Biomedical subjects

Ying Zhang

Publications and source records attributed to Ying Zhang.

At least 469 records · Page 26Linked to original sources

PubMed2003

[Oxygen-limited autotrophic nitrification and denitrification--a novel technology for biological nitrogen removal].

Oxygen-limited autotrophic nitrification and denitrification (OLAND) is a biological nitrogen removal process coupled with partial nitrification and anaerobic ammonium oxidation. In our study, the nitrification was blocked at nitrite stage by controlling the dissolved oxygen concentration at 0.1-0.3 mg.L-1, and then, the denitrification proceeded, with the residual ammonium at the partial nitrification stage as electron donor. As a completely autotrophic nitrification-denitrification process, the OLAND was of many advantages (e.g., low energy consumption, high nitrogen removal rate and small footprint of system), and suitable in particular for treating low COD/NH4(+)-N ratio wastewater. It has become one of the most prosperous and practicable biological nitrogen removal technologies. The recent research of OLAND was reviewed, and its microbial mechanism as well as its applicable prospect was remarked in this paper.

Ammonia↗

PubMed2003

[The expression of 5 immune molecules on rat peripheral leucocytes after heart transplantation].

AIM: To observe 5 kinds of immune molecule expressions on rat peripheral leucocytes at varying time points after ectopic heart transplantation and explore the mechanism of acute rejection reaction. METHODS: Donor's heart derived from SD rat was transplanted into the abdomen cavity of Wistar rat by anastomosis of donor's aorta and pulmonary artery to recipient's abdominal aorta and inferior-venacava for establishing coronary perfusion. Before and after transplantation, peripheral leucocytes were isolated from venous blood and labelled with the monoclonal antibodies(mAbs) against CD4, CD8, IL-2R, ICAM-I and MHC-II molecules, respectively. The these molecule levels were assessed by flowcytometry. Simultaneity, graft's pathological changes and their survival rate were observed. RESULTS: At 24 hours after transplantation, MHC-II molecule expression was increased, while expressions of CD4, IL-2R and ICAM-I were significantly decreased, but CD8 expression had no change. At 72 hours after operation, the expressions of CD4, CD8 and IL-2R increased and expressions of CD8 and IL-2R reached to peak. At 7-10 days after operation, except that CD4 expression increased continuously, the expressions of 4 other molecules decreased gradually. The survival rate of graft at varying times after operation were 100%( 24 h), 85.7%(3 days), 16.7%(7 days) and, 0 (10 and 12 days), respectively. Pathological examination showed that there was no notable pathological change in cardiac muscle tissue. At the third day after operation, 4 out of 7 transplanted hearts had only grade I A pathological change. Grade II and above grade II pathological changes were observed in all 6 grafts at the 7th day after operation. CONCLUSION: These data indicate that graft rejection reaction begin to appear in first 72 hours, and effector phase of the reaction appear mainly within 3-7 days after heart transplantation.

Animals↗

PubMed2003

[Study on extraction conditions for minute powder of processed rhizome of Corydalis with vinegar].

OBJECTIVE: To examine the factors in extracting the minute powder of processed rhizome of Corydalis with vinegar for its application. METHOD: The one-way variation analysis was used for experimental design. Tetrahydropalmatine was determined with HPLC method. The samples were separated on a Diamonsil C18 column with mobile phase of acetonitrile-TEA phosphate buffer (pH 7.0) (50:50) and detection wavelength was 280 mm. RESULT: The extraction conditions were established as follows: extraction temperature is 60 degrees C, water-added amount is 20 times the weight of the powder, and extraction time is 30 minutes. CONCLUSION: The extraction rate of the tetrahydropalmatine in the minute power is about 10% higher than that of the processed rhizome with vinegar. But less water amount, less time, and lower temperature were needed for extraction. The application of minute powder can reduce energy consumption and raise economic benefit in industrial production.

Acetic Acid↗

PubMed2003

[Study on the process of degrading filter paper cellulose by Sporocytophaga sp. JL-01].

