Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

At least 469 records · Page 26Linked to original sources

PubMed2003

[Structure and heterogeneity of urban vegetation landscape in Shenyang].

Studies on the structure and heterogeneity of urban vegetation landscape in Shenyang city showed that the most vegetation patches were in the street corner, accounted for more than 50% of the total vegetation patch, and their area was only 4.45% of the total vegetation area. In terms of the size of the patches, the average area of shelter vegetation and park vegetation was 66.97 hm2 and 59.31 hm2, respectively, while that of street corner vegetation and garden vegetation was 0.71 hm2 and 0.38 hm2, respectively. Street corner vegetation had the highest index of landscape diversity, while park vegetation had the lowest one. In the seven districts of Shenyang city, all types of vegetation had a small landscape dominance and evenness, but patch vegetation had a more than 10 times of landscape dominance than corridor vegetation, indicating that there was somewhat imbalance in the allocation of different vegetation patch types. It's suggested that the quantity of patch vegetation should be increased, and the public vegetation should be distributed evenly. Increasing vegetation corridor is also important because it can link the downtown area to the suburb natural vegetation ecosystems. For example, the South Canal Belt Park of Shenyang is a good vegetation corridor, which can beautify Shenyang city, discharge sewage, drain flood, and improve microclimate.

Agriculture↗

PubMed2003

[Quantitative analysis of urban forest structure: a case study on Shenyang arboretum].

The spatial features and attribute data of urban forests in Shenyang arboretum were acquired by using aerial photographs and field investigation. After systemic and quantitative analysis of the species composition and spatial distribution pattern of urban forest community based on geographic information system (GIS), the following results were achieved: 1) the vegetation in the arboretum was rich and in a good condition. Phellodendron amurense, Robinia pseudoacacia, and Ulmus punita were the main species according to their abundant individuals and relative dominance. The spatial distribution pattern of this vegetation indicated that it was in a growing level and in the best state for ecological benefits; 2) the tree species relative dominance based on vegetation quantity had no distinct relationship with the species abundance, and the species having abundant individuals might have a low relative dominance; and 3) the curve displayed in the relationship diagram between tree individuals and tree height showed ascending and protruding. With the increment of tree height class, the individuals were unchanged nearly at the beginning, but when the height was more than 12 m, the individuals reduced distinctly, and the curve displayed a quickly declined trend. The relationship between tree individuals and tree diameter at the breast height (DBH) showed the same result.

City Planning↗

PubMed2003

[Flora and vegetation types in the downtown area of Shenyang].

Shenyang city is located in the intersect zone among Changbai, Mongolia and North China flora, which has a plenty of plant species belonging to 98 families, 371 genera and 779 species. There are 85 plant species in the largest family Companulaceae, and more than 20 species in the families Cyperaceae, Rosaceae, Leguminoseae, Polygonuceae, Labiatae, Lilaceae and Ranunculaceae. These families have 384 species in total, and 49.3% of them are found in Shenyang city. The flora had 23 geographical components types, and 89.3% of them were of the temperate type. Based on the epigenesis and functions of vegetation and the role of the dominant species, the urban vegetation in the downtown area of Shenyang was divided into 3 vegetation classes, 14 vegetation groups and 57 vegetation types, and the components, structure, dynamics and functions of 3 representative vegetation classes were analysised.

China↗

PubMed2003

[Selection of tree species composition in Shenyang's urban forest communities].

Tree species selection is the most important basis in urban forest construction, and the key is the selection of tree species composition. Through investigating and analyzing the tree species composition in the parks in Shenyang built-up area, the sequencing of integrate evaluation of various tree species was obtained. By correlation analysis among tree species with the Jaccard quantitative coefficient of correction, the optimal tree species composition and the reference tree composition of Shenyang urban forest were also obtained. The existing status of tree species distribution in Shenyang built-up area was analyzed, the keynote tree species and 8 reference skeleton tree species were recommended, and some advices were presented.

China↗

PubMed2003

[Structure and ecological benefits of urban forest in Shenyang build-up area].

