Biomedical subjects

Yi Wang

Publications and source records attributed to Yi Wang.

At least 109 records · Page 6Linked to original sources

PubMed2006

[Effects of different interventional modalities on vascular endothelial dysfunction of obese rats].

OBJECTIVE: To observe the effect of diet-control only, diet-control with swimming training or with polysaccharide sulfate (PSS), a kind of blood lipid-lowering drug on the serum lipid level and vascular endothelial function in obese rats fed by fat-rich-diet. METHODS: Forty Wistar rats were randomly divided into the following 5 groups: group F (n = 8), group N (n = 8), group A (n = 8), group B (n = 8) and group C (n = 8), where the rats were given fat-rich-diet, basic-diet, 12 weeks of diet-control after 8 weeks of fat-rich-diet, 12 weeks of diet-control with swimming training after 8 weeks of fat-rich-diet and 12 weeks of diet-control with PSS after 8 weeks of fat-rich-diet, respectively. All rats were sacrificed after 12 weeks of intervention. Then the levels of Lee index, serum total cholesterol (TC), triglyceride (TG), plasma endothelin (ET), nitric oxide (NO) and von Willebrand Factor (vWF) were measured. The protein expression of intercellular adhesion molecule-1 (ICAM-1) in artery endothelium was evaluated by immunohistochemistry (IHC) and the gene expression of ICAM-1 was examined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: After the interventions for 12 weeks, the levels of serum TC, TG and ET decreased in group A (P < 0.05). The levels of Lee index, TC, TG, ET, vWF, ICAM-1 protein and ICAM-1 mRNA decreased in group B and C (P < 0.05). Three interventions increased serum NO production (P < 0.05) in group B. CONCLUSIONS: Diet-control could a meliorate the hyperlipidemia and vascular function. Diet-control with swimming training and diet-control with PSS could result in weight loss of rats and meliorate the hyperlipidemia, vascular endothelial function, coagulatory activities and adhesive dysfunction. The effects of diet-control with swimming on vascular endothelial function were prominent.

Animals↗

PubMed2006

Therapeutic efficacy and bone marrow protection of the mdr1 gene and over-dose chemotherapy with doxorubicin for rabbits with VX2 hepatocarcinoma.

BACKGROUND: Malignant tumors are common diseases threatening to the health and life of human being. Clinically, the multidrug resistance of tumor cells and bone marrow depression caused by chemotherapeutic agents are the main obstacles to the treatment of tumors, and both are related to the mdr1 gene. The over expression of the mdr1 gene in tumor cells contributes to the multidrug resistance of malignant tumor cells. With little expression of the mdr1 gene, bone marrow cells particularly susceptible to multidrug resistance-sensitive agents, which cause serious toxicity in bone marrow. This study was undertaken to assess therapeutic efficacy of transplantation of bone marrow mononuclear cells transferred with the mdr1 gene and over-dose chemotherapy with doxorubicin for VX2 hepatocarcinoma of rabbits. METHODS: The mdr1 gene was transferred into the bone marrow mononuclear cells of rabbits, which was co-cultured with retroviral vector-containing supernatant, and the cells were autotransplanted into a rabbit model with VX2 hepatocarcinoma. After chemotherapy with doxorubicin, the protective effects of the mdr1 gene and therapeutic efficacy of over-dose chemotherapy were observed. RESULTS: The mdr1 gene was transferred successfully into the bone marrow mononuclear cells, with a transduction efficiency of 35%. After autotransplantation, the mdr1 gene was expressed functionally in bone marrow with a positive rate of 8%, indicating that the gene played an important role in bone marrow protection. The rabbits with VX2 hepatocarcinoma, which had received the mdr1 gene-transduced cells, survived after chemotherapy with a 3-fold dose of adriamycin, and their white blood cell counts were (4.26 +/- 1.03) x 10(4)/L. Since hepatocarcinoma cells were eradicated, the survival time (97.00 +/- 46.75 d) of the rabbits was extended (P<0.05) and the healing rate of the tumor was increased (P<0.05). CONCLUSIONS: The transferring of the mdr1 gene into bone marrow mononuclear cells could confer chemoprotection to bone marrow, and over-dose chemotherapy could be prescribed for the treatment of malignant tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

[Effects of sodium arsenite on catalase in human keratinocytes].

