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Biomedical subjects

Hui Chen

Publications and source records attributed to Hui Chen.

At least 163 records · Page 9Linked to original sources
PubMed2003

Imatinib inhibits various types of activating mutant kit found in gastrointestinal stromal tumors.

Mutations of proto-oncogene c-KIT in gastrointestinal stromal tumors (GISTs) are considered to cause a constitutive activation of KIT responsible for their oncogenesis. Imatinib has therapeutic potential for GISTs because of its inhibitory effect on KIT kinase activity. To investigate the effect of Imatinib on various c-KIT mutations found in GISTs, we examined kinase activity of KIT, cell proliferation and tumorigenicity of transfectants with various c-KIT mutations. Murine lymphoid Ba/F3 cells transfected with one of the three types of mutants (KIT(del559-560), KIT(642Glu), and KIT(820Tyr)) or wild-type KIT were used for the experiments. Phosphorylation of KIT, mitogen-activated protein (MAP) and Akt was studied by immunoblotting with or without immunoprecipitation. In vitro studies on cell proliferation using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylcetrazolium bromide colorimetric assay and in vivo tumorigenicity assay using nude mice were also carried out. Imatinib could inhibit the KIT, MAP and Akt phosphorylation of all the transfectants but had a weaker effect on KIT(820Tyr). Imatinib potently inhibited the proliferation of cells transfected with KIT(820Tyr) at the concentration of 10 microM whereas it inhibited the other 3 types at 1 microM. Moreover, Imatinib could inhibit the tumor formation in nude mice transplanted with transfectants. In various types of activating mutant KIT, Imatinib could inhibit the constitutive activation of KIT signal transduction and cell proliferation both in vitro and in vivo although the effect of Imatinib on KIT(820Tyr) was weaker than that on KIT(del559-560) or KIT(642Glu).

Animals↗
PubMed2003

Role of pleckstrin homology domain in regulating membrane targeting and metabolic function of insulin receptor substrate 3.

The insulin receptor phosphorylates insulin receptor substrate (IRS) proteins on multiple tyrosine residues that act as docking sites to recruit a number of downstream signaling molecules. Here we show that IRS3 is localized both at the plasma membrane and in the nucleus. Interestingly, the nuclear localization of the protein is restricted to specific regions involved in mRNA processing and known as speckles. By using different truncated versions of the protein, we demonstrate that the pleckstrin homology (PH) domain is involved in IRS3 localization at the level of both plasma membrane and nucleus. To our knowledge this is the first report of a PH domain responsible for a nuclear targeting of the host protein. By site-directed mutagenesis, we identify residues within the PH domain critical for proper localization of IRS3. Mutations within the PH domain preventing IRS3 intracellular localization result in an inhibition of IRS3-induced glucose uptake. We conclude that the PH domain is required for IRS3 intracellular localization and, furthermore, that it has a key role in metabolic functions of IRS3. In particular, our data suggest that IRS3 intracellular localization at the plasma membrane and in the nucleus is the result of two different cooperative mechanisms both involving the PH domain.

Amino Acid Sequence↗
PubMed2003

Discovery of 5-[5-fluoro-2-oxo-1,2- dihydroindol-(3Z)-ylidenemethyl]-2,4- dimethyl-1H-pyrrole-3-carboxylic acid (2-diethylaminoethyl)amide, a novel tyrosine kinase inhibitor targeting vascular endothelial and platelet-derived growth factor receptor tyrosine kinase.

To improve the antitumor properties and optimize the pharmaceutical properties including solubility and protein binding of indolin-2-ones, a number of different basic and weakly basic analogues were designed and synthesized. 5-[5-Fluoro-2-oxo-1,2-dihydroindol-(3Z)-ylidenemethyl]-2,4-dimethyl-1H-pyrrole-3-carboxylic acid (2-diethylaminoethyl)amide (12b or SU11248) has been found to show the best overall profile in terms of potency for the VEGF-R2 and PDGF-Rbeta tyrosine kinase at biochemical and cellular levels, solubility, protein binding, and bioavailability. 12b is currently in phase I clinical trials for the treatment of cancers.

