Biomedical subjects

Tao Liu

Publications and source records attributed to Tao Liu.

At least 91 records · Page 5Linked to original sources

PubMed2006

[Isolation and determination of homoeriodictyol-7-O-beta-D-glycoside in Viscum coloratum].

The homoeriodictyol-7-O-beta-D-glycoside was isolated from Viscum coloratum and identified by mass spectrometry and nuclear magnetic resonance (NMR) (1H NMR and 13C NMR). A method for determination of homoeriodictyol-7-O-beta-D-glycoside in Viscum coloratum was developed by using a Kromasil C18 column (200 mm x 4.6 mm i.d., 5 microm) with a mixture of acetonitrile and 0.5% glacial acetic acid solution (18:82, v/v) as mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 284 nm and temperature was set at 30 degrees C. The volume of injection was 10 miccro L. Good linear relationship (r = 0.9997) between the mass concentration and the peak area of homoeriodictyol-7-O-beta-D-glycoside was obtained in the range of 1.0-32.0 mg/L. The recoveries were found to be in the range of 96.0%-100.1%. The results of the experiments demonstrated that the established method is rapid and simple with good accuracy and reproducibility. The method is suitable for the quality control of Viscum coloratum from different sources.

Flavonoids↗

PubMed2006

[Simultaneous determination of five isoflavonoids in commercial Radix Astragali by high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method (RP-HPLC) was developed for the simultaneous analysis of five isoflavonoids of Huangqi, the roots of Astragalus mongholicus. HPLC determination was performed on a Diamonsil C18 column (200 mm x 4.6 mm i.d., 5 microm) and detected at 230 nm. The mobile phase consisted of (A) acetonitrile and (B) water. Gradient program was adopted as follows: 0-25 min from 17% A to 31% A, 25 -45 min 35% A. The flow rate was maintained at 1.0 mL/min. The method was proved to be linear in the ranges of 20.12-201.2 mg/L (r = 0.9992), 4.62-46.2 mg/L (r = 0.9997), 4.86 -48.6 mg/L (r = 0.9997), 9.24-92.4 mg/L (r = 0.9995) and 6.92-69.2 mg/L (r = 0. 999 5) for the five isoflavonoids, calycosin-7-O-beta-D-glucoside, formononetin-7-O-beta-D-glucoside,9,10-dimethoxypterocarpan-3-O-beta-D-glucoside, calycosin and formononetin, respectively. The recoveries were greater than 94%, and relative standard deviations were less than 3.2%. The method has been successfully applied to the simultaneous determination of the five isoflavonoids of radix astragali.

Astragalus Plant↗

PubMed2006

[Experimental study on corneal organ culture preservation and its application].

OBJECTIVE: To develop a optimal method of corneal organ culture preservation, to evaluate the characteristics of organ cultured cornea and to examine the feasibility of application of organ cultured corneas. METHODS: Thirty-six adult New Zealand rabbit corneas were stored in the closed storage system consisting of fetal calf serum and were transferred to a hyperosmosis dextran-containing medium for 48 hours' deswelling for further experiment after storage for 1, 2, 3 and 4 weeks. The measurement of corneal endothelium density and central thickness was performed prior to and after the storage. The morphology and the contamination of preserved cornea, as well as allogenic grafts' conditions within 7 days after corneal transplantation were also observed. The class II MHC antigen immunofluorescence marker was performed for the examination of corneal dendritic cells by confocal microscopy. RESULTS: The corneal organ culture preservation was successfully established. The contamination rate was approximately 8.3%. All of the rabbit corneas stored within 4 weeks remained transparent. There were little folds in peripheral descemet's membrane when the storage time was up to 3 weeks and the whole descemet's membrane folds was seen when the corneas had been preserved for 4 weeks. The density of corneal endothelium decreased when the preservation time was extended. The loss of corneal endothelium preserved up to 4 weeks was 15.7%. Correlation existed between the thickness of center cornea and the preservation time. The average central thickness of the cornea was 0.7 mm after 4 weeks. The light micrographs showed that the endothelium layer still covered the descemet's membrane completely after 4 weeks. The dendritic cells resided in the limbus epithelium and they were lost after stored for 3 weeks. After allogenic corneal transplantation, the grafts retained transparency within 7 days postoperatively, which indicated that there was no primary failure of grafts. CONCLUSION: Corneal organ culture preservation can ensure the normal function of cultured cornea within a certain preservation time and offer some advantages, e.g. the decrease of corneal immunogenicity.