OBJECTIVE: To evaluate the effects of sodium arsenite on the activity, the mRNA and the protein expression of CAT in human keratinocyte cell line (HaCaT). METHODS: The activity of catalase (CAT) was detected by ultraviolet direct velocity assay. RT-PCR was used to detect the mRNA expression of CAT and Western blotting was conducted to detect the protein expression of CAT. RESULTS: If the cells were treated with higher than 5.0 micromol/L sodium arsenite, the activity, mRNA and protein expression of CAT were decreased significantly and in a dosage dependent fashion (P < 0.05). CONCLUSION: CAT is inhibited by sodium arsenite in the transcription, translation and activity levels.

Arsenites↗

PubMed2006

[8B7 spectrin--a new member of spectrin family].

OBJECTIVE: To analyze the nature of the protein encoded by 8B7cDNA (1 835 bp) and to examine the localization of the protein in cells. METHODS: The nature of the protein was analyzed using Blastn, Blastp, and TMpred. Expressions of 8B7 mRNA in tissues and cells were examined by Northern blotting. Recombinant expression vectors for localization test were constructed and transfected into COS-7 cells. Fluorescence emission in cells was examined upon a laser scan confocal microscope. RESULTS: The protein encoded by 8B7cDNA was 363 amino acids long and contained spectrin repeats. It was completely homologous to the C-terminal 363 amino acids of Enaptin, Nasprin-1, Mynel, and Syne-1 proteins. It belonged to Spectrin super-family and was called 8B7 spectrin. Northern blotting revealed a 1.8 kb mRNA expression in human spleen and small intestine tissues. EGFP-8B7 fusion protein was observed to express on the nuclear membrane and in the cytoplasm in a reticular form in a localization assay on COS-7 cells. The position of fluorescence in COS-7 cells transfected with pEGFP-delta SR8B7 was similar to that in the cells transfected with pEGFP-8B7cDNA. CONCLUSIONS: 8 B7 spectrin is a novel member of spectrin super-family. It localizes to the nuclear membrane and the cytoplasm in a reticular form in COS-7 cells. The localization is determined by the C-terminal KASH domain in 8B7 spectrin molecule.

Amino Acid Sequence↗

PubMed2006

Effect of ginseng saponin, arsenic trioxide, beta-elemene combined with CTX on telomere-telomerase system in K562 cell line.

This study was aimed to investigate the modulating effects on telomere length and telomerase activity in K562 cells treated by arsenic trioxide, ginseng saponin, beta-elemene alone or in combination with cyclophosphamide (CTX) and to explore the possible mechanism and new therapy for acute leukemia. Human erythroleukemic cell line K562 was co-cultured with the above-mentioned drugs. Cells were collected after 24, 48 and 72 hours for further detection. Telomere length and telomerase activity were detected by Southern-blot and PCR-ELISA respectively. The effects of these drugs were observed at different concentrations and exposure time. The results showed that (1) ginseng saponin, arsenic trioxide, beta-elemene, or CTX could completely inhibit the telomerase activity of K562 cells at proper concentrations and exposure time. The inhibiting effects were enhanced when the three former drugs were used with CTX. Telomerase activity decreased proportionally with the concentrations and length of time. (2) viability of K562 cells was decreased after being co-cultured with arsenic trioxide, ginseng saponin, beta-elemene and CTX. The level of inhibition depends on the concentration and exposure time. (3) telomere length of K562 cells was 5.36 +/- 0.18 kb. After being co-cultured with those drugs for 72 hours, telomere length was 5.90 kb -6.50 kb, significantly longer than that of control (5.18 - 5.35 kb). It is concluded that arsenic trioxide, ginseng saponin, and beta-elemene can inhibit the growth and telomerase activity of K562 cells. The inhibiting effects were enhanced when they were used in combination with CTX. The depression of telomerase activity may be one of the mechanisms of anti-tumor effect. Less dosage and shorter course can be expected when arsenic trioxide, ginseng saponin, and beta-elemene are used in combination with CTX. When telomerase activity was depressed, the telomere length prolonged a little, indicating K562 cell line may extend telomeres by some alternative way other than telomerase activation.

