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Biomedical subjects

Hui Wang

Publications and source records attributed to Hui Wang.

At least 181 records · Page 10Linked to original sources
PubMed2005

IL-3 induces inhibitor of DNA-binding protein-1 in hemopoietic progenitor cells and promotes myeloid cell development.

Hemopoiesis depends on the expression and regulation of transcription factors, which control the maturation of specific cell lineages. We found that the helix-loop-helix transcription factor inhibitor of DNA-binding protein 1 (Id1) is not expressed in hemopoietic stem cells (HSC), but is increased in more committed myeloid progenitors. Id1 levels decrease during neutrophil differentiation, but remain high in differentiated macrophages. Id1 is expressed at low levels or is absent in developing lymphoid or erythroid cells. Id1 expression can be induced by IL-3 in HSC during myeloid differentiation, but not by growth factors that promote erythroid and B cell development. HSC were transduced with retroviral vectors that express Id1 and were transplanted in vivo to evaluate their developmental potential. Overexpression of Id1 in HSC promotes myeloid but impairs B and erythroid cell development. Enforced expression of Id1 in committed myeloid progenitor cells inhibits granulocyte but not macrophage differentiation. Therefore, Id1 may be part of the mechanism regulating myeloid vs lymphoid/erythroid cell fates, and macrophage vs neutrophil maturation.

Animals↗
PubMed2005

The use of non-uniform electrokinetics to enhance in situ bioremediation of phenol-contaminated soil.

In situ bioremediation is an attractive and often cost-effective technology for the cleanup of organics-contaminated sites, but it often requires extended treatment time under field conditions. This study explored the feasibility of using non-uniform electrokinetic transport processes to enhance in situ bioremediation. A bench-scale non-uniform electrokinetic system with periodic polarity-reversal was developed for this purpose, and tested by using a sandy loam spiked with phenol as a model organic pollutant. The results demonstrated that non-uniform electrokinetic processes could accelerate the movement and in situ biodegradation of phenol in the soil. Bidirectional operation enhanced the phenol biodegradation more effectively than unidirectional operation. At the same time, a smaller polarity-reversing interval induced a higher and more uniform removal of phenol from the soil. The results also showed that reversing the polarity of electric field applied could maintain the soil pH and moisture, but it increased the consumption of electricity.

Biodegradation, Environmental↗
PubMed2005

Crystal structure of human E1 enzyme and its complex with a substrate analog reveals the mechanism of its phosphatase/enolase activity.

Enolase-phosphatase E1 (MASA) is a bifunctional enzyme in the ubiquitous methionine salvage pathway that catalyzes the continuous reactions of 2,3-diketo-5-methylthio-1-phosphopentane to yield the aci-reductone metabolite using Mg2+ as cofactor. In this study, we have determined the crystal structure of MASA and its complex with a substrate analog to 1.7A resolution by multi-wavelength anomalous diffraction and molecular replacement techniques, respectively. The structures support the proposed mechanism of phosphatase activity and further suggest the probable mechanism of enolization. We establish a model for substrate binding to describe in detail the enzymatic reaction and the formation of the transition state, which will provide insight into the reaction mechanisms of other enzymes in the same family.

Amino Acid Motifs↗
PubMed2005

Preclinical pharmacology of 2-methoxyantimycin A compounds as novel antitumor agents.

