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Yan Wang

Publications and source records attributed to Yan Wang.

At least 523 records · Page 29Linked to original sources
PubMed2003

[Fingerprint construction of Panax notoginseng].

OBJECTIVE: To provide application and identification basis for Panax notoginseng by constructing the HPLC-FP of Panax Notoginsing. METHOD: The luna C18(2) column was used with a mobile phase of (A) acetonitrile-(B) 0.05% phosphoric acid gradient elution, 0-8 min (20% A, 80% B), 8-20 min (20% A-40% A, 80% B-60% B), 20-30 min(40% A-20% A, 60% B-80% B), 30-36 min(20% A-100% A, 80% B-0), 36-50 min(100% A), 50-65 min (100% A-20% A, 0-80% B). The flow rate was 1.0 ml.min-1. The wavelength of detecter was set at 203 nm. Caffeine was internal standard. RESULT: By Cluster Analysis, the twenty-one notoginseng samples were classified as four clusters: the superior in producing area, the ordinary in producing area, the ordinary and the inferior. By Similarty Calculation, the similarity of the twenty-one notoginseng samples were 0.9-1.0, and the similarity of the eight common falses are less than 0.9. CONCLUSION: The HPLC-FP of notoginseng has been established. The method can be used to identify and evaluate the quality of notoginseng.

Chromatography, High Pressure Liquid↗
PubMed2003

[Purification and characterization of glutamate dehydrogenase. from Corynebacterium glutamicum S9114].

Glutamate dehydrogenase (GDH) is a key enzyme in the biosynthesis of glutamate. The GDHs from Corynebacterium glutamicum S9114 the most commonly used strain in glutamate fermentation, were purified and their molecular structures and properties characterized. The coenzymes were also studied in the hope to increase glutamate production. Cells were harvested at mid-exponential phase by centrifugation and washed with Tris-HCl buffer containing DTT and EDTA (pH 7.5). The cells were then disrupted using a French pressure cell press and the supernatant was collected by centrifugation. The extract was concentrated by 70-fold using the AKTA-100 FPLC system employing a DEAE-cellulose ion exchange column, a hydrophobic interaction chromatography (HIC) and Sephadex G-200 gel filtration. The purified extracts contained NADPH-dependent GDH and NADH-dependent GDH. Both of the enzymes were highly specific for the coenzymes. The molecular masses of the NADPH-dependent GDH and its subunit were 188kD and 32kD respectively, suggesting the enzyme is a homo-hexamer. Our data reported for the first time the presence of NADH- dependent GDH in Corynebacterium glutamicum S9114, similar to other microorganisms containing both GDHs. The NADPH-dependent and NADH-dependent GDH in Corynebacterium glutamicum S9114 may participate in the assimilation and dissimilation of ammonia respectively. The absorptions of NADPH-dependent GDH was very weak at 280nm but very high at 215nm, suggesting a low phenylalanine and tyrosine content in the enzyme.

Chromatography, Gel↗
PubMed2003

[Preliminary study of characteristics of a special Nitrosomonas].

A special obligately-autotrophic Nitrosomonas was isolated from high temperature and hypersaline drainage water obtained off a wastewater treatment plant. It was Gram-negative, nonsporulating, ellipsoidal or short-rod shaped bacterium that singly arranged or arranged in a circle or in a row. Cells were 0.7 to 0.9 microm wide and 1.2 to 1.98 microm long. Electron-microscopic scanning of these cells indicated that they were wrapped by unknown fluff-like matter. They oxidized ammonium to nitrite and caused the removal of nitrogen from the system. But the decrease of NH4+ -N did not accord with the increase of NO2 - -N and NO3- -N was almost not detected. After 12 d of cultivation at 50 degrees C, about 10% of the NH4+ -N was converted to NO2- -N, 15% remained as NH4+ -N, and the other 75% was removed from the system, including 17% of NH4+ -N volatilized.

Nitrites↗
PubMed2002

Mice with a homozygous deletion of the Mgat2 gene encoding UDP-N-acetylglucosamine:alpha-6-D-mannoside beta1,2-N-acetylglucosaminyltransferase II: a model for congenital disorder of glycosylation type IIa.

