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Biomedical subjects

Yang Chen

Publications and source records attributed to Yang Chen.

At least 37 records · Page 2Linked to original sources
PubMed2006

[The expression of dystrophin in human viral myocarditis and dilated cardiomyopathy].

OBJECTIVE: In order to improve the accuracy and reliability in sudden cardiac death, the pathogenesis and relationship between the viral myocarditis and dilated cardiomyopathy were investigated. METHODS: Improved immunohistochemical technique was adopted to detect the expression of the dystrophin in myocardium from 25 viral myocarditis, 28 dilated cardiomyopathy and 17 control cases including normal, coronary atherosclerotic heart disease and hypertension heart disease as control. RESULTS: The positive rate of dystrophin protein expression in control group was 100%, that in viral myocarditis was 88%, and that in dilated cardiomyopathy was 57%, There were significant differences among three groups (P<0.05), and the correlation between viral myocarditis and dilated cardiomyopathy group (r = -0.526)were also found. CONCLUSION: The myocardial cytoskeletal protein is disrupted in viral myocarditis and dilated cardiomyopathy, and the dystrophin protein may be involved in the pathogenesis of viral myocarditis and dilated cardiomyopathy. The viral infect and impair heart functions by cleaving host dystrophin proteins may ultimately contributes to the viral myocarditis to the converting from dilated cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2006

[Treatment of cleft lip and palate: past, present and future].

Comparing the survey results of 224 Centers of Cleft Lip and Palate in the United States with the current status in China, and reviewing the experience and lessons systemically, we could get a conclusion that the repair of cleft lip and palate depends on the experience and excellent skills of the surgeons, and its important role in combined and sequential treatment (team approach) of cleft lip and palate should not be ignored. The team approach program requires multidisciplinary cooperation and good compliance of the patients. In order to improve the treatment outcomes of cleft lip and palate, it is necessary for us to study the advanced program and methods and combined the situation of our country.

China↗
PubMed2006

[Polymorphism of DYS287 on Y chromosome in 28 ethnic populations of China].

OBJECTIVE: To investigate the polymorphism of DYS287 among 28 ethnic populations in 9 provinces of China. METHOD: YAP element was detected by Touchdown PCR amplification and 2% agarose gel electrophoresis. RESULTS: YAP+ frequencies in these ethnic populations were as follows: Zang 36.7%, Tu 23.8%, Yi 18.4%, Pumi 11.3%, Tajik 7.4%, Bai 6.7%, Jino 5.1%, Shandong Han 4%, Mulao 2.7%, and Maonan 1.3%. The rest ethnic populations in our study, including Gansu Han, Yunnan Han, Zhuangzu, Daizu, Lizu, Nuzu, Lisu, Naxi, Lahu, Dulong, Hani, Shezu, Weiwuer, Sala, Kerkizi, Dongxiang, Vazu, and Korea didn't carry YAP + element. CONCLUSIONS: Zangzu, Tuzu, Yizu, Pumi, Jino, and Baizu, which belong to Sino-Tibetan language family, carry a high YAP + frequency. Sala, Tuzu, and Tajik, regarded as Central Asia by origin in history and linguistics, also have a high YAP + frequency. Mulao and Maonan, which origin from "Baiyue" ancient ethnic groups, also have a considerable YAP + frequency.

Alu Elements↗
PubMed2006

[Linkage analysis of keloid susceptibility loci on chromosome 7p11 in a Chinese pedigree].

OBJECTIVE: To investigate whether the keloid susceptibility loci occur on chromosome 7p11 in a Chinese pedigree. METHODS: Peripheral venous blood samples from 32 members significant for hereditary investigation from a large Chinese keloid pedigree (with 5 affected generations) were collected for extracting genomic DNA. Four microsatellites on chromosome 7p11 with known maximal two-point LOD scores were selected as the genetic markers according to the method described in a recent report of the similar study. These markers were subsequently amplified by PCR, and all the PCR products were genotyped and linkage analyses were conducted. RESULTS: With the theta value of 0-0.1, the two-point LOD scores for these markers were all less than -2, which excluded the linkages of these markers to chromosome 7p11. CONCLUSION: This study provides the first genetic evidence that keloid susceptibility loci in Chinese pedigree do not locate on chromosome 7p11, suggesting the heterogeneity of familial keloid susceptibility loci.

Adolescent↗
PubMed2006

[Distribution of HLA-B allele polymorphism of 8962 Han population in Liaoning of China].