PURPOSE: The present study was designed to determine pharmacological and biochemical properties of 2-methoxyantimycin A analogs (OMe-A1, OMe-A2, OMe-A3, and OMe-A5), which are novel antitumor compounds, and provide a basis for future pharmaceutical development, preclinical evaluation, and clinical trials. METHODS: A high-performance liquid chromatography (HPLC) method was established and employed to assess the biostability of these analogs and to determine their pharmacokinetic properties in mice and rats. RESULTS: In vitro biostability of the 2-methoxyantimycin analogs was esterase-dependent, compound-dependent, and species-dependent. In the absence of esterase inhibitors, all of the analogs were relatively unstable. Stability was greater, however, in human and dog plasma than in rat and mouse plasma. In the presence of esterase inhibitors, OMe-A1 was stable at 37 degrees C for 60 min in mouse and rat plasma, moderately stable in human plasma, and unstable in dog plasma. OMe-A2 was generally stable in all types of plasma. OMe-A3 was stable in dog and rat plasma, but not in human or mouse plasma. OMe-A5 was stable in human and dog plasma, but not in mouse or rat plasma. Each of these analogs was highly bound to plasma proteins. Of S9 fractions from four species, human S9 was least efficient in metabolizing OMe-A3. Following an intravenous dose of OMe-A1 in mice, plasma levels decreased rapidly, with an initial half-life of 2.7 min and a terminal half life of 34 min. Following an intraperitoneal dose in mice, plasma levels decreased less rapidly with a terminal half-life of 215 min. Following an intravenous dose of OMe-A1 or OMe-A3 in rats, plasma levels decreased more rapidly with initial half-lives of about 1.0 min. At an equivalent dose, OMe-A3 had a faster clearance than OMe-A1. CONCLUSIONS: For 2-methoxyantimycin A analogs, species differences in biostability, metabolism, and pharmacokinetics may be pertinent in assessing their pharmacological and toxicological profiles and antitumor activity in humans.

Animals↗
PubMed2005

Preclinical pharmacology of epothilone D, a novel tubulin-stabilizing antitumor agent.

PURPOSE: To determine, for various species, the pharmacological and biochemical properties of epothilone D (EpoD) that are relevant in establishing an appropriate animal model for further evaluation of this promising antitumor agent. METHODS: A method involving high-performance liquid chromatography (HPLC) was developed and used to assess the stability and protein binding of EpoD in plasma from various species, its metabolism by various S9 fractions, and its pharmacokinetics in mice. RESULTS: EpoD was stable in dog and human plasma. In plasma from other species, stability decreased in the order: hamster > mouse > guinea pig > rat. EpoD was highly bound to proteins in dog and human plasma. In an evaluation of S9 fractions from mouse, rat, guinea pig, dog, and human, mouse S9 was most efficient in metabolizing EpoD. Following administration to CD2F1 mice, the initial half-lives for plasma elimination of EpoD were <5 min for an intravenous dose and <20 min for an intraperitoneal dose. CONCLUSIONS: The species differences in EpoD biostability and metabolism may have implications in assessing its antitumor activity and pharmacologic and toxicologic profiles in humans. Relative to humans, the mouse is not a good model for disposition of EpoD; the dog would be more appropriate.

Animals↗
PubMed2005

Purification, crystallization and preliminary X-ray diffraction analysis of human enolase-phosphatase E1.

Enolase-phosphatase E1 (MASA) is a bifunctional enzyme in the ubiquitous methionine-salvage pathway and catalyzes the continuous reaction of 2,3-diketo-5-methylthio-1-phosphopentane to yield the acireductone metabolite. Recombinant human E1 enzyme has been crystallized using the hanging-drop vapour-diffusion method and diffraction-quality crystals were grown at 291 K using PEG 4000 as precipitant. Diffraction data were collected to 1.7 A resolution from SeMet-derivative crystals at 100 K using synchrotron radiation. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 54.02, b = 57.55, c = 87.32 A. The structure was subsequently solved by the multi-wavelength anomalous diffraction (MAD) phasing method.

Crystallization↗
PubMed2005

Phase-I dose escalation and sequencing study of docetaxel and continuous infusion topotecan in patients with advanced malignancies.

