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Li Wang

Publications and source records attributed to Li Wang.

At least 235 records · Page 13Linked to original sources
PubMed2005

Theoretical study and rate constant calculation for the reactions of SH (SD) with Cl2, Br2, and BrCl.

The mechanisms of the SH (SD) radicals with Cl2 (R1), Br2 (R2), and BrCl (R3) are investigated theoretically, and the rate constants are calculated using a dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points are calculated at the MP2/6-311G(d,p) and MPW1K/6-311G(d,p) levels. Higher-level energies are obtained at the approximate QCISD(T)/6-311++G(3df, 2pd) level using the MP2 geometries as well as by the multicoefficient correlation method based on QCISD (MC-QCISD) using the MPW1K geometries. Complexes with energies less than those of the reactants or products are located at the entrance or the exit channels of these reactions, which indicate that the reactions may proceed via an indirect mechanism. The enthalpies of formation for the species XSH/XSD (X = Cl and Br) are evaluated using hydrogenation working reactions method. By canonical variational transition-state theory (CVT), the rate constants of SH and SD radicals with Cl2, Br2, and BrCl are calculated over a wide temperature range of 200-2000 K at the a-QCISD(T)/6-311++G(3df, 2pd)//MP2/6-311G(d, p) level. Good agreement between the calculated and experimental rate constants is obtained in the measured temperature range. Our calculations show that for SH (SD) + BrCl reaction bromine abstraction (R3a or R3a') leading to the formation of BrSH (BrSD) + Cl in a barrierless process dominants the reaction with the branching ratios for channels 3a and 3a' of 99% at 298 K, which is quite different from the experimental result of k3a'/k3' = 54 +/- 10%. Negative activation energies are found at the higher level for the SH + Br2 and SH + BrCl (Br-abstraction) reactions; as a result, the rate constants show a slightly negative temperature dependence, which is consistent with the determination in the literature. The kinetic isotope effects for the three reactions are "inverse". The values of kH/kD are 0.88, 0.91, and 0.69 at room temperature, respectively, and they increase as the temperature increases.

Journal Article↗
PubMed2005

Induction of specific human primary immune responses to a Semliki Forest virus-based tumor vaccine in a Trimera mouse model.

Recombinant Semliki Forest virus (rSFV) enables high-level, transient expression of heterologous proteins in vivo, and is believed to be a superior vector for genetic vaccination, compared with the conventional DNA plasmid. Nonetheless, the efficacy of rSFV-based vaccine in eliciting human immune responses has not been tested. We used a Trimera mouse model, consisting of lethally irradiated BALB/c host reconstituted with nonobese diabetes/severe combined immunodeficiency (NOD/SCID) bone marrow plus human peripheral blood mononuclear cells (PBMCs), to characterize the in vivo immune responses against rSFV-encoded human melanoma antigen MAGE-3. MAGE-3-specific antibody and cytotoxic T lymphocyte (CTL) activity were detected by ELISA and 51Cr-release assay, respectively, and the responses were compared with those induced by a plasmid DNA vaccine encoding the same antigen. The results showed that rSFV vaccine could elicit human MAGE-3-specific antibody and CTL response in the Trimera mice, and the antitumor responses were more potent than those by plasmid DNA vaccination. This is the first report to evaluate human immune responses to an rSFV-based tumor vaccine in the Trimera mouse model. Our data suggest that rSFV vector is better than DNA plasmid in inducing protective immunity, and the Trimera model may serve as a general tool to evaluate the efficacy of tumor vaccines in eliciting human primary immune response in vivo.

Animals↗
PubMed2005

Differential proton sensitivity of related G protein-coupled receptors T cell death-associated gene 8 and G2A expressed in immune cells.

