Biomedical subjects

Fang Wang

Publications and source records attributed to Fang Wang.

At least 55 records · Page 3Linked to original sources

PubMed2006

A hydrogen peroxide biosensor based on the direct electrochemistry of hemoglobin modified with quantum dots.

Direct electron transfer of hemoglobin modified with quantum dots (QDs) (CdS) has been performed at a normal graphite electrode. The response current is linearly dependent on the scan rate, indicating the direct electrochemistry of hemoglobin in that case is a surface-controlled electrode process. UV-vis spectra suggest that the conformation of hemoglobin modified with CdS is little different from that of hemoglobin alone, and the conformation changes reversibly in the pH range 3.0-10.0. The hemoglobin in a QD film can retain its bioactivity and the modified electrode can work as a hydrogen peroxide biosensor because of its peroxidase-like activity. This biosensor shows an excellent response to the reduction of H2O2 without the aid of an electron mediator. The catalytic current shows a linear dependence on the concentration of H2O2 in the range 5x10(-7)-3x10(-4) M with a detection limit of 6x10(-8) M. The response shows Michaelis-Menten behavior at higher H2O2 concentrations and the apparent Michaelis-Menten constant is estimated to be 112 microM.

Biosensing Techniques↗

PubMed2006

Estrogen-related receptors stimulate pyruvate dehydrogenase kinase isoform 4 gene expression.

The pyruvate dehydrogenase complex (PDC) catalyzes the conversion of pyruvate to acetyl-CoA in mitochondria and is a key regulatory enzyme in the oxidation of glucose to acetyl-CoA. Phosphorylation of PDC by the pyruvate dehydrogenase kinases (PDK2 and PDK4) inhibits PDC activity. Expression of the PDK genes is elevated in diabetes, leading to the decreased oxidation of pyruvate to acetyl-CoA. In these studies we have investigated the transcriptional regulation of the PDK4 gene by the estrogen-related receptors (ERRalpha and ERRgamma). The ERRs are orphan nuclear receptors whose physiological roles include the induction of fatty acid oxidation in heart and muscle. Previously, we found that the peroxisome proliferator-activated receptor gamma coactivator (PGC-1alpha) stimulates the expression of PDK4. Here we report that ERRalpha and ERRgamma stimulate the PDK4 gene in hepatoma cells, suggesting a novel role for ERRs in controlling pyruvate metabolism. In addition, both ERR isoforms recruit PGC-1alpha to the PDK4 promoter. Insulin, which decreases the expression of the PDK4 gene, inhibits the induction of PDK4 by ERRalpha and ERRgamma. The forkhead transcription factor (FoxO1) binds the PDK4 gene and contributes to the induction of PDK4 by ERRs and PGC-1alpha. Insulin suppresses PDK4 expression in part through the dissociation of FoxO1 and PGC-1alpha from the PDK4 promoter. Our data demonstrate a key role for the ERRs in the induction of hepatic PDK4 gene expression.

3-Phosphoinositide-Dependent Protein Kinases↗

PubMed2006

Mapping ERK2-MKP3 binding interfaces by hydrogen/deuterium exchange mass spectrometry.

ERK2, a prototypic member of the MAPK family, plays a central role in regulating cell growth and differentiation. MKP3, an ERK2-specific phosphatase, terminates ERK2 signaling. To understand the molecular basis of ERK2 recognition by MKP3, we carried out hydrogen/deuterium exchange mass spectrometry experiments to map the interaction surfaces between the two proteins. The results show that the exquisite specificity of MKP3 for ERK2 is governed by two distinctive protein-protein interactions. To increase the "effective concentration" of the interacting molecules, the kinase interaction motif in MKP3 ((64)RRLQKGNLPVR(74)) and an MKP3-specific segment ((101)NSSDWNE(107)) bind the common docking site in ERK2 defined by residues in L(16), L(5), beta(7)-beta(8), and alpha(d)-L(8)-alpha(e), located opposite the kinase active site. In addition to this "tethering" effect, additional interactions between the (364)FTAP(367) sequence in MKP3 and the ERK2 substrate-binding site, formed by residues in the activation lip and the P+1 site (beta(9)-alpha(f) loop), L(13) (alpha(f)-alpha(g) loop), and the MAPK insert (L(14)-alpha(1L14)-alpha(2L14)), are essential for allosteric activation of MKP3 and formation of a productive complex whereby the MKP3 catalytic site is correctly juxtaposed to carry out the dephosphorylation of phospho-Thr(183)/phospho-Tyr(185) in ERK2. This bipartite protein-protein interaction model may be applicable to the recognition of other MAPKs by their cognate regulators and substrates.

