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Biomedical subjects

Wei Shi

Publications and source records attributed to Wei Shi.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Effect of heme oxugenase-1 on delayed xenograft rejection: experiment of guinea pig-to-rat liver xenotransplantation].

OBJECTIVE: To investigate the effects and mechanism of heme oxygenase-1 (HO-1) in liver xenotransplantation and mechanism thereof. METHODS: Thirty male guinea-pigs used as donors were injected intravenously with cobra venom factor (CVF) and then randomly divided into 3 groups 24 hours after: Group A injected intraperineally with NaCl, Group B injected intraperineally with cobalt-protoporphyrin (CoPP), heme oxygenase-1 inducer, and Group C injected intraperineally with CoPP and zinc protoporphyrin (ZnPP), HO-1 inhibitor zinc before their livers were harvested. Thirty male SD rats used as recipients underwent the above-mentioned treatment 24 hours before receiving the xenografts. Five pairs of guinea pigs and rats in each group underwent collection of blood and liver tissues 3 hours after the recovery of blood perfusion in the transplanted livers for detection of serum enzymes by biochemical methods and expression of HO-1 mRNA and protein in the transplanted livers by RT-PCR and Western blotting respectively. The other 5 pairs in each group were used to observe the survival time. RESULTS: The survival time of Group B was 15.5 h +/- 3.8 h, significantly longer than those of Group A (7.3 h +/- 2.1 h) and Group C (6.7 h +/- 2.9 h, both P < 0.01). The values of ALT and LDH of Group B were significantly lower than those of Group A and C (all P < 0.05). HOI-1 mRNA expression was not detected or only expressed in trace amount in the livers of normal guinea pigs, expressed in a small amount in the transplanted livers of Group A. The expression of HO-1 mRNA and that of HO-1 protein in the transplanted livers of Group B were significantly higher than those of Group A (both P < 0.01), and the expression of HO-1 mRNA and that of HO-1 protein in the transplanted livers of Group C were not significantly different from those of Group A (both P > 0.05). Remarkable NF-kB band was detected in Groups A and C, and only weak NF-kB band was seen in Group B. The E-selectin expression was significantly lower in the transplanted livers of Group B than in those of Group A and C (both P < 0.05). CONCLUSION: HO-1 delays the occurrence of delayed xenograft rejection in liver xenotransplantation. This effect depends, at least in part, on HO-1-mediated inhibition of endothelium activation in xenografts.

Animals↗
PubMed2005

A novel function for the protein tyrosine phosphatase Shp2 during lung branching morphogenesis.

Branching morphogenesis of many organs, including the embryonic lung, is a dynamic process in which growth factor mediated tyrosine kinase receptor activation is required, but must be tightly regulated to direct ramifications of the terminal branches. However, the specific regulators that modulate growth factor signaling downstream of the tyrosine kinase receptor remain to be determined. Herein, we demonstrate for the first time an important function for the intracellular protein tyrosine phosphatase Shp2 in directing embryonic lung epithelial morphogenesis. We show that Shp2 is specifically expressed in embryonic lung epithelial buds, and that loss of function by the suppression of Shp2 mRNA expression results in a 53% reduction in branching morphogenesis. Furthermore, by intra-tracheal microinjection of a catalytically inactive adenoviral Shp2 construct, we provide direct evidence that the catalytic activity of Shp2 is required for proper embryonic lung branch formation. We demonstrate that Shp2 activity is required for FGF10 induced endodermal budding. Furthermore, a loss of Shp2 catalytic activity in the embryonic lung was associated with a reduction in ERK phosphorylation and epithelial cell proliferation. However, epithelial cell differentiation was not affected. Our results show that the protein tyrosine phosphatase Shp2 plays an essential role in modulating growth factor mediated tyrosine kinase receptor activation in early embryonic lung branching morphogenesis.

Adenoviridae↗
PubMed2005

Effect of the semirigid capping ligand on the structure formation of cyano-bridged bimetallic assemblies: syntheses, crystal structures, and magnetic properties.

