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Biomedical subjects

Yang Song

Publications and source records attributed to Yang Song.

52 records · Page 3Linked to original sources
PubMed2005

[Role of cyclooxygenase-2 in inhibition of human gastric adenocarcinoma cell line SGC-7901 by c9, t11-conjugated linoleic acid].

OBJECTIVE: To study the effects of c9, t11-conjugated linoleic acid (c9, t11-CLA) on the critical enzyme (COX-2) and its product - prostaglandin E2 (PGE2) of linoleic acid metabolism path in human gastric adenocarcinoma cell line (SGC-7901). METHODS: Expression of COX-2 mRNA and protein were measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, PGE2 was determined by radioimmunoassay (RIA). RESULTS: At the concentrations of 25, 50, 100, 200 pmol/L, c9, t11-CLA suppressed the expression of COX-2 mRNA, protein and PGE. CONCLUSION: COX-2 is involved anti-cancer action of c9, t11-CLA and is likely to act as an important target.

Adenocarcinoma↗
PubMed2004

A dual role for the N-terminal region of Mycobacterium tuberculosis Hsp16.3 in self-oligomerization and binding denaturing substrate proteins.

The N-terminal regions, which are highly variable in small heat-shock proteins, were found to be structurally disordered in all the 24 subunits of Methanococcus jannaschii Hsp16.5 oligomer and half of the 12 subunits of wheat Hsp16.9 oligomer. The structural and functional roles of the corresponding region (potentially disordered) in Mycobacterium tuberculosis Hsp16.3, existing as nonamers, were investigated in this work. The data demonstrate that the mutant Hsp16.3 protein with 35 N-terminal residues removed (DeltaN35) existed as trimers/dimers rather than as nonamers, failing to bind the hydrophobic probe (1,1'-bi(4-anilino)naphthalene-5,5'-disulfonic acid) and exhibiting no chaperone-like activity. Nevertheless, another mutant protein with the C-terminal extension (of nine residues) removed, although existing predominantly as dimers, exhibited efficient chaperone-like activity even at room temperatures, indicating that pre-existence as nonamers is not a prerequisite for its chaperone-like activity. Meanwhile, the mutant protein with both the N- and C-terminal ends removed fully exists as a dimer lacking any chaperone-like activity. Furthermore, the N-terminal region alone, either as a synthesized peptide or in fusion protein with glutathione S-transferase, was capable of interacting with denaturing proteins. These observations strongly suggest that the N-terminal region of Hsp16.3 is not only involved in self-oligomerization but also contains the critical site for substrate binding. Such a dual role for the N-terminal region would provide an effective mechanism for the small heat-shock protein to modulate its chaperone-like activity through oligomeric dissociation/reassociation. In addition, this study demonstrated that the wild-type protein was able to form heterononamers with DeltaN35 via subunit exchange at a subunit ratio of 2:1. This implies that the 35 N-terminal residues in three of the nine subunits in the wild-type nonamer are not needed for the assembly of nonamers from trimers and are thus probably structurally disordered.

Amino Acid Sequence↗
PubMed2004

Voltammetric detection of metal nanoparticles separated by liquid chromatography.

Fast-scan cyclic voltammetric (FSCV) detection of the separation of small (< 2-nm core diameter) organothiolate monolayer-protected gold clusters (MPCs) by high-performance liquid chromatography (HPLC) is demonstrated in this paper. Cyclic voltammograms taken at 1-s intervals (scan rate 150 V/s) display distinctive current-potential patterns for different MPCs, aiding in their identification. Previous amperometric detection of MPC separations required multiple HPLC runs at different electrode potentials to construct hydrodynamic current-potential voltammograms. Theory for ratiometric response of photodiode array absorbance and constant potential amperometry detectors was further tested on the fast-scan voltammetric detector and gave reasonable relative core size results for a mixture of Au140 and Au38 MPCs. In the first analysis of mixed MPC monolayer composition that is not simply an overall average result, preliminary HPLC experiments on MPCs with mixed hexanethiolate and ferrocenyl-octanethiolate monolayers resolved peaks that are shown to correspond to different average numbers of ferrocene-labeled ligands per MPC.

Chromatography, High Pressure Liquid↗
PubMed2004

High pressure study of Ru3(CO)12 by X-ray diffraction, Raman, and infrared spectroscopy.

The single-crystal X-ray structure of Ru(3)(CO)(12) is reported at 8 pressures ranging from 1 atm (0.0 GPa) to 8.14(5) GPa. Although intramolecular bonding parameters remain relatively constant, intramolecular and intermolecular nonbonding contact distances decrease by an average of 4% and 15%, respectively. At 8.14 GPa, O...O, C...O, and C...C intermolecular distances as short as 2.54(4), 2.64(6), and 3.07(4) A, respectively, are observed, and the unit cell compresses to 75% of the ambient pressure volume. Raman and infrared spectroscopic measurements show that carbonyl stretching frequencies shift to higher wavenumber values by as much as 80 cm(-)(1), even though Ru-C and C-O distances stay roughly constant throughout the entire pressure range studied. Compression of the sample to above 18 GPa with laser radiation results in an irreversible transformation due to either decomposition or a total collapse of D(3)(h) molecular geometry accompanied by color darkening.

