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G Wu

Publications and source records attributed to G Wu.

At least 361 records · Page 20Linked to original sources
PubMed1997

sel-10, a negative regulator of lin-12 activity in Caenorhabditis elegans, encodes a member of the CDC4 family of proteins.

Mutations that influence lin-12 activity in Caenorhabditis elegans may identify conserved factors that regulate the activity of lin-12/Notch proteins. We describe genetic evidence indicating that sel-10 is a negative regulator of lin-12/Notch-mediated signaling in C. elegans. Sequence analysis shows that SEL-10 is a member of the CDC4 family of proteins and has a potential human ortholog. Coimmunoprecipitation data indicate that C. elegans SEL-10 complexes with LIN-12 and with murine Notch4. We propose that SEL-10 promotes the ubiquitin-mediated turnover of LIN-12/Notch proteins, and discuss potential roles for the regulation of lin-12/Notch activity by sel-10 in cell fate decisions and tumorigenesis.

Amino Acid Sequence↗
PubMed1997

Adsorption of Dyes on Nanosize Modified Silica Particles

The adsorption of several anionic dyes on nanosize alumina-modified silica particles of different compositions and modal sizes has been studied. These silica cores have the same surface properties as alumina dispersed in aqueous solutions. The negatively charged dyes are electrostatically attracted to positively charged cores and chemisorbed by forming a surface Al lake. The application of so obtained pigments in the preparation of color films and their optical characteristics are described. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Stoichiometry of the interaction of prostaglandin H synthase with substrates.

Prostaglandin H synthase (PGHS) catalyzes both peroxidase and cyclooxygenase reactions. Resolution of several current issues regarding the PGHS catalytic mechanism hinges on the stoichiometry of the reaction of PGHS with hydroperoxide, fatty acid, and oxygen. The dependence of wide-doublet tyrosyl radical accumulation in PGHS isoform 1 on hydroperoxide stoichiometry, has been determined; this catalytically active radical is formed efficiently at stoichiometries </=1 after only 300 ms of reaction. This is consistent with intramolecular formation of the radical from PGHS Compound I but inconsistent with an alternative pathway involving reduction of Compound I to Compound II by a second hydroperoxide molecule. Results from stopped-flow studies indicate that the hydroperoxide level influences the rate of Compound II formation indirectly, via changes in the transient accumulation of Compound I, rather than by reducing Compound I. PGHS and soybean lipoxygenase reactions with 11,14-eicosadienoic acid (20:2) were also analyzed using a spectrophotometer cuvette fitted with an oxygen electrode to monitor lipid product formation and oxygen consumption simultaneously. The results show that the oxygen electrode signal is inherently dampened and thus underestimates the oxygen consumption rate; the discrepancy is much larger for the more rapidly accelerating PGHS reaction than for the lipoxygenase reaction. When correction is made for the electrode dampening, the ratio between the peak rates of oxygen consumption and lipid product formation was near unity for both PGHS and lipoxygenase, indicating a reaction stoichiometry of about 1 mol of O2 consumed/mol of 20:2 oxygenated for both enzymes. Separately, a stoichiometry of 0.9 mol of O2 consumed / mol oxygenated fatty acid was obtained when limiting amounts of 20:2 were reacted to completion with excess PGHS; the corresponding stoichiometry with arachidonic acid was 1.9. These O2/fatty acid stoichiometries are consistent with a dioxygenase mechanism for reaction of PGHS with both fatty acids and inconsistent with a mixed dioxygenase/monooxygenase mechanism proposed for the reaction with 20:2. The present conclusions reduce the complexity of the mechanisms that need to be considered for PGHS catalysis.

Animals↗
PubMed1997

Molecular cloning, cDNA sequence analysis, and chromosomal localization of mouse Pkd2.

The gene responsible for the second form of autosomal dominant polycystic kidney disease, PKD2, has recently been identified. We now describe the cloning, genomic localization, cDNA sequence, and expression analysis of its murine homologue, Pkd2. The cloned cDNA sequence is 5134 bp long and is predicted to encode a 966-amino-acid integral membrane protein with six membrane-spanning domains and intracellular NH2 and COOH termini. Pkd2 is highly conserved with 91% identity and 98% similarity to polycystin-2 at the amino acid level. Pkd2 mRNA is widely expressed in mouse tissues. Pkd2 maps to mouse Chromosome 5 and is excluded as a candidate gene for previously mapped mouse mutations resulting in a polycystic kidney phenotype.

