Browsing by Author "Wang, H"

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    Analysis of monoPEGylated human galectin-2 by small-angle x-ray and neutron scattering: concentration dependence of PEG conformation in the conjugate
    (American Chemical Society, 2010-12-01) He, LH; Wang, H; Garamus, VM; Hanley, TL; Lensch, M; Gabius, HJ; Fee, CJ; Middelberg, APJ
    Protein conjugation with polyethylene glycol (PEG) is a valuable means for improving stability, solubility, and bioavailability of pharmaceutical proteins. Using human galectin-2 (hGal-2) and 5 kDa PEG as a model system we first produced a PEG-hGal-2 conjugate exclusively at the Cys75 residue, resulting in two monosubstituted subunits per hGal-2 homodimer. Small angle X-ray and neutron scattering (SAXS and SANS) were combined to provide complementary structural information about the PEG-hGal-2 conjugate, wherein signal generation in SAXS depends mainly on the protein while SANS data presents signals from both the protein and PEG moieties. SAXS data gave a constant radius of gyration (Rg = 21.5 Å) for the conjugate at different concentrations and provided no evidence for an alteration of homodimeric structure or hGal-2 ellipsoidal shape upon PEGylation. In contrast, SANS data revealed a concentration dependence of Rg for the conjugate, with the value decreasing from 31.5 Å at 2 mg/mL to 26 Å at 14 mg/mL (based on hGal-2 concentration). Scattering data have been successfully described by the model of the ellipsoidal homogeneous core (hGal-2) attached with polymer chains (PEG) at the surface. Evidently, the PEG conformation of the conjugate strongly depends on conjugate concentration and PEG’s radius of gyration decreases from 24.5 to 15 Å. An excluded volume effect, arising from steric clashes between PEG molecules at high concentration, was quantified by estimating the second virial coefficient, A2, of PEGylated hGal-2 from the SANS data. A positive value of A2 (6.0 ± 0.4 × 10−4 cm3 mol g−2) indicates repulsive interactions between molecules, which are expected to protect the PEGylated protein against aggregation. © 2010 American Chemical Society
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    Cannabinoid administration increases 5HT1A receptor binding and mRNA expression in the hippocampus of adult but not adolescent rats
    (Elsevier B.V., 2010-08-11) Zavitsanou, K; Wang, H; Dalton, VS; Nguyen, VH
    The endocannabinoid and serotonin systems share a high level of overlap in terms of the physiological processes that they regulate, however, little is known about their functional interactions particularly during adolescence, a vulnerable period for both the development of psychosis and for initiation to substance use. In the present study, the effects of cannabinoid treatment on serotonin 5HT1A receptor density and mRNA expression were investigated in two age groups: Adolescent (postnatal day 35) and adult (postnatal day 70) rats were injected with the synthetic cannabinoid HU210 (25, 50 or 100 μg/kg) or vehicle for 1, 4 or 14 days and sacrificed 24 h after the last injection. 5HT1A receptor density was measured in different brain regions using [3H]8-OH-DPAT quantitative autoradiography whereas mRNA expression was measured in adjacent brain sections. Higher levels of both serotonin 5HT1A receptor binding and mRNA expression were observed in limbic regions in adolescent control animals compared to adults. 5HT1A receptor density was increased by 23% in the CA1 region of the hippocampus of adult rats treated with 100 μg/kg HU210 for 4 days compared to vehicle treated controls. The same treatment increased mRNA expression by 27% and by 14% in the CA1 region and dentate gyrus of the hippocampus respectively. 5HT1A receptor density was increased by 22% in the CA1 of adult animals treated with 50 μg HU210, by 26% in the dentate gurus of adult rats treated with 100 μg for 14 days. By contrast, 5HT1A receptor density or mRNA expression was not affected in the brain of adolescent animals in any of the brain regions examined. These results suggest that cannabinoid treatment has differential effects on serotonin-related neurochemistry in adolescent compared to adult rats. The effects in the adult brain may compromise hippocampal function and could account for the cognitive deficits seen in habitual heavy cannabis users. © 2010 IBRO
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    Differential Treatment Regimen-Related Effects of HU210 on CB(1) and D(2)-Like Receptor Functionality in the Rat Basal Ganglia
    (Karger, 2012-02-01) Nguyen, VH; Wang, H; Verdurand, M; Zavitsanou, K
    Background/Aims: Functional linkages between the cannabinoid CB(1) and the dopaminergic systems have been reported although the observations and the mechanisms hypothesizing their interactions at the G protein-coupled receptor (GPCR) functionality level are conflicting. Methods: Administration of a potent cannabinoid agonist, HU210, at various doses (25-100 μg/kg) and treatment regimens (1- to 14-day treatment) in rats was carried out to investigate the effect of HU210 treatment on the CB(1) and D(2)-like agonist-mediated GPCR activation. Results: The desensitizations (reduced coupling) of both D(2) agonist- and CB(1) agonist-mediated GPCR activation was found to be treatment duration dependent and region specific, suggesting implication of receptor tolerance and adaptation due to the cannabinoid treatment. The effect of HU210 on the CB(1) agonist-mediated GPCR desensitization in all treatment groups was not dose dependent. Conclusions: The desensitization of D(2)-like receptors found after a cannabinoid treatment in this study strengthens the evidence that the two neurotransmitter systems interact at the intercellular level; this interaction might occur via multiple mechanisms, which also vary according to region. Copyright © 2012 S. Karger AG, Basel.