3T3 Cells↗
PubMed2003

Lamellipodia protrusion: moving interactions of vinculin and Arp2/3.

A direct, transient interaction between vinculin and Arp2/3 is required to promote receptor-stimulated lamellipodial extension and cell spreading. Vinculin selectively recruits Arp2/3 to the leading edge of the lamellipodium, where it may couple the actin polymerization machinery to adhesion complexes to promote membrane protrusion over ruffling.

Actin-Related Protein 2↗
PubMed2003

Study of the fragmentation mechanism of novel functionalized macrocycles by Fourier transform ion cyclotron resonance mass spectrometry.

Liquid secondary ion mass spectrometry (L-SIMS) of six new functionalized macrocycles was investigated. All six compounds yielded abundant fragment ions and protonation molecular ions [M + H](+) under L-SIMS conditions. The proposed fragmentation mechanisms were supported by high-resolution accurate mass data from Fourier transform ion cyclotron resonance mass spectrometric and MS(n) experiments on using sustained off-resonance irradiation collision-induced dissociation.

Cyclotrons↗
PubMed2003

Matrix-assisted laser desorption/ionization study of cationization of PEO-PPP rod-coil diblock polymers.

Five PEO-PPP rod-coil diblock polymers were synthesized and characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). By using a series of alkali chlorides as cation salts, relative cation affinities were studied. Different cation affinities and shifts in molecular weight distributions were found as a result of changing the cation type and size. Also, a study of lithium cationization resulted in determination of a recommended quantity of lithium to be used.

Journal Article↗
PubMed2003

The polymorphisms of intron1 sequences of HLA-A and -B.

Human leucocyte antigen (HLA) class I antigens are highly polymorphic membrane glycoproteins present on most nucleated cells. The polymorphism region is mainly located in exons 2 and 3 of HLA class I genes, which is flanked by introns 1 and 3. Thus, the sequence information of introns 1 and 3 is important for the genotyping of HLA. However, the information about them has not been extensively reported by now. In this work, the intron 1 sequences of HLA-A and -B of 51 standard genomic DNAs provided by the 13th International Histocompatibility Work Group (IHWG) were cloned and sequenced. The polymorphism of the intron sequences were also analyzed by the software Clustal W 1.82. Some sequences were chosen to compare with the standard sequences published in National Center for Biotechnology Information (NCBI). The comparison showed that all the sequences matched exactly with the standard sequences. The knowledge of intron 1 sequences could be very important not only for developing DNA-based typing strategies for the HLA-A and -B alleles but also for establishing an understanding of the evolutionary mechanisms involved in the polymorphism generation of HLA class I alleles.

HLA-A Antigens↗
PubMed2003

c-kit gene mutation at exon 17 or 13 is very rare in sporadic gastrointestinal stromal tumors.

BACKGROUND AND AIM: Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the human gut. They frequently have gain-of-function mutations of the c-kit gene, which encodes a receptor, tyrosine kinase. The mutations were found at exon 11 in most cases, and either at exon 9 or at exon 13 in rare cases. Recently, we found a family with multiple GIST and a gain-of-function mutation at exon 17. The family was the first reported GIST case with c-kit gene mutation at exon 17 including sporadic GIST. Although we previously reported that the c-kit gene mutation at exon 17 was not detected in 124 sporadic GIST by single-strand conformation polymorphism (SSCP) analysis, the mutation at exon 17 observed in the familial GIST was detectable by the use of direct sequencing but not by our SSCP method. In the present study, we examined the mutations at exon 17 and exon 13 by using direct sequencing. METHODS: Genomic DNA was extracted from formalin-fixed, paraffin-embedded GIST tissues. We could obtain 143 sporadic GIST cases appropriate for DNA analysis at exon 17 and 141 at exon 13. Exons 17 and 13 were amplified by using polymerase chain reaction and direct sequencing was conducted. RESULTS: No mutation was found at exon 17, and only one case with the mutation at exon 13 was observed. The GIST with the mutation at exon 13 was large and showed frequent mitosis, and the patient died of the recurrent GIST 3 years after the first operation. CONCLUSION: The mutation at exons 17 or 13 was considered to be very rare in sporadic GIST.

