Biomedical subjects

Xiao Wang

Publications and source records attributed to Xiao Wang.

At least 37 records · Page 2Linked to original sources

PubMed2006

GEPS: the Gene Expression Pattern Scanner.

Gene Expression Pattern Scanner (GEPS) is a web-based server to provide interactive pattern analysis of user-submitted microarray data for facilitating their further interpretation. Putative gene expression patterns such as correlated expression, similar expression and specific expression are determined globally and systematically using geometric comparison and correlation analysis methods. These patterns can be visualized via linear plot with quantitative measures. User-defined threshold value is allowed to customize the format of the pattern search results. For better understanding of gene expression, patterns derived from 329,205 non-redundant gene expression records from the GNF SymAltas and the Gene Expression Omnibus are also provided. These profiles cover 24,277 human genes in 79 tissues, 32,905 mouse genes in 61 tissues and 4201 rat genes in 44 tissues. GEPS is available at http://bioinf.xmu.edu.cn/software/geps/geps.php.

Animals↗

PubMed2006

Heterogeneous reactions of sulfur dioxide on typical mineral particles.

The heterogeneous reaction of SO2 on Al2O3, CaO, TiO2, MgO, FeOOH, Fe2O3, MnO2, and SiO2, as well as authentic aerosol sample, was investigated by using a White Cell coupled with in situ-FTIR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). Simultaneous observations of reactants and products were performed to obtain full information on the mechanism and kinetics of the reactions. SO2 was irreversibly adsorbed to form surface sulfite (SO3(2-)), bisulfite (HSO3(-)), and sulfate (SO4(2-)). The reactivity order of these particles is the following: FeOOH >Al2O3 > mixture > MgO > Fe2O3 > SiO2. Field-collected aerosol showed significant activity for the oxidation of SO2. The uptake coefficient of SO2 on Al2O3 with different acidity varied in the order of basic Al2O3 > neutral Al2O3 > acidic Al2O3. The surface-active oxygen and hydroxyl might be the key factors for the conversion of SO2 to SO4(2-). The faster reaction rate could be achieved with greater surface area on particles with the same mass. On the basis of the same surface area Fe2O3 could be most reactive in the reaction with SO2 compared with all other particles. The apparent rate constants were determined to be 1.35 x 10(-2) and 9.4 x 10(-3) for uptake on Al2O3 and MgO, respectively, which are the same as the results of other scientists.

Journal Article↗

PubMed2006

Comparison of clonogenic assay with premature chromosome condensation assay in prediction of human cell radiosensitivity.

AIM: To determine whether the number of non-rejoining G2-chromatid breaks can predict the radiosensitivity of human cell lines. METHODS: Cell lines of human ovary carcinoma cells (HO8910), human hepatoma cells (HepG2) and liver cells (L02) were irradiated with a range of doses and assessed both of cell survival and non-rejoining G2-chromatid breaks at 24 h after irradiation. Cell survival was documented by a colony assay. Non-rejoining G2-chromatid breaks were measured by counting the number of non-rejoining G2 chromatid breaks at 24 h after irradiation, detected by the prematurely chromosome condensed (PCC) technique. RESULTS: A linear-quadratic survival curve was observed in three cell lines, and HepG2 was the most sensitive to gamma-radiation. A dose-dependent linear increase was observed in radiation-induced non-rejoining G2-PCC breaks measured at 24 h after irradiation in all cell lines, and HepG2 was the most susceptible to induction of non-rejoining G2-PCC breaks. A close correlation was found between the clonogenic radiosensitivity and the radiation-induced non-rejoining G2-PCC breaks (r = 0.923). Furthermore, survival-aberration correlations for two or more than two doses lever were also significant. CONCLUSION: The number of non-rejoining G2 PCC breaks holds considerable promise for predicting the radiosensitivity of normal and tumor cells when two or more than two doses lever is tested.

Cell Line, Tumor↗

PubMed2006

Large-scale separation of alkaloids from Corydalis decumbens by pH-zone-refining counter-current chromatography.

pH-zone-refining counter-current chromatography was successfully applied to the separation of alkaloids from a crude extract of Corydalis decumbens (Thunb.) Pers. using a multilayer coil planet centrifuge (CPC). The experiment was performed with a two-phase solvent system composed of methyl tert-butyl ether (MtBE)-acetonitrile-water (2:2:3, v/v) where triethylamine (5-10 mM) was added to the upper organic stationary phase as a retainer and hydrochloric acid (5-10 mM) to the aqueous mobile phase as an eluter. From 3.1 g of the crude extract, 495 mg protopine, 626 mg tetrahydropalmatine and 423 mg bicuculline were obtained each with a purity of over 93% as determined by high performance liquid chromatography. The structures of the isolated compounds were identified by electron ionization mass spectrometry (EI-MS), high-performance liquid chromatography (HPLC)-electrospray ionisation-mass spectrometry (ESI-MS) and 1H NMR.

