Biomedical subjects

Bing Liu

Publications and source records attributed to Bing Liu.

At least 73 records · Page 4Linked to original sources

PubMed2004

Protective effects of N-n-butyl haloperidol iodide on myocardial ischemia-reperfusion injury in rabbits.

N-n-butyl haloperidol iodide (F2), a novel compound derived from haloperidol, was synthesized by our drugs research lab. The present study aims to evaluate the protective effects of F2 on myocardial ischemia-reperfusion injury in vivo, and to try to find the protective mechanism of F2. The animal model of myocardial ischemia-reperfusion injury was established by ligaturing rabbit's left ventricular branch of coronary artery for 40 min and removing the ligation later to reperfuse for 40 min. Different doses of F2 were intravenously injected before the onset of ischemia. The changes of hemodynamics were recorded during the experiment, and the activities of superoxide dismutase (SOD), creatine kinase (CK), Ca2+-ATPase, Na+,K+-ATPase and the level of malondialdehyde (MDA) of myocardial tissue were detected after reperfusion. Administration of F2 could dose-dependently ameliorate the hemodynamics of ischemia-reperfusion injured myocardium. During the course of reperfusion, MAP, LVSP, +/-dP/dt(max) in all F2 groups were obviously higher than those in the ischemia-reperfusion control group, and LVEDP were lower. F2 could also reduce the production of MDA, and maintain the activities of SOD, Ca2+-ATPase, Na+,K+-ATPase, and minimize the leakage of CK out of myocardial cells in a dose-dependent manner. These results suggested that F2 had apparent protective effects against myocardial ischemia-reperfusion injury.

Animals↗

PubMed2004

Zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework.

Five zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid (H(3)L) with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework have been obtained based on different building blocks. X-ray single crystal analyses show that the T-shaped information of H(3)L was nicely expressed in the construction of herringbone-like or ladder-like structure. All compounds were found to display blue fluorescent emissions.

Journal Article↗

PubMed2004

Esub8: a novel tool to predict protein subcellular localizations in eukaryotic organisms.

BACKGROUND: Subcellular localization of a new protein sequence is very important and fruitful for understanding its function. As the number of new genomes has dramatically increased over recent years, a reliable and efficient system to predict protein subcellular location is urgently needed. RESULTS: Esub8 was developed to predict protein subcellular localizations for eukaryotic proteins based on amino acid composition. In this research, the proteins are classified into the following eight groups: chloroplast, cytoplasm, extracellular, Golgi apparatus, lysosome, mitochondria, nucleus and peroxisome. We know subcellular localization is a typical classification problem; consequently, a one-against-one (1-v-1) multi-class support vector machine was introduced to construct the classifier. Unlike previous methods, ours considers the order information of protein sequences by a different method. Our method is tested in three subcellular localization predictions for prokaryotic proteins and four subcellular localization predictions for eukaryotic proteins on Reinhardt's dataset. The results are then compared to several other methods. The total prediction accuracies of two tests are both 100% by a self-consistency test, and are 92.9% and 84.14% by the jackknife test, respectively. Esub8 also provides excellent results: the total prediction accuracies are 100% by a self-consistency test and 87% by the jackknife test. CONCLUSIONS: Our method represents a different approach for predicting protein subcellular localization and achieved a satisfactory result; furthermore, we believe Esub8 will be a useful tool for predicting protein subcellular localizations in eukaryotic organisms.

Computational Biology↗

PubMed2004

Expression and roles of Cl- channel ClC-5 in cell cycles of myeloid cells.

ClC-5 is a chloride channel known to be expressed in the kidney. We previously reported that ClC-5 mRNA was also strongly expressed in immature human myeloid cell line (HL-60), but weakly expressed in mature neutrophils. To clarify the underlying mechanisms, we examined the relationship between ClC-5 expression and cell cycle. Dimethyl sulfoxide treatment of HL-60 that causes differentiation with G0/G1 cell cycle arrest decreased the expression of ClC-5 mRNA. Cell sorting and synchronization experiments revealed that ClC-5 mRNA expression was high in S and G2/M phases and low in G0/G1 phase. ClC-5 antisense oligonucleotide suppressed proliferation of HL-60 cells with a decrease in ClC-5 protein expression, probably due to G2 arrest. These results suggest that cell cycle-dependent expression of ClC-5 has a role in cell cycle progression in myeloid cells.