PURPOSE: Anti-tumor activity can often be enhanced with combination therapy in managing patients with metastatic cancer. However, dose sequence and schedule of delivery can alter the pharmacokinetics, toxicity, and anti-tumor response. Therefore, attention to drug-drug interactions which may be sequence or schedule-dependent are necessary. Docetaxel and topotecan are non-cross-resistance cytotoxic agents with activity in a variety of malignancies. The goal of this study was to determine the maximum tolerated dose of docetaxel and continuous infusion topotecan using two sequences of administration. EXPERIMENTAL DESIGN: Patients were randomized to schedule A or B and enrolled in four escalating-dose cohorts. On schedule A, docetaxel was administered over 1 h and followed by topotecan administered over 72 h. On schedule B, topotecan was given as a 72 h continuous infusion followed by a 1 h infusion of docetaxel. While the doses for the docetaxel and topotecan were the same for schedule A and schedule B, the toxicities, and thus the determination of maximum tolerated dose (MTD), were assessed independently. The plasma pharmacokinetic disposition of topotecan and docetaxel were evaluated during the first cycle of each sequence to assess drug interactions. RESULTS: Thirty patients, 20 males and 10 females were evaluable for toxicity and response. Four patients were chemonaive. Mean number cycles given were 3. Grade 3/4 thrombocytopenia and neutropenia were comparable on both schedules, as was the dose-limiting toxicity (DLT) for both schedules. There were no apparent differences in absolute neutrophil count or platelet nadirs between schedules A and B for three of the four cohorts. The principal non-hematologic toxicity was nausea and vomiting. The time of overlap of topotecan lactone or total concentrations and docetaxel concentrations were greater on schedule A as compared with schedule B and was associated with reduced clearance of docetaxel on schedule A as compared to schedule B. However, the mean clearance for docetaxel (18 for all 16 L h(-1) m(-2) and 29 for all 28 L h(-1) m(-2) on schedules A and B, respectively, and topotecan 16 for all 10 L h(-1) m(-2) and 7 for all 6 L h(-1) m(-2) on schedules A and B, respectively) were not statistically different (P > 0.05). CONCLUSIONS: The observed toxicity was not sequence-dependent, despite the observed change in kinetics. Docetaxel and topotecan can be administered with acceptable toxicity at the recommended phase-II dose of docetaxel 60 mg m(-2) and topotecan 0.85 mg m(-2) day(-1)x3 days.

Adult↗
PubMed2005

Bayesian shrinkage estimation of quantitative trait loci parameters.

Mapping multiple QTL is a typical problem of variable selection in an oversaturated model because the potential number of QTL can be substantially larger than the sample size. Currently, model selection is still the most effective approach to mapping multiple QTL, although further research is needed. An alternative approach to analyzing an oversaturated model is the shrinkage estimation in which all candidate variables are included in the model but their estimated effects are forced to shrink toward zero. In contrast to the usual shrinkage estimation where all model effects are shrunk by the same factor, we develop a Bayesian method that allows the shrinkage factor to vary across different effects. The new shrinkage method forces marker intervals that contain no QTL to have estimated effects close to zero whereas intervals containing notable QTL have estimated effects subject to virtually no shrinkage. We demonstrate the method using both simulated and real data for QTL mapping. A simulation experiment with 500 backcross (BC) individuals showed that the method can localize closely linked QTL and QTL with effects as small as 1% of the phenotypic variance of the trait. The method was also used to map QTL responsible for wound healing in a family of a (MRL/MPJ x SJL/J) cross with 633 F(2) mice derived from two inbred lines.

Animals↗
PubMed2005

Activation of nuclear factor-kappa B and effects of pyrrolidine dithiocarbamate on TNBS-induced rat colitis.

