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Biomedical subjects

Ying Zhang

Publications and source records attributed to Ying Zhang.

At least 235 records · Page 13Linked to original sources
PubMed2005

Co-solvent effects on drag reduction, rheological properties and micelle microstructures of cationic surfactants.

Some quaternary cationic surfactants, when mixed with a counterion, are known to self-assemble into threadlike micelles in water. Such behavior causes drastic changes in rheological properties of even very dilute solutions, allowing them to be used as drag reducing agents (DRA) in turbulent pipe flow circulating systems, such as district cooling/heating systems. Surfactant self-assembly is a physicochemical phenomenon whose character depends on surfactant nature and concentration, nature of the solvent, temperature and type and concentration of counterions. This study investigates drag reduction (DR) and rheological properties of two cationic surfactants, Ethoquad O/12 (oleyl bis(hydroxyethyl)methylammonium chloride) and Ethoquad O/13 (oleyl tris(hydroxyethyl) ammonium acetate), with excess salicylate counterion (NaSal), in mixed solvents containing 0 to 28 wt% ethylene glycol (EG) and water. The addition of EG to the solvent had greater effects on solutions' DR ability, shear viscosity, apparent extensional viscosity and viscoelasticity at 25 degrees C than at approximately 0 degrees C. Cryo-TEM images show threadlike micelle in these systems. DR at low temperatures in solutions containing moderate amount of EG can be utilized in a new approach to energy saving in district cooling systems using EG-water based mixtures as the cooling fluids.

Journal Article↗
PubMed2005

Relaxation to equilibrium in few-particle adiabatic piston systems.

A Hamiltonian system with few particles and a heavy adiabatic piston is studied. With ensemble averages based on proper classification of slow and fast variables, a nonequilibrium state is defined and the relaxation from nonequilibrium to equilibrium is investigated. Coherent oscillation, dissipative oscillation damping, and anti-intuition energy transfer of the adiabatic piston are observed by numerical simulations. Noise-driven thermodynamic equations of slow variables are derived, based on the assumption of local equilibrium and the fluctuation-dissipation theorem, to understand and quantitatively reproduce all the above few-body nonequilibrium relaxation features.

Journal Article↗
PubMed2005

Biodesulfurization of dibenzothiophene and other organic sulfur compounds by a newly isolated Microbacterium strain ZD-M2.

A new bacterial strain capable of selectively desulfurizing dibenzothiphene (DBT) was isolated from sludge. This organism, designated ZD-M2, clustered most closely with members of the genus Microbacterium, as determined by 16S rRNA gene sequence analysis. Metabolites produced by DBT desulfurization were identified by GC-MS, and two sulfur-free products, 2-methoxybiphenyl (2-MBP) and biphenyl, were detected in addition to 2-hydroxybiphenyl (2-HBP). This strain can also totally degrade 4,6-dimethyl-DBT, thiophene, benzothiophene and 70% diphenylsulfide.

Actinomycetales↗
PubMed2005

Surface morphology and kinetic properties in rapid growth of EAFP protein crystals investigated by atomic force microscopy.

The whole process of EAFP protein monoclinic crystal growth with an extremely fast rate has been observed by atomic force microscopy. The results showed that the patterns of the growth images in rapidly growing crystals are complicated. The two-dimensional multi-layered stacks of growth steps are characteristic of higher supersaturation and the growth of steps proceeds in a manner of strong anisotropic spiral dislocations dominantly under lower supersaturation conditions. The complex dislocation sources, including multiple dislocation and multi-interacting single dislocation sources, the constant step-split and the propagation of trooped steps were observed on the {100} surfaces of growing EAFP crystals. The step height of each layer generated either by two-dimensional nucleation at higher supersaturation or by screw dislocation at lower supersaturation is about 2-3 nm, which corresponds to the length of the crystallographic unit cell. Although the rate of advancement for each growth step is similar to that of other protein crystal growth, the unique way of the propagation distinct with the trooped steps, by which a bundle of steps are strapped together, would be responsible for the rapid growth of EAFP crystals. All features show a possible mechanism by which the fast growth of EAFP crystals could be attained. The structural basis of the growth mechanism is also discussed.

Eucommiaceae↗
PubMed2005

[Comparison of therapeutic effects of low-dose versus high-dose interferon alpha-2b treatment on chronic myelocytic leukemia: a prospective randomized study].