Amino Acid Sequence↗
PubMed1997

Human endothelial cells in culture and in vivo express on their surface all four components of the glycoprotein Ib/IX/V complex.

The platelet glycoprotein Ib (GpIb) complex is composed of four polypeptides: the disulfide-linked GpIb alpha and GpIb beta and the noncovalently associated GpIX and GpV. GpIb alpha contains binding sites for von Willebrand factor and for thrombin and mediates platelet adhesion to the subendothelium under conditions of high shear stress. We have previously shown the presence of GpIb alpha and GpIb beta mRNA and protein in cultured human umbilical vein endothelial cells (HUVECs) as well as the presence of GpIb alpha mRNA and protein in tonsillar endothelium. We, therefore, probed ECs for the presence of the other components of the GpIb/IX/V complex. We have identified the presence of GpIX and GpV mRNA in cultured HUVEC monolayers. The sequence of HUVEC GpIX cDNA was identical to the previously published human erythroleukemia (HEL) cell GpIX cDNA sequence. Two species of GpV mRNA, one of 3 kb and one of 4.4 kb, were found in HUVECs, whereas HEL cells displayed only the 4.4-kb species and the megakaryocytic cell line CHRF-288 contained only the 3-kb species. We previously showed that EC GpIb alpha protein is identical in molecular weight to platelet GpIb alpha. HUVEC GpIb beta, in contrast to its platelet counterpart, has a molecular weight of 50 kD and forms a correspondingly larger disulfide-bonded complex with EC GpIb alpha. The molecular weights of GpIX and GpV were 22 and 88 kD, respectively, identical to the corresponding platelet polypeptides. Furthermore, we have identified all four components of the complex in tonsillar vessels. Using flow cytometry, we have established that all four polypeptides of the GpIb/IX/V complex are expressed on the surface membranes of cultured HUVECs and adult aortic ECs. Furthermore, using two-color fluorescence, we have shown that all ECs expressing GpIb alpha also express GpIX and GpV on their surface. The ratio of GpIb alpha:GpIX:GpV is 1:1:0.5, which is identical to the ratio present in platelets. None of the polypeptides of the GpIb complex could be identified on the surface of human smooth muscle cells or lymphocytes. The presence of all members of the GpIb complex in the EC membrane suggests that this complex may play a role in endothelial function in vivo.

Adult↗
PubMed1997

Modulation of cell cycle control by vitamin D3 and its analogue, EB1089, in human breast cancer cells.

Examination of a panel of ER positive breast cancer cell lines showed that they were differentially growth inhibited by vitamin D3 and its analogue EB1089. EB1089 treatment of the breast cancer cell lines MCF-7 E, BT20, T47D, and ZR75 demonstrated a correlation between a reduction in Cdk2 kinase activity towards phosphorylation of histone H1 and a decrease in DNA synthesis, while no modulation of Cdk2 activity was observed in the vitamin D3 and EB1089 resistant cell line MCF-7 L. This was accompanied by a time dependent decrease in the percentage of S phase cells in the responsive lines. Characterization of the expression levels of Cdk2 and its related cell cycle proteins in MCF-7 E cells showed that after EB1089 treatment, there was a concentration and time dependent up-regulation of p21 as well as a decrease in cyclin A proteins. Paradoxically, cyclin E levels were increased as a function of treatment. Analysis of cyclin-Cdk2-Cdki complex formation showed that in EB1089 treated MCF-7 E cells, Cdk2, cyclin A and cyclin E immunoprecipitates contained an increased abundance of p21. In contrast to MCF-7 E cells, increases in both p21 and p27 as well as their complex formation with Cdk2 were observed in BT20 and ZR75 cells. These findings indicate that up-regulation of p21 as well as p27 in some cell types may account for the inactivation of Cdk2 activity and a G1 block of the cell cycle following EB1089 treatment.

Antineoplastic Agents↗
PubMed1997

Characterization of the exon structure of the polycystic kidney disease 2 gene (PKD2).