AIM: To explore the changes of nuclear factor-kappa B (NF-kappaB) DNA-binding activity, the expression of intercellular adhesion molecule-1 (ICAM-1) regulated by NF-kappaB at various times and to evaluate the effects of pyrrolidine dithiocarbamate (PDTC) on trinitrobenzene sulfonic acid (TNBS)-induced rat colitis. METHODS: TNBS of 0.6 mL was mixed with ethanol of 0.3 mL solution and instilled into the lumen of the rat colon. The rat models were divided into 6 groups, which were killed at 24 h, 3, 7, 14, and 21 d after enema. Colonic inflammation and damage were assessed by macroscopical and histological criteria. Activity of NF-kappaB DNA-binding was analyzed by electrophoresis mobility shift assays (EMSA). Expression of ICAM-1 was detected by in situ hybridization (ISH) and immunohistochemistry (IH). Then various doses of PDTC were injected into rat abdomen 30 min before enema with TNBS/ethanol as pretreatment. The rats were killed 4 h after enema and the colonic inflammation, myeloperoxidase (MPO) activity, malondialdehyde (MDA) level, and DNA-binding activity of NF-kappaB were assessed. Finally, PDTC was injected intraperitoneally after colitis was induced. Changes of morphology were assayed. RESULTS: During the first week, hyperemia, hemorrhage, edema and ulceration of the colonic mucosa appeared with predominant infiltration of leukocytes. Neutrophils, macrophages, lymphocytes infiltrated in mucosa and submucosa 14 d later. Fibroblasts and granuloma-like structures were also obviously seen. The binding activity of NF-kappaB began to increase at 24 h time point and reached a peak at 14 d, then decreased but still was higher than control group at 21 d (P<0.01). Levels of ICAM-1 mRNA and protein significantly elevated at 24 h and the peak was at 21 d. Pretreatment with PDTC could attenuate the development of inflammation but not by reducing NF-kappaB activity. This attenuation of inflammation had a positive relationship with the dose of PDTC. PDTC at the dose of 100 mg/kg had no therapeutic effect after colitis was induced. CONCLUSION: NF-kappaB activation is an important event that may be involved in acute and chronic inflammation development and may contribute to self-protection against early inflammation damage. NF-kappaB also regulates ICAM-1 expression during colonic inflammation. Pretreatment of PDTC may attenuate the inflammation development. But PDTC has no therapeutic effect after the colitis is induced.

Animals↗
PubMed2005

Genome-wide RNAi screen reveals a specific sensitivity of IRES-containing RNA viruses to host translation inhibition.

The widespread class of RNA viruses that utilize internal ribosome entry sites (IRESs) for translation include poliovirus and Hepatitis C virus. To identify host factors required for IRES-dependent translation and viral replication, we performed a genome-wide RNAi screen in Drosophila cells infected with Drosophila C virus (DCV). We identified 66 ribosomal proteins that, when depleted, specifically inhibit DCV growth, but not a non-IRES-containing RNA virus. Moreover, treatment of flies with a translation inhibitor is protective in vivo. Finally, this increased sensitivity to ribosome levels also holds true for poliovirus infection of human cells, demonstrating the generality of these findings.

Animals↗
PubMed2005

Chiral separations on multichannel microfluidic chips.

Chiral separations of FITC-labeled basic drugs on multichannel microfluidic chips with LIF detector were investigated. A preliminary screening procedure for seven neutral CDs was performed under optimized conditions for chiral separations of three FITC-labeled drugs (baclofen, norfenefrine, and tocainide) on a mono-channel microfluidic chip. According to the results of screening, FITC-baclofen and FITC-norfenefrine as well as two chiral selectors including gamma-CD and dimethyl-beta-CD (DM-beta-CD) were selected as models to perform chiral separations on a two-channel chip. FITC-baclofen enantiomers were separated completely by gamma-CD in one channel, while resolution of FITC-norfenefrine enantiomers was achieved by DM-beta-CD in the other channel in the same run. Furthermore, the feasibility of using one chiral selector to separate multiple chiral samples was studied on a four-channel chip. These results show that multichannel chip has a potential for chiral high-throughput screening.

Baclofen↗
PubMed2005

Quantitative structure-retention relationships of benzoylphenylureas on polystyrene-octadecene-encapsulated zirconia stationary phase in reversed-phase high performance liquid chromatography.