Aged↗
PubMed2003

Construction and analysis of SSH cDNA library of human vascular endothelial cells related to gastrocarcinoma.

AIM: To construct subtracted cDNA libraries of human vascular endothelial cells (VECs) related to gastrocarcinoma using suppression substractive hybridization (SSH) and to analyze cDNA libraries of gastrocarcinoma and VECs in Cancer Gene Anatomy Project (CGAP) database. METHODS: Human VECs related to gastric adenocarcinoma and corresponding normal tissue were separated by magnetic beads coupled with antibody CD31 (Dynabeads CD31). A few amount of total RNA were synthesized and amplified by SMART PCR cDNA Synthesis Kit. Then, using SSH and T/A cloning techniques, cDNA fragments of differentially expressed genes in human VECs of gastric adenocarcinoma were inserted into JM109 bacteria. One hundred positive bacteria clones were randomly picked and identified by colony PCR method. To analyze cDNA libraries of gastrocarcinoma and VECs in CGAP database, the tools of Library Finder, cDNA xProfiler, Digital GENE Expression Displayer (DGED), and Digital Differential Display (DDD) were used. RESULTS: Forward and reverse subtraction cDNA libraries of human VECs related to gastrocarcinoma were constructed successfully with SSH and T/A cloning techniques. Analysis of CGAP database indicated that no appropriate library of VECs related to carcinoma was constructed. CONCLUSION: Construction of subtraction cDNA libraries of human VECs related to gastrocarcinoma was successful and necessary, which laid a foundation for screening and cloning new and specific genes of VECs related to gastrocarcinoma.

DNA, Complementary↗
PubMed2003

[Confocal microprobe Raman spectroscopic study of electrochemical reduction of benzene on a platinum electrode].

The electrochemical reduction of benzene on a smooth Pt electrode has been studied by confocal microprobe Raman spectroscopy. The results show that benzene can be reduced directly to cyclohexane, which is insoluble in water, adhered onto the electrode surface to form the third phase. After the drops have been formed on the electrode surface, the relative concentration of benzene to cyclohexane in the drops will rather increase with prolonging the time at a certain electrode potential, although it decreases with the negative shift of the electrode potential at first.

Adsorption↗
PubMed2003

[Research advances in biodegradation of chlorophenols in environment].

This paper examines the biodegradation of chlorophenols by microbes and deals with the chlorophenols-degrading microbes and the usage of biotechnology with special emphasis on degradation mechanisms. Dechlorination is the first critical step in the bacterial degradation of many chloroniated pollutans. Under aerobic condition, the degradation of mono- and dichlorophenols is shown to be initiated by oxygenation into chlorocatechols, and dechlorination occurs only after ring cleavage of the chlorocatechols. The degradation of polychlorinated phenols starts by hydrolytic para-hydroxylation, yielding chlorinated para-hydroquinone. The anaerobic biodegradation of chlorophenols occurs by reductive dechlorination, a process by which chlorines are replaced with hydrogen.

Biodegradation, Environmental↗
PubMed2003

Pharmacokinetic-pharmacodynamic modeling of daurisoline and dauricine in beagle dogs.

AIM: To study the combined pharmacokinetic-pharmacodynamic (PK-PD) model of daurisoline and dauricine, and compare their effects on cardiac electrophsiology, blood pressure, and hemodynamics in beagle dogs. METHODS: The plasma drug concentration was determined by the reversed-phase HPLC method and the effects on cardiac and hemodynamics were recorded by polygraph. The pharmacokinetic and PK-PD model parameters were calculated. RESULTS: The pharmacokinetics were best fitted to a two-compartment open model, and the relationship between effect and effect compartment concentration of both drugs could be represented by the sigmoid-E(max) model. There were no significant differences in main pharmacokinetics and PK-PD parameters between the two drugs. CONCLUSION: No statistically different kinetic disposition characteristics and potencies of inhibitory effects on myocardial function of daurisoline and dauricine were found in beagle dogs.