Cell Cycle↗

PubMed2004

Single cell RT-PCR demonstrates differential expression of GABAC receptor rho subunits in rat hippocampal pyramidal and granule cells.

Although gamma-aminobutyric acid (GABA)C receptor rho1, rho2 and rho3 subunits are reportedly expressed in pyramidal and granule cells in the hippocampus at various developmental stages, it is not clear whether these three rho subunits are coexpressed in a single neuron. To attempt to answer this question, we performed single-cell RT-PCR for rho subunits from neurons of rat brain hippocampus. In hippocampal cultures, pyramidal cells were positive for rho1 mRNA expression in 89%, rho2 in 94% and rho3 in 94%, while granule cells were positive for rho1 mRNA in only 6%, rho2 in 36% and rho3 in 91%. Intensive amplification of the RT-PCR products by the second PCR revealed that all the three rho subunits were coexpressed in a single pyramidal and granule cells from both of the cultures and the slices. These results suggest that all the three GABAC receptor rho1, rho2 and rho3 subunits are present probably in different compositions in pyramidal and granule cells in the rat hippocampus.

Animals↗

PubMed2004

Suppression of cell proliferation with induction of p21 by Cl(-) channel blockers in human leukemic cells.

The existence of Cl(-) channels in lymphocytes and neutrophils has been increasingly recognized, but the biological functions are not yet clear. We examined the effects of Cl(-) channel blockers on the cell proliferation and the cell cycle of human leukemic cell lines. The growth of leukemic cells was suppressed most efficiently by NPPB (5-nitro-2-(3-phenylpropylamino) benzoic acid), partially by 9-AC (9-anthracenecarboxylic acid) and tamoxifen, but not by stilbene compounds. NPPB increased the G0/G1 population and induced the expression of p21, one of the critical molecules for G1/S checkpoint. Antisense oligonucleotide for a NPPB-sensitive and stilbene-insensitive Cl(-) channel, ClC-2, sufficiently suppressed the ClC-2 protein synthesis, but did not affect the growth of leukemic cells. These findings suggest that NPPB-sensitive and stilbene-insensitive Cl(-) channels other than ClC-2 play important roles in cell cycles and cell proliferation of human leukemic cells.

Blotting, Northern↗

PubMed2004

Significance of conservative asparagine residues in the thermal hysteresis activity of carrot antifreeze protein.

The approximately 24-amino-acid leucine-rich tandem repeat motif (PXXXXXLXXLXXLXLSXNXLXGXI) of carrot antifreeze protein comprises most of the processed protein and should contribute at least partly to the ice-binding site. Structural predictions using publicly available online sources indicated that the theoretical three-dimensional model of this plant protein includes a 10-loop beta-helix containing the approximately 24-amino-acid tandem repeat. This theoretical model indicated that conservative asparagine residues create putative ice-binding sites with surface complementarity to the 1010 prism plane of ice. We used site-specific mutagenesis to test the importance of these residues, and observed a distinct loss of thermal hysteresis activity when conservative asparagines were replaced with valine or glutamine, whereas a large increase in thermal hysteresis was observed when phenylalanine or threonine residues were replaced with asparagine, putatively resulting in the formation of an ice-binding site. These results confirmed that the ice-binding site of carrot antifreeze protein consists of conservative asparagine residues in each beta-loop. We also found that its thermal hysteresis activity is directly correlated with the length of its asparagine-rich binding site, and hence with the size of its ice-binding face.

Amino Acid Sequence↗

PubMed2004

Combustion behaviors of a compression-ignition engine fueled with diesel/methanol blends under various fuel delivery advance angles.

