Biomedical subjects

Yu Liu

Publications and source records attributed to Yu Liu.

At least 91 records · Page 5Linked to original sources

PubMed2006

[Effects of estradiol intervention on peripheral blood CD90+ cells and cardiac function in de-ovary rats before and after myocardial infarction].

AIM: To investigate the effects of estradiol intervention on peripheral blood CD90+ cells and cardiac function in de-ovary rats before and after myocardial infarction. METHODS: Thirty SD female rats were divided into the control group, acute myocardial infarction group, de-ovary myocardial infarction group, de-ovary replacement group with estradiol, and de-ovary therapy group with estradiol. CD90+ cell percentage was determined with flow cytometry. The left ventricle end systolic pressure (LVESP), left ventricle end diastolic pressure (LVEDP), +dp/dt(max) and -dp/dt(max) were also measured with the POWERLAB4.12 system. RESULTS: The percentage of peripheral blood CD90+ cells in the de-ovary myocardial infarction group was remarkably lower than that in the acute myocardial infarction group and the de-ovary replacement group with estradiol (P<0.01). In the de-ovary replacement group with estradiol, the percentage of peripheral blood CD90+ cells was remarkably elevated following the first day of operation (P<0.05), reaching the peak value at day 3. In the de-ovary therapy group with estradiol, it started to elevate at day 7 after the operation, much lower than that in the de-ovary replacement group with estradiol. LVESP in each operation group decreased, especially in the acute myocardial infarction group, whereas LVEDP increased in the de-ovary group and de-ovary therapy group with estradiol (P<0.01). CONCLUSION: Replacement with estradiol before myocardial infarction exerts more beneficial effects than estradiol replacement after myocardial infarction in de-ovary rats.

Animals↗

PubMed2006

[Inhibition activity of Scutellariae barbata extracts against human hepatocellular carcinoma cells].

OBJECTIVE: To investigate the inhibition effect of Scutellariae barbata extracts on the proliferation of human hepatocellular carcinoma cell line QGY-7701. METHODS: The inhibition activity of the extracts against cell line QGY-7701 was estimated by MTT assay. Morphologic changes of the cells were observed under light microscope and electronic microscope. Cell cycle distribution, cell apoptosis and expressions of apoptosis-associated genes as Bcl-2, Bax and Fas were analyzed by flow cytometry. RESULTS: Extracts of Scutellariae barbata could inhibit the proliferation of QGY-7701. When treated with the extracts for 72 h, cells at the early stage of apoptosis showed morphologic changes, apoptotic cells increased, cells at G0/G1 phase decreased and those at G2/M phase increased, the expression of Bax significantly up-regulated and that of Bcl-2 down-regulated with no change in Fas gene. CONCLUSION: The extracts of Scutellariae barbata inhibit the proliferation of QGY-7701, which may relate to the activation of anti-oncogene Bcl-2, induction of cell apoptosis and inhibition of G to S phase cell cycle progress.

Antineoplastic Agents, Phytogenic↗

PubMed2006

[Effect of Scutellaria barbata extract against human hepatocellular Hep-G2 cell proliferation and its mechanism].

OBJECTIVE: To observe the effects of Scutellaria barbata extract (ESB) on human hepatoma cell line Hep-G2 proliferation in vitro and explore the mechanism. METHODS: The inhibitory effect of ESB on Hep-G2 proliferation was estimated by MTT assay, and the morphological changes of the cells were observed under optical and electron microscopes. Distribution of cell cycle, cell apoptosis and the protein expressions of apoptosis-associated genes as bcl-2, bax and fas were analyzed using flow cytometry. RESULTS: ESB inhibited the proliferation of Hep-G2 cells in a time- and dose-dependent manner. ESB treatment for 72 h resulted in changes of early apoptotic morphology of the cells as observed under optical and the transmission electron microscopes and increased cell apoptosis. Cell cycle analysis revealed decreased S-phase and increased G0/G1-phase cells. Fas expression was significantly up-regulated in response to ESB treatment whereas Bcl-2 and Bax expressions underwent no significant changes. CONCLUSION: ESB can inhibit Hep-G2 cell proliferation, induce cell cycle block, and increase cell apoptosis, which may relate to the activation of FNFR superfamily.

Antineoplastic Agents, Phytogenic↗

PubMed2006

[SCT-OGP fusion protein expression and its potential role as osteoporosis therapy].