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    High yield expression and efficient purification of deuterated human protein galectin-2
    (Elsevier, 2012-07-01) Chen, XJ; Wilde, KL; Wang, H; Lake, V; Holden, PJ; Middelberg, APJ; He, LH; Duff, AP
    Structural studies of biological macromolecules often require deuterated proteins, necessitating an effective bioprocessing strategy for high yield deuteration and purification. The fermentation and bioseparation studies reported here concern deuterated human protein galectin-2 mutant C57M (hGal-2), a protein showing potential for therapeutic applications. Using the vector pET-28a and a defined D2O based minimal medium with glycerol as the sole carbon source and kanamycin for selection, we have demonstrated that a high density of Escherichia coli expressing deuterated protein at a bench bioreactor scale (7L) can be achieved, with due attention to prevention of oxygen limitation. Yields achieved were 58 g\L biomass (wet weight) containing 0.7 g/L hGal-2. Affinity chromatography and ion-exchange chromatography were combined to achieve high purity as well as removal of hGal-2 aggregates, giving an overall yield of 1200 mg deuterated hGal-2. The deuterated hGal-2 was characterized and compared with the non-deuterated protein by size exclusion chromatography (SEC), HPLC, N-terminal sequencing, mass spectrometry (MS) and a dot blot immunoassay, showing that deuteration and subsequent purification did not impact the lactose binding and antibody recognition abilities of hGal-2. MS for both intact and trypsin-digested hGal-2 demonstrated that the extent of labeling of non-exchangeable hydrogen atoms by deuterium was (66 +/- 1)%, which provides sufficient contrast variation for structural studies using small angle neutron scattering. The fermentation and bioseparation method established in this work can be applied to process other deuterated proteins with high yield and purity, opening the way to advanced structural studies. © Institution of Chemical Engineers 2014.
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    On the structure of α-BiFeO3
    (American Chemical Society, 2013-03-04) Wang, H; Yang, CX; Lu, J; Wu, MM; Su, J; Li, K; Zhang, JR; Li, GB; Jin, T; Kamiyama, T; Liao, FH; Lin, JH; Wu, YC
    Polycrystalline and monocrystalline α-BiFeO3 crystals have been synthesized by solid state reaction and flux growth method, respectively. X-ray, neutron, and electron diffraction techniques are used to study the crystallographic and magnetic structure of α-BiFeO3. The present data show that α-BiFeO3 crystallizes in space group P1 with a = 0.563?17(1) nm, b = 0.563?84(1) nm, c = 0.563?70(1) nm, α = 59.33(1)°, ? = 59.35(1)°, ? = 59.38(1)°, and the magnetic structure of α-BiFeO3 can be described by space group P1 with magnetic modulation vector in reciprocal space q = 0.0045a* ? 0.0045b*, which is the magnetic structure model proposed by I. Sosnowska(1) applied to the new P1 crystal symmetry of α-BiFeO3. © 2013 American Chemical Society
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    Residual stress study of Al/Al laminates processed by accumulative roll bonding
    (Materials Research Forum LLC, 2016-07-03) Su, L; Lu, C; Li, H; Luzin, V; Wang, H; Tieu, K
    In this work accumulative roll bonding (ARB) was used to combine AA1050 and AA6061 sheets to produce AA1050/AA1050, AA6061/AA6061 and AA1050/AA6061 laminates with ultrafine grained (UFG) structure. Two sheets of starting materials were roll bonded with 200 °C preheating for 180 s before rolling. The through-thickness residual stress distribution of these laminates processed up to two cycles of ARB was determined by neutron diffraction with spatial resolution of 0.2 mm through 1.5 mm thickness. The measurements also required high accuracy of only few MPa since residual stresses in the laminates peaked at only about 15 MPa. The laminates composed of the same material (AA1050/AA1050 and AA6061/AA6061) showed symmetric residual stress profile with tensile stress at the centre of the sheets and compressive stress at the surfaces. The AA1050/AA6061 laminates showed asymmetric distribution with residual tensile stress in the AA1050 layer and compressive stress in the AA6061 layer. A finite element model (FEM) was used to simulate the residual stress distribution and the results were in agreement with the measured results qualitatively. © 2016 The Authors
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    Silver─gallium nano-amalgamated particles as a novel, biocompatible solution for antibacterial coatings
    (Wiley, 2023-11-05) Nguyen, TT; Zhang, PF; Bi, JW; Nguyen, NH; Dang, Y; Xu, ZN; Wang, H; Ninan, N; Bright, R; Pham, T; Nguyen, CK; Sabri, YM; Nguyen, MT; Vingsvivut, JP; Zhao, YP; Vasilev, K; Truong, VK
    Bacterial infections account for countless deaths globally. Antibiotics are the primary countermeasure; however, the alarming spread of antibiotic-resistant strains necessitates alternative solutions. Silver and silver compounds have emerged as promising antibacterial agents. However, issues related to cytotoxicity and genotoxicity of silver remain concern. To overcome these challenges, this proposes an easy-to-control and straightforward method to synthesize novel Silver─gallium (Ag─Ga) nano-amalgamated particles. Gallium liquid metal (GaLM) is used to facilitate the galvanic deposition of silver nanocrystals (Ag) on oxide layer. The GaLM not only serves as a carrier for silver through the galvanic replacement process, but also provides a controlled-release mechanism for silver, in this way improving biocompatibility, reducing inflammation, and stimulating bone growth. Notably, Ag─Ga suspensions can be conveniently deposited by spray-coating on a range of devices and material surfaces, effectively eliminating pathogenic bacteria with efficacy comparable to that of silver ions. In vivo studies in rat models affirm the antibacterial capabilities, especially against methicillin-resistant Staphylococcus aureus and Escherichia coli, when placed on implants such as titanium rods and magnesium discs. Furthermore, Ag─Ga promotes bone matrix formation and collagen growth without eliciting an inflammatory response, indicating a major promise for coatings on a wide variety of biomedical devices and materials. © 2023 The Authors. Published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License.