Journal Article↗
PubMed2004

Substituent effects on the exchange dynamics of ligands on 1.6 nm diameter gold nanoparticles.

The kinetics of exchange ofphenylethanethiolate ligands (PhC2S) of monolayer-protected clusters (MPCs, average formula Au140(PhC2S)53) by para-substituted arylthiols (p-X-ArSH) are described. 1H NMR measurements of thiol concentrations show that the exchange reaction is initially rapid and gradually slows almost to a standstill. The most labile ligands, exchanging at the shortest reaction times, are thought to be those at defect sites (edges, vertexes) on the nanoparticle core surface. The pseudo-first-order rate constants derived from the first 10% of the exchange reaction profile vary linearly with in-coming arylthiol concentration, meaning that the labile ligands exchange in a second-order process, which is consistent with ligand exchange being an associative process. A linear Hammett relationship with slope p = 0.44 demonstrates a substituent effect in the ligand place exchange reaction, in which the bimolecular rate constants increase for ligands with electron-withdrawing substituents (1.4 x 10-2 and 3.8 x 10(-3) M(-1) s(-1) for X = NO2 and 4-OH, respectively). This is interpreted as the more polar Au-S bonds at the defect sites favoring bonding with more electron deficient sulfur moieties. At longer reaction times, where ligands exchange on nondefect (terrace) as well as defect sites, the extent of ligand exchange is higher for thiols with more electron-donating substituents. The difference between short-time kinetics and longer-time pseudoequilibria is rationalized based on differences in Au-S bonding at defect vs nondefect MPC core sites. The study adds substance to the mechanisms of exchange of protecting ligands on nanoparticles. The scope and limitations of 1H NMR spectroscopy for determining rate data are also discussed.

Journal Article↗
PubMed2004

Differential expression of vascular endothelial growth factor (VEGF), endocrine gland derived-VEGF, and VEGF receptors in human placentas from normal and preeclamptic pregnancies.

Vascular endothelial growth factor (VEGF) is a potent regulator of placental vascular function. Endothelial dysfunction is a key factor associated with preeclampsia. In this study, we examined expression of VEGF, endocrine gland-derived VEGF (EG-VEGF), VEGF receptors 1 and 2 (VEGFR-1 and VEGFR-2), and neuropilin-1 and -2 (NP-1 and NP-2) in human placentas from women with normal and preeclamptic (PE) pregnancies using quantitative or semiquantitative PCR. We found that total VEGF mRNA expression was increased 2.8-fold (P < 0.05), along with increases in mRNA expression of VEGF121, 165, and 189 (P < 0.05; 1.7-, 1.9-, and 1.8-fold, respectively) in PE vs. normal placentas. Expression of VEGFR-1 mRNA, but not EG-VEGF and the other three VEGF receptors studied, was elevated (P < 0.05) 2.7-fold in PE vs. normal placentas. Protein expression of VEGF and its four receptors was determined using Western blot analysis. For VEGF, two major isoforms (VEGF165 and 189) were detected. For VEGFR-1, VEGFR-2, NP-1, and NP-2, one major band was observed at 180, 235, 130, and 130 kDa, respectively. All of these bands were corresponding to their positive controls. Of these five proteins studied, only VEGFR-1 levels were increased (P < 0.05; 1.7-fold) in PE placentas. The expression of VEGF and the four VEGF receptors was confirmed using immunohistochemistry. They were primarily present in syncytiotrophoblasts and endothelial cells of villous capillaries and large vessels. Thus, together with previous reports that VEGFR-1 mediates trophoblast function and inhibits VEGF-induced angiogenesis and endothelium-dependent vasodilation, these data suggest that the increased VEGFR-1 expression may alter VEGF- mediated function on trophoblast and endothelial cells in PE placentas.

Case-Control Studies↗
PubMed2004

[Establishment of high-yield suspension cell line of Curcuma zedoaria (Berg.) Rosc and study on the volatile oil synthesis-controlling with precursors].