OBJECTIVE: To compare the therapeutic effects of low-dose and high-dose interferon alpha-2b (IFN) treatment on chronic myelocytic leukemia (CML). METHODS: A real-time quantitative reverse transcriptase PCR (RQ-PCR) method was established to detect the fusion gene bcr-abl expression, thereby studying the reduction of leukemic cells. Thirty newly diagnosed CML patients, 21 males and 9 females, aged 14 - 69, were treated with hydroxyurea to keep the white blood cell count less than 20 x 10(9)/L, and then randomized into 2 groups: high-dose IFN group receiving IFN alpha-2b 5MIU 6 times per week for 3 - 6 months and low-dose IFN group receiving IFN alpha-2b 3MIU every other day for 3 - 6 months. Bone marrow was collected every month to Real-time PCR was used to detect the expression of bcr-abl mRNA. Mononuclear cells were isolated and RNA was extracted to detect the expression of fusion gene bcr-abl and a control gene GAPDH. The results were reported as the number of bcr-abl copies/GAPDH copy. RESULTS: The established real-time quantitative PCR method could detect the bcr-abl molecules as low as 50 copies. The intra-assay coefficient of variation (CV) was less than 5% and the inter-assay CV was 5.13%. The median bcr-abl fusion gene expression level of 30 CML patients before IFN therapy was 0.098 (range: 0.010 - 5.799). The bcr-abl expression level decreased by 19.37% and 24.86% in the low-dose and high-dose IFN groups respectively after 3 months' therapy. No significant difference was observed between the two groups (P = 0.398). Relatively more side effects were observed in the high-dose IFN group than in low-dose group. CONCLUSION: RQ-PCR is a reliable method to monitor CML therapy by analyzing fusion gene bcr-abl expression. There is a difference in bcr-abl fusion gene expression levels among the newly diagnosed patients, and low-dose IFN is as effective as high-dose IFN in reducing bcr-abl expression but with less side effects.

Adolescent↗
PubMed2005

Occurrence and analytical methods of acrylamide in heat-treated foods. Review and recent developments.

In early 2002, Swedish National Food Administration (SNFA) and University of Stockholm together announced that certain foods that are processed or cooked at high temperature contain relatively high levels of acrylamide. The occurrence of acrylamide is derived from heat-induced reactions between the amino group of asparagine and the carbonyl group of reducing sugars during baking and frying. Corresponding chromatographic methods are used to determine various structural groups present during this process. Gas chromatography (GC)-mass spectrometry (MS) and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis are both acknowledged as the major useful and authoritative methods for the acrylamide determination and other chromatographic methods are also briefly introduced. The aim of this review is to summarize the state-of-the-art about the occurrence, analytical methods, and extraction and clean-up procedures of acrylamide. Special attention is given to chromatographic techniques applied for the occurrence and determination of acrylamide.

Acrylamide↗
PubMed2005

Reversible blockade of experience-dependent plasticity by calcineurin in mouse visual cortex.

Numerous protein kinases have been implicated in visual cortex plasticity, but the role of serine/threonine protein phosphatases has not yet been established. Calcineurin, the only known Ca2+/calmodulin-activated protein phosphatase in the brain, has been identified as a molecular constraint on synaptic plasticity in the hippocampus and on memory. Using transgenic mice overexpressing calcineurin inducibly in forebrain neurons, we now provide evidence that calcineurin is also involved in ocular dominance plasticity. A transient increase in calcineurin activity is found to prevent the shift of responsiveness in the visual cortex following monocular deprivation, and this effect is reversible. These results imply that the balance between protein kinases and phosphatases is critical for visual cortex plasticity.

Aging↗
PubMed2005

[Binding capacity of aberrantly glycosylated serum IgA1 with human umbilical vein endothelial cells].