Quantitative Structure-Retention Relationships of benzoylphenylureas and similar compounds have been studied on a new type of stationary phase (polystyrene-octadecene-encapsulated zirconia) in reversed-phase high performance liquid chromatography. Using stepwise regression analysis, the relationships between the structural descriptors of the compound and its chromatographic retention were examined. It was confirmed that the retention of the dihalogenobenzoylphenylureas is mainly governed by the dipole moment (DM), the calculated molar refractivity (CMR), and the hydrophobicity parameter (C log P) of the compounds. The predicting equations for the 18 dihalogenobenzoylphenylureas and similar compounds were also established; there is a good agreement between the observed k values and the predicted k values. In addition, a typical ODS (Kromasil-C18-SiO2) was compared with C18-PS-ZrO2. The results showed that there were some differences between the two stationary phase for the separation of the compounds investigated, which are certainly related to surface characteristics of the two different supports.

Journal Article↗
PubMed2005

Analysis of flavonoids in leaves of Adinandra nitida by capillary electrochromatography on monolithic columns with stepwise gradient elution.

Extracts of Adinandra nitida leaves, known as Shiyacha in China, were analyzed by monolithic columns of capillary electrochromatography (CEC). To obtain good resolution within a short time, stepwise gradient elution of CEC was employed, and the effects of experimental parameters, such as the buffer, the gradient conditions, and the mode of injection were studied systematically. Under optimized conditions, analysis could be accomplished in 25 min on a monolithic rod of macroporous poly(butyl methacrylate-co-ethylene dimethacrylate). With two identified flavonoids, epicatechin and apigenin, as markers, a quality control method for Shiyacha and its relevant products was established. The calibration curves exhibited good linear behavior over the concentration range of two orders of magnitude. On combination with an on-line concentration technique, the detection limit of flavonoids could be decreased to 25 ng for apigenin.

Apigenin↗
PubMed2005

Modification of a poly(methyl methacrylate) injection-molded microchip and its use for high performance analysis of DNA.

Inexpensive and permanently modified poly(methyl methacrylate)(PMMA) microchips were fabricated by an injection-molding process. A novel sealing method for plastic microchips at room temperature was introduced. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values between 1-3% for the run-to-run and less than 2.1% for the chip-to-chip comparisons. Acrylonitrile-butadiene-styrene (ABS) was used as an additive in PMMA substrates. The proportions of PMMA and ABS were optimized. ABS may be considered as a modifier, which obviously improved some characteristics of the microchip, such as the hydrophilicity and the electro-osmotic flow (EOF). The detection limit of Rhodamine 6G dye for the modified microchip on the home-made microchip analyzer showed a dramatic 100-fold improvement over that for the unmodified PMMA chip. A detection limit of the order of 10(-20) mole has been achieved for each injected psiX-174/HaeIII DNA fragment with the baseline separation between 271 and 281 bp, and fast separation of 11 DNA restriction fragments within 180 seconds. Analysis of a PCR product from the tobacco ACT gene was performed on the modified microchip as an application example.

DNA↗
PubMed2005

Roles of protein kinase C and fructose in hepatic injury caused by obstructive jaundice.