Animals↗

PubMed2006

[Clinical characteristics of Candida septicemia seen in a neonatal intensive care unit: analysis of 9 cases].

OBJECTIVE: To analyze the clinical characteristics of Candida septicemia occurred in neonatal intensive care unit (NICU). METHODS: The clinical characteristics of 9 confirmed cases with septicemia caused by Candida species yeasts were analyzed and summarized. RESULTS: All the 9 cases were preterm infants, including 6 cases of very low birth weight infants. All these cases were treated with broad-spectrum antibiotics and parenteral nutrition before fungal infections occurred. Eight cases had percutaneous inserted central catheter (PICC). Three cases had been on ventilator. The symptoms of fungal infection were presented at 8 to 22 days of age. Apnea, poor perfusion and lethargy were common symptoms of these cases with fungal infection. Seven of the 9 cases developed thrombocytopenia. C reactive protein was elevated in 7 cases. Blood culture showed C. albicans in 1 case, C. parapsilosis in 2 cases, and C. guilliermondii in 6 cases. In 5 cases PICC culture showed the same fungus as blood culture revealed at the same time. All the 9 patients received antifungal therapy. Six patients were cured, two died and in one patient the treatments were given up by the parents. CONCLUSIONS: The high risk factors of Candida septicemia in newborn infants include preterm, PICC, broad-spectrum antibiotic therapy and mechanical ventilation. The clinical presentations are always nonspecific. Thrombocytopenia and elevated C reactive protein are common in Candida septicemia patients. Early-started antifungal therapy can improve the prognosis.

Antifungal Agents↗

PubMed2006

[Cloning human heat shock protein 90beta-cDNA and constructing its eukaryon vector].

The purpose of this study was to clone human HSP90beta cDNA and construct its eukaryote expression vector . The total RNA was isolated by TRIzol Reagent (Invitrogen) from human NPC and its cDNA was gained by RT-PCR. The purified RT-PCR products and PGEM-T Easy Vector were ligated and transformed into XL1-blue E. coli bacteria. The white clones were selected and the plasmid was purified, which was further identified by double enzyme digestion and sequenced. PGEM-hHSP90beta and pcDNA3.1(+) DNA were digested by AflII and Xbal respectively. After purification, the two fragments obtained were ligased by using T4 DNA ligase (Fermentas). This recombinant DNA was then transformed into E. coli Competent Cells XL1-blue and positive clones were selected on the LB agarose plate containing Ampr (100 microg/ml). Single clones were identified by double digestion with AflII and Xbal, and two fragments with the size 5.4 kb and 2.1 kb were produced as expected. The hHSP90beta gene was successfully inserted into the eukaryote expression vector pcDNA3.1(+) by the recombination technique in vitro.

Cloning, Molecular↗

PubMed2005

Redundant and synergistic effect of Cdx-2 and Brn-4 on regulating proglucagon gene expression.

Cdx-2 and Brn-4 are recognized as transcriptional activators for the proglucagon gene. These two homeodomain (HD) proteins are able to interact with the correspondent motifs on the G1 enhancer element of proglucagon promoter, separated by only 8 bp. We have examined Brn-4 expression in proglucagon-producing cells, isolated hamster Brn-4 cDNA, and localized its activation domain. Ectopic expression of either Cdx-2 or Brn-4 in the pancreatic B cell line In111 provoked it to express proglucagon mRNA, whereas ectopically expressing both of them further stimulated proglucagon mRNA expression in this cell line. Furthermore, Brn-4 was found to synergize with Cdx-2 in activating proglucagon promoter, and the Brn-4 activation domain was not required for this synergistic activation. When the binding site for either Cdx-2 or Brn-4 was mutated, the synergistic activation by these two HD proteins was significantly attenuated, but not abolished. We propose that both cooperative DNA binding and mutual recruitment between Cdx-2 and Brn-4 are involved in this synergistic activation and have detected physical interaction between Cdx-2 and Brn-4 by glutathione-S-transferase-fusion protein pull-down assay. Our observations suggest that Cdx-2 and Brn-4, two HD proteins that belong to two different families, exert a synergistic and redundant effect on proglucagon gene expression.

Animals↗

PubMed2005

Differential gene expression during stationary phase between amicronucleates and micronucleates of the ciliated protist, Pseudourostyla cristata.