G2A, T cell death-associated gene 8 (TDAG8), ovarian cancer G protein-coupled receptor 1 (OGR1), and G protein-coupled receptor 4 (GPR4) form a group of structurally related G protein-coupled receptors (GPCRs) originally proposed to bind proinflammatory lipids. More recent studies have challenged the identification of lipid agonists for these GPCRs and have suggested that they function primarily as proton sensors. We compared the ability of these four receptors to modulate pH-dependent responses by using transiently transfected cell lines. In accordance with previously published reports, OGR1 was found to evoke strong pH-dependent responses as measured by inositol phosphate accumulation. We also confirmed the pH-dependent cAMP production by GPR4 and TDAG8. However, we found the activity of the human G2A receptor and its mouse homolog to be significantly less sensitive to pH fluctuations as measured by inositol phosphate and cAMP accumulation. Sequence homology analysis indicated that, with one exception, the histidine residues that were previously shown to be important for pH sensing by OGR1, GPR4, and TDAG8 were not conserved in the G2A receptor. We further addressed the pH-sensing properties of G2A and TDAG8 in a cellular context where these receptors are coexpressed. In thymocytes and splenocytes explanted from receptor-deficient mice, TDAG8 was found to be critical for pH-dependent cAMP production. In contrast, G2A was found to be dispensable for this process. We conclude that members of this GPCR group exhibit differential sensitivity to extracellular protons, and that expression of TDAG8 by immune cells may regulate responses in acidic microenvironments.

1-Methyl-3-isobutylxanthine↗
PubMed2005

Conducting polymer polypyrrole supported bilayer lipid membranes.

Electrochemically synthesized conducting polymer polypyrrole (PPy) film on gold electrode surface was used as a novel support for bilayer lipid membranes (BLMs). Investigations by surface plasmon resonance (SPR) suggest that dimyristoyl-L-alpha-phosphatidylcholine (DMPC) and dimyristoyl-L-alpha-phosphatidyl-L-serine (DMPS) can form BLMs on PPy film surface but dimyristoyl-L-alpha-phosphatidylglycerol (DMPG) and didodecyldimethylammonium bromide (DDAB) can not do so, indicating the formation of PPy supported bilayer lipid membranes (s-BLMs) is dependent on the chemical structure of the lipids used. The self-assembly of DMPC induces a smoother topography than the PPy layer with rms roughness decreasing from 4.484 to 2.914 nm convinced by atomic force microscopy (AFM). Impedance spectroscopy measurements confirm that the deposition of BLM substantially increases the resistance of the system indicating a very densely packed BLM structures. The little change of PPy film in capacitance shows that solvent and electrolyte ions still retain within the porous PPy film after BLM deposition. Therefore, the PPy supported BLM is to some extent comparable to conventional BLM with aqueous medium retaining at its two sides. As an example and preliminary application, horseradish peroxidase (HRP) reconstituted into the s-BLM shows the expected protein activity and can transfer electron from or to the underlying PPy support for its response to electrocatalytic reduction of hydrogen peroxide in solution. Thus the system maybe possesses potential applications to biomimetic membrane studies.

Biosensing Techniques↗
PubMed2005

Silencing near tRNA genes requires nucleolar localization.

Transcription by RNA polymerase II is antagonized by the presence of a nearby tRNA gene in Saccharomyces cerevisiae. To test hypotheses concerning the mechanism of this tRNA gene-mediated (tgm) silencing, the effects of specific gene deletions were determined. The results show that the mechanism of silencing near tRNA genes is fundamentally different from other forms of transcriptional silencing in yeast. Rather, tgm silencing is dependent on the ability to cluster the dispersed tRNA genes in or near the nucleolus, constituting a form of three-dimensional gene control.

Cell Nucleolus↗
PubMed2005

Effect of ginkgo biloba extract on livers in aged rats.

AIM: To investigate the protective effect of ginkgo biloba extract (GBE) on livers of aged rats and the associated mechanisms. METHODS: Two-mo- and 20-mo-old rats were treated with GBE/saline for 3 mo. Liver tissue samples from 5-mo-old rats treated with saline (group Y) and 23-mo-old rats treated with GBE (group E) or saline (group N) were used for histopathological examinations (hematoxylin-eosin and Masson staining, Lipofuscin staining-Schmorl staining) and determination of expression of tissue inhibitor-1 of metalloproteinase (TIMP-1) and the level of malondialdehyde (MDA), glutathione peroxidase (GPx) and superoxide dismutase (SOD). Blood samples were collected for determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and albumin. RESULTS: Microscopic studies with Masson staining revealed mild liver fibrosis in aged rats (group N), while the livers of aged rats receiving GBE (group E) showed amelioration in fibrosis (2.2+/-0.1 vs 2.8+/-0.1, P<0.01) and deposition of lipofuscin (33.7+/-5.3 vs 62.8+/-5.7, P<0.01). The expression of TIMP-1 and the level of liver MDA (1.0+/-0.1 vs 1.2+/-0.2, P<0.05) also decreased but the activity of GPx (97.1+/-15.3 vs 61.8+/-14.5, P<0.01) increased in group E. Compared with group Y, the level of liver MDA (0.8+/-0.1 vs 1.2+/-0.2, P<0.01), lipofuscin (32.4+/-6.0 vs 62.8+/-5.7, P<0.01) and TIMP-1 expression were increased, while the activity of GPx (103.2+/-17.6 vs 61.8+/-14.5, P<0.01) and SOD (16.7+/-4.4 vs 11.8+/-3.9, P<0.05) was decreased in group N. There was no difference in liver function among these three groups. CONCLUSION: GBE has protective effects on aging liver. The possible mechanisms might be its antioxidant activity and inhibition of TIMP-1 expression.