The regulating mechanism in hepatic injury caused by obstructive jaundice (OJ) was examined in this study. Rat hepatocytes were harvested by in situ collagenase perfusion and subjected to primary culture. The heptocytes were pre-treated with various concentrations of protein kinase C (PKC) agonist PMA and its inhibitor chelerythrine and cultured for 20 min. After the treatment, 50 micromol/L glycochenodeoxycholate (GCDC) was added and the cells were cultured for an additional 24 h. Cells were then detected by flow cytometry (FCM) and TUNEL. After hepatocytes were treated with different concentrations of fructose and 100 microM GCDC, the cells were examined by FCM and TUNEL. Experimental obstructive jaundice (BDL) was induced by double ligation of the bile duct. After BDL, the rats were fed with or without fructos and sacrificed 3, 7, 14 and 21 days after the ligation. The apoptotic status was observed in liver of all rats with TUNEL and PKC protein in liver of OJ was studied by immunohistochemical method. Our results showed that PMA increased GCDC-induced apoptosis and chelerythrine decreased GCDC-induced apoptosis in a concentration-dependent manner. After the treatment with fructose of different concentrations, 100 microM GCDC decreased the apoptotic rate and the apoptotic rate decreased with the increase of fructose concentration. The apoptotic rate of liver was related to the time of OJ. Without the treatment of fructose, PKC and apoptosis index (AI) were highest 14 days after the bile duct ligation. With the treatment of fructose, apoptosis index (AI) and PKC were decreased from the 14th day after the bile duct ligation. It is concluded that PKC is involved in the regulation of apoptosis in the liver cells with OJ and plays important roles in the development and progression of liver injury caused by OJ. Fructose can protect hepatocytes in the bile salt-induced apoptosis by regulating PKC.

Alkaloids↗
PubMed2005

Identification of natural compounds with antiviral activities against SARS-associated coronavirus.

More than 200 Chinese medicinal herb extracts were screened for antiviral activities against Severe Acute Respiratory Syndrome-associated coronavirus (SARS-CoV) using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay for virus-induced cytopathic effect (CPE). Four of these extracts showed moderate to potent antiviral activities against SARS-CoV with 50% effective concentration (EC50) ranging from 2.4 +/- 0.2 to 88.2 +/- 7.7 microg/ml. Out of the four, Lycoris radiata was most potent. To identify the active component, L. radiata extract was subjected to further fractionation, purification, and CPE/MTS assays. This process led to the identification of a single substance lycorine as an anti-SARS-CoV component with an EC50 value of 15.7 +/- 1.2 nM. This compound has a CC50 value of 14980.0 +/- 912.0 nM in cytotoxicity assay and a selective index (SI) greater than 900. The results suggested that four herbal extracts and the compound lycorine are candidates for the development of new anti-SARS-CoV drugs in the treatment of SARS.

Amaryllidaceae Alkaloids↗
PubMed2005

Mobilization of phenol and dichlorophenol in unsaturated soils by non-uniform electrokinetics.

The poor mobility of organic pollutants in contaminated sites frequently results in slow remediation processes. Organics, especially hydrophobic compounds, are generally retained strongly in soil matrix as a result of sorption, sequestration, or even formation into non-aqueous-phase liquids and their mobility is thus greatly reduced. The objective of this study was to evaluate the feasibility of using non-uniform electrokinetic transport processes to enhance the mobility of organic pollutants in unsaturated soils with no injection reagents. Phenol and 2,4-dichlorophenol (2,4-DCP), and kaolin and a natural sandy loam soil were selected as model organics and soils, respectively. The results showed that non-uniform electrokinetics can accelerate the desorption and movement of phenol and 2,4-DCP in unsaturated soils. Electromigration and electroosmotic flow were the main driving forces, and their role in the mobilization of phenol and 2,4-DCP varied with soil pH. The movement of 2,4-DCP in the sandy loam towards the anode (about 1.0 cmd(-1)V(-1)) was 1.0-1.5 cmd(-1)V(-1) slower than that in the kaolin soil, but about 0.5 cmd(-1)V(-1) greater than that of phenol in the sandy loam. When the sandy loam was adjusted to pH 9.3, the movement of phenol and 2,4-DCP towards the anode was about twice and five times faster than that at pH 7.7, respectively. The results also demonstrated that the movement of phenol and 2,4-DCP in soils can be easily controlled by regulating the operational mode of electric field. It is believed that non-uniform electrokinetics has the potential for practical application to in situ remediation of organics-contaminated sites.

Adsorption↗