The syntheses, crystal structures, and magnetic properties of three novel cyano-bridged bimetallic assemblies, [Ni(bpm)(2)](3)[Co(CN)(6)](2)x3.5H(2)O (1), [Co(bpm)(2)][Fe(CN)(5)NO]x2H(2)O (2), and [Co(bpm)(2)][Ni(CN)(4)] (3) (bpm = bis(1-pyrazolyl)methane), are reported. Complex 1 crystallizes in the tetragonal space group P4(3)2(1)2 with a = 12.800(5) A, b = 12.800(5) A, c = 42.80(3) A, V = 7012(6) A(3), and Z = 8. Complex 2 crystallizes in the chiral trigonal space group P3(2)21 with a = 11.9961(19) A, b = 11.9961(19) A, c = 16.062(5) A, gamma = 120 degrees , V = 2001.7(8) A(3), and Z = 3. Complex 1 is a trigonal bipyramidal complex in which three [Ni(bpm)(2)](2+) units are situated in the equatorial plane and are connected to the two apical [Co(CN)(6)](3)(-) units via three N ends of the cyanide groups. Complex 2 possesses a triangular left-handed helical chain structure composed of [Co(bpm)(2)](2+) linked by [Fe(CN)(5)NO](2)(-); the shortest intramolecular Co...Fe distance is 5.162 A. To the best of our knowledge, this is the first observation of a heteronuclear helical chain structure based on pentacyanonitrosylferrate(II). The structure of complex 3 is roughly determined by X-ray crystallograhy analysis to be a 1D zigzag chain. These structure variations, from a discrete cluster to a 1D helical chain and a 1D zigzag chain, rely on the semirigidity of the capping ligand bpm. Magnetic susceptibility measurements indicate that complex 1 has an intramolecular ferromagnetic interaction (J = 4.06 cm(-)(1)) between the nickel(II) ions; this is further confirmed by the magnetization measurements. In complexes 2 and 3, the cobalt(II) ions are located in a moderately strong field.

Journal Article↗
PubMed2005

Adsorption of bilirubin with polylysine carrying chitosan-coated nylon affinity membranes.

Microporous polyamide membranes were activated by bisoxirane and subsequently bound with chitosan (CS) to amplify reactive groups. Then polylysine (PLL) as ligand was immobilized onto the CS-coated nylon membranes. The contents of CS and PLL of PLL-attached membranes were 93.2 and 90.4 mg/g nylon membrane, respectively. Such PLL-attached membranes were used to adsorb bilirubin from the bilirubin-phosphate solution and bilirubin-albumin solution. The adsorption mechanism of bilirubin and the effects of temperature, initial concentration of bilirubin, albumin concentration and ionic strength on adsorption were investigated by batch experiments. The results showed that the adsorption capacity increased with increasing the temperature while decreased with increasing the NaCl concentration and albumin concentration, and the adsorption isotherm fitted the Freundlich model well. The result of dynamic experiment showed PLL-attached membranes can well remove the bilirubin from the bilirubin-albumin solution.

Adsorption↗
PubMed2005

Tunable terahertz waves generated by mixing two copropagating infrared beams in GaP.

By mixing two copropagating coherent beams near 1 microm in a zinc blende GaP crystal, we have efficiently generated coherent terahertz (THz) waves. Such efficient conversion is made possible by use of a rest-strahlen band in the THz region to achieve phase matching in an isotropic crystal. A tuning range as wide as 71.1-2830 microm (0.106-4.22 THz) was achieved, whereas the highest output peak power reached 15.6 W at 173 microm. To obtain such a tuning range we continuously tuned the wavelength of one coherent infrared beam within a bandwidth of approximately 15.3 nm.

Journal Article↗
PubMed2005

[A case study of leukemia with irregular anti-Ce IgG antibody].

When we did compatibility testing, we found a case of leukemia with irregular antibody. The antibody specificity was identified as anti-Ce using panel-cell, and was IgG antibody. The anti-Ce antibody had both anti-C and anti-e activity. It is very difficult to find a Ce antigen negative blood for transfusion. The compatible donors rate is very low, only 2%-3%.

ABO Blood-Group System↗
PubMed2005

Molecular mechanisms of early lung specification and branching morphogenesis.

The "hard wiring" encoded within the genome that determines the emergence of the laryngotracheal groove and subsequently early lung branching morphogenesis is mediated by finely regulated, interactive growth factor signaling mechanisms that determine the automaticity of branching, interbranch length, stereotypy of branching, left-right asymmetry, and finally gas diffusion surface area. The extracellular matrix is an important regulator as well as a target for growth factor signaling in lung branching morphogenesis and alveolarization. Coordination not only of epithelial but also endothelial branching morphogenesis determines bronchial branching and the eventual alveolar-capillary interface. Improved prospects for lung protection, repair, regeneration, and engineering will depend on more detailed understanding of these processes. Herein, we concisely review the functionally integrated morphogenetic signaling network comprising the critical bone morphogenetic protein, fibroblast growth factor, Sonic hedgehog, transforming growth factor-beta, vascular endothelial growth factor, and Wnt signaling pathways that specify and drive early embryonic lung morphogenesis.