Investigations were made in the sampling plots covering 243 km2 of the Shenyang urban area, and the results were used as the input for the Urban Forest Management Information System (UFMIS), which was developed based on the model of CITY green. With this system, and using tree species, tree density, tree height grade distribution, tree DBH (diameter at beast height) grade distribution, and tree health condition as parameters, the land use and forest structure in Shenyang City were analyzed. It was found that there were 1,914,500 trees in Shenyang, belonging to 136 species. The 25 dominant species accounted for 84.78% of the total number of trees, and the forest coverage was 9.765%. Trees with DBH < 0.25 m and > 0.5 m accounted for 82.8% of the total, and the young, middle-aged and old trees occupied 27%, 58% and 15% of the total, respectively. The healthy status of 84% of the trees was above middle level. Therefore, the forest in Shenyang urban is at a stable stage. According to the statistical results from UFMIS, the ecological value of forest in Shenyang urban is as high as 26,526,955. 1 USD in terms of economy.

China↗

PubMed2003

[Dust absorption effect of urban conifers in northeast China].

Dust pollution is much heavier in winter than in other seasons in the cities of Northeast China, because the urban heating system consumes mainly coal as energy resources. Deciduous trees can hardly absorb dust because of their defoliation, and hence, urban conifer trees become more important in dust absorption in winter. This paper studied the dust absorption ability of 7 conifers under the same and different dust pollution status in Shenyang city, Northeast China. The results showed that the dust absorption ability of conifers was decreased in the order of Abies holophilla > Picea mongolica > P. koraiensis > Taxus cupidata > Pinus bungeana > P. armandi > P. tabulaeformis. Different conifers had different surface structures. Pinus bungeana, P. armandi and P. tabulaeformis had smooth surfaces, their cells and stomata arranged in order, and hence, their dust absorption ability was poor. P. koraiensis, Abies holophilla and Taxus cupidata had coarse surfaces, and their cells and stomata arranged out of order. There were even many tubercular things on the surface of P. koraiensis, and hence, their dust absorption ability was stronger. The dust absorption ability of conifers was related the shape of their leaf sections. The upper leaf surface of Pinus bungeana and P. tabulaeformis was arc, not opted to absorb the dust. The leaf section of P. armandi was prism, and its upper surface was narrow, and hence, its dust absorption ability was also poor. The leaves of Picea mongolica and P. koraiensis had four edges, their upper surfaces were broader and flatter than the former three species, and hence, they had stronger dust absorption ability. The leaf section's shape of Abies holophilla and Taxus cupidata was also broad and flat, which made the dust absorption ability of the two latter's was stronger than other three Pinus species and two Picea species.

Absorption↗

PubMed2003

[Quantitative analysis on sharp-tooth oak stands in Qinling Mountains].

The arbor stratum of Quercus aliena var. acuteserrata stands included two substratums. Phanerophyta synusium was in first position, and hemicryptophyta was inferior to it. The DBH structures of Quercus aliena var. acuteserrata and Pinus armandii were sinister normal school, which could finish self-regeneration under the natural conditions. The small DBH class individuals of Pinus tabulaeformis were dominant, their DBH classes being distributed irregularly and absent very much. The large DBH classes of Toxicodendron vernicifluum took biggish proportion, belonging to declining population. Young trees were the principal individuals of Castanea mollissima, and in transitional age stage from the young to the middle. Populus davidiana was in the transitional stage from progressive to stable and young-middle age stands. The stands DBH structure was mainly influenced by the DBH variety of Quercus aliena var. acuteserrata population. Quantitative classification (ward's method ward) and ordination (PCA) were used to study the community types of sharp-tooth oak. The results showed that the community could be divided into 6 types: 1. Ass. Smilax stans + Rosa multiflora-Quercus variabilis + Ulmus glaucescens-Quercus aliena var. acuteserrata; 2. Ass. Smilax stans + Lespedeza bicolor-Castanea mollissima-Q. aliena var. acuteserrata; 3. Ass. Corylus mandshurica-Populus davidiana + Dendrobenthamia angustata-Q. aliena var. acuteserrata; 4. Ass. Prunus pseudoccrasus + Corylus mandshurica-Toxicodendron vernicifluum-Q. aliena var. acuteserrata; 5. Ass. Corylus mandshurica + Rosa multiflora-Pinus armandii-Q. aliena var. acuteserrata; and 6. Ass. Sinarundinaria nitida-Pinus armandii + Pinus tabulaeformis-Q. aliena var. acuteserrata. Ward's method ward was better for classifying community types than the other clustering analyses in Qinling Mountains. The PCA results were consistent with the clustering, and demonstrated that the sharp-tooth oak stands were influenced by the altitude, site gradient and soil mainly.

