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Biomedical subjects

Qiang Wu

Publications and source records attributed to Qiang Wu.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Increased levels of advanced oxidation protein products are associated with atherosclerosis in chronic kidney disease].

OBJECTIVE: Accumulation of advanced oxidation protein products (AOPP) has been found in patients with chronic kidney disease (CKD). The study was performed to investigate the association between serum levels of AOPP and atherosclerosis in CKD. METHODS: 109 CKD patients were involved in this cross-sectional cohort study. Carotid artery intima-medial thickness (IMT), cross-sectional calculated intima-media area (cIM area) and plaques were determined with non-invasive high-resolution B-mode ultrasonography. Serum levels of AOPP, malonyldialdehyde (MDA), glutathione peroxidase (GSHPx) and C-reactive protein (CRP) were also determined. RESULTS: Higher serum AOPP levels were found in patients with CKD [(64.72 +/- 19.69) micromol/L] as compared with those in healthy controls [(30.16 +/- 6.46) micromol/L, P < 0.01]. AOPP levels in dialysis patients [(70.02 +/- 16.51) micromol/L] were significantly higher than those in pre-dialysis patients [(51.71 +/- 15.53) micromol/L, P < 0.01]. AOPP levels increased with the progression of renal dysfunction and inversely correlated with creatinine clearance (Ccr) (r = -0.292, P < 0.05). Patients with carotid artery plaques showed significantly higher levels of AOPP [(73.87 +/- 19.40) micromol/L] as compared with patients without carotid artery plaques [(58.41 +/- 16.09) micromol/L, P < 0.01]. Serum levels of AOPP were strongly associated with carotid artery IMT (r = 0.332, P < 0.01) and cIM area (r = 0.288, P < 0.05). By stepwise multiple regression analysis and adjusting for age, gender, blood pressure, smoking, diabetes, body mass index (BMI), hemoglobin, lipid and albumin, strong association was still present between AOPP levels and carotid artery IMT (beta = 0.313, P < 0.001) and cIMarea (beta = 0.301, P < 0.01). Serum levels of AOPP were correlated positively with serum MDA (r = 0.300, P = 0.01) and CRP levels (r = 0.255, P < 0.05), while negatively with serum GSHPx (r = -0.647, P < 0.01). CONCLUSIONS: Serum levels of AOPP increased with the progression of renal failure and closely associated with occurrence of atherosclerosis. Strong association between serum AOPP and CRP suggests that AOPP might be involved in the pathogenesis of micro-inflammation which has been considered as a contributing factor for atherosclerosis in CKD.

Adult↗
PubMed2005

[Diagnosis and treatment of functional delayed gastric emptying after gastrectomy].

OBJECTIVE: To explore the clinical characteristics and treatment of functional delayed gastric emptying(FDGE) after gastrectomy. METHODS: From 1998 to 2003, clinical data of 224 patients undergone gastrectomy were analyzed retrospectively. RESULTS: Nine of 224 patients (4%) had FDGE from three days to ten days (average 7.2 days) after operation. Diagnosis was confirmed by clinical features,gastric contrast examination and gastroscope. The incidence of FDGE was 6.1% in the patients treated with Billroth II gastroenterostomy, which was higher than that with Billroth I gastroenterostomy (1.8%). Eight patients were cured by palliative treatment with recovery time from 9 to 56 days (average 22 days), but one patient died of severe pulmonary infection. CONCLUSIONS: FDGE is a common and early complication after gastrectomy, PDGE is more likely to occur in patients with Billroth II gastroenterostomy. Diagnosis can be confirmed by barium meal examination of gastrointestinal tract and gastroscopy. PDGE can be mostly cured by palliative treatment.

Adult↗
PubMed2005

[Study on the groundwater petroleum contaminant biodegradation by high efficient microorganism].