PKD2, the gene defective in the second form of autosomal dominant polycystic kidney disease (ADPKD), has been identified by positional cloning and found to encode an integral membrane protein with similarity to the gene for the more common form of ADPKD and to calcium channels. We have determined the exon-intron structure of the PKD2 gene. PKD2 is encoded in at least 15 exons with the translation start site in exon 1. All the splice acceptor and donor sites conform to the AG/GT rule. We have designed a series of intronic oligonucleotide primers for amplifying the entire coding sequence from genomic DNA in segments well suited to mutation analysis using conventional screening strategies such as SSCA or heteroduplex analysis.

Cloning, Molecular↗
PubMed1997

Clonality in nodular lymphocyte-predominant Hodgkin's disease.

BACKGROUND: There is general agreement that lymphocytic and histiocytic (L&H) cells, the variants of Reed-Sternberg cells in nodular lymphocyte-predominant Hodgkin's disease, belong to the B-cell lineage. However, the clonality of L&H cells remains controversial. METHODS: We used complementarity-determining region 3 (CDR3) of the immunoglobulin heavy-chain gene as a clonal marker to study individual L&H cells isolated by micromanipulation from tissue sections of five patients with nodular lymphocyte-predominant Hodgkin's disease. The heavy-chain CDR3 of each cell was amplified by the polymerase chain reaction. The products were analyzed by gel electrophoresis, and representative amplification products from each patient were sequenced. RESULTS: L&H cells whose heavy-chain CDR3 was related, indicating the presence of a clonal population, were detected in all five patients and were the dominant population in three. In four of the five patients, members of the clone were found in different nodules in the tissue section, different tissue blocks from the same tumor, or different lymph nodes from the same patient. The CDR3 sequences in each clone frequently contained nucleotide substitutions indicative of intraclonal mutation. CONCLUSIONS: Clonal populations of L&H cells occur in nodular lymphocyte-predominant Hodgkin's disease. Intraclonal variation in nucleotide sequences suggests that hypermutation of the heavy-chain CDR3 continues to occur among the clonal progeny.

B-Lymphocytes↗
PubMed1997

Interaction of arrestins with intracellular domains of muscarinic and alpha2-adrenergic receptors.

The intracellular domains of G-protein-coupled receptors provide sites for interaction with key proteins involved in signal initiation and termination. As an initial approach to identify proteins interacting with these receptors and the receptor motifs required for such interactions, we used intracellular subdomains of G-protein-coupled receptors as probes to screen brain cytosol proteins. Peptides from the third intracellular loop (i3) of the M2-muscarinic receptor (MR) (His208-Arg387), M3-MR (Gly308-Leu497), or alpha2A/D-adrenergic receptor (AR) (Lys224-Phe374) were generated in bacteria as glutathione S-transferase (GST) fusion proteins, bound to glutathione-Sepharose and used as affinity matrices to detect interacting proteins in fractionated bovine brain cytosol. Bound proteins were identified by immunoblotting following SDS-polyacrylamide gel electrophoresis. Brain arrestins bound to the GST-M3 fusion protein, but not to the control GST peptide or i3 peptides derived from the alpha2A/D-AR and M2-MR. However, each of the receptor subdomains bound purified beta-arrestin and arrestin-3. The interaction of the M3-MR and M2-MR i3 peptides with arrestins was further investigated. The M3-MR i3 peptide bound in vitro translated [3H]beta-arrestin and [3H]arrestin-3, but did not interact with in vitro translated or purified visual arrestin. The properties and specificity of the interaction of in vitro translated [3H]beta-arrestin, [3H]visual arrestin, and [3H]beta-arrestin/visual arrestin chimeras with the M2-MR i3 peptide were similar to those observed with the intact purified M2-MR that was phosphorylated and/or activated by agonist. Subsequent binding site localization studies indicated that the interaction of beta-arrestin with the M3-MR peptide required both the amino (Gly308-Leu368) and carboxyl portions (Lys425-Leu497) of the receptor subdomain. In contrast, the carboxyl region of the M3-MR i3 peptide was sufficient for its interaction with arrestin-3.

Animals↗
PubMed1997

An integrated genetic and physical map of the autosomal recessive polycystic kidney disease region.