OBJECTIVE: To investigate the binding capacities of differently glycosylated IgA1 on human umbilical vein endothelial cells (HUVEC). METHODS: Serum IgA1 was purified by jacalin affinity chromatography and then was desialylated and/or degalactosylated with neuraminidase and/or beta-galactosidase respectively. The efficacy of deglycosylations were assessed by peanut agglutinin (PNA) and vicia villosa lectin (VVL). Binding capacties of differently glycosylated IgA1 to HUVEC were evaluated by flow cytometry. RESULTS: IgA1 could bind to HUVEC and the binding capacities of IgA1, DesIgA1 and Des/DeGalIgA1 were expressed by median fluorescence intensity (MFI) and they were 2.67+/-0.35, 4.62+/-1.09, 4.08+/-0.41 (IgA1 vs DesIgA1, P=0.015, IgA1 vs DesIgA1/DeGalIgA1, P=0.049, DesIgA1 vs DesIgA1/DeGalIgA1 , P>0.05), respectively. CONCLUSION: IgA1 could bind to HUVEC directly, and the binding capacities of DesIgA1 and Des/DeGalIgA1 to HUVEC were significantly higher than that of normal IgA1. Serum IgA1, especially deglycosylated IgA1, might play some role in vascular lesions of IgAN.

Binding Sites↗
PubMed2005

Regulation of metastasis-suppressive gene Nm23-H1 on glycosyl-transferases involved in the synthesis of sialyl Lewis antigens.

By using reverse transcriptase-polymerase chain reaction (RT-PCR), the mRNA expressions of three families of glycosyltransferases involved in the synthesis of sialyl Lewis antigens were determined in H7721 human hepatocarcinoma cell line before and after the transfection of metastasis-suppressive gene nm23-H1. These glycosyltransferases included alpha1,3fucosyltransferase (alpha1,3FucT)-III, -IV, -VI, -VII, and -IX, alpha2,3-sialyltransferase (ST3Gal)-I, -II, -III, and -IV as well as O-glycan core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT)-I and -II. In mock cells transfected with the vector, the expression-order of alpha1,3FucTs was IV>VI>III>VII>IX, that of ST3Gals was IV>I>II>III, and that of C2GnT was I>II. Nm23-H1 downregulated the mRNA expressions of all five subtypes of alpha1,3FucT and -I, -III, -IV subtypes of ST3Gal, but not ST3Gal-II and C2GnT-I, II. On the other hand, the expressions of cell surface sialyl Lewis X (SLe(x)) and alpha2,3 sialyl residues were decreased on nm23-H1 transfected cells as detected with monoclonal antibody of SLe(x) and enzyme-labeled lectins, respectively. Since SLe(x) was reported to be a metastasis-associated glycan structure, the reduced expressions of SLe(x) and some enzymes related to its synthesis may be one of the mechanisms to explain the metastasis-suppressive effect of nm23-H1.

Antigens↗
PubMed2005

Expression, purification and crystallization of a human protein SH3BGRL at atomic resolution.

The protein SH3BGRL, containing both SH3-binding and Homer EVH1-binding motifs, has been crystallized using the hanging-drop vapour-diffusion method. The crystals diffract to 0.88 A resolution and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 28.8886, b = 34.9676, c = 98.0016 A. Preliminary analysis indicates that the asymmetric unit contains one molecule and has a solvent content of about 34%.

Cloning, Molecular↗
PubMed2005

Overexpression of dimethylarginine dimethylaminohydrolase reduces tissue asymmetric dimethylarginine levels and enhances angiogenesis.

BACKGROUND: This study was designed to determine whether overexpression of the enzyme dimethylarginine dimethylaminohydrolase (DDAH) could enhance angiogenesis by reducing levels of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA). METHODS AND RESULTS: In DDAH1 transgenic (TG) and wild-type mice (each n=42), the role of DDAH overexpression on angiogenesis was studied by use of the disk angiogenesis system and a murine model of hindlimb ischemia (each n=21). After surgery, animals were treated with either PBS or the NOS inhibitors ADMA or N(omega)-nitro-L-arginine methyl ester (L-NAME; each 250 micromol x kg(-1) x d(-1)) by use of osmotic minipumps (each n=7). L-NAME was chosen to study an inhibitor that is not degraded by DDAH. Neovascularization in the disk angiogenesis system was impaired by both NOS inhibitors; however, TG animals were resistant to the effects of ADMA on neovascularization. Similarly, TG mice were more resistant to the inhibitory effect of ADMA on angioadaptation (angiogenesis and arteriogenesis) after hindlimb ischemia, as assessed by fluorescent microsphere studies and postmortem microangiograms. Enhanced neovascularization and limb perfusion in TG mice were associated with reduced plasma and tissue ADMA levels and enhanced tissue NOS enzyme activity. CONCLUSIONS: We describe a novel mechanism by which DDAH regulates postnatal neovascularization. Therapeutic manipulation of DDAH expression or activity may represent a novel approach to restore tissue perfusion.