The groundwater petroleum contaminant biodegradation effect by high efficient hybrid microorganism was. investigated and the groundwater contaminant biodegradation transportation mathematical model was established in this study. The high efficient bacteria was separated and filtrated from the soil contaminated by petroleum hydrocarbon, and it was identified as Pseudomonas, Flavobacterium and Micrococcus. The petroleum degradation rates by these three kinds microorganism were 62%, 56% and 62% respectively in 24 h, and the high petroleum biodegradation rate 85% could be achieved by the hybrid microorganism constituted by these three kinds of microorganism, which was higher than that of any other each single bacteria community. The hybrid microorganism in-flowed into the reactor imitating the aquifer media with the petroleum wastewater, and it could form a steady microorganism zone in the foreside of the reactor. The petroleum biodegradation rate could achieve 60% when the petroleum wastewater flowed through this microorganism zone and the average petroleum biodegradation rate could reach up to 90% in the effluent. The groundwater contaminant biodegradation transportation mathematical model can predict the biodegradation of the wastewater through the microorganism zone effectively, of which the calculating values have good relativity with those of measurement.

Bacteria↗
PubMed2004

Analysis of nonuniformities of sampled fiber Bragg gratings.

We have analyzed the effects of various normally distributed nonuniformities of sampled fiber Bragg gratings on the reflective spectra and group time delay. Through numerical simulations we have drawn the following conclusions: (1) the magnitude of nonuniformity with normal distribution of the fiber's average refractive-index modulation deltaneff greatly influences the characteristics of both reflective spectra and group time delay, whose suggested precision varies from 20% to 10%; (2) the nonuniformities of sampling periods P and sampling lengths L are important factors that influence the characteristics of the group time delay, and the accepted tolerance of dimensional precision of both P and L are +/- 4 microm; and (3) the tolerance of nonuniformity of the sampling period's chirp coefficient is high, and its precision can be as great as 100% with few adverse effects.

Journal Article↗
PubMed2004

The Tlx gene regulates the timing of neurogenesis in the cortex.

The tailless (tlx) gene is a forebrain-restricted transcription factor. Tlx mutant animals exhibit a reduction in the size of the cerebral hemispheres and associated structures (Monaghan et al., 1997). Superficial cortical layers are specifically reduced, whereas deep layers are relatively unaltered (Land and Monaghan, 2003). To determine whether the adult laminar phenotype has a developmental etiology and whether it is associated with a change in proliferation/differentiation decisions, we examined the cell cycle and neurogenesis in the embryonic cortex. We found that there is a temporal and regional requirement for the Tlx protein in progenitor cells (PCs). Neurons prematurely differentiate at all rostrocaudal levels up to mid-neurogenesis in mutant animals. Heterozygote animals have an intermediate phenotype indicating there is a threshold requirement for Tlx in early cortical neurogenesis. Our studies indicate that PCs in the ventricular zone are sensitive to loss of Tlx in caudal regions only; however, PCs in the subventricular zone are altered at all rostrocaudal levels in tlx-deficient animals. Furthermore, we found that the cell cycle is shorter from embryonic day 9.5 in tlx-/- embryos. At mid-neurogenesis, the PC population becomes depleted, and late PCs have a longer cell cycle in tlx-deficient animals. Consequently, later generated structures, such as upper cortical layers, the dentate gyrus, and the olfactory bulbs, are severely reduced. These studies indicate that tlx is an essential intrinsic regulator in the decision to proliferate or differentiate in the developing forebrain.

Animals↗
PubMed2004

Hemoglobin site-mutants reveal dynamical role of interhelical H-bonds in the allosteric pathway: time-resolved UV resonance Raman evidence for intra-dimer coupling.