Mice homozygous for a deletion of the Mgat2 gene encoding UDP-N-acetylglucosamine:alpha-6-D-mannoside beta1,2-N-acetylglucosaminyltransferase II (GlcNAcT-II, EC 2.4.1.143) have been reported. GlcNAcT-II is essential for the synthesis of complex N-glycans. The Mgat2-null mice were studied in a comparison with the symptoms of congenital disorder of glycosylation type IIa (CDG-IIa) in humans. Mutant mouse tissues were shown to be deficient in GlcNAcT-II enzyme activity and complex N-glycan synthesis, resulting in severe gastrointestinal, hematologic and osteogenic abnormalities. All mutant mice died in early post-natal development. However, crossing the Mgat2 mutation into a distinct genetic background resulted in a low frequency of survivors exhibiting additional and novel disease signs of CDG-IIa. Analysis of N-glycan structures in the kidneys of Mgat2-null mice showed a novel bisected hybrid N-glycan structure in which the bisecting GlcNAc residue was substituted with a beta1,4-linked galactose or the Lewis(x) structure. These studies suggest that some of the functions of complex N-glycan branches are conserved in mammals and that human disease due to aberrant protein N-glycosylation may be modeled in the mouse, with the expectation in this case of gaining insights into CDG-IIa disease pathogenesis. Further analyses of the Mgat2-deficient phenotype in the mouse have been accomplished involving cells in which the Mgat2 gene is dispensable, as well as other cell lineages in which a severe defect is present. Pre-natal defects appear in a significant number of embryos, and likely reflect a limited window of time in which a future therapeutic approach might effectively operate.

Animals↗
PubMed2002

Modulation of peripheral-type benzodiazepine receptor levels in a reperfusion injury pig kidney-graft model.

BACKGROUND: Ischemia-reperfusion injury is associated with an increased risk of acute rejection, delayed graft function, or chronic graft dysfunction. Mitochondria play a central role in this process. METHODS: Using an autotransplantation pig kidney model, both early (40 min and 7 days) and late (2-16 weeks) changes in renal function and morphology were determined after different periods of cold ischemia in University of Wisconsin or Euro-Collins solutions. We have also investigated the expression of the peripheral-type benzodiazepine receptor (PBR), which is also critical in maintaining outer mitochondrial membrane stability. RESULTS: Function of the kidneys was better preserved after 1 hr and 24 hr than after 48 hr and 72 hr in Euro-Collins and University of Wisconsin solutions. Medulla injury was reduced in 1 hr-preserved and 24 hr-preserved groups. PBR was found to be present in epithelial cells of the deep cortical and outer medulla in both normal human and well-preserved pig kidneys. PBR expression was modulated by ischemia-reperfusion injury and the concurrent tubular injury and repair processes. CONCLUSION: This study indicates that PBR expression correlates with the quality of kidney preservation and might serve as an index of kidney and mitochondria viability. Moreover, these data suggest that PBR might be involved in membrane biogenesis during reperfusion. In addition, considering the identical localization of PBR in human and pig kidneys, these findings could have a direct application in human clinical settings of kidney pathology.

Animals↗
PubMed2002

Inhibition of ultraviolet light-induced oxidative events in the skin and internal organs of hairless mice by isoflavone genistein.

We have previously demonstrated that soybean isoflavone genistein inhibits ultraviolet-B (UVB)-induced skin tumorigenesis in hairless mice. In the present study, we further investigated the possible mechanism(s) of action whereby genistein inhibits photocarcinogenesis with focuses on UVB-induced oxidative events, including hydrogen peroxide (H(2)O(2)) production, lipid peroxidation (as represented by malondialdehyde, MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in vivo. We demonstrated that subacute exposure to UVB substantially increased the level of H(2)O(2), lipid peroxides, and 8-OHdG in skin of hairless mice. In addition, chronic exposure to low-dose UVB (0.9-1.2 kJ/m(2) for 20 weeks) substantially increased the levels of 8-OHdG not only in the epidermis, but also in the internal organs such as liver, brain, and spleen of mice with exception of kidney. However, genistein did not affect the level of UVB-induced pyrimidine dimmers in the same UVB exposed mouse skin, indicating selective inhibition of oxidative DNA damage by genistein. Induction of H(2)O(2) was independent of UVB fluences whereas the levels of MDA and 8-OHdG were induced in an UVB fluence-dependent manner. The results suggest that H(2)O(2) be generated as an acute cutaneous response to UVB irradiation, while MDA and 8-OHdG are accumulated with increasing UVB exposure and more closely related to chronic effects of UVB radiation. Pre-treatment of animals with 10 micromol of genistein 1 h prior to UVB exposure significantly inhibited UVB-induced H(2)O(2) and MDA in skin and 8-OHdG in epidermis as well as internal organs. Suppression of 8-OHdG formation by genistein has been corroborated in purified DNA irradiated with UVA and B. In summary, our results suggest that UVB irradiation elicit a series of oxidative events, which can be substantially inhibited by isoflavonoid genistein through either direct quenching of reactive oxygen species or indirect antiinflammatory effects. Thus, the antioxidative properties of genistein may explain for the mechanisms of anti-photocarcinogenic action of genistein.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Resolution of tert-butyl-1-(2-methyinaphthyl)phosphine oxide using selectors identified from a chemical combinatorial library.