Ciliates are unicellular eukaryotic organisms with two types of nuclei, the 'germline' micronucleus (MIC) and the 'somatic' macronucleus (MAC). We previously reported that when the MIC of Pseudourostyla cristata was eliminated by amputation, the resultant amicronucleate organisms exhibited a lower viability and abnormal oral structures. To gain insight into the genetic reorganization involved in or induced by removal of the MIC and the mechanism by which nuclear dimorphism was established, we investigated gene expression differences between amicronucleates and micronucleates, using suppression subtractive hybridization (SSH) techniques. Approximately 250 clones from each library were screened by cDNA array dot blotting. Altogether, 22 unique genes from the forward-subtractive library (micronucleates as tester, amicronucleates as driver) and 23 unique genes from the reverse-subtractive library (micronucleates as driver and amicronucleates as tester) were shown to be differentially expressed. These 45 differentially expressed genes were found to be homologs of genes involved in various cellular processes including signal transduction, transcription, cell cycle accomplishment and general metabolism, cell structure, and stress response. We highlighted 14 genes, 7 that were unique from both the forward-subtractive and the reverse-subtractive libraries, using real time semi-quantitative RT-PCR. The characterization of these cDNAs represents a starting point in understanding the molecular mechanisms of amicronucleates disruption.

Animals↗

PubMed2005

Size effect of polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability.

In this paper, the size effect of the polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability has been studied. Polydiacetylene vesicles in which were incorporated glycolipids acted as a model system for the affinochromatic property. Visible color changes from blue to red could be observed to the naked eye owing to Con A binding to the sugar moiety and be detected quantitatively by the visible absorption spectrum. In the experiment, small and uniform vesicles were obtained after extrusion through membranes with different pore sizes. The morphology and mean size distribution of the extruded vesicles were studied by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. Our work shows that the smaller the vesicles are, the stronger is the effect, making the detection of Con A easier. The results may apply to the sensitivity enhancement of polydiacetylene biosensors for the recognition of other biomolecules.

Colorimetry↗

PubMed2005

Intersection of nonidentical optical waveguides based on photonic crystals.

An intersection based on photonic crystal coupled resonator optical waveguides is proposed and analyzed. The two waveguides are designed to have different transmission bands without overlap, which enables light in the two corresponding bands to propagate through the intersection with no cross talk and with excellent transmission. The MIT Photonic-Bands code is used to calculate the band structures of photonic crystal waveguides. The finite-difference time-domain method is used to simulate the relevant structures.

Journal Article↗

PubMed2005

Rhinosinusitis derived Staphylococcal enterotoxin B possibly associates with pathogenesis of ulcerative colitis.

BACKGROUND: During clinical practice, we noticed that some patients with both ulcerative colitis (UC) and chronic rhinosinusitis (CRS) showed amelioration of UC after treatment of CRS. This study was designed to identify a possible association between CRS and UC. METHODS: Thirty-two patients with both CRS and UC received treatment with functional endoscopic sinus surgery (FESS) for CRS. Clinical symptom scores for CRS and UC, as well as serum levels of anti-Staphylococcal enterotoxin B (SEB) were evaluated at week 0 and week 12. Sinus wash fluid SEB content was measured with enzyme-linked immunosorbent assay (ELISA). The surgically removed tissues were cultured to identify growth of Staphylococcus. aureus (S. aureus). Immunohistochemistry was employed to identify anti-SEB positive cells in the colonic mucosa. Colonic biopsies were obtained and incubated with SEB. Mast cell activation in the colonic mucosa in response to incubation with SEB was observed with electron microscopy and immunoassay. RESULTS: The clinical symptom scores of CRS and UC severe scores (UCSS) were significantly reduced in the UC-CRS patients after FESS. The number of cultured S. aureus colonies from the surgically removed sinus mucosa significantly correlated with the decrease in UCSS. High levels of SEB were detected in the sinus wash fluids of the patients with UC-CRS. Histamine and tryptase release was significantly higher in the culture supernate in the patients with UC-CRS than the patients with UC-only and normal controls. Anti-SEB positive cells were located in the colonic mucosa. CONCLUSION: The pathogenesis of UC in some patients may be associated with their pre-existing CRS by a mechanism of swallowing sinusitis-derived SEB. We speculate that SEB initiates inappropriate immune reactions and inflammation in the colonic mucosa that further progresses to UC.

Adult↗

PubMed2005

High level expression of functionally active human lactoferrin in silkworm larvae.