A stabilized diesel/methanol blend was described and the basic combustion behaviors based on the cylinder pressure analysis was conducted in a compression-ignition engine. The study showed that increasing methanol mass fraction of the diesel/methanol blends would increase the heat release rate in the premixed burning phase and shorten the combustion duration of the diffusive burning phase. The ignition delay increased with the advancing of the fuel delivery advance angle for both the diesel fuel and the diesel/methanol blends. For a specific fuel delivery advance angle, the ignition delay increased with the increase of the methanol mass fraction (oxygen mass fraction) in the fuel blends and the behaviors were more obvious at low engine load and/or high engine speed. The rapid burn duration and the total combustion duration increased with the advancing of the fuel delivery advance angle. The centre of the heat release curve was close to the top-dead-centre with the advancing of the fuel delivery advance angle. Maximum cylinder gas pressure increased with the advancing of the fuel delivery advance angle, and the maximum cylinder gas pressure of the diesel/methanol blends gave a higher value than that of the diesel fuel. The maximum mean gas temperature remained almost unchanged or had a slight increase with the advancing of the fuel delivery advance angle, and it only slightly increased for the diesel/methanol blends compared to that of the diesel fuel. The maximum rate of pressure rise and the maximum rate of heat release increased with the advancing of the fuel delivery advance angle of the diesel/methanol blends and the value was highest for the diesel/methanol blends.

Engineering↗

PubMed2004

Human placenta-derived mesenchymal progenitor cells support culture expansion of long-term culture-initiating cells from cord blood CD34+ cells.

OBJECTIVE: Allogeneic transplantation with umbilical cord blood (UCB) in adult recipients is limited mainly by a low CD34+ cell dose. To overcome this shortcoming, human placenta as a novel source of human mesenchymal progenitor cell (MPC) was incorporated in an attempt to expand CD34+ cells from UCB in vitro. MATERIALS AND METHODS: Human placenta MPC was isolated and characterized by morphologic, immunophenotypical, and functional analysis. UCB CD34+ cells were expanded by coculture with placental MPC. Suitable aliquots of cells were used to monitor cell production, clonogenic activity, and long-term culture-initiating culture (LTC-IC) output. Finally, the immunoregulatory effect of placental MPC was evaluated by T-cell proliferation assay. RESULTS: In its undifferentiated state, placental MPC displayed fibroblastoid morphology; was CD73, CD105, CD29, CD44, HLA-ABC, and CD166 positive; produced fibronectin, laminin, and vimentin; but was negative for CD14, CD31, CD34, CD45, HLA-DR, and alpha-smooth muscle actin. Functionally, it could be induced into adipocytes, osteocytes, and chondrocytes. In vitro expansion of UCB hematopoietic cells, when cocultured with placental MPC in the presence of cytokines, was significantly enhanced: CD34+ cells by 14.89 +/- 2.32 fold; colony-forming cell (CFC) by 36.73 +/- 5.79 fold; and LTC-IC by 7.43 +/- 2.66 fold. Moreover, placental MPC could suppress T-cell proliferation induced by cellular stimuli. CONCLUSION: These results strongly suggest that human placental MPC may be a suitable feeder layer for expansion of hematopoietic progenitors from UCB in vitro.

Antigens, CD↗

PubMed2004

Expression, purification, and antifreeze activity of carrot antifreeze protein and its mutants.

Antifreeze proteins (AFPs) enable organisms to survive under freezing or sub-freezing conditions. AFPs have a great potential in the low temperature storage of cells, tissues, organs, and foods. This process will require a large number of recombinant AFPs. In the present study, the recombinant carrot AFP was highly expressed in Escherichia coli strain BL21 (DE3). The activity of the purified and refolded recombinant proteins was analyzed by measurement of thermal hysteresis (TH) activity and detection of in vitro antifreeze activity by measuring enhanced cold resistance of bacteria. Two carrot AFP mutants generated by site-directed mutagenesis were also expressed and purified under these conditions for use in parallel experiments. Recombinant DcAFP displayed a TH activity equivalent to that of native DcAFP, while mutants DcAFP-N130Q and rDcAFP-N130V showed 32 and 43% decreases in TH activity, respectively. Both the recombinant DcAFP and its mutants were able to enhance the cold resistance of bacteria, to degrees consistent with their respective TH activities.

Antifreeze Proteins↗

PubMed2004

Smad5: signaling roles in hematopoiesis and osteogenesis.