Animals↗
PubMed2005

Microbial catabolic diversity in soils contaminated with hydrocarbons and heavy metals.

Understanding indigenous microbial function in contaminated soil is crucial to the successful development and use of bioremediation technologies. We measured the catabolic diversity of indigenous microbial communities in soils with a 30-yr history of Pb, Cr, and hydrocarbon (HC) contamination using a modified substrate-induced respiration method. There were characteristic differences of microbial respirations in the response of highly versus less contaminated soils to the range of organic substrates used. The catabolic response to glucose as compared to succinic acid was approximately 1:5 in less contaminated soils, but 1:25 in highly contaminated soils. In contrast, the response ratio to glucose versus aromatics was about 1:0.4 in less contaminated soils and 1:1 in highly contaminated soils. Principal components analysis (PCA) of the responses confirmed that catabolic diversity differed between highly and less contaminated soils. Univariate analysis also indicated that catabolic diversity was reduced in highly contaminated soils. This catabolic difference was strongly associated with the alteration of microbial community composition. Statistical analyses suggested that the variation in microbial community catabolic diversity was attributed to HCs more than to Pb and Cr.

Bacteria↗
PubMed2005

Synthesis of titanium dioxide nanoparticles with mesoporous anatase wall and high photocatalytic activity.

Mesoporous titanium dioxide nanosized powder with high specific surface area and anatase wall was synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting materials were characterized by XRD, nitrogen adsorption, FESEM, TEM, and FT-IR spectroscopy. The as-synthesized mesoporous TiO2 nanoparticles have mean diameter of 17.6 nm with mean pore size of 2.1 nm. The specific surface area of the as-synthesized mesoporous nanosized TiO2 exceeded 430 m2/g and that of the samples after calcination at 600 degrees C still have 221.9 m2/g. The mesoporous TiO2 nanoparticles show significant activities on the oxidation of Rhodamine B (RB). The large surface area, small crystalline size, and well-crystallized anatase mesostructure can explain the high photocatalytic activity of mesoporous TiO2 nanoparticles calcined at 400 degrees C.

Journal Article↗
PubMed2005

Theoretical ONIOM2 study on pyridine adsorption in the channels and intersection of ZSM-5.

The structures of the acid sites in the channels and intersections of H-, Li-, and Na-ZSM-5 (ZSM = zeolite socony mobil) and their interactions with pyridine molecule have been computed by using three corresponding models containing 22 tetrahedral sites. The calculated adsorption energies of pyridine in the intersection regions of H-, Li-, and Na-ZSM-5 are 197.0, 172.5, and 122.3 kJ/mol, respectively, in good agreement with the respective experimental values of 200 +/- 5, 155-195, and 120 kJ/mol, while those in the straight and sinusoidal channels are much smaller (157.9 and 127.6, 152.2 and 149.4, and 150.4 and 109.9 kJ/mol, respectively). These indicate that the most probable adsorption site for pyridine in ZSM-5 is the acidic site located in the intersection region. The structural parameters of the adsorption complexes show that the acidic proton in the three models of H-ZSM-5 has been transferred to the nitrogen of pyridine, while in alkali cation-exchanged ZSM-5, the coordination of the alkali cation to the nitrogen atom of pyridine dominates the overall interaction. In addition, the adsorption complexes were further stabilized by the long-range electrostatic interaction between the positively charged pyridine hydrogen atoms and the negatively charged lattice oxygen atoms of the zeolite framework. In the intersection regions of H-, Li-, and Na-ZSM-5, the coordination energy of the charge-compensating cation to the pyridine nitrogen amounts to 58, 60, and 68% of the total adsorption energy, respectively, while another 42, 40, and 32%, respectively, is due to long-range electrostatic interactions. This indicates that the zeolite lattice framework surrounding the adsorption site has important contributions to the adsorption energy of the pyridine molecule.

Journal Article↗
PubMed2005

Poly(acrylamide-co-alkylacrylamides) for electrophoretic DNA purification in microchannels.