In this paper, recombinant human lactoferrin (rhLf) was expressed very well using Bombyx mori nuclear polyhedrosis baculovirus expression system. Infection of silkworm larvae with recombinant virus, vBm-hLf, the rhLf was efficiently secreted into larvae hemolymph and the concentration of product purified was about 65 microg/ml. The isolated rhLf molecular mass was approximately 78 kDa, lower than that of the human lactoferrin (hLf) standards, which may be due to incomplete glycosylation or protein degradation. Furthermore, the rhLf was characterized and its biological activities were evaluated by in vivo bioassay using dextran sodium sulfate (DSS)-induced colitis mouse model that mimics some characteristics of colitis disease in human. We conclude that silkworm expression system can be used successfully to express functional human lactoferrin.

Animals↗

PubMed2005

Metabolic profiling of livers and blood from obese Zucker rats.

BACKGROUND/AIMS: Obesity frequently leads to changes in fatty acid metabolism with subsequent fatty infiltration in the liver. METHODS: In this study, metabolic profile of the livers and blood from lean and obese Zucker rats was established based on quantitative nuclear magnetic resonance spectroscopy (NMR) analysis. RESULTS: (1)H NMR on liver lipid extracts indicated significantly increased concentrations of total fatty acids and triglycerides. (31)P NMR on liver extracts revealed that obese livers have a compromised energy balance (low [ATP/ADP]) with decreased mitochondrial activity. Simultaneously, increased glycolytic activity was detected. The most pronounced differences were highly increased methionine and decreased betaine concentrations in obese animals. This suggests a significant alteration in methionine metabolism, which may be in part responsible for the development of steatosis, induction of mitochondrial dysfunction, and increased vulnerability of fatty livers to ischemia/reperfusion injury. A trend towards decreased hepatic glutathione concentrations as well as a reduced [PUFA/MUFA] ratio were present in the obese group, indicating increased oxidative stress and lipid peroxidation. CONCLUSIONS: In conclusion, NMR analysis on blood and liver tissue from obese Zucker rats reveals specific metabolic abnormalities in mitochondrial function and methionine metabolism, which result in a decreased hepatic energy state.

Animals↗

PubMed2005

Effect of nano cadmium sulfide on the electron transfer reactivity and peroxidase activity of hemoglobin.

Hemoglobin (Hb) is immobilized with cadmium sulfide (CdS) nanoparticles (NPs) on pyrolytic graphite (PG) electrode to characterize the electrochemical reactivity and peroxidase activity of the protein. The result demonstrates that fine redox waves of Hb can be achieved after this protein is entrapped in CdS NPs. Meanwhile, the protein can exhibit nice catalytic activity towards hydrogen peroxide (H2O2). Linear relationship between the reductive peak current and the H2O2 concentration has been obtained from 5.0 x 10(-6) to 4.0 x 10(-4) mol/L, on the basis of which a new kind of H2O2 biosensor might be developed in the future.

Biosensing Techniques↗

PubMed2005

DNA electrochemistry through the base pairs not the sugar-phosphate backbone.

Using intercalated, covalently bound daunomycin as a redox probe, ground state charge transport in DNA films with a perturbation in base pair stacking was examined in comparison with breaks in the sugar-phosphate backbone. While the introduction of one or even two nicks in the sugar-phosphate backbone yields no detectable effect on electron transfer, a CA mismatch significantly attenuates the electron transfer yield. These results confirm that the base pair stack is the pathway for DNA-mediated charge transfer, not the sugar-phosphate backbone.

Base Pair Mismatch↗

PubMed2005

XAFS studies and computational simulation of calixcrowns-caesium complexes in solution.

Caesium L(3)-edge XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure) have been evaluated as means of probing the local structure and the interaction of caesium ions with BPC6 {1,3-alternate bis(2-propyloxy)calix[4]arenecrown-6}, BOC6 {1,3-alternate bis(octyloxy)calix[4]arenecrown-6} and BisC6 (1,3-alternate calix[4]arene bis-crown-6) in NPME (o-nitrophenyl methyl ether) or OA (n-octyl alcohol). The XANES results indicate that the molecular symmetry is enhanced as the caesium ions are embedded. The EXAFS spectra demonstrate that the coordination numbers (N) and average distances (R) from the central caesium ion to the O atoms are: for BPC6, N = 7.0, R = 3.22 Angstroms (in NPME), and N = 7.0, R = 3.23 Angstroms (in OA); for BOC6, N = 6.8, R = 3.28 Angstroms (in NPME), and N = 6.9, R = 3.27 Angstroms (in OA); for BisC6, N = 6.9, R = 3.21 Angstroms (in NPME). Density functional theory at the triple-zeta adding polarization basis set level was used to simulate the BPC6, BOC6 and BisC6 coordination with the caesium ions. Data show that the seven-oxygen-configuration average distances from the central caesium ion to the O atoms are R = 3.38 for BPC6, R = 3.40 for BisC6 and R = 3.39 for BOC6.