Aging↗
PubMed2005

Effect of decentration of wavefront-corrected intraocular lenses on the higher-order aberrations of the eye.

OBJECTIVE: To evaluate the theoretical effect of decentration of aspherical intraocular lenses (IOLs) and wavefront-corrected IOLs up to the sixth order on higher-order aberrations (HOAs) (third through sixth order) of the eye. METHODS: An aspherical IOL with HOAs of fourth-order spherical aberrations only (-0.287 microm with a 6-mm pupil) and a wavefront-corrected IOL with HOAs of equal magnitude and opposite from the corneal HOAs were created and laterally shifted up to 1 mm to simulate decentered IOLs. The residual HOAs for pupils of 3 to 6 mm were calculated by combining the HOAs from the cornea and the decentered IOL. Based on the residual HOAs, optical quality was rated by 3 criteria: the Marechal criterion, a diffraction-limited optical system with an aberration less than lambda/14; P(10), the lower 10th percentile of the corneal HOAs in this study group; and decreased HOA, residual ocular HOAs less than the corresponding corneal HOAs. RESULTS: Simulated implantation of the aspherical IOLs and wavefront-corrected IOLs was performed in 154 eyes of 94 patients aged 40 to 80 years. For a centered aspherical IOL and a 6-mm pupil, no eyes met the Marechal criterion, and the P(10) and decreased-HOA criteria were met by 46% and 93% of eyes, respectively. For a 6-mm pupil, the required centration was 0.47 mm to meet the decreased-HOA criterion in 50% of eyes. With a wavefront-corrected IOL and a 6-mm pupil, the centrations required to meet the criteria for 90% of eyes were 0.04 mm for the Marechal criterion, 0.36 mm for P(10), and 0.48 mm for the decreased-HOA criterion. CONCLUSION: Excellent centration is required to maximize the visual outcome of wavefront-corrected IOLs. CLINICAL RELEVANCE: With current surgical techniques, implantation of aspherical IOLs and wavefront-corrected IOLs will reduce total ocular HOAs below corneal HOAs in approximately 45% and 86% of eyes (6-mm pupil), respectively.

Adult↗
PubMed2005

Mechanically engraved mica surface using the atomic force microscope tip facilitates return to a specific sample location.

By controlling the interaction between the atomic force microscope tip and mica, patterns of different sizes and shape have been produced on the surface of mica. Using these operator-constructed patterns as a reliable marker, the original scanned sample location can be re-located and imaged again on the same mica surface by atomic force microscopy (AFM). This location technique can be used to find the same object again even if the sample was removed from the AFM instrument or the sample was imaged in a different mode.

Aluminum Silicates↗
PubMed2005

Immobilization of DNA on 11-mercaptoundecanoic acid-modified gold (111) surface for atomic force microscopy imaging.

Immobilized DNA on preformed 11-mercaptoundecanoic acids (MUDA) self-assembled monolayers (SAMs) on a gold (111) surface was bound by a divalent cation bridges was imaged by atomic force microscopy (AFM). The DNA immobilization was attributed to the formation of ionic bridges between the carboxylate groups of MUDA and the phosphate groups of DNA. AFM images revealed that DNA molecules could be immobilized strongly enough to permit stable and reproducible imaging. The effect of different bridge cations, such as Mg(2+), Zn(2+) and Cu(2+), and the pH of DNA assembled solution on immobilization and conformation of DNA was studied. Plasmid DNA pBR 322/Pst I molecules were straightened by using a molecular combing technique on the MUDA surface.