Sporocytophaga is a kind of bacteria that can glide on the solid medium surface. It can decompose the cotton and filter paper after 6 days cultured. The sporocytophaga can only produce a low extracellular carboxymethylcellulase activity and no other cellulase activities. In this work, the process about degradation of filter paper fibre by a strain of Sporocytophaga was studied using scan electronmicroscopy. The morphological changes that Sporocytophaga sp. JI-01 grew on filter paper were observed. The study revealed the JL-01 adhered tightly to the surface of filter paper fibre or penetrated into interior of the fibre through its 2.5 microm - 4.0 microm bacilliform cells in the process of degrading. The bacilliform cells degrade the cellulose strongly and produced a mass of sticky polysaccharides. At the anaphase of cultured, the bacteria existed as a cycloidal dormancy body-sporocyst.

Bacterial Proteins↗

PubMed2002

Gene expression profile of human endothelial cells exposed to sustained fluid shear stress.

Biomechanical forces can modulate endothelial phenotype through changes in gene expression. We hypothesized that physiological laminar shear stresses (LSS) act as differentiative stimuli on endothelial cells (EC) to alter gene expression, creating an antioxidant, anti-apoptotic and anti-proliferative environment. The transcriptional profile of cultured human umbilical vein endothelial cells (HUVEC) exposed to LSS was evaluated by GeneCalling; 107 genes demonstrated at least a twofold change in expression at 24 h (LSS vs. static). These flow-responsive genes represent a limited number of functional clusters that include transcription factors, antioxidants, signaling molecules, cell cycle regulators, and genes involved in cellular differentiation. Immunohistochemistry and in situ hybridization confirmed that many of these flow-responsive genes, including the novel basic helix-loop-helix transcription factor Hath6, are expressed in EC in vivo. Thus these data identify a limited set of flow-responsive genes expressed in the endothelium that may be responsible for the establishment and maintenance of the flow-adapted endothelial phenotype in vivo.

Amino Acid Sequence↗

PubMed2002

[Prevention of bone loss by estradiol valerate combined with medroxyprogesterone acetate among postmenopausal women with osteopenia].

OBJECTIVE: To observe the efficacy of estradiol valerate (E(2)V) combined with medroxyprogesterone acetate (MPA) in prevention of bone loss among postmenopausal women with osteopenia. METHODS: Ninety-two women 1 to 8 years after menopause with osteopenia were randomly divided into 4 groups: 1) control group: 23 cases, taking calcium carbonate (Ca) 400 mg/d+ vitamin D 200 IU/D; 2) treatment group 1: 24 cases, taking E(2)V 1.0 mg/d+ MPA 2 mg/d+ Ca 400 mg/d; 3) treatment group 2: taking E(2)V 1.0 mg/d+ MPA 2 mg/d+ Ca 400 mg/d+ vitamin D 200 IU/d; and 4) treatment group 3: taking E(2)V 1.5 mg/d+ MPA 2 mg/d+ Ca 400 mg/d+ vitamin D 200 IU/d. The bone mineral density (BMD) of L(2- 4) and neck of femur was measured by DEXA method, and the bone metabolic markers such as serum alkaline phosphatase (ALP) and urine Ca/Cr and Ntx/Cr were examined just before the drug administration and 6, 12, and 18 months after the beginning of experiment. Vaginal bleeding and breast tenderness were recorded by the subjects themselves and examined by investigators. RESULTS: Seventy-eight subjects (84.5%) were followed up for I year and 77 of them (83.7%) were followed up for 1.5 years. The fasting morning Ca/Cr remained almost unchanged in the control group, and decreased by 43.8%, 33.3%, and 33.3% by the third month respectively and then remained unchanged in the treatment groups 1, 2, and 3. The urine Ntx/Cr decreased mildly but insignificantly in the control group (P > 0.05), and decreased since the 3rd month by 42.2%, 53.2%, and 29.1% respectively in the treatment groups 1 approximately 3 and then decreased very slowly. The ALP remained almost unchanged in the control group, and decreased by 6.8%, 17.0%, and 16.4% by the 6th months respectively and by 14.2%, 17.9%, and 28.8% by the 12th month and then remained almost unchanged in the treatment groups 1 approximately 3. The BMD of L2-4 increased by 7.1% +/- 4.6%, 6.8% +/- 5.3%, and 9.0% +/- 4.0% in the treatment 1 approximately 3 by the 18th month. The BMD of neck of femur increased by 4.1% +/- 3.2%, 4.0% +/- 5.9%, and 5.9% +/- 4.8% in the treatment 1 approximately 3 by the 18th month. Fracture occurred in 2 cases of the control group and 2 cases of the treatment group because of accidents. The vaginal bleeding rate was the highest in the treatment group 3 (47.4%). The breast tenderness rates were 27.3% approximately 47.6% in the 3 treatment groups. CONCLUSION: Administration of E(2)V I mg/d combined with MPA 2 mg/d is an optional regimen for postmenopausal women with intact uterine.