Arsenic Trioxide↗

PubMed2005

Stereospecific preparation of (Z)- and (E)-2,3-difluoro-3-stannylacrylic ester synthons and a new, efficient stereospecific route to (Z)- and (E)-2,3-difluoroacrylic esters.

[reaction: see text] The (Z)-2,3-difluoro-3-stannylacrylic ester is readily prepared from (Z)-1,2-difluorovinyltriethylsilane via stereospecific stannyl/silyl exchange with KF/(Bu3Sn)2O or Bu3SnCl in DMF at 70 degrees C. The corresponding (E)-2,3-difluoro-3-stannylacrylate is prepared by stereospecific carbonylation of (E)-1,2-difluorovinyl iodide followed by low temperature/in situ stannylation of the resultant (Z)-2,3-difluoroacrylic ester. With Cu(I) iodide and Pd(PPh3)4 catalysis, the (Z)- and (E)-stannylacrylate esters readily couple with aryl iodides and vinyl bromides, as well as 2-iodothiophene, at room temperature to stereospecifically produce the respective (E)- and (Z)-2,3-difluoro-3-aryl substituted acrylic esters or conjugated dienes in high yields.

Journal Article↗

PubMed2005

Structural mechanism of plant aquaporin gating.

Plants counteract fluctuations in water supply by regulating all aquaporins in the cell plasma membrane. Channel closure results either from the dephosphorylation of two conserved serine residues under conditions of drought stress, or from the protonation of a conserved histidine residue following a drop in cytoplasmic pH due to anoxia during flooding. Here we report the X-ray structure of the spinach plasma membrane aquaporin SoPIP2;1 in its closed conformation at 2.1 A resolution and in its open conformation at 3.9 A resolution, and molecular dynamics simulations of the initial events governing gating. In the closed conformation loop D caps the channel from the cytoplasm and thereby occludes the pore. In the open conformation loop D is displaced up to 16 A and this movement opens a hydrophobic gate blocking the channel entrance from the cytoplasm. These results reveal a molecular gating mechanism which appears conserved throughout all plant plasma membrane aquaporins.

Aquaporins↗

PubMed2005

pH-dependence of the properties of hydrophobically modified polyvinylamine.

A series of N-alkyl or N-benzyl substituted polyvinylamines (PVAm) were prepared and the properties of aqueous solutions were measured as functions of pH. The polymer solutions showed almost no surface activity under acidic conditions whereas surface tension was reduced to 40-50 mN/m around pH 9. Increasing either the degree of hydrophobic substitution or the hydrophobic chain length lowered the pH at which surface tension lowering was observed. Hydrophobic substitution also shifted plots of the degree of ionization versus pH toward lower pH which means lower pH values were required to achieve a given value of polymer charging. The hydrophobically modified PVAm associated in water giving species whose apparent diameter measured by dynamic light scattering decreased with increasing pH, whereas the electrophoretic mobilities of the associated species increased with decreasing pH. Although many hydrophobically modified and pH sensitive polymers have been described in the literature for applications in biomaterials, drug release and as pH sensitive surfactants, the hydrophobically modified PVAms are particularly attractive because they are easily prepared from commercially available polyvinylamines.

Journal Article↗

PubMed2005

'Top-down' characterization of site-directed mutagenesis products of Staphylococcus aureus dihydroneopterin aldolase by multistage tandem mass spectrometry in a linear quadrupole ion trap.