Resolution of racemic tert-butyl-1-(2-methylnaphthyl)-phosphine oxide 1, a chiral phosphorus compound, was achieved using selectors developed from a small peptide library. Separation factors as high as 3.2 were observed. The library consists of 81 peptide-based potential chiral selectors on polymeric synthesis resins. The linker needed to immobilize the identified chiral selectors onto silica gel proved important in the chiral separation; a longer linker provided a significantly higher separation factor in this study.

Chromatography, High Pressure Liquid↗
PubMed2002

Absolute configuration of tert-butyl-1-(2-methylnaphthyl)phosphine oxide.

The enantiomers of tert-butyl-1-(2-methylnaphthyl)phosphine oxide 1 have been separated using a homemade HPLC column and an analytical gradient system. Vibrational absorption and circular dichroism spectra for both enantiomers have been measured in CD2Cl2 and CH2Cl2 solutions in the 2000-900 cm(-1) region. The fully relaxed potential energy surface of (S)-tert-butyl-1-(2-methylnaphthyl)phosphine oxide, obtained using the B3LYP functional with a 6-31G basis set, indicated two stable conformers with their populations in a approximately 2:1 ratio. The vibrational absorption and VCD spectra are predicted for these two conformers using the B3LYP functional with a 6-31G basis set. The comparison of predicted and experimental spectra indicated that (+)-tert-butyl-1-(2-methylnaphthyl)phosphine oxide is in the (S)-configuration. This assignment is supported by the ab initio prediction of positive optical rotation for the most stable conformer with an (S)-configuration and the nonequivalence sense of the tert-butyl group chemical shift observed in the 1H NMR spectrum of this enantiomer measured in the presence of (+)-(S)-mandelic acid as a chiral solvating agent.

Chromatography, High Pressure Liquid↗
PubMed2002

Spatial distribution and density of prefrontal cortical cells projecting to three sectors of the premotor cortex.

The spatial distribution of prefrontal cortical cells projecting to three different sectors in the premotor cortex was examined. The cells projecting to the three sectors were distributed in separate regions in the dorsolateral prefrontal cortex with a small overlap. Cells projecting to the ventral sector were distributed in the lower bank of the principal sulcus (PS). Those projecting to the restro-dorsal sector were located near the superior limb of the arcuate sulcus, and in the dorsal convexity and upper bank of the PS. Cells projecting to the caudo-dorsal sector were observed in the upper bank of the PS and in the area 8a. These findings suggest that each of the three sectors of the premotor cortex receive different sets of information from the prefrontal cortex.

Amidines↗
PubMed2002

A close association of the ganglioside-specific sialidase Neu3 with caveolin in membrane microdomains.

The ganglioside-specific sialidase Neu3 has been suggested to play essential roles in regulation of cell surface functions because of its major localization in the plasma membrane and strict substrate preference for gangliosides involved in signal transduction. Here we show that human Neu3 sialidase is enriched in caveolae microdomains and closely associates with caveolin like other caveolin-binding signaling molecules. Using HeLa cells and Neu3-transfected COS-1 cells, endogenous and exogenous Neu3 was found to co-concentrate caveolin-1 in low density Triton X-100-insoluble membrane fractions on sucrose density gradients of the respective cell extracts, as assessed by enzyme activity assays and immunoblotting with a monoclonal antibody to human Neu3. The presence of a putative caveolin-binding motif within Neu3 prompted us to determine whether Neu3 binds to caveolin-1. In transfectants expressing a polyhistidine-tagged form of Neu3, caveolin-1 co-eluted with Neu3 on affinity column chromatography. A mutation with a single amino acid change in the caveolin-binding motif led to inhibition of recruitment of the sialidase to the microdomain, accompanied by reduction of the enzyme activity. Neu3 also failed to associate with caveolin-enriched microdomains by cholesterol depletion with beta-cyclodextrin (with concomitant decrease of the sialidase activity), whereas Neu3 was activated by increased caveolin-1 expression. The tight association of Neu3 with caveolin-1 was supported further by co-immunoprecipitation of Neu3 by anti-caveolin-1 antibody. These results strongly suggest that Neu3 functions as a caveolin-related signaling molecule within caveolin-rich microdomains.