Adult↗

PubMed2002

Block principal component analysis with application to gene microarray data classification.

We propose a block principal component analysis method for extracting information from a database with a large number of variables and a relatively small number of subjects, such as a microarray gene expression database. This new procedure has the advantage of computational simplicity, and theory and numerical results demonstrate it to be as efficient as the ordinary principal component analysis when used for dimension reduction, variable selection and data visualization and classification. The method is illustrated with the well-known National Cancer Institute database of 60 human cancer cell lines data (NCI60) of gene microarray expressions, in the context of classification of cancer cell lines.

DNA, Neoplasm↗

PubMed2002

CADA inhibits human immunodeficiency virus and human herpesvirus 7 replication by down-modulation of the cellular CD4 receptor.

The novel antiviral agent cyclotriazadisulfonamide (CADA) inhibited human immunodeficiency virus (HIV) (IC50, 0.3-3.2 microM) and human herpesvirus 7 (HHV-7) infection (IC50, 0.3-1.5 microM) in T-cell lines and PBMCs. When T-cells were pretreated with CADA for 24 h, they became markedly protected from viral infection. Flow cytometric analysis revealed a significant decrease in the expression of the CD4 glycoprotein, the primary receptor needed for entry of both viruses. Moreover, the antiviral activity of CADA correlated with its ability to down-modulate the CD4 receptor. CADA did not alter the expression of any other cellular receptor (or HIV coreceptor) examined. Time course experiments showed that CD4 down-modulation by CADA differs in mechanism from the effects of aurintricarboxylic acid, which binds directly to CD4, and phorbol myristate acetate, which activates protein kinase C. Further analysis of CD4 mRNA levels suggested that CADA was not involved in the regulation of CD4 expression at a transcriptional level, but very likely at (post) translational levels. This unique mechanism of action makes CADA an important lead in developing new drugs for treatment of AIDS, autoimmune diseases, and inflammatory disorders.

Anti-Infective Agents↗

PubMed2002

Localized excitations in (2+1)-dimensional systems.

By means of a special variable separation approach, a common formula with some arbitrary functions has been obtained for some suitable physical quantities of various (2+1)-dimensional models such as the Davey-Stewartson (DS) model, the Nizhnik-Novikov-Veselov (NNV) system, asymmetric NNV equation, asymmetric DS equation, dispersive long wave equation, Broer-Kaup-Kupershmidt system, long wave-short wave interaction model, Maccari system, and a general (N+M)-component Ablowitz-Kaup-Newell-Segur (AKNS) system. Selecting the arbitrary functions appropriately, one may obtain abundant stable localized interesting excitations such as the multidromions, lumps, ring soliton solutions, breathers, instantons, etc. It is shown that some types of lower dimensional chaotic patterns such as the chaotic-chaotic patterns, periodic-chaotic patterns, chaotic line soliton patterns, chaotic dromion patterns, fractal lump patterns, and fractal dromion patterns may be found in higher dimensional soliton systems. The interactions between the traveling ring type soliton solutions are completely elastic. The traveling ring solitons pass through each other and preserve their shapes, velocities, and phases. Some types of localized weak solutions, peakons, are also discussed. Especially, the interactions between two peakons are not completely elastic. After the interactions, the traveling peakons also pass through each other and preserve their velocities and phases, however, they completely exchange their shapes.