Amino Acid Sequence↗

PubMed2006

Investigations of EPR parameters for the trigonal Ti3+-Ti3+ pair in beryl crystal.

By using the complete diagonalization of energy matrix of 3d1 ions in trigonal symmetry, the EPR parameters (g factors g( parallel), g( perpendicular) and zero-field splitting D) of the trigonal Ti3+-Ti3+ pair in beryl crystal are calculated. In the calculations, the exchange interaction in the Ti3+-Ti3+ pair is taken as the perturbation and the local trigonal distortion in the defect center is considered. The results (which are in agreement with the experimental values) are discussed.

Aluminum Silicates↗

PubMed2006

Ca2+ sensitivity of regulated cardiac thin filament sliding does not depend on myosin isoform.

Myosin heavy chain (MHC) isoforms in vertebrate striated muscles are distinguished functionally by differences in chemomechanical kinetics. These kinetic differences may influence the cross-bridge-dependent co-operativity of thin filament Ca(2+) activation. To determine whether Ca(2+) sensitivity of unloaded thin filament sliding depends upon MHC isoform kinetics, we performed in vitro motility assays with rabbit skeletal heavy meromyosin (rsHMM) or porcine cardiac myosin (pcMyosin). Regulated thin filaments were reconstituted with recombinant human cardiac troponin (rhcTn) and alpha-tropomyosin (rhcTm) expressed in Escherichia coli. All three subunits of rhcTn were coexpressed as a functional complex using a novel construct with a glutathione S-transferase (GST) affinity tag at the N-terminus of human cardiac troponin T (hcTnT) and an intervening tobacco etch virus (TEV) protease site that allows purification of rhcTn without denaturation, and removal of the GST tag without proteolysis of rhcTn subunits. Use of this highly purified rhcTn in our motility studies resulted in a clear definition of the regulated motility profile for both fast and slow MHC isoforms. Maximum sliding speed (pCa 5) of regulated thin filaments was roughly fivefold faster with rsHMM compared with pcMyosin, although speed was increased by 1.6- to 1.9-fold for regulated over unregulated actin with both MHC isoforms. The Ca(2+) sensitivity of regulated thin filament sliding speed was unaffected by MHC isoform. Our motility results suggest that the cellular changes in isoform expression that result in regulation of myosin kinetics can occur independently of changes that influence thin filament Ca(2+) sensitivity.

Actin Cytoskeleton↗

PubMed2006

Comparative proteomics analysis to annexin B1 DNA and protein vaccination in mice.

DNA vaccines have been widely reported to elicit both effective humoral and cellular immune responses, but the mechanisms of antigen processing and presentation in DNA immunization is still ambiguous. Aiming to molecular mechanisms involved in DNA immunization, comparative serum proteomics was introduced to discover differentially expressed proteins after different immunizations. Using two-dimensional electrophoresis and matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry, 23 three-fold or greater up-regulated proteins were separated and identified, including 14 from ANXB1 DNA immunized mice and 9 from annexin B1 protein immunized mice. The histocompatibility class I molecule H2-Q10 (HA10_MOUSE) and proteasome activator PA28 alpha-subunit (PSME1_MOUSE) were found up-regulated in ANXB1 DNA immunized mice, which may contribute to the augmented activation of T lymphocytes. These proteins may serve as potential surrogate markers of successful vaccination and provide research targets for molecular mechanisms of vaccinology.