Autosomal recessive polycystic kidney disease is one of the most common hereditary renal cystic diseases in children. Genetic studies have recently assigned the only known locus for this disorder, PKHD1, to chromosome 6p21-p12. We have generated a YAC contig that spans approximately 5 cM of this region, defined by the markers D6S1253-D6S295, and have mapped 43 sequence-tagged sites (STS) within this interval. This set includes 20 novel STSs, which define 12 unique positions in the region, and three ESTs. A minimal set of two YACs spans the segment D6S465-D6S466, which contains PKHD1, and estimates of their sizes based on information in public databases suggest that the size of the critical region is < 3.1 Mb. Twenty-eight STSs map to this interval, giving an average STS density of < 1/150 kb. These resources will be useful for establishing a complete transcription map of the PKHD1 region.

Base Sequence↗
PubMed1997

Antiapoptotic compound to enhance hypothermic liver preservation.

BACKGROUND: Apoptosis (programmed cell death) occurs as a consequence of global organ ischemia during isolation and storage prior to transplantation. If apoptosis is inhibited during ischemia, organ preservation should be improved, and the length of time for permissible storage may be increased. The objective of this study was to test the effect of a newly developed antiapoptotic compound, LXR-015, during extended hypothermic liver preservation. METHODS: Three groups of 12 rats each were studied. In the normal group, liver function was studied immediately after harvesting. In the study group, harvested livers were flushed with Euro-Collins solution (30 ml/kg body weight) containing LXR-015 at a concentration equivalent to 9 mg/kg animal body weight (300 microg/ml). The livers were then stored at 4 degrees C for 24 hr before liver function was studied. In the control group, harvested livers were flushed with Euro-Collins solution without LXR-015 and then stored at 4 degrees C for 24 hr before liver function was studied. RESULTS: Portal venous flow was higher (P<0.05) in the normal and study groups compared with the control group. Portal venous resistance was lower (P<0.05) in the normal and study groups compared with the control group. Liver tissue oxygen consumption in the study group was significantly higher than in both the normal and control groups (P<0.05). Liver enzyme production (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatine kinase) was higher in the control group than in either the study or normal group (P<0.05). Bile production in both the normal and study groups was higher than in the control group (P<0.05). The liver tissue wet to dry weight ratio in both the normal and study groups was lower than in the control group (P<0.05). Histopathology studies revealed fewer apoptotic bodies (P<0.05) in both the normal (1.70+/-0.15 per high-power field) and study groups (2.08+/-0.10 per high-power field) than in the control group (7.92+/-.33 per high-power field). CONCLUSIONS: Adding an antiapoptotic compound, LXR-015, to Euro-Collins solution significantly improves hypothermic preservation of the rat liver compared with Euro-Collins solution alone.

Alanine Transaminase↗
PubMed1997

Comparative localization of fibroblast growth factor receptor-1, -2, and -3 mRNAs in the rat brain: in situ hybridization analysis.

The present study provides a detailed comparative description in the adult rat brain of areas that express mRNAs coding for the fibroblast growth factor subtype receptors 1-3 (FGFR1-3). One observation in this analysis was a widespread expression in the brain of all three FGFR mRNAs, according to the following rank order: FGFR1, diencephalon < telencephalon < mesencephalon and metencephalon < myelencephalon; FGFR2 and FGFR3, telencephalon < diencephalon < mesencephalon and metencephalon < myelencephalon. Another observation was an apparent cellular specificity in their basal expression. Thus, the FGFR1 mRNA was expressed mainly in large and weakly stained cells, whereas FGFR2 transcripts were expressed primarily in small and strongly stained cells and in cells of brain regions devoid of neuronal cells, such as the white matter. FGFR3 mRNA was always detected in small and strongly stained cells with scattered distribution and was not expressed in the white matter. However, FGFR2 mRNA was weakly expressed also in large cells localized in some nuclei of the lower brainstem, in the diagonal band, and in the septum. Furthermore, in the medial habenula and in the nuclei of the pons, there exists a high density of cells expressing both FGFR1 and FGFR2 (60-100%). With neurotoxic lesions involving 6-hydroxydopamine microinjections in the substantia nigra, reactive glial cells in the lesioned area and surrounding the cannula tract showed an increase in the expression of both FGFR1 and FGFR2 mRNAs, whereas no increased expression was found for FGFR3 mRNA. Taken together, these findings showed that these three FGF receptors exist in all subtypes of cells of each brain region. Their apparent cellular specificity suggests that these receptor subtypes can have a differential trophic role in the brain, reflecting the various biological activities shown by the ligands of the FGF family.