OBJECTIVE: To investigate the distribution of genetic polymorphism of HLA-B locus in Liaoning Han population. METHODS: The technique of polymerase chain reaction-sequence specific primers (PCR-SSP) was adopted in genotyping a sample of 8962 unrelated healthy individuals collected from a Chinese Han population in Liaoning area. The allele frequency of HLA-B was calculated and was compared with the results from other population. RESULTS: Thirty-four HLA-B alleles were detected. The more common HLA-B allele included B*15(14.42%), B*40(14.33%) and B*13(11.99%). The B*82 and B*83 were absent. Forty-nine HLA-B antigens were detected. CONCLUSION: The HLA-B allele polymorphism distribution of Liaoning Han population exhibits its own characteristic and the difference from old south and north Han population in China.

Alleles↗
PubMed2005

Comparisons of NMR spectral quality and success in crystallization demonstrate that NMR and X-ray crystallography are complementary methods for small protein structure determination.

X-ray crystallography and NMR spectroscopy provide the only sources of experimental data from which protein structures can be analyzed at high or even atomic resolution. The degree to which these methods complement each other as sources of structural knowledge is a matter of debate; it is often proposed that small proteins yielding high quality, readily analyzed NMR spectra are a subset of those that readily yield strongly diffracting crystals. We have examined the correlation between NMR spectral quality and success in structure determination by X-ray crystallography for 159 prokaryotic and eukaryotic proteins, prescreened to avoid proteins providing polydisperse and/or aggregated samples. This study demonstrates that, across this protein sample set, the quality of a protein's [15N-1H]-heteronuclear correlation (HSQC) spectrum recorded under conditions generally suitable for 3D structure determination by NMR, a key predictor of the ability to determine a structure by NMR, is not correlated with successful crystallization and structure determination by X-ray crystallography. These results, together with similar results of an independent study presented in the accompanying paper (Yee, et al., J. Am. Chem. Soc., accompanying paper), demonstrate that X-ray crystallography and NMR often provide complementary sources of structural data and that both methods are required in order to optimize success for as many targets as possible in large-scale structural proteomics efforts.

Animals↗
PubMed2005

Optical, real-time monitoring of the glomerular filtration rate.

An easy and accurate assessment of the renal function is a critical requirement for detecting the initial functional decline of the kidney induced by acute or chronic renal disease. A method for measuring the glomerular filtration rate is developed with the accuracy of clearance techniques and the convenience of plasma creatinine. The renal function is measured in rats as the rate of clearance determined from time-resolved transcutaneous fluorescence measurements of a new fluorescent glomerular filtration agent. The agent has a large dose-safety coefficient and the same space distribution and clearance characteristics as iothalamate. This new approach is a convenient and accurate way to perform real-time measurements of the glomerular filtration rate to detect early kidney disease before the renal function becomes severely and irreversibly compromised.

Animals↗
PubMed2005

On-chip temperature gradient interaction chromatography.

This paper reports the first integrated microelectromechanical system (MEMS) HPLC chip that consists of a parylene high-pressure LC column, an electrochemical sensor, a resistive heater and a thermal-isolation structure for on-chip temperature gradient interaction chromatography application. The separation column was 8 mm long, 100 microm wide, 25 microm high and was packed with 5 microm sized, C18-coated beads using conventional slurry-packing technique. A novel parylene-enhanced, air-gap thermal isolation technology was used to reduce heater power consumption by 58% and to reduce temperature rise in the off-column area by 67%. The fabricated chip consumed 400 mW when operated at 100 degrees C. To test the chromatography performance of the fabricated system, a mixture of derivatized amino acids was chosen for separation. A temporal temperature gradient scanning from 25 to 65 degrees C with a ramping rate of 3.6 degrees C/min was applied to the column during separation. Successful chromatographic separation of derivatized amino acids was carried out using our chip. Compared with conventional temperature gradient HPLC system which incorporates "macro oven" to generate temporal temperature gradient on the column, our chip's thermal performance, i.e., power consumption and thermal response, is greatly improved without sacrificing chromatography quality.

Chromatography, High Pressure Liquid↗
PubMed2005

Time-resolved kinetic studies on quenching of HCF(A1A'') by alkane and alcohol molecules.

HCF(X1A') radicals were produced by laser photolysis of CHFBr2 at 213 nm and were electronically excited from the ground state to A1A''(030) at 492.7 nm with a dye laser pumped by a Nd:YAG laser. With the analysis of the lifetime of the time-resolved total fluorescence signals collected in the reaction cell where the total pressure was fixed to be 14.0 Torr, the quenching data of HCF(A1A'') by alkane and alcohol molecules at room temperature were derived from variation of pseudo-first-order rate constant with different quencher pressures. It is found that the quenching rate constants are close to the collision rate constants (10(-10) cm3 molecule(-1) s(-1)), indicating the long-range attractive forces between the collision partners play an important role in the entrance channel of quenching process. Several kinetic models were applied to analyze the mechanism of the quenching process. The complex formation cross sections are calculated with the collision complex model. Correlations of the quenching rate constant for the removal of the HCF(A1A'') state with ionization potential of the quenching partners show that the insertion reactive mechanism is probably the dominant reaction channel, which is analogous to the behaviors of other three-atom carbenes in corresponding electronic states.

