of SVs but decrease the number of SVs and transmitter release. However, it remains elusive whether a reduction in the total vesicle pool directly affects transmitter release. Further, it is unknown whether the lap mutation also affects vesicle protein retrieval and synaptic protein localization and, if so, how it might affect exocytosis. Using a combination of electrophysiology, optical imaging, electron microscopy, and immunocytochemistry, we have further characterized the lap mutant and hereby show that LAP plays additional roles in maintaining both normal synaptic transmission and protein distribution at synapses. While increasing the rate of spontaneous vesicle fusion, the lap mutation dramatically reduces impulse-evoked transmitter release at steps downstream of calcium entry and vesicle docking. Notably, lap mutations disrupt calcium coupling to exocytosis and reduce calcium cooperativity. These results suggest a primary defect in calcium sensors on the vesicles or on the release machinery. Consistent with this hypothesis, three vesicle proteins critical for calcium-mediated exocytosis, synaptotagmin I, cysteine-string protein, and neuronal synaptobrevin, are all mislocalized to the extrasynaptic axonal regions along with Dap160, an active zone marker (nc82), and glutamate receptors in the mutant. These results suggest that AP180 is required for either recycling vesicle proteins and/or maintaining the distribution of both vesicle and synaptic proteins in the nerve terminal.

Animals↗

PubMed2005

Ornithine decarboxylase gene is overexpressed in colorectal carcinoma.

AIM: To investigate the ornithine decarboxylase (ODC) gene expression in colorectal carcinoma, ODC mRNA was assayed by RT-PCR and ODC protein was detected by a monoclonal antibody against fusion of human colon ODC prepared by hybridoma technology. METHODS: Total RNA was extracted from human colorectal cancer tissues and their normal counterpart tissues. ODC mRNA levels were examined by RT-PCR. ODC genes amplified from RT-PCR were cloned into a prokaryotic vector pQE-30. The expressed proteins were purified by chromatography. Anti-ODC mAb was prepared with classical hybridoma techniques and used to determine the ODC expression in colon cancer tissues by immunohistochemical and Western blotting assay. RESULTS: A cell line, which could steadily secrete anti-ODC mAb, was selected through subcloning four times. Western blotting reconfirmed the mAb and ELISA showed that its subtype was IgG2a. RT-PCR showed that the ODC mRNA level increased greatly in colon cancer tissues (P<0.01). Immunohistochemical staining showed that colorectal carcinoma cells expressed a significantly higher level of ODC than normal colorectal mucosa (98.6+/-1.03% vs 5.26+/-5%, P<0.01). CONCLUSION: ODC gene overexpression is significantly related to human colorectal carcinoma. ODC gene expression may be a marker for the gene diagnosis and therapy of colorectal carcinoma.

Animals↗

PubMed2005

The Genomes of Oryza sativa: a history of duplications.

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000-40,000. Only 2%-3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family.

Base Sequence↗

PubMed2005

[Phenotype and function of myeloid dendritic cells pulsed with hepatitis B virus antigens in patients with HBV-associated hepatocellular carcinoma].