The gas-phase fragmentation reactions of a series of site-directed mutagenesis products of Staphylococcus aureus dihydroneopterin aldolase have been examined by multistage tandem mass spectrometry (MS/MS and MS(3)) in a linear quadrupole ion trap in order to explore the utility of this instrumentation for routine 'top-down' recombinant protein characterization. Following a rapid low resolution survey of the fragmentation behavior of the precursor ions from the wild type (WT) protein, selected charge states were subjected to detailed structural characterization by using high resolution 'zoom' and 'ultrazoom' resonance ejection MS/MS product ion scans. Dissociation of the [M + 18H](18+) charge state yielded a range of product ions from which extensive sequence information could be derived. In contrast, dissociation of the [M + 20H](20+) charge state resulted in a single dominant y(96) product ion formed by fragmentation between adjacent Ile/Gly residues, with only limited sequence coverage. Further extensive sequence information was readily obtained however, by MS(3) dissociation of this initial product. From the combined MS/MS and MS(3) spectra an overall sequence coverage of 66.9%, with fragmentation of 85 of the 127 amide bonds within the WT protein, was obtained. MS/MS and MS(3) of three of the four site-directed mutagenesis products (E29A), (Y61F) and (E81A) were found to yield essentially identical product ion spectra to the WT protein, indicating that these modifications had no significant influence on the fragmentation behavior. The specific site of modification could be unambiguously determined in each case by characterization of product ions resulting from fragmentation of amide bonds on either side of the mutation site. In contrast, MS/MS and MS(3) of the K107A mutant led to significantly different product ion spectra dominated by cleavages occurring N-terminal to proline, which restricted the ability to localize the modification site to within only an 8 amino acid region of the sequence. This work highlights the need for further studies to characterize the charge state, sequence and structural dependence to the low energy collision induced dissociation reactions of multiply protonated intact protein ions.

Aldehyde-Lyases↗

PubMed2005

Corticotropin-releasing factor receptor subtype 1 and somatostatin modulating hypoxia-caused downregulated mRNA of pituitary growth hormone and upregulated mRNA of hepatic insulin-like growth factor-I of rats.

The study aims to examine the effects of restraint, cold, and in combination of hypoxia on pituitary GH mRNA and hepatic IGF-I mRNA and its protein in rats, and the potential involvement of corticotropin-releasing factor receptor subtype 1 (CRFR1) and SS in mediating the effects of continual hypoxia. Continual or intermittent hypoxia of 5 km (10.8% O2) was simulated in a hypobaric chamber. The mRNAs and peptides were determined using RT-PCR and Elisa or histochemistry. Continual hypoxia of 5 km markedly enhanced immunostaining pituitary GH and hepatic IGF-I for 1 and 2 days restoring afterward. The hypoxia for 5 days significantly reduced the pituitary GH mRNA and increased the hepatic IGF-I mRNA. Intermittent hypoxia of 5 km 4 h/day for 2 days, cold (4 degrees C) 4h/day for 2 days, and restraint 4 h/day for 2 days alone or in combination significantly enhanced immunostaining pituitary GH and hepatic IGF-I (except cold). The combined stresses had greater effects than single stresses alone. CRFR1 antagonist (CP154526) or SS antagonist (cysteamine) markedly blocked hypoxia-reduced pituitary GH mRNA and hypoxia-activated hepatic IGF-I mRNA, and further reduced hypoxia-reduced plasma IGF. In conclusion, hypoxia (continually or intermittently), restraint, cold alone or in combination modulate pituitary GH and hepatic IGF-I. The pituitary GH/GH mRNA and hepatic IGF-I/IGF-I mRNA, and plasma IGF-I are modified by hypoxia through SS and CRFR1 mediation.

Animals↗

PubMed2005

[Detection of p53 gene mutation in the plasma of gastric cancer patients].