Animals↗
PubMed1997

Laser photoablation of experimental post-infarction ventricular tachycardia guided by three dimensional activation mapping.

BACKGROUND AND OBJECTIVE: The purpose of this study was to evaluate the efficacy of epicardially delivered laser energy to ablate induced ventricular tachycardia in a post-infarction canine model. STUDY DESIGN/MATERIALS AND METHODS: In 13 canines, the left anterior wall myocardial infarction was created. Five days later, 240 plunged electrodes were inserted into the heart. Three-dimensional ventricular activation sequences were analyzed on line by a computerized mapping system. RESULTS: Sixteen sustained monomorphic ventricular tachycardias were reproducibly induced in 10 canines. Epicardially contacted Nd:YAG laser irradiated the areas of the final pathway in macro-reentrant activation and the impulse origin in focal excitation. Linear photocoagulation lesions (11-16 x 50-72 mm) were created. Seven macro-reentrant circuits and six of nine focal origins were eliminated (success rate 81%). Pathology showed that laser photocoagulation involved all surviving subepicardial and intramural fibers. CONCLUSION: Epicardially delivered laser energy in conjunction with electrical activation mapping has a high probability of ablating post-infarction ventricular tachycardia.

Animals↗
PubMed1997

Spinning sidebands in slow-magic-angle-spinning NMR spectra arising from tightly J-coupled spin pairs.

Complex spinning sidebands are observed in magic-angle-spinning (MAS) NMR spectra arising from isolated tightly J-coupled spin pairs under slow spinning conditions. Such spinning sidebands are sensitive to the magnitude and relative orientation of the chemical-shift tensors, the dipolar-coupling tensor, and the sign of the indirect spin-spin (J) coupling. We show that it is possible to extract information concerning such NMR parameters from an analysis of the observed spinning sidebands. As an example, numerical simulations are carried out to reproduce observed 31P MAS NMR spectra of a phosphole tetramer (1) and o-bis(diphenylphosphino)benzene (2), so that invaluable information concerning the orientations of the phosphorus chemical-shift tensors and the sign of J(31P, 31P) can be deduced. Simulations are carried out by numerically evaluating the spin-density matrix of the spin system.

Anisotropy↗
PubMed1997

An explanation for failure to predict cyclosporine area under the curve using a limited sampling strategy: a beginner's second note.

Recently, limited sampling strategies have been developed to predict the area under a blood drug concentration-time curve (AUC). Multiple stepwise linear regression is the method used to develop limited sampling strategies. Several limited sampling strategies are used to predict cyclosporine AUC. However, recent findings demonstrated that, of all the developed limited sampling strategies, none can predict cyclosporine AUC correctly. Although several explanations have been given for this, the possible mathematical reason has not yet been fully explored. In the present study, we demonstrated that: (i) a steady-state blood drug concentration can be decomposed into the linear and non-linear components using the Fourier series; (ii) the non-linear component of the steady-state blood drug concentration leads to an AUC with a non-linear component, which affects the validation of limited sampling strategies; (iii) the correlation coefficient in a limited sampling strategy can only account for the linear association of linear components between a steady-state blood drug concentration and the AUC; (iv) the average steady-state blood drug concentration is a linear component of the steady-state blood drug concentration; and (v) when developing a limited sampling strategy, the non-linear component can be effectively ignored by: (a) choosing the sampling time around the middle point between the peak and the trough steady-state blood drug concentrations; and (b) increasing the trough steady-state blood drug concentration. However, the latter is restricted by clinical considerations.

Animals↗
PubMed1997

Separation of DL-dopa by means of micellar electrokinetic capillary chromatography after derivatization with Marfey's reagent.

Micellar electrokinetic capillary chromatography was used to separate levodopa (L-3,4-dihydroxyphenyl-L-alanine), dextrodopa (D-3,4-dihydroxyphenyl-L-alanine) and DL-3-O-methyl-dopa, a metabolite of dopa, which were derivatised with the Marfey's reagent, in sodium borate, sodium dodecyl sulfate and acetonitile buffer system. Whereas DL-dopa derivatives could be separated, DL-3-O-methyl-dopa derivatives could not.

Chromatography↗