Acetonitriles↗

PubMed2006

Role and mechanism of rosiglitazone on the impairment of insulin secretion induced by free fatty acids on isolated rat islets.

BACKGROUND: Prolonged exposure of pancreatic beta-cells to fatty acids increases basal insulin secretion but inhibits glucose-stimulated insulin secretion. Rosiglitazone is a new antidiabetic agent of the thiazolidinediones. However, the relationship between thiazolidinediones and insulin secretion is highly controversial. The aim of this study is to explore the effect and mechanism of rosiglitazone on insulin secretion of islets under chronic exposure to free fatty acids (FFA). METHODS: Pancreatic islets were isolated from the pancreata of male Sprague-Dawley rats by the collagenase digestion and by the dextran gradient centrifugation method. The purified islets were cultured in the presence or absence of rosiglitazone and palmitate for 48 hours. The insulin secretion was measured by radioimmunoassay. The mRNA level of peroxisome proliferator-activated receptor gamma, uncoupling protein 2 (UCP-2) and insulin were determined by real-time polymerase chain reaction (PCR). The cell cytotoxicity assay was measured by cell counting kit-8. RESULTS: Islets exposed to elevated palmitate for 48 hours showed an increased basal and a decreased glucose-stimulated insulin secretion (P < 0.01). The mRNA level of UCP-2 was increased by 3.7 fold in the 0.5 mmol/L concentration of palmitate. When islets were cultured with palmitate (0.5 mmol/L) in the presence of rosiglitazone (1.0 micromol/L), both basal and glucose-stimulated insulin secretion reversed to a pattern of control islets (P < 0.05, P < 0.01). The addition of rosiglitazone in the culture medium decreased the mRNA level of UCP-2 by 2.2 fold, having a statistically significant difference (P < 0.05) as compared with islets cultured with palmitate alone. The cell viability was not affected. CONCLUSION: The protective effects of rosiglitazone on insulin secretion of isolated pancreatic islets under chronic exposure to palmitate might be mediated through the downregulation of UCP-2 expression.

Animals↗

PubMed2006

Acquiring 1053 nm femtosecond laser emission by optical parametric amplification based on supercontinuum white-light injection.

We report a terawatt-Ti:sapphire-laser-pumped high-energy femtosecond optical parametric amplifier (OPA) with supercontinuum white-light injection. Signal pulses with a duration less than 100 fs and energy up to 4 mJ are obtained with large-aperture LiNbO3 crystals. This megajoule-class femtosecond OPA at 1053 nm presents a feasible alternative to optical parametric chirped-pulse amplification and is ready to be applied to petawatt lasers.

Journal Article↗

PubMed2006

Characterization of a fungal strain capable of degrading chlorpyrifos and its use in detoxification of the insecticide on vegetables.

A fungal strain capable of utilizing chlorpyrifos as sole carbon and energy sources was isolated from soil by enrichment cultivation approach. The half-lives of degradation (DT(50)) for chlorpyrifos at concentrations of 1, 10, and 100 mg l(-1) by the fungal strain DSP in mineral salt medium were measured to be 2.03, 2.93, and 3.49 days, respectively. Two cell-free extracts [E (1:10) and E (1:20)] from the fungal strain DSP in bran-glucose medium were prepared and used to enhance chlorpyrifos degradation on vegetables. Compared with the controls, the DT(50) of chlorpyrifos were reduced by 70.3%, 65.6%, 80.6%, 80.6%, and 86.1%, and by 53.8%, 43.2%, 66.0%, 54.3%, and 67.7% on E (1:20) and E (1:10) treated pakchoi, water spinach, Malabar spinach, haricot beans, and pepper, respectively. The 7-day residual values (R (7)) of chlorpyrifos on E (1:10) treated vegetables were all lower than the corresponding maximum residue levels of European Union (EU MRLs), except that the R (7) value on haricot beans was slightly higher than the corresponding EU MRLs. The results indicate that cell-free extracts could rapidly degrade chlorpyrifos residues on vegetables.