Smad5 belongs to the receptor-activated Smad that function as intracellular signal transducers for transforming growth factor-beta superfamily. Smad5 protein is composed of N-terminal domain responsible for DNA-binding, C-terminal domain primarily required for protein-protein interaction, and the linker region containing motif essential for ubiquitinized degradation. Recent investigation reveals Smad5 as a negative regulator of embryonic hematopoiesis in a haploinsufficiency fashion, helping to elucidate the cytogenetic mechanism, by which Smad5 acts as leukemia suppressor. To date, osteogenesis governed by Smad5-mediated signals is delicately orchestrated by its comprehensive interactions with global osteogenesis regulator Runx2, transcriptional repressor Rob and Smad-interacting protein 1. Further delineation of its roles in hematopoiesis and osteogenesis will undoubtedly provide valuable insights into leukemia therapy and tissue engineering.

Bone Morphogenetic Protein Receptors↗

PubMed2004

The periodic competing Lotka-Volterra model with impulsive effect.

In this paper, the dynamic behaviour of a classical periodic Lotka-Volterra competing system with impulsive effect is investigated. By applying the Floquet theory of linear periodic impulsive equations, some conditions are obtained for the linear stability of the trivial and semi-trivial periodic solutions. It is proved that the system can be permanent if all the trivial and semi-trivial periodic solutions are linearly unstable. We use standard bifurcation theory to show the existence of nontrivial periodic solutions which arise near the semi-trivial periodic solution. As an application, a fish harvest problem is considered. We explain how two competing species, one of which in a periodic environment without impulsive effect would be doomed to extinction, can coexist with suitably periodic impulsive harvesting.

Animals↗

PubMed2004

Pathophysiological concentrations of amyloid beta proteins directly inhibit rat brain and recombinant human type II phosphatidylinositol 4-kinase activity.

We previously found that pathophysiological concentrations (< or = 10 nm) of an amyloid beta protein (Abeta25-35) reduced the plasma membrane phosphatidylinositol monophosphate level in cultured rat hippocampal neurons with a decrease in phosphatidylinositol 4-monophosphate-dependent Cl- -ATPase activity. As this suggested an inhibitory effect of Abeta25-35 on plasma membrane phosphatidylinositol 4-kinase (PI4K) activity, in vitro effects of Abetas on PI4K activity was examined using rat brain subcellular fractions and recombinant human type II PI4K (PI4KII). Abeta25-35 (10 nm) inhibited PI4KII activity, but neither PI 3-kinase (PI3K) nor type III PI4K (PI4KIII) activity, in microsomal fractions, while 100 nm Abeta25-35 inhibited PI3K activity in mitochondrial fractions. In plasma membrane-rich fractions, Abetas (> 0.5 nm) dose-dependently inhibited PI4KII activity, the maximal inhibition to 77-87% of control being reached around 10 nm of Abetas without significant changes in apparent Km values for ATP and PI, suggesting non-competitive inhibition by Abetas. The inhibition by 10 nm Abeta25-35 was reversible. In recombinant human PI4KIIalpha, inhibition profiles of Abetas were similar to those in rat brain plasma membranes. Therefore, pathophysiological concentrations of Abetas directly and reversibly inhibited plasma membrane PI4KII activity, suggesting that plasma membrane PI4KII is a target of Abetas in the pathogenesis of Alzheimer's disease.

1-Phosphatidylinositol 4-Kinase↗

PubMed2004

An empirical study of the universal chemical key algorithm for assigning unique keys to chemical compounds.

In this paper, we introduce an algorithm that assigns an essentially unique key called the Universal Chemical Key (UCK) to molecular structures. The molecular structures are represented as labeled graphs whose nodes abstract atoms and whose edges abstract bonds. The algorithm was tested on 236,917 compounds obtained from the National Cancer Institute (NCI) database of chemical compounds. On this database, the UCK algorithm assigned unique keys for chemicals with distinct molecular structures.

Algorithms↗

PubMed2004

Hepatic insulin resistance precedes the development of diabetes in a model of intrauterine growth retardation.