We have created a family of water-soluble block copolymers of acrylamide and N-alkylacrylamides that are designed to selectively remove proteins from DNA via microchannel electrophoresis. It was hypothesized that the inclusion of hydrophobic subunits in the polymer chain, in sufficient concentration, could lead to protein adsorption due to hydrophobic interactions. A series ofN-alkylacrylamide comonomers with varying alkyl chain lengths (C4, C6, C8) and also an N,N-dialkyl group (C6-C6) were synthesized via reactions between acryloyl chloride and the respective alkylamines. Copolymers were synthesized using an aqueous "micellar" polymerization technique, which involves dissolving acrylamide in the aqueous phase while hydrophobic monomers are solubilized in sodium dodecyl sulfate micelles. Copolymers comprising up to 4 mol % of a hydrophobic subunit (as verified by (1)H NMR) were synthesized. Polymer molecular weights were determined by tandem gel permeation chromatography-multiangle laser light scattering, and ranged from 1.5 x 10(6) to 4.3 x 10(6). Capillary electrophoresis analysis of bovine serum albumin and beta-lactoglobulin migration in these matrixes revealed that the octylacrylamide and dihexylacrylamide copolymers show the most significant extent of protein adsorption while butylacrylamides show no noteworthy adsorption trend. All copolymer matrixes studied allowed the passage of a dsDNA digest, and displayed some DNA sieving ability at 0.5% (w/w) in TTE (50 mM Tris, 50 mM TAPS, 2 mM EDTA, pH 8.4) buffer. These matrixes are demonstrated in on-chip experiments to adsorb protein, in a step toward meeting the front-end processing goals of mu-TAS for genetic analysis applications.

Acrylamides↗
PubMed2005

Smad1 expression and function during mouse embryonic lung branching morphogenesis.

Bone morphogenetic protein (BMP) 4 plays very important roles in regulating developmental processes of many organs, including lung. Smad1 is one of the BMP receptor downstream signaling proteins that transduce BMP4 ligand signaling from cell surface to nucleus. The dynamic expression patterns of Smad1 in embryonic mouse lungs were examined using immunohistochemistry. Smad1 protein was predominantly detected in peripheral airway epithelial cells of early embryonic lung tissue [embryonic day 12.5 (E12.5)], whereas Smad1 protein expression in mesenchymal cells increased during mid-late gestation. Many Smad1-positive mesenchymal cells were localized adjacent to large airway epithelial cells and endothelial cells of blood vessels, which colocalized with a molecular marker of smooth muscle cells (alpha-smooth muscle actin). The biological function of Smad1 in early lung branching morphogenesis was then studied in our established E11.5 lung explant culture model. Reduction of endogenous Smad1 expression was achieved by adding a Smad1-specific antisense DNA oligonucleotide, causing approximately 20% reduction of lung epithelial branching. Furthermore, airway epithelial cell proliferation and differentiation were also inhibited when endogenous Smad1 expression was knocked down. Therefore, these data indicate that Smad1, acting as an intracellular BMP signaling pathway component, positively regulates early mouse embryonic lung branching morphogenesis.

Animals↗
PubMed2005

Expression and functional analysis of genes deregulated in mouse placental overgrowth models: Car2 and Ncam1.

Different causes, such as maternal diabetes, cloning by nuclear transfer, interspecific hybridization, and deletion of some genes such as Esx1, Ipl, or Cdkn1c, may underlie placental overgrowth. In a previous study, we carried out comparative gene expression analysis in three models of placental hyperplasias, cloning, interspecies hybridization (IHPD), and Esx1 deletion. This study identified a large number of genes that exhibited differential expression between normal and enlarged placentas; however, it remained unclear how altered expression of any specific gene was related to any specific placental phenotype. In the present study, we focused on two genes, Car2 and Ncam1, which both exhibited increased expression in interspecies and cloned hyperplastic placentas. Apart from a detailed expression analysis of both genes during normal murine placentation, we also assessed morphology of placentas that were null for Car2 or Ncam1. Finally, we attempted to rescue placental hyperplasia in a congenic model of IHPD by decreasing transcript levels of Car2 or Ncam1. In situ analysis showed that both genes are expressed mainly in the spongiotrophoblast, however, expression patterns exhibited significant variability during development. Contrary to expectations, homozygous deletion of either Car2 or Ncam1 did not result in placental phenotypes. However, expression analysis of Car3 and Ncam2, which can take over the function of Car2 and Ncam1, respectively, indicated a possible rescue mechanism, as Car3 and Ncam2 were expressed in spongiotrophoblast of Car2 and Ncam1 mutant placentas. On the other hand, downregulation of either Car2 or Ncam1 did not rescue any of the placental phenotypes of AT24 placentas, a congenic model for interspecies hybrid placentas. This strongly suggested that altered expression of Car2 and Ncam1 is a downstream event in placental hyperplasia.

Animals↗
PubMed2005

Fetal loss in homozygous mutant Norrie disease mice: a new role of Norrin in reproduction.