Journal Article↗

PubMed2002

Astrocytic basic fibroblast growth factor expression in dopaminergic regions after perinatal anoxia.

BACKGROUND: Perinatal anoxia leads to persistent behavioral and neurochemical alterations suggestive of sensitized dopaminergic function. Because astrocytic basic fibroblast growth factor (bFGF) activity in the midbrain dopaminergic cell body region is required for the development of enduring changes in dopaminergic function induced by stimulant drugs, we investigated the effects of intrauterine anoxia on astrocytic bFGF expression in dopaminergic regions at 2 weeks of age and after a stress manipulation in adults. METHODS: We examined bFGF immunoreactivity in dopaminergic regions of young and adult rats born by cesarean section, cesarean section + 15 min of intrauterine anoxia, or vaginally. bFGF immunoreactivity was also assessed before and after tail-pinch stress in adult animals exposed to the same perinatal interventions. RESULTS: Perinatal anoxia produced persistent decreases in basal bFGF immunoreactivity in the ventral tegmental area (VTA), but enhanced the effect of stress on VTA bFGF immunoreactivity. CONCLUSIONS: Perinatal anoxia has enduring effects on VTA bFGF immunoreactivity and influences adult neuroadaptations to stress. The mechanisms whereby perinatal anoxia alters dopaminergic function may be similar to those responsible for the development of sensitization to stimulant drugs and may involve bFGF.

Age Factors↗

PubMed2002

Silencing of transcription of the human luteinizing hormone receptor gene by histone deacetylase-mSin3A complex.

Modification of chromatin structure by histone acetylases and deacetylases is an important mechanism in modulation of eukaryotic gene transcription. The present study investigated regulation of the human luteinizing hormone receptor (hLHR) gene by histone deacetylases. Inhibition of histone deacetylases (HDACs) by trichostatin A (TSA) increased hLHR promoter activity by 40-fold in JAR cells and markedly elevated endogenous hLHR mRNA levels. Acetylated histones H3 and H4 accumulated in TSA-treated cells and associated predominantly with the hLHR promoter. Furthermore, TSA significantly enhanced the recruitment of RNA polymerase II to the promoter. One of the two Sp1 sites essential for basal promoter activity was identified as critical for the TSA effect, but the binding of Sp1/Sp3 to this site remained unchanged in the absence or presence of TSA. A multiprotein complex was recruited to the hLHR promoter via interaction with Sp1 and Sp3, in which HDAC1 and HDAC2 were docked directly to Sp1-bound DNA and indirectly to Sp3-bound DNA through RbAp48, while mSin3A interacted with both HDACs. HDAC1 and HDAC2 were shown to potently repress the hLHR gene transcription, and mSin3A potentiated the inhibition mediated by HDAC1. Our studies have demonstrated that the HDAC-mSin3A complex has an important role in the regulation of hLHR gene transcription by interaction with Sp1/Sp3 and by region-specific changes in histone acetylation and polymerase II recruitment within the hLHR promoter.

Blotting, Western↗

PubMed2002

Two novel antifungal peptides distinct with a five-disulfide motif from the bark of Eucommia ulmoides Oliv.

Two antifungal peptides, named EAFP1 and EAFP2, have been purified from the bark of Eucommia ulmoides Oliv. Each of the sequences consists of 41 residues with a N-terminal blockage by pyroglutamic acid determined by automated Edman degradation in combination with the tandem mass spectroscopy and the C-terminal ladder sequencing analysis. The primary structurs all contain 10 cysteines, which are cross-linked to form five disulfide bridges with a pairing pattern (C1-C5, C2-C9, C3-C6, C4-C7, C8-C10). This is the first finding of a plant antifungal peptide with a five-disulfide motif. EAFP1 and EAFP2 show characteristics of hevein domain and exhibit chitin-binding properties similar to the previously identified hevein-like peptides. They exhibit relatively broad spectra of antifungal activities against eight pathogenic fungi from cotton, wheat, potato, tomato and tobacco. The inhibition activity of EAFP1 and EAFP2 can be effective on both chitin-containing and chitin-free fungi. The values of IC(50) range from 35 to 155 microg/ml for EAFP1 and 18 to 109 microg/ml for EAFP2. Their antifungal effects are strongly antagonized by calcium ions.