Biodegradation, Environmental↗

PubMed2006

A bottom-up approach to gene regulation.

The ability to construct synthetic gene networks enables experimental investigations of deliberately simplified systems that can be compared to qualitative and quantitative models. If simple, well-characterized modules can be coupled together into more complex networks with behaviour that can be predicted from that of the individual components, we may begin to build an understanding of cellular regulatory processes from the 'bottom up'. Here we have engineered a promoter to allow simultaneous repression and activation of gene expression in Escherichia coli. We studied its behaviour in synthetic gene networks under increasingly complex conditions: unregulated, repressed, activated, and simultaneously repressed and activated. We develop a stochastic model that quantitatively captures the means and distributions of the expression from the engineered promoter of this modular system, and show that the model can be extended and used to accurately predict the in vivo behaviour of the network when it is expanded to include positive feedback. The model also reveals the counterintuitive prediction that noise in protein expression levels can increase upon arrest of cell growth and division, which we confirm experimentally. This work shows that the properties of regulatory subsystems can be used to predict the behaviour of larger, more complex regulatory networks, and that this bottom-up approach can provide insights into gene regulation.

Arabinose↗

PubMed2006

A clinical assessment of the Glidescope videolaryngoscope in nasotracheal intubation with general anesthesia.

STUDY OBJECTIVES: To evaluate the efficacy and safety of the Glidescope videolaryngoscope as a device to aid nasotracheal intubation, and to determine whether the GSVL provides a better laryngeal view in patients with difficult laryngoscopy compared with the Macintosh laryngoscope. DESIGN: Prospective, clinical study. SETTING: Two university hospitals. PATIENTS: 156 healthy adult ASA physical status I and II undergoing elective plastic and intraoral surgery with general anesthesia. INTERVENTIONS: After anesthesia induction with intravenous injection of fentanyl 2 microg/kg, propofol 2 mg/kg, and vecuronium 0.1 mg/kg, nasotracheal intubation was performed using GSVL. MEASUREMENTS: Preoperative airway measurements were taken to predict potential difficult airways. During nasotracheal intubation using GSVL, laryngeal views, times required for full visualization of glottis and successful intubation, difficulty encountered and auxiliary maneuvers adopted, and upper airway trauma were recorded. The laryngeal views obtained by GSVL and by Macintosh laryngoscope were compared. MAIN RESULTS: The laryngeal views obtained by GSVL in all patients were Cormack and Lehane (C&L) grades I and II, and the success rate of intubation using GSVL at one attempt was 98.1%. The times required for visualization of the glottis and successful intubation were 40.2 +/- 11.5 s and 52.7 +/- 12.3 seconds, respectively. Patients with C&L grade II needed more auxiliary maneuvers to achieve successful intubation than did those with C&L grade I (P < 0.001). In 36 patients with potential difficult airways, the frequency of difficult laryngoscopy (C&L grades III and IV) with the Macintosh laryngoscope (58.3%) was significantly higher than with the GSVL (0%, P < 0.05). The frequency of minor upper airway trauma was 4.5%. CONCLUSIONS: The GSVL is an effective device for nasotracheal intubation and may be incorporated easily into routine clinical practice. Compared with the Macintosh laryngoscope, the GSVL can provide an improved laryngeal view in the patient with difficult airway.

Adolescent↗

PubMed2006

Paracrine release of insulin-like growth factor 1 from a bioengineered tissue stimulates skeletal muscle growth in vitro.

Bioengineered tissues transduced to secrete recombinant proteins may serve as a long-term delivery vehicle for therapeutic proteins when implanted in vivo. Insulin-like growth factor 1 (IGF1) is an anabolic growth factor for skeletal muscle that can stimulate myoblast proliferation and myofiber hypertrophy. To determine whether the release of IGF1 from an engineered bioartificial skeletal muscle (BAM) could stimulate the growth of skeletal muscle in a paracrine manner, we established an in vitro perfusion system for genetically engineered IGF1 BAMs. BAMs were bioengineered from C2C12 murine myoblasts stably transduced with a retroviral vector to synthesize and secrete IGF1 (C2-IGF1 BAMs). C2-IGF1 BAMs or nontransduced control C2 BAMs were cocultured with avian BAMS (ABAMs) in constantly perfused biochambers. During 11 days of perfusion, IGF1 levels in the C2-IGF1 BAM perfusion medium increased linearly from 1 to 20 ng/mL. The ABAMs maintained in biochambers with the C2-IGF1 BAMs had significantly more myofibers (69%, p < 0.005) and larger myofiber cross-sectional areas (40%, p < 0.001) compared to those cocultured with control C2 BAMs. These studies show that levels of IGF1 secreted from the C2-IGF1 BAMs are sufficient to produce an anabolic paracrine effect on nongenetically engineered BAMs, and the in vitro perfusion system provides a model for screening proteins effective in stimulating localized skeletal muscle growth.