The condition for high-yield suspension cell line and the precursors of volatile oil synthesis of Curcuma zedoaria (Berg.) Rosc were studied. The results showed that the light yellow particle callus was suitable for establishment of the high-yield suspension cell line. The optimum conditions for cell growth were MS medium added 15-30 g/L glucose and 15-30 g/L sucrose (1:1) as carbon source, the total concentration of 80 mmol/L nitrogen source combined NH4+ with NO3- (1:3), hormones of 3.0-5.0 mg/L 6-BA, 1.0 mg/L 2,4-D and dark culture after 10-15 days light culture. The 229 g/L cell (FW) and 2.11% content of volatile oil were obtained in vitro. The addition of precursors of calcium pantothenate, ammonium acetate and potassium acetate during the middle period of the cell suspension culture enhanced the volatile oil content respectively, and ammonium acetate was most effective among them. The highest yield of volatile oil obtained was 3.11% and 8.27 g/L respectively , which was 1.25 and 1.2 times of the control group.

Acetates↗
PubMed2003

Heterophase ligand exchange and metal transfer between monolayer protected clusters.

This paper describes reactions in which ligands are exchanged and metals are transferred between monolayer-protected metal clusters (MPCs) that are in different phases (heterophase exchange) or are in the same phase. For example, contact of toluene solutions of alkanethiolate-coated gold MPCs with aqueous solutions of tiopronin-coated gold MPCs yields toluene-phase MPCs that have some tiopronin ligands and aqueous-phase MPCs that have some alkanethiolate ligands. In a second example, heterophase transfer reactions occur between toluene solutions of alkanethiolate-coated gold MPCs and aqueous solutions of tiopronin-coated silver MPCs, in which tiopronin ligands are transferred to the former and gold metal to the latter phase. These ligand and metal exchange reactions are inhibited when conducted under N(2). The results implicate participation of an oxidized form of Au (such as a Au(I) thiolate, Au(I)-SR) as both a ligand and metal carrier in the exchange reactions. Au(I)-SR is demonstrated to be an exchange catalyst.

Journal Article↗
PubMed2003

[Effects of naloxone on rat cortical neuron apoptosis induced by anoxia].

OBJECTIVE: To investigate the damage of anoxia on the cultured rat's cortical neurons and the protective effects of naloxone. METHODS: Cortical neurons cultured for 12 days were randomly divided into three groups: control, anoxic group and anoxic group plus naloxone treated. Cortical neurons were exposed to anoxic environment for 6 hours and then cultured for 24 hours under normoxic condition. The apoptosis of neurons was detected with the method of TdT-mediated dUTP nick end labeling (TUNEL) and the apoptotic rate of neurons was measured using flow cytometry. RESULTS: Anoxia could lead to increasing apoptosis and death of rate cortical neurons. Naloxone could reduce neuron apoptosis. There was a significant difference between the anoxic group and anoxic group plus naloxone (P<0.01). CONCLUSION: Naloxone can ameliorate the toxicity damage of neurons caused by anoxia through reducing neuron apoptosis, which suggests that naloxone could protect rat's cortical neurons from damage under anoxia condition.

Animals↗
PubMed2003

[Preparation of fiber complexes and its role in lipid peroxidation].

This study was designed to prepare the artificial fiber complexes and examine its role in lipid peroxidation in comparison with other fibers. Sixty-four healthy, female Wistar rats (50-80 g) were randomly divided into eight groups based on body weight. All seven kinds of DF (cellulose--group B, pectin--group C, sodium alginate--group D, cellulose-pectin complex--group E, cellulose-sodium alginate complex--group F, cellulose-pectin mixture--group G, cellulose-sodium alginate mixture--group H) were given at a level of 10% in the diet fed on a lipid-rich diet. The control group (group A) was fed on a lipid-rich diet alone without DF. After eight weeks, the effect on growth and development, lipid metabolism and lipid peroxidation in rats were studied. The results showed that: 1. Seven kinds of DF did not affect the growth and development of the experimental rats. 2. Seven kinds of DF all can increase serum superoxide dismutase (SOD) and glutathione peroxidase (GsH-Px) activities and reduce malondiadehyde (MDA) content (except group B and D). Erythrocyte membrane fluidity was significantly increased in DF groups, and fiber complex groups were most effective. 3. The fecal weight and fat contents in all DF groups were significantly higher than that in control group, especially for fiber mixture and complex groups. It is concluded that all these kinds of DF have the effect of reducing lipid peroxidation to some extent in rats, and fiber complexes might be the most effective.

Alginates↗
PubMed2003

[Analysis of short-term pain occurrence applying different materials for root canal therapy].

OBJECTIVE: The aim of this study is to compare the occurrence of pain applying different materials of root canal therapy in vital teeth. METHODS: 288 vital teeth were divided into 4 groups, Cortisomol sealer+gutta-percha and Vitapex+gutta-percha were used respectively in 2 groups of one time method; while Cortisomol sealer+gutta-percha and Vitapex+gutta-percha were used after 24-48 hours drainage in the other 2 groups. The occurrence of pain after 1 week was recorded. RESULTS: In all treated teeth,the occurrence rate of self-healing pain after root canal therapy was 22.6%, the occurrence rate of non-self-healing was 2.08%; in the groups of one time method,the occurrence rate of pain using Cortisomol was lower than the group using Vitapex with significant difference(P<0.01); while in the groups of root canal filling after drainage,the occurrence of self-healing pain in the group using Cortisomol was lower than the group of using Vitapex without significant difference(P>0.05);the pain occurred within 72 hours in most of the teeth. CONCLUSION: Root canal treatment applying Cortisomol sealer+gutta-percha can decrease the rate of pain occurrence after root canal filling.