Alternaria↗

PubMed2002

Escherichia coli genes involved in resistance to pyrazinoic acid, the active component of the tuberculosis drug pyrazinamide.

The natural resistance of Escherichia coli to pyrazinoic acid (POA), the active derivative of pyrazinamide, was investigated. The TolC mutant was found to be more susceptible to POA and other weak acids than the wild-type strain. Mutation in EmrB but not AcrB efflux protein slightly increased POA susceptibility. Two transposon mutants with increased susceptibility to POA were found to harbor mutations in acnA encoding aconitase-1 and ygiY encoding a putative two-component sensor protein. Complementation of the AcnA and YgiY mutants conferred resistance to POA, whereas the complemented TolC mutant became resistant to POA and other weak acids.

Amidohydrolases↗

PubMed2002

PKC regulation of the human equilibrative nucleoside transporter, hENT1.

Regulation of nucleoside transporters is poorly understood. We show that acute stimulation of protein kinase C (PKC) causes a rapid increase in S-(4-nitrobenzyl)-6-thioinosine-sensitive (human equilibrative nucleoside transporter 1, hENT1) nucleoside uptake, in human cultured cells, which is not due to increased metabolism and which can be blocked by PKC inhibitors. Use of isoform-specific inhibitors indicates that PKC delta and/or epsilon (but not alpha, beta or gamma) are responsible for the acute effects. Down-regulation of PKC decreases hENT1-dependent uridine uptake. These are the first data to show rapid PKC delta/epsilon-dependent stimulation of hENT1 transport by a mechanism that may involve activation of transporters at the membrane possibly by post-translational modification of the protein.

Amphetamine↗

PubMed2002

Correlated alternative side chain conformations in the RNA-recognition motif of heterogeneous nuclear ribonucleoprotein A1.

The RNA-recognition motif (RRM) is a common and evolutionarily conserved RNA-binding module. Crystallographic and solution structural studies have shown that RRMs adopt a compact alpha/beta structure, in which four antiparallel beta-strands form the major RNA-binding surface. Conserved aromatic residues in the RRM are located on the surface of the beta-sheet and are important for RNA binding. To further our understanding of the structural basis of RRM-nucleic acid interaction, we carried out a high resolution analysis of UP1, the N-terminal, two-RRM domain of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), whose structure was previously solved at 1.75-1.9 A resolution. The two RRMs of hnRNP A1 are closely related but have distinct functions in regulating alternative pre-mRNA splice site selection. Our present 1.1 A resolution crystal structure reveals that two conserved solvent-exposed phenylalanines in the first RRM have alternative side chain conformations. These conformations are spatially correlated, as the individual amino acids cannot adopt each of the observed conformations independently. These phenylalanines are critical for nucleic acid binding and the observed alternative side chain conformations may serve as a mechanism for regulating nucleic acid binding by RRM-containing proteins.

Amino Acids↗

PubMed2002

Overexpression of copper zinc superoxide dismutase suppresses human glioma cell growth.