OBJECTIVE: To investigated p53 gene mutation in plasma of gastric cancer patients. METHODS: DNA extracted from plasma and matched tumor and tumor-adjacent normal tissues of 96 gastric cancer patients, and DNA from 20 healthy people were studied. Exons 5, 6, 7, and 8 of p53 were amplified by PCR. The mutation status was analyzed by denaturing high-performance liquid chromatography (DHPLC), followed by direct sequencing of cases with aberrant chromatographic patterns. RESULTS: Heterozygous mutations of p53 gene were detected in 19.9% (19/96) of primary tumor tissues and 5.2% (5/96) of corresponding plasma. All p53 gene mutations detected in plasma DNA consisted with mutations in the matched primary tumor samples. Neither the tumor-adjacent gastric mucosa tissues nor control plasma from healthy volunteers showed p53 gene mutation. No correlation was found between p53 mutation status and clinicopathological features of gastric cancer patients. CONCLUSION: p53 gene mutation in plasma can be detected in tissues and plasma of gastric cancer patients, which could be applied in screening and surveillance of this disease.

Adenocarcinoma↗

PubMed2005

MPS-1 is a K+ channel beta-subunit and a serine/threonine kinase.

We report the first example of a K+ channel beta-subunit that is also a serine/threonine kinase. MPS-1 is a single-transmembrane domain protein that coassembles with voltage-gated K+ channel KVS-1 in the nervous system of the nematode Caenorhabditis elegans. Biochemical analysis shows that MPS-1 can phosphorylate KVS-1 and other substrates. Electrophysiological analysis in Chinese hamster ovary (CHO) cells demonstrates that MPS-1 activity leads to a significant decrease in the macroscopic current. Single-channel analysis and biotinylation assays indicate that MPS-1 reduces the macroscopic current by lowering the open probability of the channel. These data are consistent with a model that predicts that the MPS-1-dependent phosphorylation of KVS-1 sustains cell excitability by controlling K+ flux.

Amino Acid Motifs↗

PubMed2005

[Experimental study on the osseointegration of nanophase hydroxyapatite biograde-coated implants].

OBJECTIVE: To study the osseointegration of the nanophase hydroxyapatite biograde-coated implants and host bone. METHODS: Nanophase hydroxyapatite biograde-coated implants, hydroxyapatite biograde-coated implants and noncoated Ti-6Al-4V implants were inserted into both femoral of Beagle canines the tissue response, dynamic osteogensis and SEM were studied at 4, 8 and 12 weeks. RESULTS: The degradation of nanophase hydroxyapatite was slower than hydroxyapatite, dynamic osteogensis and the form of osteoblast were better than the control groups. CONCLUSION: The biological reaction of Nanophase hydroxyapatite biograde-coated implants is better than hydroxyapatite coated implant.

Animals↗

PubMed2005

Extended Holstein small polaron model for charge transfer in dry DNA.

In this paper, the charge transfer problem in dry DNA was investigated by employing an extended Holstein small polaron model with external potential traps being involved in consideration. The ground state energy and the probability amplitude of polaron in various DNA chains with different external trap potentials were obtained by variational method with the trial function being taken in coherent state form. The stability of transfered charges in various circumstances was discussed accordingly.

Chemical Phenomena↗

PubMed2005

Simultaneous determination of quercetin, kaempferol and isorhamnetin accumulated human breast cancer cells, by high-performance liquid chromatography.

Quercetin, kaempferol and isorhamnetin are the most important constituents in ginkgo flavonoids. A simple, rapid and sensitive high-performance liquid chromatography method was developed to simultaneously determine quercetin, kaempferol and isorhamnetin absorped by human breast cancer cells. Cells were treated with ginkgo flavonols and then lysed with Triton-X 100. The flavonols in the samples were measured by RP-HPLC with a C18 column after a simple extraction with a mixture of ether and acetone. The mobile phase contained phosphate buffer (pH 2.0; 10 mM) tetrahydrofuran, methanol and isopropanol (65:15:10:20, v/v/v/v). The ultraviolet detector was operated at 380 nm. The calibration curve was linear from 0.1 to 1.0 microM (r > 0.999) for each flavonol. The mean extraction efficiency was about 70%. The recovery of the assay was between 98.9 and 100.6%. The limit of detection was 0.01 microM for quercetin and kaempferol and 0.05 microM for isorhamnetin. The limit of quantitation was 0.1 microM (R.S.D.<10%) for each flavonol. The intra- and inter-day coefficients of variation were less than 10% (R.S.D.). The validated method was applied to quantify quercetin, kaempferol and isorhamnetin in human breast cancer Bcap37 and Bcap37/MDR1 cells.