Amidohydrolases↗
PubMed2005

Inhibiting the expression of CD28 costimulatory molecule on human lymphocytes by special siRNA.

BACKGROUND: The B7/CD28 pathway provides critical costimulatory signals for complete T cell activation, and members of this pathway have served as useful targets for immunotherapeutic strategies. In this study, we investigated the RNA interference (RNAi) effect induced by small interfering RNA (siRNA) targeting CD28 mRNA on human lymphocytes and its specificity. METHODS: According to CD28 gene sequence, we designed and synthysized three different siRNAs (siRNA-1, siRNA-2, siRNA-3) containing 21 bases using Silencertrade mark siRNA construction kit. These siRNAs were transfected into freshly isolated human lymphocytes with Lipofectamine 2000 reagent. At 24-hour, 48-hour and 72-hour post transfection, these cells were collected and analyzed. The changes of surface expression of CD28 gene were detected by flow cytometry, and the changes of CD28 mRNA levels were determined by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The cell viability of transfected lymphocytes was determined by methyl thiazolyl tetrazolium (MTT) assay and trypan blue dye exclusion assay. RESULTS: Three siRNAs (siRNA-1, siRNA-2, siRNA-3) specifically targeting CD28 mRNA were successfully designed and constructed. Flow cytometry analysis showed that a decrease in CD28 expression was detectable at 24-hour post transfection. Different siRNA showed different inhibition effects on CD28 expression. At 48-hour post transfection, the degrees of reduction with siRNA-1, siRNA-2 and siRNA-3 were 22.10% +/- 1.63%, 73.50% +/- 1.02% and 42.90% +/- 0.89% respectively compared with the control (P < 0.001). Neither of the groups transfected only with siRNA or lipo showed marked reduction in CD28 expression (3.15% +/- 0.75% and 4.55% +/- 0.80%) (P > 0.05). Moreover, lymphocytes treated with siRNA-co showed no marked reduction in CD28 expression (5.07% +/- 0.96%) (P > 0.05). The results of semi-quantitative RT-PCR assay indicated CD28 mRNA level was inhibited after transfection of specific siRNAs. At least 4-fold of reduction in siRNA-2 group occurred at 48-hour post transfection compared with the control (P < 0.001). MTT assay and trypan blue dye exclusion assay demonstrated that the viable cell rations of transfected lymphocytes were significantly reduced in siRNA-1, siRNA-2 and siRNA-3 groups at 48-hour post transfection (P < 0.01). The control groups showed no marked reduction in cell viability (P > 0.05). CONCLUSIONS: Three different siRNAs were synthesized and transfected into lymphocytes. They could reduce the expression of CD28 and the CD28 mRNA level. siRNA-2 was the most efficient. The cell viability reduced correspondingly. Therefore, the silencing effect on CD28 mRNA induced by siRNA may contribute to costimulatory blockade. This result show that siRNA may be useful for further study on graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (allo-BMT).

Adolescent↗
PubMed2005

[Association between familial febrile convulsions and HCN2 gene].

OBJECTIVE: To investigate the possible association of familial febrile convulsions with HCN2 gene. METHODS: PCR was conducted on the DNA of peripheral blood white cells from 60 children with familial febrile convulsion (FC) of Han nationality population in northern China aged 1.5 +/- 1.0 (8 months to 5 years old), to amplify the exons of HCN2 gene. The PCR products underwent sequencing to identify the possible mutations. 101 normal children from the same area were used as controls. RESULTS: No mutation was found in the exons of HCN2 gene, however, 14 single nucleotide polymorphisms (SNPs) were found among which there were 8 newly identified SNPs. Using 9 SNPs as markers, association study was conducted between the FC group and control group. There were no significant differences in allele frequencies and genotype frequencies of the 9 SNPs between the FC group and control group. CONCLUSION: HCN2 may not be a susceptibility gene for FC in Chinese population.

Alleles↗
PubMed2005

Mycobacterial catalase-peroxidase is a tissue antigen and target of the adaptive immune response in systemic sarcoidosis.

