Biomedical subjects

T F Wang

Publications and source records attributed to T F Wang.

At least 19 recordsLinked to original sources

PubMed2006

Effects of docosahexaenoic acid supplementation on blood lipids, estrogen metabolism, and in vivo oxidative stress in postmenopausal vegetarian women.

BACKGROUND: Vegetarians are generally deficient in long-chain n-3 fatty acids. Long-chain n-3 fatty acids have a beneficial effect on plasma lipid levels, and some studies showed that they had breast cancer suppression effect. One of the biomarkers of breast cancer risk is the ratio of urinary 2-hydroxyestrone (2-OHE(1)) to 16alpha-hydroxyestrone (16alpha-OHE(1)). OBJECTIVE: To investigate the effect of docosahexaenoic acid (DHA, 22:6n-3) supplementation on blood lipids, estrogen metabolism and oxidative stress in vegetarians. DESIGN: Single-blind, randomized, placebo-controlled trial. INTERVENTIONS: Twenty-seven postmenopausal vegetarian women were recruited. After a 2-week run-in period with 6 g placebo corn oil, the subjects were subsequently randomized to receive either 6 g corn oil (n=13) or 6 g DHA-rich algae oil (2.14 g of DHA/day) (n=14) for 6 weeks. Two subjects in corn oil group withdrew before completion. MAIN OUTCOME MEASURES: Plasma lipids, urinary 2-OHE(1) and 16alpha-OHE(1), urinary F(2)-isoprostanes and plasma alpha-tocopherol. RESULTS: Plasma LDL-DHA and EPA level increased significantly by DHA supplementation. DHA decreased plasma cholesterol (C) levels (P=0.04), but did not influence the levels of plasma TG, LDL-C and HDL-C, alpha-tocopherol, urinary F(2)-isoprostanes, 2-OHE(1), 16alpha-OHE(1) and ratio of 2-OHE(1) to 16alpha-OHE(1) as compared to corn oil. CONCLUSION: DHA supplementation at a dose of 2.14 g/day for 42 days decreases plasma cholesterol but neither does it show beneficial effects on estrogen metabolism, nor does it induce deleterious effects on the observed in vivo antioxidant or oxidative stress marker in postmenopausal vegetarian women. SPONSORSHIP: A grant (# DOH89-TD-1062) from Department of Health, Executive Yuan, Taiwan.

Biomarkers↗

PubMed2001

Search for x-ray induced acceleration of the decay of the 31-yr isomer of (178)Hf using synchrotron radiation.

Enhanced decay of the 31-yr isomer of (178)Hf induced by x-ray irradiation has been reported previously. Here we describe an attempt to reproduce this result with an intense "white" x-ray beam from the Advanced Photon Source. No induced decay was observed. The upper limits for the energy-integrated cross sections for such a process, over the range of energies of 20--60 keV x rays, are less than 2 x 10(-27) cm(2) keV, below the previously reported values by more than 5 orders of magnitude; at 8 keV the limit is 5 x 10(-26) cm(2) keV.

Journal Article↗

PubMed2001

8-Nitroxanthine, an adduct derived from 2'-deoxyguanosine or DNA reaction with nitryl chloride.

Activated phagocytic cells generate reactive nitrogen species, including nitryl chloride and peroxynitrite, for host defense against invading pathogens. It has been proposed that these reactive nitrogen species may cause DNA damage and thus contribute to the multistage carcinogenesis process associated with chronic infections and inflammation. Previous studies showed that peroxynitrite reacted with guanine, 2'-deoxyguanosine, or DNA forming 8-nitroguanine. We herein report formation of 8-nitroxanthine as the major nitration product in reactions of 2'-deoxyguanosine or calf thymus DNA with nitryl chloride produced by mixing nitrite with hypochlorous acid, and 8-nitroguanine was a minor product in these reactions. 8-Nitroxanthine was characterized by its NMR and laser desorption ionization mass spectra and by deamination of 8-nitroguanine. Formation of 8-nitroxanthine was also detected by xanthine reaction with various reactive nitrogen species, including nitryl chloride, peroxynitrite, nitronium tetrafluoroborate, and heated nitric and nitrous acid. The identity of 8-nitroxanthine in nitryl chloride-treated dG and DNA was confirmed by co-injection with synthetic 8-nitroxanthine and by its reduction to 8-aminoxanthine. Levels of 8-nitroxanthine and 8-nitroguanine in these reactions were quantified by reversed-phase HPLC with photodiode array detection. Once formed, 8-nitroxanthine was spontaneously removed from DNA with a half-life of 2 h at 37 degrees C and pH 7.4. Therefore, 8-nitroxanthine might be an important DNA lesion derived from reactive nitrogen species in vivo.