The dynamical effect of eliminating specific tertiary H-bonds in the hemoglobin (Hb) tetramer has been investigated by site-directed mutagenesis and time-resolved absorption and ultraviolet resonance Raman (UVRR) spectroscopy. The Trp alpha 14...Thr alpha 67 and Trp beta 15...Ser beta 72 H-bonds connect the A and E helices in the alpha and beta chains, and are proposed to break in the earliest protein intermediate (Rdeoxy) following photo-deligation of HbCO, along with a second pair of H-bonds involving tyrosine residues. Mutation of the acceptor residues Thr alpha 67 and Ser beta 72 to Val and Ala eliminates the A-E H-bonds, but has been shown to have no significant effect on ligand-binding affinity or cooperativity, or on spectroscopic markers of the T-state quaternary interactions. However, the mutations have profound and unexpected effects on the character of the Rdeoxy intermediate, and on the dynamics of the subsequent steps leading to the T state. Formation of the initial quaternary contact (RT intermediate) is accelerated, by an order of magnitude, but the locking-in of the T state is delayed by a factor of 2. These rate effects are essentially the same for either mutation, or for the double mutation, suggesting that the alpha beta dimer behaves as a mechanically coupled dynamical unit. Further evidence for intra-dimer coupling is provided by the Rdeoxy UVRR spectrum, in which either or both mutations eliminate the tyrosine difference intensity, although only tryptophan H-bonds are directly affected. A possible mechanism for mechanical coupling is outlined, involving transmission of forces through the alpha(1)beta(1) (and alpha(2)beta(2)) interface. The present observations establish that quaternary motions can occur on the approximately 100 ns time-scale. They show also that a full complement of interhelical H-bonds actually slows the initial quaternary motion in Hb, but accelerates the locking in of the T-contacts.

Absorption↗
PubMed2004

In situ TA-MS study of the six-membered-ring-based growth of carbon nanotubes with benzene precursor.

By using the in situ thermal analysis-mass spectroscopic technique, combined with transmission electron microscopic characterization of the carbon nanotube (CNT) product, we have studied the chemical vapor deposition (CVD) growth of CNTs with Fe-Co/gamma-Al2O3 catalyst and benzene precursor in the range of room temperature to 700 degrees C. The growth process has been clearly illuminated, which starts from the reduction of catalyst around 645 degrees C followed by the dissociation of carbon-hydrogen bonds of benzene and the sequential growth of CNTs. A surprising fact is that no possible hydrocarbon species derived from benzene was detected, indicating that the carbon-carbon bond was not broken under our experimental conditions. All of the experimental results strongly reinforce the six-membered-ring-based growth model, and a schematic elucidation is presented accordingly. This in situ study not only reveals the unique and convincing information directly related to the growth mechanism from the involved chemistry, but also provides a powerful way to clarify the mechanism of CVD synthesis of CNTs with other precursors.

Journal Article↗
PubMed2004

Blockade of lymphotoxin signaling inhibits the clinical expression of murine graft-versus-host skin disease.

Adhesion molecules are essential for the recruitment of T cells into the skin during the development of graft-vs-host skin disease (GVHSD). However, the mechanisms responsible for the regulation of expression of cutaneous adhesion molecules in this setting are still poorly understood. In this study we blocked lymphotoxin (LT) signaling in a murine model of minor histocompatibility Ag system mismatch GVHSD by using an LTbeta receptor-Ig fusion protein (LTbetaR-Ig). The recipient mice treated with control human Ig developed clinically apparent, severe skin lesions. However, none of the mice treated with LTbetaR-Ig developed clinical skin disease. The expression of ICAM-1 in cutaneous tissue was also much lower in mice treated with LTbetaR-Ig than in mice treated with human Ig. Thus, the inhibition of LT signaling via LTbetaR-Ig treatment appears to be capable of markedly ameliorating the development of GVHSD, possibly by inhibiting the expression of adhesion molecules.

Animals↗
PubMed2004

Dysregulated LIGHT expression on T cells mediates intestinal inflammation and contributes to IgA nephropathy.

Whether and how T cells contribute to the pathogenesis of immunoglobulin A nephropathy (IgAN) has not been well defined. Here, we explore a murine model that spontaneously develops T cell-mediated intestinal inflammation accompanied by pathological features similar to those of human IgAN. Intestinal inflammation mediated by LIGHT, a ligand for lymphotoxin beta receptor (LTbetaR), not only stimulates IgA overproduction in the gut but also results in defective IgA transportation into the gut lumen, causing a dramatic increase in serum polymeric IgA. Engagement of LTbetaR by LIGHT is essential for both intestinal inflammation and hyperserum IgA syndrome in our LIGHT transgenic model. Impressively, the majority of patients with inflammatory bowel disease showed increased IgA-producing cells in the gut, elevated serum IgA levels, and severe hematuria, a hallmark of IgAN. These observations indicate the critical contributions of dysregulated LIGHT expression and intestinal inflammation to the pathogenesis of IgAN.