China↗

PubMed2003

[The significance of fluorescent patterns of antineutrophil cytoplasmic antibodies (ANCA) in renal diseases].

AIM: To further explore significance of fluorescent patterns of antineutrophil cytoplasmic antibodies in renal diseases. METHODS: ANCA fluorescent patterns and its target antigens in sera of 251 patients with renal diseases were detected by indirect immunofluorescence (IIF) and ELISA. RESULTS: The positive percentage of ANCA is 20.3% (51/251), in which 3.98%(10/251) is cANCA, 11.95% (30/251) pANCA and 4.38%(11/251) aANCA. CONCLUSION: The simultaneous screening for ANCA and its target antigens by IIF and ELISA can increase the positive percentage of ANCA in renal diseases. This novel screening strategy is able to distinguish atypical ANCA(aANCA) from pANCA with ANA and therefore useful for differential diagnosis between vasculitis and autoimmune diseases.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed2003

[The effect of continuous high-volume hemofiltration therapy on TNF-alpha of pancreatitis patients complicated with acute renal function failure].

AIM: To explore the role of continuous high-volume renal replacement therapy(HV-CRRT) in serum TNF-alpha removal. METHODS: 13 panceatitis patients complicated with acute renal failure were treated by continuous venovenous hemofiltration (CVVH), and they were divided into two groups according to the substitution rate during CVVH. The substitution rate of group I (8 cases) was 2 L/h, the that of group II(5 cases) was 4 L/h. 1ml blood samples were taken from the post-filter at 0,1,2,3,6 and 24 h after CRRT, respectively. The TNF-alpha level produced from endotoxin-induced periphral blood mononuclear cells (PBMCs) was detected by ELISA. Ultrafiltrate samples were co-incubated with donor's whole blood containing ET so as to detect suppression activity of ultrafiltrate. RESULTS: Production of TNF-alpha by ET-induced PBMCs was significantly suppressed in group I and II. During CVVH treatment, suppressed ET-induced TNF-alpha production increased variously in the first 3 h, and then decreased gradually. In contrast, the increased levels of ET-induced TNF-alpha production in group II were higher than that in group I, and maintained a higher level until 24 h after CVVH therapy. The ultrafiltrate from group I had no suppressing activity, but the ultrafiltrate from group II suppressed ET-induced TNF-alpha production, the suppression rate was (15+/-6)%. CONCLUSION: HV-CRRT is more effective than standard CRRT in removal of inflammatory mediators. The mediators are removed mainly by filter membrane adsorption, and maybe partly by convection. Therefore, HV-CRRT with large-pore filter membranes is an effective way in removal of inflammatory mediators.

Acute Kidney Injury↗

PubMed2003

On half gapped seed.

In this paper, we proposed a new type of seed for Blast-like homology search tools called "half seed''. This new seed is better than the "consecutive seed'' used by the original Blast tools in both sensitivity and efficiency. When compared with the "gapped seed'', which is proposed together with a new Blast-like searching tool, PatternHunter, this new seed offers a much wider range of choices for performing tradeoff between sensitivity and efficiency. This property is especially useful when some searching applications want to get more precise results with limitation on hardware resources, or vice versa.

Algorithms↗

PubMed2003

[Construction of an anti-apoptosis CHO cell line for biopharmaceutical production].

Mammalian cells are prone to apoptosis when cultured in large scale for production of biopharmaceuticals. And this will reduce production duration and result in high cost of production. Apoptosis is triggered by various factors, and delicately regulated by a set of genes. Bcl-2, a component integrated in mitochondria membrane, is an important member of these genes. By maintaining the integrity of mitochondria membrane, Bcl-2 keeps cytochrome C from releasing into cytoplasm, and thus blocks the activation of caspases, and subsequent onset of apoptosis. Over-expression of Bcl-2 has proven to be useful in blocking apoptosis in various cell lines, including CHO, hybridoma, myeloma, lymphoma and insect cells. Ammonia, a metabolite of cultured cells, however, showed apparent pro-apoptosis activity. In living cells, ammonia can be utilized by glutamine synthetase (GS) to synthesize glutamine, and thus lower the concentration of ammonia in medium, and its negative effects. Glutamine is essential to living cells. If not added into medium, glutamine can only be synthesized by GS, which makes GS a qualified selection marker. This marker can be used for gene amplification by adding into medium increased concentration of MSX, an inhibitor of GS. In this study, we over-expressed Bcl-2 using GS amplification in a recombinant CHO cell line stably expressing human interferon-beta. The modified cell line, with higher expression of Bcl-2 and lower production of ammonia, exhibited good anti-apoptosis quality and higher interferon-beta production in continuous culture.