Animals↗

PubMed2006

Ectopic expression of ThCYP1, a stress-responsive cyclophilin gene from Thellungiella halophila, confers salt tolerance in fission yeast and tobacco cells.

The halophyte Thellungiella halophila (salt cress) is an ideal model system for studying the molecular mechanisms of salinity tolerance in plants. Herein, we report the identification of a stress-responsive cyclophilin gene (ThCYP1) from T. halophila, using fission yeast as a functional system. The expression of ThCYP1 is highly inducible by salt, abscisic acid (ABA), H(2)O(2) and heat shock. Ectopic overexpression of the ThCYP1 gene enhance the salt tolerance capacity of fission yeast and tobacco (Nicotiana tabacum L.) cv. Bright Yellow 2 (BY-2) cells significantly. ThCYP1 is expressed constitutively in roots, stems, leaves and flowers, with higher expression occurring in the roots and flowers. The ThCYP1 proteins are distributed widely within the cell, but are enriched significantly in the nucleus. The present results suggest that ThCYP1 may participate in response to stresses in the salt cress, perhaps by regulating appropriate folding of certain stress-related proteins, or in the signal transduction processes.

Abscisic Acid↗

PubMed2006

High sensitivity voltammetric determination of sodium nitroprusside at acetylene black electrode in the presence of CTAB.

A sensitive electroanalytical method for detection of sodium nitroprusside (SNP) was investigated, on the basis of the enhanced electrochemical response of SNP at an acetylene black electrode (ABE) in the presence of cetyltrimethylammonium bromide (CTAB). Voltammetric studies showed that SNP exhibited a pair of quasi-reversible redox peaks at ABE in the presence of CTAB while no any redox peak was observed in the absence of CTAB. This was attributed to the enhanced adsorption of SNP at AB through electrostatic interactions between SNP and CTAB as well as hydrophobic adsorption of CTAB at the hydrophobic surface of ABE. Under optimal working conditions, the reduction current was proportional to the concentration of SNP in the range of 1.0x10(-7) to 1.0x10(-5) mol/L and 1.0x10(-5) to 1.0x10(-2) mol/L. A low detection limit of 5.0x10(-9) mol/L was obtained for 2 min accumulation at open circuit (S/N=3). The proposed method was successfully applied to the determination of SNP in pharmaceutical dosage forms.

Acetylene↗

PubMed2006

Hormonal control of androgen receptor function through SIRT1.

The NAD-dependent histone deacetylase Sir2 plays a key role in connecting cellular metabolism with gene silencing and aging. The androgen receptor (AR) is a ligand-regulated modular nuclear receptor governing prostate cancer cellular proliferation, differentiation, and apoptosis in response to androgens, including dihydrotestosterone (DHT). Here, SIRT1 antagonists induce endogenous AR expression and enhance DHT-mediated AR expression. SIRT1 binds and deacetylates the AR at a conserved lysine motif. Human SIRT1 (hSIRT1) repression of DHT-induced AR signaling requires the NAD-dependent catalytic function of hSIRT1 and the AR lysine residues deacetylated by SIRT1. SIRT1 inhibited coactivator-induced interactions between the AR amino and carboxyl termini. DHT-induced prostate cancer cellular contact-independent growth is also blocked by SIRT1, providing a direct functional link between the AR, which is a critical determinant of progression of human prostate cancer, and the sirtuins.

Acetylation↗

PubMed2006

Human microRNA clusters: genomic organization and expression profile in leukemia cell lines.