DNA↗
PubMed2005

Capillary array electrophoresis for the research of asymmetric transformation reaction of L-proline to D-proline.

One asymmetric transformation reaction of L-proline (L-Pro) to D-proline was studied by a home-made capillary array electrophoresis (CAE) for the first time. The aldehyde catalysts and the organic acid solvents for the asymmetric transformation reaction were rapidly screened and the enantiomeric excess values of the asymmetric product of L-Pro were directly obtained from the electrophoretogram of CAE.

Aldehydes↗
PubMed2005

Effect of Homoharringtonine on corneal haze after excimer laser photorefractive keratectomy in rabbits.

To evaluate the inhibiting effect of Homoharringtonine (HHT) on the corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits. 18 healthy rabbits which underwent PRK were randomly divided into three groups (A, B and C). The refractive degree of ablation was - 10.0DS in each group. Group A was locally treated with a piece of filter paper soaked with 1 mg/mL HHT for 5 min, and then the entire cornea was repeatedly irrigated with balance solution; Group B was dropped with 0.1 mg/mL HHT after PRK for 3 months; Group C was the control group. Corneal haze, histopathology, response, ect. were investigated. The corneal haze was significantly less in group A, while the difference between group B and group C was insignificant. Keratocytes and fibrocytes in corneal stroma were more active up to 3 months in group B and group C. Intraoperative use of topical HHT can reduce corneal haze after PRK in rabbits.

Animals↗
PubMed2005

Genetic diversity and genetic structure of an endangered species, Trillium tschonoskii.

The genetic diversity and genetic structure of Trillium tschonoskii (Maxim) were investigated using amplified fragment length polymorphism markers. Eight primer combinations were carried out on 105 different individuals sampled from seven populations. Of the 619 discernible DNA fragments generated, 169 (27.3%) were polymorphic. The percentage of polymorphic bands within populations ranged from 4.52 to 10.50. Genetic diversity (H(E)) within populations ranged from 0.0130 to 0.0379, averaging 0.0536 at the species level. Genetic differentiation among populations was detected based on Nei's genetic diversity analysis (53.03%) and analysis of molecular variance (AMOVA) (52.43%). AMOVA indicated significant genetic differentiation among populations (52.43% of the variance) and within populations (47.57% of the variance) (p < 0.0002). Gene flow was low (0.4429) among populations. Species breeding system and limited gene flow among populations are plausible reasons for the high genetic differentiation observed for this species. We propose an appropriate strategy for conserving the genetic resources of T. tschonoskii in China.

China↗
PubMed2005

The presence of serum anti-p53 antibodies from patients with invasive ductal carcinoma of breast: correlation to other clinical and biological parameters.

Breast cancer has been the most common malignant tumor among women in many large cities of China. The aim of this study was to clarify the prognostic significance of serum anti-p53 antibodies (p53 Abs) in Chinese patients of breast cancer. One hundred and forty-four patients with invasive ductal carcinoma of breast were involved in this study. The expressions of ER, PR, c-erbB-2 and p53 were immunostained in tumor tissues and serum p53 Abs were assayed using ELISA method. The correlations between p53 Abs and other clinical and biological markers were analyzed. Among 144 patients, 31 (21.5%) had positive p53 Abs, which was associated with several poor prognostic parameters including higher clinical stage (p = 0.0233), lymph nodes metastasis (p = 0.0033), negative ER expression (p = 0.0250) and positive c-erbB-2 status (p = 0.0227). There was also a strong correlation between p53 Abs and tumor p53 positivity (p < 0.0001). These results indicated that the presence of p53 Abs is probably triggered by the accumulation of tumor p53 protein, and it could be a useful marker to complement routine prognostic factors in breast cancer patients.

Antibodies, Neoplasm↗
PubMed2005

Anterior lenticonus detected by wavefront aberrometry.

PURPOSE: To illustrate the utility of wavefront aberrometry in delineating a subtle lenticular abnormality responsible for decreased best-corrected visual acuity in a patient. DESIGN: Case report. METHODS: Clinical data, corneal topography, and wavefront aberrometry with separation of corneal and lenticular components of the higher-order aberrations are analyzed in a patient who presented for refractive surgery evaluation. RESULTS: Clinical evaluation indicated that the cause of visual loss was lenticular, and wavefront aberrometry indicated high negative spherical aberration, leading to the diagnosis of anterior lenticonus. CONCLUSIONS: Wavefront aberrometry has an adjunctive and distinctive role in the preoperative screening process for refractive surgery candidates and in those with subtle unexplained loss of best-corrected visual acuity.