OBJECTIVE: To investigate the characteristics of phenotype and function of myeloid dendritic cells (mDCs) pulsed with HBV antigens derived from HBV-associated hepatocellular carcinoma (HCC) patients. METHODS: Peripheral blood mononuclear cells (PBMCs) were collected, using blood cell separator, from 21 primary HCC patients and 4 healthy donors. mDCs were propagated in serum-free AIM-V medium in the presence of cytokine cocktail, and pulsed with HBcAg or HBsAg. After 9 days' incubation, the phenotypic patterns of mDC were characterized by flow cytometry and the levels of IL-10 and IL-12 produced by mDCs were analyzed by ELISA. Autologous T cells proliferation stimulated by mDC was tested by non-radioactive cell proliferation assay kit. RESULTS: The expression rates of CD80, CD86, CD40, and HLA-DR in the mDCs pulsed with HBcAg were 55% +/- 26%, 80% +/- 13%, 70% +/- 13% and 73% +/- 24% respectively, significantly higher than those of the control group (29% +/- 25%, 35% +/- 18%, 44% +/- 26% and 45% +/- 23% respectively, all P < 0.05). Among the expression rates of surface molecules of the mDCs pulsed with HBsAg only the expression rate of HLA-DR was significantly higher than that of the un-pulsed mDCs (63% +/- 15% vs 45% +/- 23%, P < 0.05). T cell proliferation assay revealed an impaired allostimulatory capacity of mDCs in HCC and the stimulatory capacity of the mDCs pulsed with HBcAg to induce proliferation of autologous T cells was more powerful than that pulsed with HBsAg (P < 0.05). The levels of IL-10 and IL-12 produced by the mDCs pulsed with HBsAg were (35 pg/ml +/- 9 pg/ml and 135 pg/ml +/- 63 pg/ml respectively, both significantly lower than those pulsed with HBcAg (236 pg/ml +/- 95 pg/ml and 733 pg/ml +/- 212 pg/ml respectively, both P < 0.05). CONCLUSION: Pulsation of mDCs in vitro by HBcAg or HBsAg enhance the expression of CD80, CD86, CD40, and HLA-DR, and increase the ability of mDCs to stimulate the proliferation of autologous T lymphocytes.

Adult↗

PubMed2005

3D QSAR studies on GSK-3 inhibition by aloisines.

GSK-3 is involved in various physiological processes and its inhibitors have been evaluated as promising drug candidates for a lot of unmet pathologies. In this paper, inhibition of GSK-3 by aloisines is investigated by 3D QSAR studies. Two alignment rules were applied to check the influence of spatial alignment of the compounds. Both the CoMFA and CoMSIA techniques were carried out and ASS procedure was applied for CoMFA to find a satisfactory model. The best QSAR model obtained is a CoMSIA model characterized with r(2) of 0.938 and q(2) of 0.673 including steric, electrostatic and hydrophobic fields, possessing good predicting ability. To get a better understanding of the relationship between chemical structure and biological activity, a complex structure of aloisine with GSK-3 was obtained by superimposing GSK-3 into the known cocrystal structure of aloisine-CDK2, and then factors that affect the inhibition activity were investigated further, combining the QSAR study with the complex structure, the results of which are in good accordance and complementary to each other.

Binding Sites↗

PubMed2005

[The clinical application and research on vas deferens laser coagulation sterilization].

OBJECTIVE: To study the effect of Ar(+) laser on human vas deferens and to compare the effects of using different radiation levels with varying thickness of tissue and varying levels of injury. METHODS: After initial tests on animals, four human scrotums were opened and treated directly with Ar(+) laser radiation. Then 58 human individual scrotums were treated with radiation by the method of trans-skin puncture. The rate of sperm reduction and elimination was tested. RESULTS: In 60 cases, the sperms were found to be eliminated completely after six months of radiation treatment. In 2 cases the sperms were found not to be eliminated completely due to the insufficient radiation. CONCLUSION: Ar(+) laser is one of the best forms of radiation for coagulation of vas deferens. It can be used to coagulate vas deferens without any complications or sequelae.

Adult↗

PubMed2005

Ab initio study of the complexes of halogen-containing molecules RX (X=Cl, Br, and I) and NH3: towards understanding the nature of halogen bonding and the electron-accepting propensities of covalently bonded halogen atoms.

Ab initio calculations have been performed on a series of complexes formed between halogen-containing molecules and ammonia to gain a deeper insight into the nature of halogen bonding. It appears that the dihalogen molecules form the strongest halogen-bonded complexes with ammonia, followed by HOX; the charge-transfer-type contribution has been demonstrated to dominate the halogen bonding in these complexes. For the complexes involving carbon-bound halogen molecules, our calculations clearly indicate that electrostatic interactions are mainly responsible for their binding energies. Whereas the halogen-bond strength is significantly enhanced by progressive fluorine substitution, the substitution of a hydrogen atom by a methyl group in the CH(3)X...NH(3) complex weakened the halogen bonding. Moreover, remote substituent effects have also been noted in the complexes of halobenzenes with different para substituents. The influence of the hybridization state of the carbon atom bonded to the halogen atom has also been examined and the results reveal that halogen-bond strengths decrease in the order HC triple bond CX > H(2)C=CHX approximately O=CHX approximately C(6)H(5)X > CH(3)X. In addition, several excellent linear correlations have been established between the interaction energies and both the amount of charge transfer and the electrostatic potentials corresponding to an electron density of 0.002 au along the R-X axis; these correlations provide good models with which to evaluate the electron-accepting abilities of the covalently bonded halogen atoms. Finally, some positively charged halogen-bonded systems have been investigated and the effect of the charge has been discussed.