Animals↗
PubMed2004

[Development and research of temporary demand pacemaker with electrocardiosignal display].

A temporary demand pacemaker with electrocardiosignal display is introduced in this paper. Double way low-noise electrocardiosignal preamplifier, amplitude limiter, high and low pass filter, 50 Hz notch filter, TTL level generator and stimulating pulse formation circuit are components of the hardware electrocircuit. The demand pacing and the electrocardiosignal display are separately controlled by the software in which the double microcontrollers communications technique is used. In this study, liquid crystal display is firstly used in body surface electrocardiosignal display or intracardial electrophysiologic signal display when the temporary demand pacemaker is installed and put into use. The machine has proven clinically useful and can be of wide appliation.

Electrocardiography↗
PubMed2004

[Development of multi-channels cardiac electrophysiological polygraph with LabVIEW as software platform and its clinical application].

Polygraph has become a necessary instrument in interventional cardiology and fundamental research of medicine up to the present. In this study, a LabView development system (DS) (developed by NI in U.S.) used as software platform, a DAQ data acquisition module and universal computer used as hardware platform, were creatively coupled with our self-made low noise multi-channels preamplifier to develop Multi-channels electrocardiograph. The device possessed the functions such as real time display of physiological process, digit highpass and lowpass, 50Hz filtered and gain adjustment, instant storing, random playback and printing, and process control stimulation. Besides, it was small-sized, economically practical and easy to operate. It could advance the spread of cardiac intervention treatment in hospitals.

Electrocardiography↗
PubMed2003

Multiple variable first exons: a mechanism for cell- and tissue-specific gene regulation.

A large family of neural protocadherin (Pcdh) proteins is encoded by three closely linked mammalian gene clusters (alpha, beta, and gamma). Pcdh alpha and gamma clusters have a striking genomic organization. Specifically, each "variable" exon is spliced to a common set of downstream "constant" exons within each cluster. Recent studies demonstrated that the cell-specific expression of each Pcdh gene is determined bya combination of variable-exon promoter activation and cis-splicing of the corresponding variable exon to the first constant exon. To determine whether there are other similarly organized gene clusters in mammalian genomes, we performed a genome-wide search and identified a large number of mammalian genes containing multiple variable first exons. Here we describe several clusters that contain about a dozen variable exons arrayed in tandem, including UDP glucuronosyltransferase (UGT1), plectin, neuronal nitric oxide synthase (NOS1), and glucocorticoid receptor (GR) genes. In all these cases, multiple variable first exons are each spliced to a common set of downstream constant exons to generate diverse functional mRNAs. As an example, we analyzed the tissue-specific expression profile of the mouse UGT1 repertoire and found that multiple isoforms are expressed in a tissue-specific manner. Therefore, this variable and constant genomic organization provides a genetic mechanism for directing distinct cell- and tissue-specific patterns of gene expression.

Animals↗
PubMed2003

Synthesis and characterization of faceted hexagonal aluminum nitride nanotubes.

The synthesis of the faceted single-crystalline h-AlN nanotubes with the length of a few micrometers and diameters from 30 to 80 nm is first reported. This provides an ideal substrate for the construction of GaN-based nanoheterostructures in future nanoelectronics. The experimental results suggest the further extensive experimental and theoretical studies on the promising nonlayered nanotubular structures.

Journal Article↗
PubMed2003

Cloning and characterization of rice HMGB1 gene.