Journal Article↗

PubMed2005

The propeptide mediates formation of stromal stores of PROMIC-1: role in determining prostate cancer outcome.

The extracellular matrix (ECM) is a reservoir of cellular binding proteins and growth factors that are critical for normal cell behavior, and aberrations in the ECM invariably accompany malignancies such as prostate cancer. Carcinomas commonly overexpress macrophage inhibitory cytokine 1 (MIC-1), a proapoptotic and antitumorigenic transforming growth factor-beta superfamily cytokine. Here we show that MIC-1 is often secreted in an unprocessed propeptide containing form. It is variably processed intracellularly, with unprocessed forms being secreted from several tumor lines, including prostate carcinoma lines, PC-3 and LNCaP. Once secreted, only unprocessed proMIC-1 binds ECM, demonstrating for the first time the occurrence of extracellular stores of MIC-1. The propeptide mediates this association via its COOH-terminal 89 amino acids. Xenograft models bearing tumors secreting various engineered forms of MIC-1 show that the propeptide regulates the balance between ECM stores and circulating serum levels of mature MIC-1 in vivo. The absence of propeptide results in approximately 20-fold increase in serum MIC-1 levels. The significance of stromal MIC-1 stores was evaluated in prostate cancer tissue cores, which show major variation in stromal levels of MIC-1. Stromal MIC-1 levels are linked to prostate cancer outcome following radical prostatectomy, with decreasing stromal levels providing an important independent predictor of disease relapse. In low-grade localized prostate cancer (Gleason sum score < or = 6), the level of MIC-1 stromal stores was the best predictor of future relapse when compared with all other clinicopathologic variables. The secretion and ECM association of unprocessed proMIC-1 is likely to play a central role in modulating local bioavailability of MIC-1 which can affect patient outcome in prostate cancer and other epithelial tumors.

Animals↗

PubMed2005

Quantitative proteome analysis of human plasma following in vivo lipopolysaccharide administration using 16O/18O labeling and the accurate mass and time tag approach.

Identification of novel diagnostic or therapeutic biomarkers from human blood plasma would benefit significantly from quantitative measurements of the proteome constituents over a range of physiological conditions. Herein we describe an initial demonstration of proteome-wide quantitative analysis of human plasma. The approach utilizes postdigestion trypsin-catalyzed 16O/18O peptide labeling, two-dimensional LC-FTICR mass spectrometry, and the accurate mass and time (AMT) tag strategy to identify and quantify peptides/proteins from complex samples. A peptide accurate mass and LC elution time AMT tag data base was initially generated using MS/MS following extensive multidimensional LC separations to provide the basis for subsequent peptide identifications. The AMT tag data base contains >8,000 putative identified peptides, providing 938 confident plasma protein identifications. The quantitative approach was applied without depletion of high abundance proteins for comparative analyses of plasma samples from an individual prior to and 9 h after lipopolysaccharide (LPS) administration. Accurate quantification of changes in protein abundance was demonstrated by both 1:1 labeling of control plasma and the comparison between the plasma samples following LPS administration. A total of 429 distinct plasma proteins were quantified from the comparative analyses, and the protein abundances for 25 proteins, including several known inflammatory response mediators, were observed to change significantly following LPS administration.

Blood Proteins↗

PubMed2005

Electroweak baryogenesis in a supersymmetric U(1)' model.

We construct an anomaly-free supersymmetric U(1)' model with a secluded U(1)'-breaking sector. We study the one-loop effective potential at finite temperature and show that there exists a strong enough first order electroweak phase transition for electroweak baryogenesis (EWBG) because of the large trilinear term AhhSHdHu in the tree-level Higgs potential. Unlike in the minimal supersymmetric standard model, the lightest top squark can be very heavy. We consider the nonlocal EWBG mechanism in the thin wall regime and find that within uncertainties the observed baryon number can be generated from the tau lepton contribution, with the secluded sector playing an essential role. The chargino and neutralino contributions and the implications for the Z' mass and electric dipole moments are briefly discussed.

Journal Article↗