Algorithms↗

PubMed2005

Protective effect of genistein on lipopolysaccharide-induced acute lung injury in rats.

To investigate the protective effect of genistein on endotoxin-induced acute lung injury in rats, and explore the underlying mechanisms, 32 male Sprague-Dawley rats were randomly divided into 4 experimental groups: saline control, genistein alone, lipopolysaccaride alone, and genistein pretreatment. Each treatment group consisted of eight animals. Animals were observed for 6 h after LPS challenge, and the wet/dry (W/D) weight ratio of the lung and bronchoalveolar lavage fluid (BALF) protein content were used as a measure of lung injury. Neutrophil recruitment and activation were evaluated by BALF cellularity and myeloperoxidase (MPO) activity. RT-PCR analysis was performed in lung tissue to assess gene expression of ICAM-1. The histopathological changes were also observed using the HE staining of lung tissue. Our results showed that lung injury parameters, including the wet/dry weight ratio and protein content in BALF, were significantly higher in the LPS alone group than in the saline control group (P < 0.01). In the LPS alone group, a larger number of neutrophils and greater MPO activity in cell-free BAL and lung homogenates were observed when compared with the saline control group (P < 0.01). There was a significant increase in lung ICAM-1 mRNA in response to LPS challenge (P < 0.01, group 1 versus group S). Genistein pretreatment significantly attenuated LPS-induced changes in these indices. LPS caused extensive lung damage, which was also lessened after genistein pretreatment. All above-mentioned parameters in the genistein alone group were not significantly different from those of the saline control group. It is concluded that genistein pretreatment attenuated LPS-induced lung injury in rats. This beneficial effect of genistein may involves, in part, an inhibition of neutrophilic recruitment and activity, possibly through an inhibition of lung ICAM-1 expression.

Animals↗

PubMed2005

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol.

Chlorophenols (ClPhs) are considered as important precursors for PCDD/Fs formation. The influences of series of metal oxides including MgO, Al2O3, CaO, BaO, TiO2, V2O5, MnO2, Fe2O3, Co3O4, CuO, Ag2O, ZnO, HgO, SnO, PbO, La2O3, CeO2, and Eu2O3 on PCDD/Fs formation from pentachlorophenol (PCP) were investigated in a laboratory-scale reactor. The results indicated that most of the above metal oxides have obvious suppressing effects on the total amount of PCDD/Fs formation from precursor PCP except for CuO, ZnO, MnO2, TiO2 and Co3O4 with promotion effects at 280 degrees C for 2 h. Although MgO, Al2O3, Fe2O3, PbO, La2O3 and Eu2O3 could reduce the amount of octachlorinated dibenzo-p-dioxin (OCDD), they promote the formation of more toxic 1,2,3,4,6,7,8-HpCDD at the same time. The total suppressing efficiencies of several metal oxides including CaO, BaO, PbO, Ag2O, HgO and SnO which have lower Z/r (charge to radius ratio) <2 are all over 90%. The theories of generalized acid-base and atomic parameter (Z/r) were used to speculate the effecting mechanisms. The factors including time and temperature on suppressing efficiencies of CaO, BaO and PbO have also been studied in the present paper. The results showed that the total suppressing efficiencies of CaO, BaO and PbO increase with the increase of heated time and temperature.

Air Pollution↗

PubMed2005

Inhibition of PCDD/Fs formation from dioxin precursors by calcium oxide.