Adult↗
PubMed2005

The orphan nuclear receptor SHP regulates PGC-1alpha expression and energy production in brown adipocytes.

Brown adipocytes increase energy production in response to induction of PGC-1alpha, a dominant regulator of energy metabolism. We have found that the orphan nuclear receptor SHP (NR0B2) is a negative regulator of PGC-1alpha expression in brown adipocytes. Mice lacking SHP show increased basal expression of PGC-1alpha, increased energy expenditure, and resistance to diet-induced obesity. Increased PGC-1alpha expression in SHP null brown adipose tissue is not due to beta-adrenergic activation, since it is also observed in primary cultures of SHP(-/-) brown adipocytes that are not exposed to such stimuli. In addition, acute inhibition of SHP expression in cultured wild-type brown adipocytes increases basal PGC-1alpha expression, and SHP overexpression in SHP null brown adipocytes decreases it. The orphan nuclear receptor ERRgamma is expressed in BAT and its transactivation of the PGC-1alpha promoter is potently inhibited by SHP. We conclude that SHP functions as a negative regulator of energy production in BAT.

Adipocytes↗
PubMed2005

Protective effects of a Traditional Chinese Medicine, You-Gui-Wan, on steroid-induced inhibition of cytokine production in mice.

You-Gui-Wan (YGW), a classical yang-tonic prescription of Traditional Chinese Medicine (TCM), is thought to boost the body function against diseases. To determine the effects of YGW on the steroid-induced inhibition of cytokine production in mice, we established a murine model with hydrocoticoid (HC)-induced cytokine suppression. The results showed that oral administration of YGW protected mice against HC-induced inhibition of IFN-gamma, IL-2, IL-4 and IL-10 transcription, and the percentages of CD4+ and CD8+ T cells containing intracellular cytokines including IFN-gamma, IL-4 and IL-10 were significantly increased in murine spleen. The protection of YGW against HC-induced inhibition of cytokine production was further confirmed by the elevated serum level of IFN-gamma in YGW-treated mice. The results suggest that YGW improve the immune function even in the serious immunosuppressive condition.

Animals↗
PubMed2005

Higher-order aberrations from the internal optics of the eye.

PURPOSE: To analyze the distribution of human higher-order wavefront aberrations (3rd- to 6th-order) from the internal optics (WA(internal)) and the variations with age and to evaluate the degree of compensation that the internal optics provide for anterior corneal aberrations (WA(cornea)). SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. METHODS: With assumption of a simple model for the eye, the WA(internal) were obtained by direct subtraction of the WA(cornea) from the ocular aberrations (WA(eye)). The WA(eye) were measured using the WaveScan system (Visx, Inc.), and the WA(cornea) were computed from the topographic data (Humphrey Atlas) using the CTView program (Sarver and Associates, Inc.). In 144 eyes of 114 normal patients (age 20 to 69 years), WA(internal) were calculated for a 6.0 mm pupil and a compensation factor (CF) was computed, with positive values representing compensation of WA(cornea) by WA(internal) and negative values indicating that the internal surfaces add aberrations to those of the cornea. RESULTS: There was wide individual variation in WA(internal). The mean coefficient for 4th-order spherical aberration (Z(4)(0)) was -0.145 microm +/-0.094 (SD) (95% confidence interval [CI], -0.160 to -0.130 microm); 95.1% of eyes had negative values. The mean root-mean-square value for HOAs was 0.334 +/- 0.096 microm (95% CI, 0.319 to 0.350 microm). Moderate to high correlations were found between the right and left eyes in HOAs, 4th-order and 6th-order spherical aberration coefficients (Z(4)(0) and Z(6)(0)). With increasing age, the HOAs did not change, whereas the negative coefficients for Z(4)(0) tended to become less negative. Only the term Z(4)(0) had a CF significantly correlated with increasing age (r=-0.338, P<.05 with Bonferroni correction). CONCLUSION: WA(internal) varied widely among patients, and a moderate to high degree of mirror symmetry existed between the right and left eyes. Internal surfaces compensated at least partially for the HOA and Z(4)(0) in most eyes, and this compensation decreased only mildly with increasing age.

Adult↗