Animals↗

PubMed2006

On image matrix based feature extraction algorithms.

Principal component analysis (PCA) and linear discriminant analysis (LDA) are two important feature extraction methods and have been widely applied in a variety of areas. A limitation of PCA and LDA is that when dealing with image data, the image matrices must be first transformed into vectors, which are usually of very high dimensionality. This causes expensive computational cost and sometimes the singularity problem. Recently two methods called two-dimensional PCA (2DPCA) and two-dimensional LDA (2DLDA) were proposed to overcome this disadvantage by working directly on 2-D image matrices without a vectorization procedure. The 2DPCA and 2DLDA significantly reduce the computational effort and the possibility of singularity in feature extraction. In this paper, we show that these matrices based 2-D algorithms are equivalent to special cases of image block based feature extraction, i.e., partition each image into several blocks and perform standard PCA or LDA on the aggregate of all image blocks. These results thus provide a better understanding of the 2-D feature extraction approaches.

Algorithms↗

PubMed2006

[Fluid management in orthotopic liver transplantation].

OBJECTIVE: To investigate the influential factors of fluid management during orthotopic liver transplantation surgery. METHODS: Ninety-six patients scheduled for orthotopic liver transplantation were divided into two groups according to the liver function: the decompensatory group (Child-Pugh score C, n=50) and the compensatory group (Child-Pugh score A or B, n=46). According to the intraoperative bleeding amount, the compensatory group was further divided into subgroup A (< 2,000 ml) and subgroup B (> or = 2,000 ml). Plasma albumin concentration and the parameters of blood coagulation were measured before and after the surgery. The intraoperative bleeding amount and the amount of the blood products infused were recorded. RESULTS: Before the surgery, prothrombin time (PT) and activated partial thromboplastin time (APTT) were significantly longer in decompensatory group than in compensatory group (both P<0.05); blood platelets (PLT) and fibrinogen were significantly lower in decompensatory group than in compensatory group (both P<0.05). After the surgery, there were no significant differences in PT, APTT, PLT, and fibrinogen between the two groups (all P>0.05). The amounts of the blood products infused intraoperatively in subgroup A were significantly lower than those in the decompensatory group (all P<0.05). There was no significant difference in the amount of the infused blood products between the subgroup B and decompensatory group (all P>0.05). CONCLUSION: During orthotopic liver transplantation surgery, patients with decompensatory liver function, or those who suffered large amounts of intraoperative bleeding, need infusion of larger amount of blood products.

Adolescent↗

PubMed2006

Dissipation of chlorpyrifos in pakchoi-vegetated soil in a greenhouse.

The dissipation of chlorpyrifos in pakchoi-vegetated soil was investigated in the summer and autumn in a greenhouse and field, respectively. The dissipation of chlorpyrifos in pakchoi-grown soil was comparatively described by fitting the residue data to seven models (1st-order, 1.5th-order, 2nd-order, RF 1st-order, RF 1.5th-order, RF 2nd-order, and bi-exponential or two-compartment models). Statistical analysis was performed using the SPSS 11.5 statistical package. The bi-exponential model was selected as the optimal model according to the coefficient of determination r2. The dissipation half-lives (DT50) of chlorpyrifos in pakchoi-vegetated soil at the recommended dose in the summer and autumn, calculated by the bi-exponential model, were 0.6 and 1.2 d in a greenhouse, 0.4 and 1.0 d in a field, respectively; the corresponding values at double dose were 1.2 and 2.1 d in a greenhouse, 0.5 and 1.3 d in a field, respectively. The kinetic data indicate the dissipation of chlorpyrifos in pakchoi-grown soil in a greenhouse is slower than that in a field, and dissipates slower in the autumn than in the summer.