Chromatography, High Pressure Liquid↗

PubMed2001

Visualization of the lipid barrier and measurement of lipid pathlength in human stratum corneum.

Detailed models of solute transport through the stratum corneum (SC) require an interpretation of apparent bulk diffusion coefficients in terms of microscopic transport properties. Modern microscopy techniques provide a tool for evaluating one key property-lipid pathway tortuosity-in more detail than previously possible. Microscopic lipid pathway measurements on alkali expanded human SC stained with the lipid-soluble dyes methylene blue, Nile red, and oil red O are described. Brightfield, differential interference contrast, fluorescence, and laser scanning confocal optics were employed to obtain 2-dimensional (2-D) and 3-dimensional (3-D) images. The 2-D techniques clearly outlined the corneocytes. Confocal microscopy using Nile red yielded a well-delineated 3-D structure of expanded SC. Quantitative assessment of the 2-D images from a small number of expanded SC samples led to an average value of 3.7 for the ratio of the shortest lipid-continuous pathway to the width of the membrane. This was corrected for the effect of alkaline expansion to arrive at an average value of 12.7 for the same ratio prior to swelling.

Azo Compounds↗

PubMed2001

Segmentation of medical ultrasonic image using hybrid neural network.

Objective. To solve one of the most difficult problems in multi-dimensional reconstruction of medical ultrasonic images: image segmentation. Method. A new segmental method based on hybrid neural network was presented in this paper. The hybrid neural network comprised two phases. The first phase was Kohonens self-organization neural network, which was used to segment and label the image coarsely. The feature vectors of those pixels within a specified distance from the cluster centers were employed to train the second phase--a three-layer perception network using back-propagation (BP) technique. Then the trained BP network was used to label every pixel of the image. In the end, a post-processing stage was used to remove the small isolated points and smooth out the contours of the segmented image. Result. The segmented image had smooth continuous edges, few noises or speckles, and the contour of ventricle was clear and accurate. Conclusion. Our method could segment the ultrasonic images accurately and effectively, and had a lot of advantages compared to traditional methods. The unsupervised segmentation problems could be solved using supervised methods.

Cardiovascular Physiological Phenomena↗

PubMed2000

Nuclear translocation and transcription regulation by the membrane-associated guanylate kinase CASK/LIN-2.

Membrane-associated guanylate kinases (MAGUKs) contain multiple protein-binding domains that allow them to assemble specific multiprotein complexes in particular regions of the cell. CASK/LIN-2, a MAGUK required for EGF receptor localization and signalling in Caenorhabditis elegans, contains a calmodulin-dependent protein kinase-like domain followed by PDZ, SH3 and guanylate kinase-like domains. In adult rat brain, CASK is concentrated at neuronal synapses and binds to the cell-surface proteins neurexin and syndecan and the cytoplasmic proteins Mint/LIN-10 and Veli/LIN-7. Here we report that, through its guanylate kinase domain, CASK interacts with Tbr-1, a T-box transcription factor that is involved in forebrain development. CASK enters the nucleus and binds to a specific DNA sequence (the T-element) in a complex with Tbr-1. CASK acts as a coactivator of Tbr-1 to induce transcription of T-element containing genes, including reelin, a gene that is essential for cerebrocortical development. Our findings show that a MAGUK which is usually associated with cell junctions has a transcription regulation function.

Animals↗

PubMed2000

Immunomodulation of Bu-Zhong-Yi-Qi-Tang on in vitro granulocyte colony-stimulating-factor and tumor necrosis factor-alpha production by peripheral blood mononuclear cells.