Animals↗

PubMed2002

Resealing dynamics of a cell membrane after electroporation.

The membrane of a living cell consists of a bilayer of amphipolar lipid molecules as well as much larger proteins. Transmembrane potentials of up to 120 mV are physiologic and well tolerated, but when the potential is more than 300 mV, this lipid bilayer is unstable. Pores are then formed through which measurable flow of ions can occur. We follow currents through frog muscle cell membranes under 4-ms pulses of up to 440 mV. We present a theory that allows us to describe the relaxation of the current back to zero after the pulse in terms of membrane parameters. We obtain a line tension of 3.6 x 10(-6) N, which is similar to that found in artificial lipid bilayers.

Animals↗

PubMed2002

A novel variant of the immunoglobulin fold in surface adhesins of Staphylococcus aureus: crystal structure of the fibrinogen-binding MSCRAMM, clumping factor A.

We report here the crystal structure of the minimal ligand-binding segment of the Staphylococcus aureus MSCRAMM, clumping factor A. This fibrinogen-binding segment contains two similarly folded domains. The fold observed is a new variant of the immunoglobulin motif that we have called DE-variant or the DEv-IgG fold. This subgroup includes the ligand-binding domain of the collagen-binding S.aureus MSCRAMM CNA, and many other structures previously classified as jelly rolls. Structure predictions suggest that the four fibrinogen-binding S.aureus MSCRAMMs identified so far would also contain the same DEv-IgG fold. A systematic docking search using the C-terminal region of the fibrinogen gamma-chain as a probe suggested that a hydrophobic pocket formed between the two DEv-IgG domains of the clumping factor as the ligand-binding site. Mutagenic substitution of residues Tyr256, Pro336, Tyr338 and Lys389 in the clumping factor, which are proposed to contact the terminal residues (408)AGDV(411) of the gamma-chain, resulted in proteins with no or markedly reduced affinity for fibrinogen.

Adhesins, Bacterial↗

PubMed2002

Sequence and analysis of rice chromosome 4.

Rice is the principal food for over half of the population of the world. With its genome size of 430 megabase pairs (Mb), the cultivated rice species Oryza sativa is a model plant for genome research. Here we report the sequence analysis of chromosome 4 of O. sativa, one of the first two rice chromosomes to be sequenced completely. The finished sequence spans 34.6 Mb and represents 97.3% of the chromosome. In addition, we report the longest known sequence for a plant centromere, a completely sequenced contig of 1.16 Mb corresponding to the centromeric region of chromosome 4. We predict 4,658 protein coding genes and 70 transfer RNA genes. A total of 1,681 predicted genes match available unique rice expressed sequence tags. Transposable elements have a pronounced bias towards the euchromatic regions, indicating a close correlation of their distributions to genes along the chromosome. Comparative genome analysis between cultivated rice subspecies shows that there is an overall syntenic relationship between the chromosomes and divergence at the level of single-nucleotide polymorphisms and insertions and deletions. By contrast, there is little conservation in gene order between rice and Arabidopsis.

Arabidopsis↗

PubMed2002

Controlled fabrication of cross-linked nanoparticles/polymer composite thin films through the combined use of surface-initiated atom transfer radical polymerization and gas/solid reaction.

A promising strategy for the controlled synthesis of inorganic/polymeric nanocomposites may be sustained by fabricating cross-linked PbS nanoparticles/polymer composite thin films through combining surface-initiated atom transfer radical polymerization (ATRP) and gas/solid reaction. The introduction of Pb ions through the extension of surface-initiated ATRP to the monomers containing metal ions provides an opportunity for generating nanoparticles on the substrate.

Journal Article↗

PubMed2002

Synthesis, crystal structure, and ESR study of a novel phosphorylated lipophilic spin trap.