Alkaloids↗
PubMed2003

[Arbitrary primed polymerase chain reaction for the genotypic identification of Streptococcus sanguis group].

OBJECTIVE: To find out an ideal method used in identification of Streptococcus sanguis group (SSG) strains by arbitrary primed polymerase chain reaction (AP-PCR). METHODS: AP-PCR was used to distinguish SSG strains by designing 25 bp arbitrary primer 5' AAG AGA GGA GCT AGC TCT TCT TGG A 3'. RESULTS: There were great differences in the main band of DNA polymorphism among SSG species. The similar band can be obtained from the different DNA extractions in the same species. CONCLUSION: AP-PCR may be useful in the identification and classification of SSG species.

Genotype↗
PubMed2003

[Preliminary study on single nucleotide polymorphisms and linkage disequilibrium in promoter region of fibrinogen B beta gene].

OBJECTIVE: To investigate the distribution characters and linkage disequilibrium of single nucleotide polymorphisms (SNPs) -148C/T, -455G/A and -854G/A in the promoter region of fibrinogen B(FGB) beta gene. METHODS: Genotype and allele frequencies of FGB beta gene were examined by polymerase chain reaction-restriction fragment length polymorphism and nucleotide sequencing methods in 377 Chinese southern Han individuals. Three FGB beta SNPs Hardy-Weinberg equilibrium and linkage disequilibrium were analyzed with population genetics methods. RESULTS: The allele frequencies of 3 SNPs are in good agreement with Hardy-Weinberg equilibrium. A total of 9 genotypes among the 377 individuals were identified in 3 SNPs. The genotype frequencies of -148CC, CT and TT were 0.597, 0.358 and 0.045, respectively; the -455G/A genotype frequencies were the same as that of -148C/T SNP; the genotype frequencies of -854GG,GA, AA were 0.820,0.178,0.002, respectively. The frequencies of rare allele -148T, -455A and -854A were 0.224,0.224 and 0.092, respectively, while the common allele frequencies were 0.776 for -148C, 0.776 for -455G, and 0.908 for -854G. There were no statistically significant differences in genotype and allele frequencies between the male and female groups (P>0.05). The relationship between -455G and -148C was completely concordant, but there was a random distribution between -854 and -148 (-445) SNPs. CONCLUSION: The results show there is a complete linkage disequilibrium between -148C/T and -455G/A and a negative linkage disequilibrium between -854G/A and -148C/T, as well as between -854G/A and -455G/A. This study has provided population genetics data on FGB beta gene promoter in Chinese southern Han population.

Adult↗
PubMed2003

Study on pharmacokinetics of scutellarin in rabbits.

AIM: To establish a solid phase extraction-high performance liquid chromatographic (SPE-HPLC) method for determining plasma scutellarin concentration, and study its pharmacokinetics after i.v. breviscapine in rabbits. METHODS: Methanol-water-phosphoric acid (50:50:0.5) mixture was used as mobile phase, Nucleosil C18 column (250 mm x 4.6 mm ID) was selected. The wavelength of UV detection was 335 nm. Fifteen rabbits, randomized into 3 groups, were given breviscapine i.v. at the dose of 10, 20 and 40 mg.kg-1. Scutellarin in plasma was determined by SPE-HPLC method. RESULTS: Linearity was obtained over the range of 0.02-10.0 mg.L-1 of scutellarin. The method recovery was 96.15%-99.31%; the within-day and between-day RSDs were all below 10%. After i.v. 10, 20 and 40 mg.kg-1 of breviscapine to rabbits, the concentration-time curve of scutellarin fitted to a three compartment model. The main pharmacokinetic parameters showed no significant difference between low and medium doses, but the difference was significant between high dose and other doses. CONCLUSION: This assay method was accurate, sensitive, simple and suitable for the measurement of plasma scutellarin concentration. The pharmacokinetic characteristics were found to fit a three-compartment model following i.v. injection of breviscapine to rabbits. The changes of drug concentration in vivo exhibited linear kinetics ove the dosage range of 10-20 mg.kg-1, but when the dosage was 40 mg.kg-1, the linear kinetic properties disappeared.

Animals↗