MicroRNAs (miRNAs) play an important role in diverse physiological and developmental processes by negatively regulating expression of target genes at the post-transcriptional level. Here, we globally analyzed the genomic organization of all registered 326 human miRNA genes in miRNA registry 7.1 and found that 148 human miRNA genes appeared in a total of 51 clusters. Alignment of the miRNA sequences in different clusters revealed a significant number of miRNA paralogs among the clusters, implying an evolution process targeting the potentially conserved roles of these molecules. Then we performed Northern blot analysis for expression profiling of all clustered miRNAs in several human leukemia cell lines. Consistent expression of the miRNAs in a single cluster was revealed in 39 clusters, while inconsistent expression of members in a single cluster was detected in the other 12 clusters. Meanwhile, we identified several hematopoietic lineage-specific or -enriched miRNA clusters (e.g., the mir-29c, mir-302, mir-98, mir-29a, and let-7a-1 clusters) and individual miRNAs (e.g., mir-181c, mir-181d, mir-191, and mir-136). These findings may suggest vital roles of these miRNA clusters or miRNAs in human hematopoiesis and oncogenesis, and provide clues for understanding the function and mechanism of miRNAs in various biological processes.

Base Sequence↗

PubMed2006

Construction of bioactive chimeric MHC class I tetramer by expression and purification of human-murine chimeric MHC heavy chain and beta(2)m as a fusion protein in Escherichia coli.

Major histocompatibility (MHC) class I tetramers are used in the quantitative analysis of epitope peptide-specific CD8+ T-cells. An MHC class I tetramer was composed of 4 MHC class I complexes and a fluorescently labeled streptavidin (SA) molecule. Each MHC class I complex consists of an MHC heavy chain, a beta(2)-microglobulin (beta(2)m) molecule and a synthetic epitope peptide. In most previous studies, an MHC class I complex was formed in the refolding buffer with an expressed MHC heavy chain molecule and beta(2)m, respectively. This procedure inevitably resulted in the disadvantages of forming unwanted multimers and self-refolding products, and the purification of each kind of monomer was time-consuming. In the present study, the genes of a human/murine chimeric MHC heavy chain (HLA-A2 alpha1, HLA-A2 alpha2 and MHC-H2D alpha3) and beta(2)m were tandem-cloned into plasmid pET17b and expressed as a fusion protein. The recombinant fusion protein was refolded with each of the three HLA-A2 restricted peptides (HBc18-27 FLPSDFFPSI, HBx52-60 HLSLRGLPV, and HBx92-100 VLHKRTLGL) and thus three chimeric MHC class I complexes were obtained. Biotinylation was performed, and its level of efficiency was observed via a band-shift assay in non-reducing polyacrylamide gel electrophoresis (PAGE). Such chimeric MHC class I tetramers showed a sensitive binding activity in monitoring HLA/A2 restrictive cytotoxic T lymphocytes (CTLs) in immunized HLA/A*0201 transgenic mice.

Animals↗

PubMed2006

Cardiovascular disease in early stages of chronic kidney disease in a Chinese population.

Cardiovascular disease (CVD) is one of the most serious complications of kidney disease, yet studies of CVD in early stage of chronic kidney disease (CKD) in Asian patients are very limited. Therefore, this study determined the prevalence and the spectrum of CVD in individuals with early-stage CKD and compared them with data of individuals without CKD. Compared with individuals with estimated GFR (eGFR) >90 ml/min per 1.73 m2, the prevalence of myocardial infarction, stroke, and total CVD of individuals with eGFR 60 to 89 ml/min per 1.73 m2 was increased by 91.4, 71.7, and 67.6%, respectively. For individuals with eGFR 30 to 59 ml/min per 1.73 m2, the percentage was 105.2, 289.1, and 200.7%, respectively. For each eGFR category, stroke was more prevalent than myocardial infarction. Compared with individuals with eGFR >90 ml/min per 1.73 m2, participants with eGFR 60 to 89 and 30 to 59 ml/min per 1.73 m2 tended to have more cardiovascular risk factors, and there were strong unadjusted and adjusted associations between CVD with different stages of eGFR (eGFR >90 ml/min per 1.73 m2 as reference). This is the first report on the prevalence and the spectrum of CVD in early stages of CKD in a community-based Chinese population. The spectrum of CVD in this Chinese population is different from reports of Western countries. Individuals with subtle decreased renal function seem much more likely to have multiple cardiovascular risk factors and have higher prevalence of CVD than those without CKD.