In this article, the synthesis of a novel alpha-phosphorus-containing spin trap DEPPEPO [2-(diethoxyphosphoryl)-2-phenethyl-3,4-dihydro-2H-pyrrole-1-oxide] and the evaluation of its ability to spin-trap radicals, especially superoxide and hydroxyl radicals, are described. Single crystal X-ray structure analysis reveals that there exist a lot of intramolecular nonbonded attractive interactions in the molecule. The phenethyl group is located away from the diethoxyphosphoryl group and the nitronyl plane, and only one face of the nitronyl plane is sterically hindered by the oxygen attached to the phosphorus with a double bond. The latter feature is responsible for the stereoselection of the free radical additions on the nitronyl moiety. The ability of DEPPEPO to trap the active superoxide anion radical generated in the HX/XO system and the stability of their spin adduct were investigated with that for DEPMPO. The half-life of DEPPEPO is about 13.4 min, and as a result, the DEPPEPO seems to be a promising lipophilic spin trap, perhaps in both in vitro and in vivo ESR investigation. Because DEPPEPO is a solid compound, it is quite easy to purify by recrystallization and to store the compound even at room temperature. In addition, an obvious increase in lipophilicity for DEPPEPO was found as a contribution of 2-substituted phenethyl.

Journal Article↗

PubMed2002

Five Lec1 CHO cell mutants have distinct Mgat1 gene mutations that encode truncated N-acetylglucosaminyltransferase I.

Lec1 CHO cell mutants lack N-acetylglucosaminyltransferase I (GlcNAc-TI) activity and do not synthesize complex or hybrid N-glycans. The origins of six independent lec1 mutations are shown to reside in the coding region of the Mgat1 gene, proving that GlcNAc-TI is mutated in Lec1 mutants. One mutant has Mgat1 gene transcripts of reduced size, whereas the others possess transcripts of approximately normal size and amount containing a unique insertion or transition mutation that leads to a premature stop codon in the Mgat1 gene coding region. The lec1 mutation in the Lec3.2.8.1 mutant, a line used to generate minimally glycosylated membrane glycoproteins for X-ray crystallography, is a G insertion that leads to a nonsense codon after amino acid 391. The Pro-Lec1.3C line from the ATCC and in laboratory stocks, a line used widely for diverse purposes, possesses a C insertion in the Mgat1 gene coding exon, causing a frame shift and producing a stable, truncated approximately 24-kDa product. Mgat1 gene mutations were confirmed by sequencing genomic DNA PCR products. Mutant cDNAs were reverted by site-directed mutagenesis and shown to confer wild-type lectin binding and GlcNAc-TI activity on Lec1 transfectants. Surprisingly, three Mgat1 gene nucleotide changes previously reported in Pro-Lec1.3C cells (Puthalakath et al. [1996] J. Biol. Chem., 271, 27818-27822) were not detected in this study. These Lec1 mutants provide a novel cohort for investigating the effects on Golgi trafficking and kin recognition of deletion mutants of GlcNAc-TI expressed at endogenous rather than nonphysiological levels.

Animals↗

PubMed2002

Regulation of ALK-1 signaling by the nuclear receptor LXRbeta.

The transforming growth factor beta (TGF-beta) receptor, ALK-1, is expressed specifically on endothelial cells and is essential for angiogenesis, as demonstrated by its targeted deletion in mice and its mutation in the human disease hereditary hemorrhagic telangiectasia. Although ALK-1 and another endothelial-specific TGF-beta receptor, endoglin, both bind TGF-beta with identical isoform specificity and form a complex together, neither has been shown to signal in response to TGF-beta, and the mechanism by which these receptors signal in endothelial cells remains unknown. Here we report the identification of the nuclear receptor liver X receptor beta (LXRbeta) as a modulator/mediator of ALK-1 signaling. The cytoplasmic domain of ALK-1 specifically binds to LXRbeta in vitro and in vivo. Expression of activated ALK-1 results in translocation of LXRbeta from the nuclear compartment to the cytoplasmic compartment. The interaction of activated ALK-1 with LXRbeta in the cytoplasmic compartment results in the specific phosphorylation of LXRbeta by ALK-1, primarily on serine residues. LXRbeta subsequently modulates signaling by ALK-1 and the closely related TGF-beta receptor, ALK-2, as demonstrated by specific and potent inhibition of ALK-1- and ALK-2-mediated transcriptional responses, establishing LXRbeta as a potential modulator/mediator of ALK-1/ALK-2 signaling.

Activin Receptors, Type I↗