We isolated a 918 bp long full-length rice HMGB1 cDNA, which has an open reading frame of 471 bp encoding 157 amino acids, with a central domain of high sequence similarity to the HMG-box domain of other plant HMGB1 proteins. RNA gel blot analysis indicated that rice HMGB1 gene is constitutively expressed in various tissues and organs. Southern hybridization and sequence analyses suggested that a single copy of the HMGB1 gene composed of seven exons and six introns exists in rice. We have also cloned a 1755 bp long 5' flanking region of the rice HMGB1 gene, which can be regarded as its promoter. 5' deletion analysis of this promoter indicated that positive cis-elements residing between -1400 and -1115 are important to enhance quantitative expression, whereas negative cis-elements between -1755 and -1400 and between -1115 and -351 inhibit expression.

5' Flanking Region↗
PubMed2003

Characterization of the interaction of wheat HMGa with linear and four-way junction DNAs.

Wheat HMGa protein is a typical member of the plant HMGA family. It has four AT hooks and a histone H1-like region. A panel of deletion mutants of HMGa was generated to study the role of different regions of HMGa in its binding to 4H (a synthetic DNA that mimics the in vivo structure of intermediates of homologous recombination and DNA repair) and linear DNAs. Although the histone H1-like region of HMGa does not bind to 4H or linear DNAs, it does enhance the binding. Mutants with any two adjacent AT hooks show specific binding to both 4H and linear P268 (and P31) with different binding affinities, which is partly due to the flanking regions between AT hooks. Conformational studies indicate that the alpha-helical content of HMGa increases significantly when it binds to 4H compared to that after binding to P31, linear DNA. In contrast, linear DNA, but not 4H, undergoes substantial conformational change when it binds to HMGa, indicating that linear DNA is relatively more flexible than 4H. A more significant difference in the affinities of binding of the mutants of HMGa to 4H was observed compared to their affinities of binding to linear DNA, P31. These differences could be due to the rigidity of the DNA and the characters of the AT hook regions in the mutants.

Amino Acid Sequence↗
PubMed2003

Rice HMGB1 protein recognizes DNA structures and bends DNA efficiently.

We analyzed the DNA-binding and DNA-bending properties of recombinant HMGB1 proteins based on a rice HMGB1 cDNA. Electrophoretic mobility shift assay demonstrated that rice HMGB1 can bind synthetic four-way junction (4H) DNA and DNA minicircles efficiently but the binding to 4H can be completed out by HMGA and histone H1. Conformational changes were detected by circular dichroism analysis with 4H DNA bound to various concentrations of HMGB1 or its truncated forms. T4 ligase-mediated circularization assays with short DNA fragments of 123 bp showed that the protein is capable of increasing DNA flexibility. The 123-bp DNA formed closed circular monomers efficiently in its presence, similar to that in an earlier study on maize HMG. Additionally, our results show for the first time that the basic N-terminal domain enhances the affinity of the plant HMGB1 protein for 4H DNA, while the acidic C-terminal domain has the converse effects.

Base Sequence↗
PubMed2003

Interaction of wheat high-mobility-group proteins with four-way-junction DNA and characterization of the structure and expression of HMGA gene.

Plant high-mobility-group (HMG) chromosomal proteins are the most abundant and ubiquitous nonhistone proteins found in the nuclei of higher eukaryotes. There are only two families of HMG proteins, namely, HMGA and HMGB in plants. The cDNA encoding wheat HMGa protein was isolated and characterized. Wheat HMGA cDNA encodes a protein of 189 amino acid residues. At its N terminus, there is a histone H1-like structure, which is a common feature of plant HMGA proteins, followed by four AT-hook motifs. Polymerase chain reaction results show that the gene contains a single intron of 134 bp. All four AT-hook motifs are encoded by the second exon. Northern blot results show that the expression of HMGA gene is much higher in organs undergoing active cell proliferation. Gel retardation analysis show that wheat HMGa, b, c and histone H1 bind to four-way-junction DNA with high binding affinity, but affinity is dramatically reduced with increasing Mg(2+) and Na(+) ion concentration. Competition binding studies show that proteins share overlapping binding sites on four-way-junction DNA. HMGd does not bind to four-way-junction DNA.

AT-Hook Motifs↗