Sarcoidosis is a disease of unknown etiology characterized by noncaseating epithelioid granulomas, oligoclonal CD4(+) T cell infiltrates, and immune complex formation. To identify pathogenic antigens relevant to immune-mediated granulomatous inflammation in sarcoidosis, we used a limited proteomics approach to detect tissue antigens that were poorly soluble in neutral detergent and resistant to protease digestion, consistent with the known biochemical properties of granuloma-inducing sarcoidosis tissue extracts. Tissue antigens with these characteristics were detected with immunoglobulin (Ig)G or F(ab')(2) fragments from the sera of sarcoidosis patients in 9 of 12 (75%) sarcoidosis tissues (150-160, 80, or 60-64 kD) but only 3 of 22 (14%) control tissues (all 62-64 kD; P = 0.0006). Matrix-assisted laser desorption/ionization time of flight mass spectrometry identified Mycobacterium tuberculosis catalase-peroxidase (mKatG) as one of these tissue antigens. Protein immunoblotting using anti-mKatG monoclonal antibodies independently confirmed the presence of mKatG in 5 of 9 (55%) sarcoidosis tissues but in none of 14 control tissues (P = 0.0037). IgG antibodies to recombinant mKatG were detected in the sera of 12 of 25 (48%) sarcoidosis patients compared with 0 of 11 (0%) purified protein derivative (PPD)(-) (P = 0.0059) and 4 of 10 (40%) PPD(+) (P = 0.7233) control subjects, suggesting that remnant mycobacterial catalase-peroxidase is one target of the adaptive immune response driving granulomatous inflammation in sarcoidosis.

Antigens, Bacterial↗
PubMed2005

[Serum levels of several chemokines in patients with rheumatoid arthritis].

OBJECTIVE: To explore the role of several chemokines in rheumatoid arthritis (RA) and their clinical significance. METHOD: ELISA was used to detect the serum levels of interleukin (IL)-8, interferon-gamma inducible protein (IP)-10, and RANTES in 58 active RA patients, 29 clinically remissive RA patients, 21 osteoarthritis (OA) patients, and 30 healthy volunteers. Clinical data of these patients were compared between different groups. RESULTS: The serum levels of IL-8, IP-10 and RANTES in the active RA patients were significantly higher than those of the healthy controls and OA patients. The serum level of IP-10 of the active patients was higher than that of the clinically remissive patients. The index IL-8/IP-10 x RANTES/IP-10 of the active patients was higher than that of the healthy controls (P = 0.01). The serum RANTES level was positively correlated with erythrocyte sedimentation rate, C-reactive protein, platelet count, and numbers of swollen joints, and was negatively correlated with the hemoglobin level. The serum level of IP-10 was negatively correlated with X-ray image grade of hand and wrist joints. CONCLUSION: The serum levels of IL-8, IP-10 and RANTES significantly increase in active RA. The level of RANTES may be a useful additional marker for disease activity and the level of IP-10 can be used as an index of prognosis.

Adult↗
PubMed2005

Preparation and characterization of ruthenium/carbon aerogel nanocomposites via a supercritical fluid route.

Carbon-aerogel-supported ruthenium nanoparticles were synthesized by impregnating carbon aerogels with Ru(acac)3 or Ru(cod)(tmhd)2 from supercritical carbon dioxide (scCO2) solutions, followed by thermal reduction of these precursors. Two different carbon aerogels with pore diameters of 4 and 21 nm were synthesized. The kinetics and the thermodynamics of impregnation of carbon aerogels with the ruthenium coordination complexes were studied. The approach-to-equilibrium data indicated very fast adsorption, and the adsorption isotherms were found to follow the Langmuir model. The impregnated carbon aerogel complexes were reduced thermally at different temperatures between 300 and 1000 degrees C in the presence of nitrogen. The resulting nanocomposites were characterized using transmission electron microscopy (TEM) and hydrogen chemisorption. TEM micrographs showed that the ruthenium nanoparticles were dispersed homogeneously throughout the porous carbon aerogel matrix, and the average sizes obtained under different conditions ranged from 1.7 to 3.8 nm. Once complete decomposition of the precursor had been achieved, the mean size of the ruthenium particles increased with increasing reduction temperature.

Adsorption↗