Alcohols↗
PubMed2005

Characterization of TRZ1, a yeast homolog of the human candidate prostate cancer susceptibility gene ELAC2 encoding tRNase Z.

BACKGROUND: In humans, mutation of ELAC2 is associated with an increased risk of prostate cancer. ELAC2 has been shown to have tRNase Z activity and is associated with the gamma-tubulin complex. RESULTS: In this work, we show that the yeast homolog of ELAC2, encoded by TRZ1 (tRNase Z 1), is involved genetically in RNA processing. The temperature sensitivity of a trz1 mutant can be rescued by multiple copies of REX2, which encodes a protein with RNA 3' processing activity, suggesting a role of Trz1p in RNA processing in vivo. Trz1p has two putative nucleotide triphosphate-binding motifs (P-loop) and a conserved histidine motif. The histidine motif and the putative nucleotide binding motif at the C-domain are important for Trz1p function because mutant proteins bearing changes to the critical residues in these motifs are unable to rescue deletion of TRZ1. The growth defect exhibited by trz1 yeast is not complemented by the heterologous ELAC2, suggesting that Trz1p may have additional functions in yeast. CONCLUSION: Our results provide genetic evidence that prostate cancer susceptibility gene ELAC2 may be involved in RNA processing, especially rRNA processing and mitochondrial function.

Amino Acid Motifs↗
PubMed2005

The kinetics of the reactions of C2 (a 3pi(u)) with alcohols.

The reactions of C2 (a 3pi(u)) radicals with a series of alcohols have been studied at about 6.5 Torr total pressure and room temperature using the pulsed laser photolysis/laser-induced fluorescence technique. The relative concentration of C2 (a 3pi(u)) radicals, which are generated via the photolysis of C2Cl4 with the focused output from the fourth harmonic of a Nd:YAG laser (266 nm), was monitored by laser-induced fluorescence (LIF) in the (0, 0) band of the C2 (d 3pi(g)<--a 3pi(u)) transition at 516.5 nm. Under pseudo-first-order conditions, we measured the time evolution of C2 (a 3pi(u)) and determined the rate constants for reactions of C2 (a 3pi(u)) with alcohols. The rate constants increase linearly with the number of C atoms in the alcohols. All of them are larger than those for reactions of C2 (a 3pi(u)) with alkanes (C1-C5). Based on the bond dissociation energy and linear free energy correlations, we believe the reactions of C2 (a 3pi(u)) with alcohols proceed via the mechanism of hydrogen abstraction. The experimental results show that the H-atom on the C-H bonds is activated at the presence of the OH substituent group in the alcohol molecule. The theoretical calculations for the reaction of C2 (a 3pi(u)) with methanol also support these hypotheses.

Journal Article↗
PubMed2005

Structural and biochemical studies identify tobacco SABP2 as a methyl salicylate esterase and implicate it in plant innate immunity.

Salicylic acid (SA) is a critical signal for the activation of plant defense responses against pathogen infections. We recently identified SA-binding protein 2 (SABP2) from tobacco as a protein that displays high affinity for SA and plays a crucial role in the activation of systemic acquired resistance to plant pathogens. Here we report the crystal structures of SABP2, alone and in complex with SA at up to 2.1-A resolution. The structures confirm that SABP2 is a member of the alpha/beta hydrolase superfamily of enzymes, with Ser-81, His-238, and Asp-210 as the catalytic triad. SA is bound in the active site and is completely shielded from the solvent, consistent with the high affinity of this compound for SABP2. Our biochemical studies reveal that SABP2 has strong esterase activity with methyl salicylate as the substrate, and that SA is a potent product inhibitor of this catalysis. Modeling of SABP2 with MeSA in the active site is consistent with all these biochemical observations. Our results suggest that SABP2 may be required to convert MeSA to SA as part of the signal transduction pathways that activate systemic acquired resistance and perhaps local defense responses as well.

Amino Acid Sequence↗
PubMed2005

Role of trichome of Pteris vittata L. in arsenic hyperaccumulation.