Breast Neoplasms↗

PubMed2005

A model for laminar diffusion-based complex electrokinetic passive micromixers.

This paper presents a model for the efficient and accurate simulations of laminar diffusion-based complex electrokinetic passive micromixers by representing them as a system of mixing elements of relatively simple geometry. Parameterized and analytical models for such elements are obtained, which hold for general sample concentration profiles and arbitrary flow ratios at the element inlet. A lumped-parameter and system-level model is constructed for a complex micromixer, in which the constituent mixing elements are represented by element models, in such a way that an appropriate set of parameters are continuous at the interface between each pair of adjacent elements. The system-level model, which simultaneously computes electric circuitry and sample concentration distributions in the entire micromixer, agrees with numerical and experimental results, and offers orders-of-magnitude improvements in computational efficiency over full numerical simulations. The efficiency and usefulness of the model is demonstrated by exploring a number of laminar diffusion based mixers and mixing networks that occur in practice.

Journal Article↗

PubMed2005

SOX13 is up-regulated in the developing mouse neuroepithelium and identifies a sub-population of differentiating neurons.

In mammals, most of the twenty SOX (SRY HMG box) transcription factors are expressed during embryogenesis and play an important role in cell fate determination. We show here that SOX13 is expressed in the developing mouse brain and spinal cord from E12.5 to E15.5, where it is largely confined to the differentiating zone rather than to the proliferating zone. In particular, we found that SOX13 expression was activated in a subset of neural progenitors as they exit the cycle of mitosis, migrate away from the ventricular zone, and start to differentiate into neurons. The SOX13 protein always localized to the nuclei of the differentiating neuronal cells, consistent with a role for SOX13 as a transcription factor during neurogenesis. Our data suggest a role for SOX13 in the specification and/or differentiation of a specific subset of neurons in the developing central nervous system.

Animals↗

PubMed2005

Anti-angiogenesis effects of meisoindigo on chronic myelogenous leukemia in vitro.

Meisoindigo, an active compound of a Chinese anti-leukemia medicine, has been effectively used in the treatment of chronic myelogenous leukemia (CML). Increasing evidences have demonstrated that angiogenesis is an important pathobiologic feature of CML. The anti-angiogenesis effect of meisoindigo on CML is unknown. In this study, we determined the effects of meisoindigo on the apoptosis, adherence and differentiation of endothelial cells as well as the secretion of vascular endothelial growth factor (VEGF) by CML cells. We found that VEGF level, measured by enzyme-linked immunosorbent assay (ELISA), was higher in bone marrow plasma from CML patients compared with the healthy controls (334.83+/-23.09 ng/L versus 102.36+/-38.76 ng/L, P<0.01). CML cell VEGF production was decreased after CML cells were treated with 10 micromol/L meisoindigo compared with the controls (212.10+/-46.13 ng/L versus 293.75+/-64.79 ng/L, P<0.05). Ten micromole per liter of meisoindigo could induce time-dependent apoptosis of ECV304 cells determined by annexin-V. Treatment of ECV304 cells with meisoindigo for 48 h reduced the number of adherent cells and the expression of VCAM-1 compared with the control cells (43.78+/-9.09% versus 73.51+/-3.21%, P<0.05). Meisoindigo also inhibited tubule formation of HUVECs in an in vitro Matrigel after HUVECs were incubated with meisoindigo for 6 h. Our findings suggest that meisoindigo could inhibit angiogeneic process through decreasing the VEGF secretion in leukemic cells and also through inhibiting the proliferation, adhesion and differentiation of endothelial cells, causing the interruption of a reciprocal stimulatory loop between leukemic and endothelial cells. This effect may contribute to the anti-leukemic effect of this drug.

Angiogenesis Inhibitors↗