Bu-Zhong-Yi-Qi-Tang (BZYQT) is a Chinese medicine, and has been used for the treatment of hepatocellular carcinoma (HCC) patients. At present, we still do not fully understand the effects of BZYQT on the cellular physiology. Present in vitro study demonstrated that BZYQT is capable of increasing granulocyte colony-stimulating-factor (G-CSF) and tumor necrosis factor-alpha (TNF-alpha) production by peripheral blood mononuclear cells (PBMC) in healthy volunteers and patients with HCC. The productions of G-CSF and TNF-alpha by PBMC of volunteers were significantly stimulated by more than 125 microg/ml of BZYQT. G-CSF levels stimulated by PBMC of healthy volunteers were higher than in PBMC of the HCC patients when more than 625 microg/ml of BZYQT was administrated. The reason may be due to the impaired immunologic reactivity of mononuclear cells in HCC patients. However, the production levels of TNF-alpha in HCC patients can be stimulated to levels as high as those in healthy volunteers. When adding high concentration (3.125 mg/ml) of BZYQT to the cultured PBMC, the increments of G-CSF and TNF-alpha production decreased although there were no obvious changes in the number of metabolic active PBMC changed. TNF-alpha andG-CSF are known to play important roles in the biological defensive mechanism. These findings show that BZYQT is a unique formula for the stimulation of PBMC to produce G-CSF and TNF-alpha. Administration of BZYQT may be beneficial for patients with HCC to modulate these cytokines.

Adjuvants, Immunologic↗

PubMed1999

Functional specificity of MutL homologs in yeast: evidence for three Mlh1-based heterocomplexes with distinct roles during meiosis in recombination and mismatch correction.

The yeast genome encodes four proteins (Pms1 and Mlh1-3) homologous to the bacterial mismatch repair component, MutL. Using two hybrid-interaction and coimmunoprecipitation studies, we show that these proteins can form only three types of complexes in vivo. Mlh1 is the common component of all three complexes, interacting with Pms1, Mlh2, and Mlh3, presumptively as heterodimers. The phenotypes of single deletion mutants reveal distinct functions for the three heterodimers during meiosis: in a pms1 mutant, frequent postmeiotic segregation indicates a defect in the correction of heteroduplex DNA, whereas the frequency of crossing-over is normal. Conversely, crossing-over in the mlh3 mutant is reduced to approximately 70% of wild-type levels but correction of heteroduplex is normal. In a mlh2 mutant, crossing-over is normal and postmeiotic segregation is not observed but non-Mendelian segregation is elevated and altered with respect to parity. Finally, to a first approximation, the mlh1 mutant represents the combined single mutant phenotypes. Taken together, these data imply modulation of a basic Mlh1 function via combination with the three other MutL homologs and suggest specifically that Mlh1 combines with Mlh3 to promote meiotic crossing-over.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Effects of berberine on arylamine N-acetyltransferase activity in human bladder tumour cells.

Berberine was used to determine inhibition of arylamine N-acetyltransferase (NAT) activity in human bladder tumour cells. The NAT activity was measured by HPLC assaying for the amounts of N-acetyl-2-aminofluorene (AAF) and N-acetyl-p-aminobenzoic acid (N-Ac-PABA) and remaining 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). Two assay systems were performed, one with cellular cytosols, the other with intact bladder tumour cell suspensions. The NAT activity in human bladder tumour cells was inhibited by berberine in a dose-dependent manner, that is, the higher the concentration of berberine, the higher the inhibition of NAT activity. The values of apparent Km and Vmax calculated from cytosol NAT and intact cells were also decreased by berberine. This report is the first demonstration to show berberine did affect human bladder tumour cell NAT activity.

4-Aminobenzoic Acid↗

PubMed1999

Effects of berberine on arylamine N-acetyltransferase activity in human colon tumor cells.

Berberine was used to determine loss of viable cells and inhibition of arylamine Nacetyltransferase (NAT) activity in a human colon tumor (adenocarcinoma) cell line. The viable cells were determined by trypan blue exclusion under a light microscope. The NAT activity was measured by high performance liquid chromatography for the amounts of N-acetyl-2-aminofluorene (AAF), N-acetyl-p-aminobenzoic acid (N-Ac-PABA), and the remaining 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). The viability and NAT activity in a human colon tumor cell line was inhibited by berberine in a dose-dependent manner, i.e., the higher the concentration of berberine, the higher the inhibition of NAT activity and cell death. The NAT activities measured in the intact human colon tumor cells were decreased over 50% by AAF and NAc-PABA production from acetylation of AF and PABA. The apparent values of Kmoff and Vmax of NAT from colon tumor cells were also inhibited by berberine in cytosols and in intact cells. This report is the first to show that berberine did affect human colon tumor cell NAT activity.

4-Aminobenzoic Acid↗

PubMed1999

Plasma concentrations of interferon-alpha in patients with liver cirrhosis: relationship to systemic and portal hemodynamics.