Environmental scanning electron microscope (ESEM) fitted with an energy dispersive X-ray microanalyzer (EDX) was used to investigate the surface micromorphology and arsenic (As) micro-distribution in Chinese brake (Pteris vittata L.). It was found that amounts of trichome, which possessed multicellular structure with the average length of 160 microm and with an average diameter of 28 microm, existed in the frond of P. vittata, and the density of trichome on the pinnate axial surface was higher than that on the petiole. Visible X-ray peak of As was recorded in the epidermal cell and trichome. The relative weight of As in the pinnate trichome, which contained the highest concentration of As among all tissues of the plant, was 2.4 and 3.9 times as much as that in the epidermal and mesophyllous cells, respectively. The As concentrations in the basal and stalk cells of the same trichome were higher than that in its cap cell. This is the first time to report that the trichome of P. vittata plays an important role in arsenic hyperaccumulation. The finding from the present study implies that much attention should be paid to the role of the trichome in understanding the hyperaccumulation and detoxicity of As in the hyperaccumulator and improving the ability of As accumulation.

Arsenic↗
PubMed2005

Protein repellant silicone surfaces by covalent immobilization of poly(ethylene oxide).

Polydimethylsiloxane elastomers were surface modified with passivating polyethylene oxide (PEO) polymers of different molecular weights, both monofunctional and bifunctional. Following the introduction of Si-H groups on the surfaces by acid-catalyzed equilibration in the presence of polymethylhydrosiloxane, the PEO was linked by platinum-catalyzed hydrosilylation. ATR-FTIR, X-ray photoelectron spectroscopy (XPS) and water contact angle results confirmed that the PEO was successfully grafted to the silicone rubber. Atomic force microscopy and XPS suggested that surface coverage with PEO was very high on the modified surfaces but not complete. The protein-resistant properties of the PEO-modified surfaces were demonstrated by measuring the adsorption of fibrinogen from both buffer and plasma. Fibrinogen adsorption from buffer to the PEO-modified surfaces was reduced by more than 90% compared with controls.

Adhesiveness↗
PubMed2005

Immobilization of heparin on a silicone surface through a heterobifunctional PEG spacer.

A novel method of immobilizing heparin on a silicone surface through a heterobifunctional PEG spacer was used yield well defined surfaces with highly active surface immobilized heparin and low non-specific protein adsorption. The heparin surface density achieved using this technique was 0.68 microg/cm2. Sessile drop water contact angles showed increased hydrophilicity of the silicone surface after PEG modification and a further decrease in the contact angles following the grafting of heparin. High specificity for ATIII with little fibrinogen adsorption was noted in plasma adsorption studies. This ATIII adsorption was mediated by the heparin layer, since surfaces modified with PEG only did not adsorb significant quantities of AT. The thrombin resistance of the heparin modified surfaces was demonstrably greater as measured by a chromogenic thrombin generation assay. The results suggest that the heterbifunctional PEG linker results in a high density of active heparin on the surfaces.

Adsorption↗
PubMed2005

Surface properties of PEO-silicone composites: reducing protein adsorption.

Silicone-based polymers with reduced protein adsorption were successfully prepared by incorporating mono- or bifunctional poly(ethylene oxide) (PEO) derivatives, respectively, into PDMS during rubber formation using classic room temperature vulcanization chemistry. Characterization of the films by water contact-angle measurements and XPS showed that the PEO was present on the film surface, with greater amounts of PEO at the interface modified with monofunctional PEO. Scanning electron microscopy showed the PEO domains segregated into regular zigzag patterns on the PEO-modified surfaces. Significant reductions in the adsorption of fibrinogen, albumin and lysozyme were observed on both PEO-modified surfaces, although the monofunctional PEO surfaces performed much better in this regard. The reductions in protein adsorption were comparable for all three proteins on both surfaces, suggesting that molecular mass of the protein is not a significant factor in determining the magnitude of protein deposition. Western blot studies showed that the adsorption of proteins from plasma to the monofunctional PEO-modified surfaces was also significantly reduced and surprisingly selective, with very few bands noted relative to the control surfaces and those modified with bifunctional PEO.

Adsorption↗
PubMed2005

[Experimental study on polylactic glycolate acid microparticles with releasing-slowly vascular endothelial growth factor].

OBJECTIVE: To observe the degradation of the polylactic glycolate acid (PLGA) microparticles with releasing-slowly vascular endothelial growth factor (VEGF) synthesized by the method of emulsification-diffusion. METHODS: The method of emulsification-diffusion is to incorporate VEGF into microparticles composed of biodegradable PLGA. The controlled release of microparticles are acquired. The content of the VEGF released slowly from PLGA microparticles in vitro was detected with ELISA at different time. RESULTS: We synthesized 100 releasing-slowly VEGF PLGA microparticles with the size of 0.20-0.33 microm by 5 times. The contents were 62 +/- 11 ng/L, 89 +/- 14 ng/L, and 127 +/- 19 ng/L in the 1st, the 2nd and the 3rd months after degradation, respectively. CONCLUSION: The PLGA microparticles with releasing-slowly VEGF can be synthesized by the method of emulsification-diffusion.

Delayed-Action Preparations↗