Adolescent↗
PubMed2002

Loss of stearoyl-CoA desaturase-1 function protects mice against adiposity.

Stearoyl-CoA desaturase (SCD) is a central lipogenic enzyme catalyzing the synthesis of monounsaturated fatty acids, mainly oleate (C18:1) and palmitoleate (C16:1), which are components of membrane phospholipids, triglycerides, wax esters, and cholesterol esters. Several SCD isoforms (SCD1-3) exist in the mouse. Here we show that mice with a targeted disruption of the SCD1 isoform have reduced body adiposity, increased insulin sensitivity, and are resistant to diet-induced weight gain. The protection from obesity involves increased energy expenditure and increased oxygen consumption. Compared with the wild-type mice the SCD1-/- mice have increased levels of plasma ketone bodies but reduced levels of plasma insulin and leptin. In the SCD1-/- mice, the expression of several genes of lipid oxidation are up-regulated, whereas lipid synthesis genes are down-regulated. These observations suggest that a consequence of SCD1 deficiency is an activation of lipid oxidation in addition to reduced triglyceride synthesis and storage.

Adipose Tissue↗
PubMed2002

Dynamics and extent of ligand exchange depend on electronic charge of metal nanoparticles.

Both the rate and extent of ligand place exchange reactions between the hexanethiolate monolayer of Au(140) monolayer protected clusters (C6 MPCs) and dissolved 6-mercapto-1-hexanol thiol (HOC6SH) increase with increasing positive electronic charge on the Au cluster core. The rate constant of the ligand place exchange, taken at the early stage of the exchange, is increased by ca. 2-fold for reaction of +3 charged Au(140) cores as compared to neutral ones. The initially exchanged ligands are thought to reside mainly on edge and vertex sites of the Au(140) core, where the lability of the slightly more ionic Au[bond]S bonds there becomes further enhanced by removing electrons from the core. The reactions slow markedly after 35-50% of the original ligands have been replaced, continuing at a much slower pace for some time to reach an apparent reaction equilibrium. On +2 charged Au(140) cores, 85% of the C6 ligands have been exchanged with HOC(6)H(12)SH after 20 h. The slower phase of the reaction includes exchange of thiolate ligands on terrace lattice sites most of which--owing to the small sizes of the nanoparticle's Au(111) faces--are no more than one Au atom row removed from the nanoparticle edge sites. This slower exchange, the extent of which is also enhanced by positively charging the core, occurs either by intramolecular place exchange with edge sites that subsequently place-exchange with solution thiol or by direct place-exchange with solution thiol. Acid-base studies show that thiolate is more reactive in place exchange reactions than the corresponding thiol.

Journal Article↗
PubMed2002

Human epidermal membrane constant conductance iontophoresis: alternating current to obtain reproducible enhanced permeation and reduced lag times of a nonionic polar permeant.

An experimental protocol, using an initial 1 min direct current (DC) applied potential of 4 V followed by alternating current (AC), was established to: (a) increase conductance and permeability and decrease lag time for human epidermal membrane (HEM) relative to unaltered HEM and; (b) maintain constant conductance and permeability during flux studies. The protocol allowed specific permeation parameters of the membrane to be characterized under electrically enhanced, constant flux conditions. The permeability, lag time, and effective membrane thickness were determined using a nonionic polar permeant, urea, while the enhanced conductance was maintained at a constant level with AC. A tortuous pore pathway model was employed to analyze the data. The AC protocol increased membrane permeability, and decreased lag time and effective membrane thickness relative to similar parameters obtained in previous studies from unaltered HEM. Lag times ranged from 32.0 to 105.5 min, and permeability coefficients calculated from steady state fluxes ranged from 1.68 to 6.03x10(-7) cm/s for HEM samples with electrical resistance values during transport of 2.3-8.0 kOmega x cm2. Effective membrane thicknesses were calculated to range from 0.34 to 0.61 cm during AC iontophoresis. Significant additional results were obtained when the protocol was applied for two consecutive runs using the same HEM sample, with time for the HEM sample to recover between runs. During the second run, the applied potential was adjusted to reproduce the conductance obtained on the first run. Under these conditions, the consecutive runs yielded essentially the same lag time, permeability and effective membrane thickness values. These results suggest that constant fluxes can be achieved by keeping HEM electrical conductance constant during AC iontophoresis.

Electric Stimulation↗