Mutations in the Norrie disease pseudoglioma gene (NDP) are known to cause X-linked recessive Norrie disease. In addition, NDP mutations have been found in other vasoproliferative retinopathies such as familial exudative vitreoretinopathy, retinopathy of prematurity, and Coats disease, suggesting a role for Norrin in vascular development. Here we report that female mice homozygous for the Norrie disease pseudoglioma homolog (Ndph) knockout allele exhibit almost complete infertility, while heterozygous females and hemizygous males are fertile. Histological examinations and RNA in situ hybridization analyses revealed defects in vascular development and decidualization in pregnant Ndph-/- females from embryonic day 7 (E7) onwards, resulting in embryonic loss. Using RT-PCR analyses we also demonstrate, for the first time, the expression of Ndph in mouse uteri and deciduae as well as the expression of NDP in human placenta. Taken together, these data provide strong evidence for Norrin playing an important role in female reproductive tissues.

Animals↗
PubMed2005

Widespread disruption of genomic imprinting in adult interspecies mouse (Mus) hybrids.

Mammalian interspecies hybrids exhibit parent-of-origin effects in that offspring of reciprocal matings, even though genetically identical, frequently exhibit opposite phenotypes, especially in growth. This was also observed in hybridization with the genus Mus. These parent-of-origin effects suggested that imbalance in the expression of imprinted genes, which are expressed differentially, depending on their transmission through the maternal or paternal germline, and/or differential loss-of-imprinting (LOI) could underlie these opposite growth phenotypes in reciprocal mammalian hybrids. Here we report that tissue-specific LOI occurs in adult Mus hybrids. Contrary to expectations, LOI patterns were not consistent with a direct influence of altered expression levels of imprinted genes on growth. Bisulfite sequencing revealed that reactivation of maternal alleles of Peg3 and Snrpn in specific tissues was accompanied by partial demethylation at their potential imprinting control regions. We propose that abnormal reprogramming after fertilization and during preimplantation development is in part responsible for hybrid dysgenesis, for which a strong epigenetic basis has been demonstrated.

Animals↗
PubMed2005

DJ-1, a novel regulator of the tumor suppressor PTEN.

The phosphatidylinositol 3' kinase (PI3'K) pathway, which regulates cell survival, is antagonized by the PTEN tumor suppressor. The regulation of PTEN is unclear. A genetic screen of Drosophila gain-of-function mutants identified DJ-1 as a suppressor of PTEN function. In mammalian cells, DJ-1 underexpression results in decreased phosphorylation of PKB/Akt, while DJ-1 overexpression leads to hyperphosphorylation of PKB/Akt and increased cell survival. In primary breast cancer samples, DJ-1 expression correlates negatively with PTEN immunoreactivity and positively with PKB/Akt hyperphosphorylation. In 19/23 primary non-small cell lung carcinoma samples, DJ-1 expression was increased compared to paired nonneoplastic lung tissue, and correlated positively with relapse incidence. DJ-1 is thus a key negative regulator of PTEN that may be a useful prognostic marker for cancer.

Animals↗
PubMed2005

Role of impaired peritubular capillary and hypoxia in progressive interstitial fibrosis after 56 subtotal nephrectomy of rats.

AIM: To investigate the potential role of peritubular capillary (PTC) loss and subsequent hypoxia as a pathogenic factor in interstitial fibrosis after renal ablation in rats. METHODS: PTC loss and tubulointerstitial hypoxia in remnant kidney rats (SNTx group), sham-operated rats (sham group) and normal animals (normal group) were assessed by peritubular CD141-positive staining lumina and tubulointerstitial hypoxia-inducible factor alpha subunit 1 (HIF-1alpha) expression, respectively, at the time points of week 3, week 6 and week 12. The related cardinal factors contributing to interstitial fibrosis, such as transforming growth factor-beta1 (TGF-beta1), alpha-smooth muscle actin (alpha-SMA) were also evaluated and analysed in the context of progressive PTC loss. Expression of TGF-beta1 mRNA in cultured renal tubular epithelial cells (MDCK cells) exposed to hypoxia was also investigated. RESULTS: PTC loss and tubulointerstitial hypoxia were noted even in the early stage (week 3) when the interstitial fibrosis was mild, and were persistent in the process of developing interstitial fibrosis. An in vitro study showed that hypoxia enhanced TGF-beta1 mRNA expression in the MDCK cells. CONCLUSION: PTC loss or hypoxic milieu in the tubulointerstitium is a pathological event, which may contribute to the developing interstitial fibrosis mediated by direct hypoxic effects and via hypoxia-induced TGF-beta1 expression.

Actins↗