Copper zinc superoxide dismutase (CuZnSOD) is an essential primary antioxidant enzyme that converts superoxide radical to hydrogen peroxide and molecular oxygen in the cytoplasm. Cytosolic glutathione peroxidase (GPx) converts hydrogen peroxide into water. The overall goal of the present study was to explore the possible role of the antioxidant enzyme CuZnSOD in expression of the malignant phenotype. We hypothesized that overexpression of CuZnSOD would lead to the suppression of at least part of the human malignant phenotype. To test this hypothesis, human CuZnSOD cDNA was transfected into U118-9 human malignant glioma cells. CuZnSOD activity levels increased 1.5-, 2.0-, 2.6-, and 3.5-fold, respectively, in four table transfected cell lines compared with wild type and vector controls. Overexpression of CuZnSOD altered cellular antioxidant enzyme profiles, including those of manganese superoxide dismutase, catalase, and GPx. The transfected clone with the highest CuZnSOD:GPx ratio (3.5) showed a 42% inhibition of tumor cell growth in vitro. The decreased rate of tumor cell growth in vitro was strongly correlated with the enzyme activity ratio of CuZnSOD:GPx. Glioma cells that stably overexpressed CuZnSOD demonstrated additional suppressive effects on the malignant phenotype when compared with the parental cells and vector controls. These cells showed decreased plating efficiency, elongated cell population doubling time, lower clonogenic fraction in soft agar, and, more significantly, inhibition of tumor formation in nude mice. This work suggested that CuZnSOD is a new tumor suppressor gene. Increased intracellular ROS levels were found in cells with high activity ratios of CuZnSOD:GPx. Change in the cellular redox status, especially change attributable to the accumulation of hydrogen peroxide or other hydroperoxides, is a possible reason to explain the suppression of tumor growth observed in CuZnSOD-overexpressing cells.

Animals↗

PubMed2002

Signaling by the Mpl receptor involves IKK and NF-kappaB.

Binding of tumor necrosis factor-alpha (TNF-alpha) to its receptor activates IKK complex, which leads to inducement of NF-kappaB activity. Here we report that activation of Mpl ligand is also linked to IKK and NF-kappaB activity. Mpl ligand, also known as thrombopoietin (TPO) or megakaryocyte growth and development factor (MGDF), induces megakaryocyte differentiation and inhibition of mitotic proliferation, followed by induction of polyploidization and fragmentation into platelets. The latter process is often observed in megakaryocytes undergoing apoptosis. Treatment of a Mpl ligand-responding megakaryocytic cell line with this cytokine led to an immediate, transient increase in IKK activity followed by a profound decrease in this kinase activity over time. This decrease was not due to an effect on the levels of the IKK regulatory components IKKalpha and IKKbeta. Proliferating megakaryocytes displayed a constitutive DNA-binding activity of NF-kappaB p50 homodimers and of NF-kappaB p50-p65 heterodimers. As expected, reduced IKK activity in Mpl ligand-treated cells was associated with a significant reduction in NF-kappaB DNA binding activity and in the activity of a NF-kappaB-dependent promoter. Our study is thus the first to identify a constitutive NF-kappaB activity in proliferating megakaryocytes as well as to describe a link between Mpl receptor signaling and IKK and NF-kappaB activities. Since a variety of proliferation-promoting genes and anti-apoptotic mechanisms are activated by NF-kappaB, retaining its low levels would be one potential mechanism by which inhibition of mitotic proliferation is maintained and apoptosis is promoted during late megakaryopoiesis.

Animals↗

PubMed2002

Evolution of the delta13C signature related to total carbon contents and carbon decomposition rate constants in a soil profile under grassland.

Evolution of the total carbon (C) content and the (13)C enrichment (delta(13)C signature) of soil organic matter (SOM) with increasing depth in a soil profile under permanent grassland (C(3) vegetation) were investigated. The relationship between the total C content and the delta(13)C signature at different depths in the upper 30 cm of the soil profile could be well fitted by the Rayleigh equation (y = -29.8 - 2.3x, R(2) = 0.95, p < 0.001), describing the enrichment in (13)C as resulting from isotopic fractionation associated with C mineralization (isotope enrichment factor epsilon = -2.3 per thousand). Potential C dynamics of SOM in four depth intervals of the profile (0-10, 10-20, 20-30 and 30-40 cm depth) were investigated through an incubation study. The C decomposition rate constants decreased with increasing sampling depth from 0.0479 yr(-1) (0-10 cm sampling depth) to 0.0256 yr(-1) (30-40 cm sampling depth) and were highly correlated (y = 0.02 + 0.13x, R(2) = 0.93, p < 0.05) with the corresponding deltadelta(13)C values (average change of the delta(13)C signature per depth increment). These results suggest that changes of the delta(13)C signature of SOM in undisturbed soil profiles under continuous C(3) vegetation may serve as an indicator of the variation of SOM quality with increasing depth.

Biodegradation, Environmental↗