Intrauterine growth retardation (IUGR) has been linked to the development of type 2 diabetes in adulthood. We developed an IUGR model in rats whereby at age 3-6 months the animals develop a diabetes that is associated with insulin resistance. Hyperinsulinemic-euglycemic clamp studies were performed at age 8 weeks, before the onset of obesity and diabetes. Basal hepatic glucose production (HGP) was significantly higher in IUGR than in control rats (14.6 +/- 0.4 vs. 12.3 +/- 0.3 mg. kg(-1). min(-1); P < 0.05). Insulin suppression of HGP was blunted in IUGR versus control rats (10.4 +/- 0.6 vs. 6.5 +/- 1.0 mg. kg(-1). min(-1); P < 0.01); however, rates of glucose uptake and glycogenolysis were similar between the two groups. Insulin-stimulated insulin receptor substrate 2 and Akt-2 phosphorylation were significantly blunted in IUGR rats. PEPCK and glucose-6-phosphatase mRNA levels were increased at least threefold in liver of IUGR compared with control rats. These studies suggest that an aberrant intrauterine milieu permanently impairs insulin signaling in the liver so that gluconeogenesis is augmented in the IUGR rat. These processes occur early in life, before the onset of hyperglycemia, and indicate that uteroplacental insufficiency causes a primary defect in gene expression and hepatic metabolism that leads to the eventual development of overt hyperglycemia.

Animals↗

PubMed2004

Influence of IL-1 beta and TNF-alpha on Fas expression of human retinal pigment epithelial cells in vitro.

PURPOSE: To observe Fas expression change of cultured human retinal pigment epithelial (RPE) cells by IL-1 beta and TNF-alpha. METHODS: With flow cytometry, immunohischemistry, and color imaging system, Fas expressions by exposure to IL-1 beta and/or TNF-alpha were measured. RESULTS: The gray degree values of Fas expression were 67.5 +/- 6.1 in IL-1 beta + TNF-alpha-treated group, 80.1 +/- 9.2 in IL-1 beta-treated group, and 70.4 +/- 6.4 in TNF-alpha-treated group, respectively. There were significant differences (P < 0.005) compared with control group (107.0 +/- 10.2). Flow cytometry showed that 15.0% cultured human RPE cells expressed Fas. Fas-positive in IL-1 beta, TNF-alpha, and IL-1 beta + TNF-alpha-treated groups expressed was 28.1%, 34.5%, and 65.2%, respectively. CONCLUSION: IL-1 beta, TNF-alpha, and combining both of them can up-regulate Fas protein expression, which may contribute to more Fas (+) cells in proliferative vitreoretinopathy (PVR). Minimizing this process by means of inducing apoptosis of Fas (+) proliferative cells of Fas/FasL pathway is a future preventive and therapeutic possibility for PVR.

Apoptosis↗

PubMed2004

[Results after laser epithelial keratectomileusis for myopia].

PURPOSE: To study the results of laser epithelial keratectomileusis (LASEK) for myopia. METHODS: LASEK was performed with the Nidek EC-5000 excimer laser. 39 patients (78 eyes) with a refraction of -1.50 to -12.00 diopters were treated and followed for 3-12 months. Postoperrative pain, uncorrected visual acuity (UCVA), refraction, corneal haze, and surgical preference were examined. RESULTS: During 3-12 months follow-up, 96.2% UCVA were above 0.5, 92.3% eyes were at least 1.0 in UCVA. The last refraction were whthin +1.00 D and -1.00 D in 18 eyes except 4 eyes. The II grade haze was found in four eye. CONCLUSIONS: LASEK was one of methods to treat eyes with myopia safely and effectively, but also studied in operation, experiment, and further effect.

Adolescent↗

PubMed2004

[A preliminary report on treatment of myelodysplastic syndrome with cyclosporin a and androgen].

The study was aimed to explore clinical result of cyclosporin A (CsA) and androgens for treatment of myelodysplastic syndrome (MDS) with refractory anemia. Four cases of MDS-RA were treated with CsA and androgens, while the changes of blood counts, bone marrow and chromosome were observed. The results showed that substantial hematological response was observed in all four patients, that their anemia improved and all transfusion-dependent patients achieved transfusion independence. In conclusion, CsA and Adr therapy was well tolerated. CsA and Adr therapy offer an alternative treatment of MDS with RA. The mechanisms of the benifical effect from this therapy remain the subject of an ongoing study.

Adolescent↗