Adult↗

PubMed2006

In vitro free radical scavenging activities and effect of synthetic oligosaccharides on antioxidant enzymes and lipid peroxidation in aged mice.

In this study we synthesized oligosaccharides using glucose as reactant via a route assisted by microwave irradiation and evaluated their antioxidant activity in vivo and in vitro. The results show that the oligosaccharides exhibited antioxidant activity in vitro as compared to standard antioxidants such as butylated hydroxytoluene (BHT), and alpha-tocopherol. This antioxidant activity depended on concentration and increased with increasing dose of sample. In addition, increased endogenous lipid peroxidation and decreased total antioxidant capacity (TAOC) were observed in aged mice. Thirty-day intraperitoneal administration of the oligosaccharides significantly decreased the lipid peroxidation in a dose-dependent manner. Oligosaccharides treatment increased TAOC and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in all organs tested in aged mice. The present study suggests that the synthetic oligosaccharides possess promising future for their strong free radical scavenging activity. Therefore they can be employed in compensating the decline in TAOC and the activities of antioxidant enzymes and in reducing the risks of lipid peroxidation.

Aging↗

PubMed2006

Behavior and fate of chlorpyrifos introduced into soil-crop systems by irrigation.

The effect of chlorpyrifos added in irrigation water to a red soil from Central South China on the growth of wheat and oilseed rape seedlings, together with its uptake, was studied in a pot experiment. Addition of chlorpyrifos (1-10 microg g-1) in a single irrigation with distilled water resulted in absorption of chlorpyrifos by wheat (0.257-4.50 microg g-1) and also oilseed rape seedlings (0.249-2.02 microg g-1) during 20 d of plant growth. An initial concentration of chlorpyrifos in soil that is equivalent to or below 10 microg g-1 did not significantly influence the growth of wheat seedlings. Similarly, an initial concentration equivalent to or below 5 microg g-1 did not significantly influence the growth of oilseed rape seedlings. The degradation rate of chlorpyrifos was 1.4-4.2 times larger in oilseed rape rhizosphere soil than in unvegetated soil. The numbers of bacteria and fungi in oilseed rape rhizosphere soil were 3.18 times and 1.84 times larger, respectively, than those in unvegetated soil. This helps to explain the difference in degradation rates obtained.

Biodegradation, Environmental↗

PubMed2006

Cloning and characterization of profilin (Pru du 4), a cross-reactive almond (Prunus dulcis) allergen.

BACKGROUND: The identity of allergenic almond proteins is incomplete. OBJECTIVE: Our objective was to characterize patient IgE reactivity to a recombinant and corresponding native almond allergen. METHODS: An almond cDNA library was screened with sera from patients with allergy for IgE binding proteins. Two reactive clones were sequenced, and 1 was expressed. The expressed recombinant allergen and its native counterpart (purified from unprocessed almond flour) were assayed by 1-dimensional and 2-dimensional gel electrophoresis, dot blot, and ELISA, and screened for cross-reactivity with grass profilin. RESULTS: The 2 selected clones encoded profilin (designated Pru du 4) sequences that differed by 2 silent mutations. By dot-blot analyses, 6 of 18 patient sera (33%) reacted with the recombinant Pru du 4 protein, and 8 of 18 (44%) reacted with the native form. ELISA results were similar. Almond and ryegrass profilins were mutually inhibitable. Two-dimensional immunoblotting revealed the presence of more than 1 native almond profilin isoform. The strength of reactivity of some patients' serum IgE differed markedly between assays and between native and recombinant profilins. CONCLUSION: Almond nut profilin is an IgE-binding food protein that is cross-reactive with grass pollen profilin and is susceptible to denaturation, resulting in variable reactivity between assay types and between patients. CLINICAL IMPLICATIONS: Serum IgE of nearly half of the tested patients with almond allergy reacts with almond nut profilin. Because most patients also had pollinosis, the well-known cross-reactivity between pollen and food profilins could account for this pattern of reactivity.