Agriculture↗

PubMed2005

Preparative separation of cichoric acid from Echinacea purpurea by pH-zone-refining counter-current chromatography.

pH-zone-refining counter-current chromatography was successfully applied to the separation of cichoric acid from Echinacea Purpurea (L.) Moench. A 3.0 g quantity of sample was separated using the following two-phase solvent system: MtBE-CH3CN-water (4:1:5, v/v), 10 mM trifluoroacetic acid in organic stationary phase and 10 mM ammonia in aqueous mobile phase. The obtained fractions were analyzed by high-performance liquid chromatography and negative ion electrospray ionization mass spectrometry. Double separations were performed with the same solvent system yielding 563 mg cichoric acid at 95.6% purity.

Caffeic Acids↗

PubMed2005

Bistability, stochasticity, and oscillations in the mitogen-activated protein kinase cascade.

Signaling pathways respond to stimuli in a variety of ways, depending on the magnitude of the input and the physiological status of the cell. For instance, yeast can respond to pheromone stimulation in either a binary or graded fashion. Here we present single cell transcription data indicating that a transient binary response in which all cells eventually become activated is typical. Stochastic modeling of the biochemical steps that regulate activation of the mitogen-activated protein kinase Fus3 reveals that this portion of the pathway can account for the graded-to-binary conversion. To test the validity of the model, genetic approaches are used to alter expression levels of Msg5 and Ste7, two of the proteins that negatively and positively regulate Fus3, respectively. Single cell measurements of the genetically altered cells are shown to be consistent with predictions of the model. Finally, computational modeling is used to investigate the effects of protein turnover on the response of the pathway. We demonstrate that the inclusion of protein turnover can lead to sustained oscillations of protein concentrations in the absence of feedback regulation. Thus, protein turnover can profoundly influence the output of a signaling pathway.

Biological Clocks↗

PubMed2005

Preparative isolation and purification of polymethoxylated flavones from Tangerine peel using high-speed counter-current chromatography.

Several polymethoxylated flavones including nobiletin, 3,5,6,7,8,3',4'-heptamethoxyflavone, tangeretin and 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone were separated from Tangerine peel (Juhong in Chinese) by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.8:1:1, v/v). Then, 26 mg of nobiletin, 6 mg of 3,5,6,7,8,3',4'-heptamethoxyflavone, 35 mg of tangeretin and 11 mg of 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone could be obtained from 150 mg crude extracts and their purities were 98.6%, 95.9%, 99.8% and 96.8%, respectively. All these constituents were identified by EI-MS and 1H NMR.

Citrus↗

PubMed2005

Isolation and purification of four flavonoid constituents from the flowers of Paeonia suffruticosa by high-speed counter-current chromatography.

Four flavonoids, apigenin-7-O-neohesperidoside, luteolin-7-O-glucoside, apigenin-7-O-glucoside and kaempferol-7-O-glucoside have been isolated and purified for the first time from the flowers of Paeonia suffruticosa by high-speed counter-current chromatography with a two-phase solvent system composed of ethyl acetate-ethanol-acetic acid-water (4:1:0.25:5, v/v). Then, 5 mg apigenin-7-O-neohesperidoside, 4 mg luteolin-7-O-glucoside, 9 mg apigenin-7-O-glucoside and 2.5 mg kaempferol-7-O-glucoside could be obtained after injecting 40 mg sample and their purities were 94, 97, 97 and 96%, respectively. All these constituents were identified by mass spectrometry and nuclear magnetic resonance.

Chromatography, High Pressure Liquid↗

PubMed2005

Light, medium, and heavy fluorous triarylphosphines exhibit comparable reactivities to triphenylphosphine in typical reactions of triarylphosphines.

[reaction: see text] The relative reactivities of triphenylphosphine (PPh(3)) and three fluorous triarylphosphines [(p-R(F)(CH(2))(2)C(6)H(4))(n)PPh(3)(-)(n), where n = 1-3] have been compared in internal competition experiments. Product ratios were determined by (31)P NMR spectroscopy. The four phosphines have about the same reactivities in oxidation, alkylation, and Staudinger reactions and give comparable yields in a preparative Mitsunobu reaction. Previously observed rate and yield differences in Staudinger reactions of the fluorous phosphines are attributed to solubility effects, not reactivity differences. A light fluorous phosphine [(p-C(8)F(17)(CH(2))(2)C(6)H(4))PPh(2)] outperforms a commercially available resin-bound phosphine in a competitive benzylation experiment by a factor of about 4.

Catalysis↗