Animals↗
PubMed2002

[Effects of insulin on the distribution of actins in vascular smooth muscle cells in the process of proliferation via mitogen-activated protein kinase in vitro].

Proliferation of vascular smooth muscle cells (VSMCs) is often accompanied by changes in intracellular actin distribution. The changes are controlled by the signal transduction pathways of protein kinase C/mitogenic activated protein kinase (PKC-MAPK), but the mechanism is unclear. In order to study the effect of insulin on the intracellular signal transduction (PKC-MAPK) probably involved in the modulation of proliferation and redistribution of actins in the VSMCs, the DNA synthesis, MAPK activities and its gene expression, and the redistribution of intracellular actins were investigated in the isolated VSMCs of SHR pretreated with PKC inhibitor and/or insulin, respectively. We found that insulin treatment resulted in proliferation of the VSMCs and an increase in [(3)H] TdR incorporation. Meanwhile, the activities and expression of MAPK increased significantly compared to the control group. These effects of insulin were blocked by PKC inhibitor. In addition, insulin caused a redistribution of the intracellular actins in VSMCs, which was also inhibited by PKC inhibitor. It is, therefore, suggested that these effects of insulin on VSMCs proliferation and distribution of the intracellular actins may be mediated by the MAPK signal transduction pathway.

Actins↗
PubMed2002

Cutting edge: a critical role for IL-10 in induction of nasal tolerance in experimental autoimmune myocarditis.

Appropriate treatment of autoimmune myocarditis following virus infection remains a major clinical problem. Induction of nasal tolerance may provide a new approach to treatment. However, the exact mechanism of nasal tolerance is unknown. To assess the mechanism of nasal tolerance, we examined the role of IL-10 in the induction and suppression of autoimmune myocarditis. First we showed that blocking IL-10 concurrent with nasal administration of Ag abolished the disease-suppressing effect of nasal tolerization. It also led to increased cardiac myosin-specific IL-1 and TNF-alpha production. Then we demonstrated that blocking IL-10 during the effector phase increased not only the incidence and severity of disease but also Ag-specific IL-2, IL-4, and TNF-alpha production as well as cardiac myosin-specific IgG1 and IgG2b production, whereas blocking IL-10 during the induction phase had no effect. This study implicates IL-10 in the induction of nasal tolerance and in limiting inflammation later during the disease process.

Administration, Intranasal↗
PubMed2002

An LC-MS method for analyzing total resveratrol in grape juice, cranberry juice, and in wine.

Resveratrol is an antioxidant found in grapes, grape products, and some other botanical sources with antiinflammatory and anticancer properties. In grapes and wine, it occurs both as free resveratrol and piceid, the 3beta-glucoside of resveratrol. Here we report a liquid chromatography-mass spectrometry method to analyze total resveratrol (including free resveratrol and resveratrol from piceid) in fruit products and wine. Samples were extracted using methanol, enzymatically hydrolyzed, and analyzed using reversed phase HPLC with positive ion atmospheric pressure chemical ionization (APCI) mass spectrometric detection. Following APCI, the abundance of protonated molecules was recorded using selected ion monitoring (SIM) of m/z 229. An external standard curve was used for quantitation, which showed a linear range of 0.52-2260 pmol of trans-resveratrol injected on-column with a correlation coefficient 0.9999. The coefficient of variance of the response factor over the same concentration range was determined to be 5.8%, and the intra-assay coefficient of variance was determined to be 4.2% (n = 7). The limit of quantitation, defined as signal-to-noise 10:1, was determined to be 0.31 pmol injected on-column. The extraction efficiency of the method was determined to be 92%. The stability of resveratrol under different conditions was also examined. For example, resveratrol was stable for up to 5 days at 4 degrees C in the dark but was not stable at room temperature without protection from light. Resveratrol was detected in grape, cranberry, and wine samples. Concentrations ranged from 1.56 to 1042 nmol/g in Concord grape products, and from 8.63 to 24.84 micromol/L in Italian red wine. The concentrations of resveratrol were silmilar in cranberry and grape juice at 1.07 and 1.56 nmol/g, respectively.

Antioxidants↗
PubMed2002

[Mass transfer model of membrane extraction for recovery of cadmium ion and zinc ion].