BACKGROUND: Nitric oxide (NO) plays an important role in the pathogenesis of the hyperdynamic circulation observed in portal hypertensive states. Interferon (IFN)-alpha can stimulate NO formation directly or indirectly via cytokines. However, IFN-alpha concentrations seem to increase or decrease in cirrhotic patients. This study investigated the plasma concentration of IFN-alpha in patients with cirrhosis and its relationship to systemic and portal hemodynamics. METHODS: Thirty-six patients with cirrhosis and 47 healthy controls had blood samples taken for the determination of plasma concentrations of IFN-alpha by enzyme-linked immunosorbent assay. Systemic and portal hemodynamics were measured in patients with cirrhosis on the same day of blood sampling using Swan-Ganz catheterization and the thermodilution technique. RESULTS: As compared with healthy subjects, patients with cirrhosis demonstrated a significantly higher IFN-alpha detectable rate (> 3 pg/ml, 14.9% vs 36.1%, p < 0.05). In cirrhotic patients, the IFN-alpha detectable rates were similar between those with and without decompensation, a hepatic venous pressure gradient greater than 12 mmHg, or the presence of large esophageal varices (p > 0.05). There was no significant difference in the systemic vascular resistance or hepatic venous pressure gradient between cirrhotic patients with and without a detectable plasma IFN-alpha concentration. CONCLUSIONS: Plasma IFN-alpha concentrations tended to increase in patients with cirrhosis. However, IFN-alpha concentrations do not play a role in the hyperdynamic circulation observed in patients with cirrhosis.

Adult↗

PubMed1999

Different densities of human eosinophils respond differently to PAF and IL-5.

Human eosinophils are heterogeneous, consisting of both normal and light density cells which may differ in their functional properties. In this study, we compared different densities of eosinophils in response to PAF and IL-5. The eosinophil activation markers were identified either by staining with monoclonal antibody EG2 or, by respiratory burst activity with dichrofluorescin diacetate (DCFH-DA). Both functions were analysed by flow cytometric analyzer. Results showed that light density eosinophils stained with a higher percentage of EG2 (EG2/ Kimura stain) in comparison with normal density eosinophils (88.5 +/- 19.1% vs. 43.9 +/- 18.5% p <0.01). When both groups of cells were analysed with the respiratory burst activity, on EG2+ cells, the activity in light density EG2+ cells were much higher than that of normal density EG2+ cells. These activities in both groups of cells can be further enchanced by PAF and IL-5. Furthermore, the light density EG2+ cells were more eligible to PAF and IL-5 stimulation than were normal density EG2+ cells. In conclusion, normal density and light density eosinophils had different respiratory burst activities; both groups of EG2+ eosinophils responded differently to PAF and IL-5.

Eosinophils↗

PubMed1998

The transmembrane domains of ectoapyrase (CD39) affect its enzymatic activity and quaternary structure.

Mammalian ectoapyrase (CD39) is an integral membrane protein with two transmembrane domains and a large extracellular region. The enzymatic activity of ectoapyrase is inhibited by most detergents used for membrane protein solubilization. In contrast, the enzymatic activities of soluble E-type ATPases, including potato tuber (Solanum tuberosum) apyrase and parasite ecto-ATPase, are not affected by detergents. Here we show that ectoapyrase is a tetramer and that detergents that reduce the activity of the enzyme promote dissociation of the tetramer to monomers. We expressed a secreted form of the ectoapyrase in COS-7 cells by fusing the signal peptide of murine CD4 with the extracellular domain of the ectoapyrase. The soluble ectoapyrase is catalytically active and its activity is not affected by detergents. Mutants of the ectoapyrase with only the NH2- or the COOH-terminal transmembrane domain are membrane-bound, and their activity is no longer affected by detergents. The enzymatic activity of all of the mutant proteins is less than that of the native enzyme. These results suggest that the proper contacts between the transmembrane domains of the monomers in the tetramer are necessary for full enzymatic activity.

Adenine Nucleotides↗

PubMed1998

Golgi localization and functional expression of human uridine diphosphatase.

A full-length E(ecto)-ATPase (Plesner, L. (1995) Int. Rev. Cytol. 158, 141-214) cDNA was cloned from a human brain cDNA library; it encodes a 610-amino acid protein that contains two putative transmembrane domains. Heterologous expression of this protein in COS-7 cells caused a significant increase in intracellular membrane-bound nucleoside phosphatase activity. The activity was highest with UDP as substrate and was stimulated by divalent cations in the following order: Ca2+ >> Mg2+ > Mn2+. The results of immunofluorescence staining indicate that this protein is located in the Golgi apparatus. UDP hydrolysis was increased in the presence of Triton X-100 or alamethicin, an ionophore that facilitates movement of UDP across the membrane, suggesting that the active site of this UDPase is on the luminal side of the Golgi apparatus. This is the first identification of a mammalian Golgi luminal UDPase gene. Computer-aided sequence analysis of the EATPase superfamily indicates that the human UDPase is highly similar to two hypothetical proteins of the nematode Caenorhabditis elegans and to an unidentified 71.9-kDa yeast protein and is less related to the previously identified yeast Golgi GDPase.