Amino Acid Sequence↗

PubMed2006

Discovery of a novel class of conotoxin from Conus litteratus, lt14a, with a unique cysteine pattern.

Conus litteratus is a worm-hunting cone snail with a highly sophisticated neuropharmacological defense strategy using small peptides in its venom. By analyzing different clones in the cDNA library of venom ducts from C. litteratus, we identified the peptide lt14a which displays a characteristic signal peptide sequence in its precursor and a unique arrangement of Cys residues (-C-C-C-C-) in its mature peptide region. RT-PCR analysis suggested that lt14a is abundantly expressed throughout the whole venom duct. An intensive analysis in sequence suggested that lt14a is similar to alpha-conotoxin qc1.1 cloned from Conus quercinus. We conducted the chemical synthesis of lt14a. The synthetic lt14a has a remarkable biological activity to suppress pain and inhibits the neuronal-type nicotinic acetylcholine receptors.

Amino Acid Sequence↗

PubMed2006

Modulation of Ca2+ signals by phosphatidylinositol-linked novel D1 dopamine receptor in hippocampal neurons.

Recent evidence indicates the existence of a putative novel phosphatidylinositol-linked D1 dopamine receptor in brain that mediates phosphatidylinositol hydrolysis via activation of phospholipase Cbeta. The present work was designed to characterize the Ca(2+) signals regulated by this phosphatidylinositol-linked D(1) dopamine receptor in primary cultures of hippocampal neurons. The results indicated that stimulation of phosphatidylinositol-linked D1 dopamine receptor by its newly identified selective agonist SKF83959 induced a long-lasting increase in basal [Ca(2+)](i) in a time- and dose-dependent manner. Stimulation was observable at 0.1 microm and reached the maximal effect at 30 microm. The [Ca(2+)](i) increase induced by 1 microm SKF83959 reached a plateau in 5 +/- 2.13 min, an average 96 +/- 5.6% increase over control. The sustained elevation of [Ca(2+)](i) was due to both intracellular calcium release and calcium influx. The initial component of Ca(2+) increase through release from intracellular stores was necessary for triggering the late component of Ca(2+) rise through influx. We further demonstrated that activation of phospholipase Cbeta/inositol triphosphate was responsible for SKF83959-induced Ca(2+) release from intracellular stores. Moreover, inhibition of voltage-operated calcium channel or NMDA receptor-gated calcium channel strongly attenuated SKF83959-induced Ca(2+) influx, indicating that both voltage-operated calcium channel and NMDA receptor contribute to phosphatidylinositol-linked D(1) receptor regulation of [Ca(2+)](i).

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed2006

The electrochemical oxidation of troxerutin and its sensitive determination in pharmaceutical dosage forms at PVP modified carbon paste electrode.

The voltammetric responses of troxerutin were investigated at polyvinylpyrrolidone (cross-linked) (PVP) modified carbon paste electrode (CPE) in 0.1 mol/L KCl by several electrochemical techniques. A well-defined oxidation peak was observed at about 0.97 V. Compared with poor responses of troxerutin at bare electrode that at this modified electrode has been greatly improved. It is PVP that enhances the adsorption of troxerutin to electrode surface based on their hydrophobic property. Under some optimized experimental conditions, a simple and sensitive electroanalytical method was developed for the quantitative analysis of troxerutin. A very low detection limit of 5.0 x 10(-9)mol/L was obtained for 5 min accumulation at open circuit (S/N=3). This proposed method was successfully applied to the detection of troxerutin in pharmaceutical dosage forms and satisfying results had been obtained.

Adsorption↗