Research aimed at understanding the inhibition effect of CaO on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation form dioxins precursors, such as chlorophenols (CPs) and chlorobenzenes (CBs). The results indicated that a clear dioxin inhibition effect occurred both in open and sealed system when CaO was used. In the open system, PCDDs were the main congeners and the inhibition efficiency was all over 99% in the experiments. In the experiments with CaO, less than 0.1% of the initial PCP was detected in the absorption tube and only about 1% of the initial PCP was examined as calcium pentachlorophenate in the reaction tube. In the sealed system, the inhibition efficiency was over 90% at temperature range between 280 and 450 degrees C when PCP was used as model precursor. When HCB and 2,3,4,5-T4CP replaced PCP, significant inhibition effect was also observed. As CaO has the advantageous properties of non-toxicity and non-volatile nature, it is our hope that the result will contribute to the development of a new technique to cope with the problem of dioxin pollution in MWIs.

Air Pollution↗

PubMed2005

Synergic effect of calcium oxide and iron (III) oxide on the dechlorination of hexachlorobenzene.

Dechlorination of hexachlorobenzene (HCB) was achieved by a mixture of commercial CaO and alpha-Fe2O3 (CaO/alpha-Fe2O3) in closed systems at temperatures of 300 degrees C and 350 degrees C, which exhibited a synergic effect compared to CaO or alpha-Fe2O3 alone, and the dechlorination efficiency was dramatically enhanced. When CaO and alpha-Fe2O3 coexisted, HCB was dechlorinated by about 98% after 0.5 h reaction at 300 degrees C. All TeCB-, TrCB-, and DCB-isomers were detected, showing the presence of more than one dechlorination pathway. The pathway to form 1,2,4-TrCB must be a major pathway because the greatest amount of 1,2,4-TrCB was detected. There existed discrepancy of the material balance between the starting and dechlorinated materials. It implies that besides dechlorination other decomposition processes may be present. The mechanism of synergic effect of calcium and iron oxides was investigated.

Calcium Compounds↗

PubMed2005

[Synthesis of 2,3,4-trihydroxyacetophenone hydrazones and study on their spectral properties].

2,3,4-Trihydroxyacetophenone was synthesized with pyrogallol. Benzoylhydrazone and p-hydroxybenzoylhydrazone were synthesized using the reaction of ethyl benzoate and methyl p-hydroxybenzoate with hydrazine hydrate. Three novel 2,3,4-trihydroxyacetophenone hydrazones were synthesized using the reaction of 2,3,4-trihydroxyacetophenone with benzoylhydrazone, p-hydroxybenzoylhydrazone and phenylhydrazine. IR, UV and the fluorescence spectrum of 2,3,4-trihydroxyacetophenone hydrazones were studied.

Acetophenones↗

PubMed2005

[On mechanism of how lipopolysaccharide induces dendritic cells to mature through TLRs signal pathway].

OBJECTIVE: To find out how lipopolysaccharide (LPS) induces dendritic cells (DC) to be more mature through Toll-like receptors (TLRs) signal pathway. METHODS: Monocytes were isolated from heparinized whole blood. 7 days later the monocytes were induced into dendritic cells by adding rhGM-CSF and rhIL-4. Total cellular RNA of unstimulated and stimulated DC were extracted by LPS 24 h later. Semi-quantitative RT-PCR and agarose gel electrophoresis were conducted to analyze the PCR products. The expression of NF-kappaB was detected by laser scanning confocal microscopy (LSCM). RESULTS: Expressions of TLR2, 3, 4 were significantly higher in monocytes-derived DC induced for 7 days, the plasm of DC was stained positive and the nucleus of DC was stained negative. After being stimulated by LPS for 24 h, the expressions of TLR2, 3, 4 decreased, and that of TLR4 was almost undetectable; the nucleus of DC was stained strong positive, the plasm of DC was stained positive. CONCLUSION: The expressions of TLR2, 3, 4 on DC change significantly after being stimulated by LPS. And NF-kappaB shifts from the plasm to the nucleus. This signifies that LPS induces DC to be more mature in function.

Adolescent↗