Amino Acid Sequence↗

PubMed1998

Widespread expression of ecto-apyrase (CD39) in the central nervous system.

We have shown that ecto-apyrase protein is expressed in primary neurons and astrocytes in cell culture (T.-F. Wang, P.A. Rosenberg, G. Guidotti, 1997. Mol. Brain Res. 1997, 47: 295-302). Here we present immunohistochemical studies showing that ecto-apyrase protein is widely distributed in rat brain, as it is present in neurons of the cerebral cortex, hippocampus and cerebellum as well as in glial cells and endothelial cells. Ecto-apyrase is enriched in brain postsynaptic density membrane fractions and is localized in proximity to synaptophysin, the marker of synaptic vesicles. These results together with the observation that P2 purinergic receptors are present throughout the brain suggest that ecto-apyrase is involved in regulating synaptic transmission mediated by extracellular ATP.

Adenosine Triphosphatases↗

PubMed1998

Effects of garlic compounds diallyl sulfide and diallyl disulfide on arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients.

Arylamine N-acctyltransferase (NAT) activities with p-aminobenzoic acid (PABA) and 2-aminofluorene (2-AF) were determined in the bacterium Helicobacter pylori collected from peptic ulcer patients. Two assay systems were performed, one with cellular cytosols, the other with intact cell suspensions. Cytosols or suspensions of H. pylori with or without specific concentrations of diallyl sulfide (DAS) or diallyl disulfide (DADS) co-treatment showed different percentages of 2-AF and PABA acetylation. The data indicated that there was decreased NAT activity associated with increased levels of DAS or DADS in H. pylori cytosols and suspensions. Viability studies on H. pylori demonstrated that DAS or DADS elicited dose-dependent bactericide affects on H. pylori cultures. The data also indicated that DAS and DADS decreased the apparent values of K(m) and Vmax of NAT enzyme from H. pylori in both systems examined. This report is the first demonstration that garlic components can affect H. pylori growth and NAT activity.

Allyl Compounds↗

PubMed1997

Characterization of factor-independent variants derived from TF-1 hematopoietic progenitor cells: the role of the Raf/MAP kinase pathway in the anti-apoptotic effect of GM-CSF.

Human hematopoietic progenitor cells (TF-1) undergo apoptosis upon deprivation of their dependent cytokine. In this report, we have isolated and characterized some spontaneously derived cytokine-independent variants from TF-1 cells. Analysis of several signaling molecules known to be activated by the GM-CSF pathway revealed that two non-autocrine variants were still responsive to GM-CSF stimulation. However, both variants, without ligand stimulation, already had some activated forms of Raf and MAP kinases. Given current knowledge, the activated Raf/MAP kinase pathway was likely to be responsible for the survival of both variants in the cytokine-free medium. However, the growth of hybrids between wild type and either variant was unexpectedly dependent on GM-CSF. Both variants like the wild type cells were still susceptible to apoptosis induced by other stimuli. These results suggest that either the activated Raf/MAP kinase pathway in both variants is not sufficient to repress the 'two-fold' death signals generated from the hybrids or that there is another mechanism that is responsible for the factor-independent growth of both variants.

Apoptosis↗

PubMed1997

Characterization of brain ecto-apyrase: evidence for only one ecto-apyrase (CD39) gene.

A rat brain cDNA coding for ecto-(Ca,Mg)-apyrase activity was isolated using human CD39 cDNA and functionally expressed in COS-7 cells. The gene codes for a protein with high similarity to human (75% identity) and murine (90% identity) CD39. It is expressed in primary neurons and astrocytes in cell culture as well as in kidney, liver, muscle and spleen. Southern analysis of the mouse genome suggests that there may be a single copy of the ecto-apyrase gene. Interestingly, the human CD39 gene cytologically co-localizes with the susceptibility gene involved in human partial epilepsy with audiogenic symptoms; such a coincidence is consistent with reports on the deficiency of ecto-apyrase activity in the brains of humans with temporal lobe epilepsy and in those of mice with audiogenic seizures.

Adenosine Triphosphatases↗