By measuring the residence time distribution (RTD) curve of shell side and tube side of hollow fiber modules, it was found that the flow status in hollow fiber module with moderate or low packing density was complicated. For tube side, there were deviation between the experimental RTD curves and the theoretical laminar flow ones, which indicated that the flow status in tube side was between laminar flow and turbulent flow. For shell side, the experimental RTD curves agreed well with the laminar flow ones. The deviations as low as +/- 5% between the experimental average residence times and the theoretical ones suggested that there was no apparent non-ideal flow in the hollow fiber module with medium packing density. Based on the comparison between the experimental results and some typical correlations, a new velocity profile was purposed to describe the flow status in hollow fiber modules. According to the results of cadmium transport, the individual mass transfer coefficient correlations were developed. The zinc outlet concentrations predicted by the new correlations agreed relatively well with the experimental results, the relative deviation was among +/- 25%.

Cadmium↗
PubMed2002

Activation mechanism of solubilized epidermal growth factor receptor tyrosine kinase.

Dimerization of epidermal growth factor receptor (EGFR) leads to the activation of its tyrosine kinase. To elucidate whether dimerization is responsible for activation of the intracellular tyrosine kinase domain or just plays a role in the stabilization of the active form, the activated status of wild-type EGFR moiety in the heterodimer with kinase activity-deficient mutant receptors was investigated. The kinase activity of the wild-type EGFR was partially activated by EGF in the heterodimer with intracellular domain deletion (sEGFR) or ATP binding-deficient mutant (K721A) EGFRs, while the wild-type EGFR in the heterodimer of wild-type and phosphate transfer activity-deficient mutant receptor D813N could be fully activated. After treatment with EGF, the ATP binding affinity and the V(max) of the wild-type EGFR increased. In the presence of sEGFR, a similar increase in the affinity for ATP was observed, but V(max) did not change. A two-step activation mechanism for EGFR was proposed: upon binding of EGF, the affinity for ATP increased and then, as a result of interaction between the neighboring tyrosine kinase domain, V(max) increased.

3T3 Cells↗
PubMed2002

Inhibition of the Bcr-Abl oncoprotein by Bcr requires phosphoserine 354.

The BCR protein is involved in the inhibition of oncogenic activity of the Bcr-Abl oncoprotein. This inhibition is believed to be the result of binding to the SH2 domain of Bcr-Abl in a non-phosphotyrosine-dependent manner. We showed that the Arg to Leu mutation in the Phe-Leu-Val-Arg-Glu-Ser (FLVRES) sequence of the SH2 domain, known to interfere with phosphotyrosine sequence binding, did not block the binding of Bcr first exon sequences to the Abl SH2 domain. We examined the structural-functional properties of a first exon mutant of BCR lacking the oligomerization domain, termed Bcr(64-413), that encodes the Ser-Thr protein kinase activity of Bcr. The autokinase product contained a M(r) 45,000-47,000 and 55,000 protein. Both species were detected by a Bcr phosphoserine 354 sequence-specific antibody. In contrast, the S354A mutant of Bcr(64-413), although maintaining autokinase activity, produced only the M(r) 45,000-47,000 kinase product. Abl SH2 binding experiments indicated that the M(r) 55,000 species of Bcr(64-413) but not the M(r) 45,000-47,000 species bound strongly to glutathime transferase-Abl SH2. The S354A mutant of Bcr(64-413) did not bind to glutathime transferase-Abl SH2. An adenovirus encoding Bcr(64-413) S354A did not induce cell death in CML cell lines in contrast to wild-type Bcr(64-413). Our findings indicate that Ser-354 of Bcr is part of a gating mechanism, which, after its phosphorylation, allows structural changes to occur in the Bcr protein. This altered phosphoserine form of the Bcr protein selectively binds to the Abl SH2 domain of the oncoprotein, which we propose down-regulates the activity of the Bcr-Abl tyrosine kinase.

Amino Acid Sequence↗
PubMed2002

Spectrofluorimetric determination of hydrogen peroxide with 2-hydroxy-1-naphthaldehyde salicyloylhydrazone (HNSH) as the substrate for horseradish peroxidase (HRP).

The oxidation reaction of HNSH with H2O2 under the catalysis of HRP was studied in detail. The possible reaction mechanism was discussed. Under optimum experimental conditions, the oxidized product of HNSH had excitation and emission maxima at 296 and 414 nm, respectively. A study to prove the existence of -O-O-H in polyethylene glycols was carried out. The proposed method was successfully applied to the determination of -O-O-H in polyethylene glycols.

Catalysis↗