Osteoporosis is a disease of bone metabolic disorder, the incidence of which increases sharply in old people. Calcitonin (CT) is a peptide hormone containing 32 amino acid that can inhibit osteoclasts activity. Osteogenic Growth Peptide (OGP) is a peptide hormone with 14 amino acid. It is an autocrine mitogen for osteoblastic and firbroblastic cells which has anabolic activiy. Six SCT and OGP DNA segments were chemically synthesized and ligated into a yeast expression vector pPIC9. The recombinant plasmid was transformed into pichia pastoris GS115. Finally, we got two stable SCT-OGP high expression clones after screening. Purifed protein can stimulate the proliferation of osteoblastic and fibroblastic cells, and also stimulate serum ALP activity and decrease serum calcium level using mice as animal models, demonstrating its potential role in oteoporosis therapy.

Animals↗

PubMed2006

[Study on the selection of crude drugs of rhubarb dispensing granule].

OBJECTIVE: To research and choose the best crude drugs of Rhubarb dispensing granule. METHODS: According to standard method from the eighth edition of China pharmacopoeia, determined and compared the contents of TLC, water, total ash, acid insoluble ash, extractives, total anthraquinones, rhein, emodin and chrysophanol of Rhubarb in diffrent producing areas and species. RESULTS: The Contents of Rheum palmatum from Rhubarb GAP base in Ganzhi state were higher than others and the drug yield was large. CONCLUSION: This species are chosen to be the crude drugs for Rhubarb dispensing granule. The preliminary study provides the scientific grounds for next study about establishment of quality criteria.

Anthraquinones↗

PubMed2006

Fenofibrate inhibits tumor necrosis factor-alpha-induced expression of CD40 and matrix metalloproteinase in human vascular endothelial cells.

OBJECTIVE: To investigate the regulatory effects of fenofibrate on TNF-alpha-induced CD40 expression and matrix metalloproteinase (MMP) activity in human vascular endothelial cells (HUVECs). METHODS: Quantitative RT-PCR and flow cytometry were employed to evaluate the effect of fenofibrate on TNF-alpha-induced CD40 mRNA and cell surface CD40 expression in HUVECs, and gelatin zymography was used to determine the effect of fenofibrate on the gelatinolytic activities of MMP-2 and MMP-9 in TNF-alpha-stimulated HUVECs. RESULTS: Fenofibrate at the concentrations of 5x10(-5), 1x10(-4) and 2x10(-4) mol/L significantly reduced TNF-alpha-induced increment of CD40 mRNA and cell surface CD40 expressions (P<0.01), with the maximal inhibition achieved at the concentration of 1x10(-4) mol/L. Fenofibrate at 2x10(-4) mol/L did not further decrease CD40 expression induced by TNF-alpha. Fenofibrate significantly inhibited the stimulatory effect of TNF-alpha on MMP-2 and MMP-9 activities in HUVECs. CONCLUSION: Fenofibrate reduces TNF-alpha-induced increment of CD40 expression and MMP-2 and MMP-9 activities in HUVECs.

CD40 Antigens↗

PubMed2006

[Construction and functional study of a cell penetrating peptide-based expression vector for targeted delivery of proteins into the cell nuclei].

OBJECTIVE: To construct an cell penetrating peptide-based expression vector capable of targeted delivery of proteins into the cell nuclei and study its function of protein transduction. METHODS: The fusion protein expression vector pET14b-HC(L)NE (pET14-b-His-CPP-Linker-NLS-EGFP) incorporating cell penetrating peptide (CPP), nuclear localization signal(NLS), linker and enhanced green fluorescent protein (EGFP) was constructed based on His-tagged pET14b-HE (pET14b-His-EGFP) by site-directed mutagenesis PCR method. After identification by enzyme digestion and DNA sequencing, the recombinant plasmid was transformed into BL21(DE(3)) strain. The HC(L)NE fusion protein was expressed following IPTG induction and purified with Ni(2+)-NTA affinity chromatography. After dialysis and filtration, the HC(L)NE fusion protein was added into cultured eukaryotic cells. The protein transduction in the living cells was observed under fluorescence microscope and analyzed by Western blotting. RESULTS: Enzyme digestion and DNA sequencing confirmed successful construction of the pET14b-HC(L)NE vector, and the fusion protein efficiently expressed in E. coli. Protein transduction experiments in eukaryotic cells revealed that the fusion protein could rapidly penetrate the cell membrane and reach the cell nucleus, and this internalization was time- and concentration-dependent. CONCLUSION: The cell penetrating peptide-based expression vector for targeted protein delivery to the cell nucleus has been successfully constructed, and a transport system that can delivery exogenous proteins or polypeptides into the cytoplasm and cell nucleus is established, which provides an economical and efficient means for functional study of the proteins and polypeptide in cells and targeted drug delivery.

Animals↗

PubMed2006

[Analysis of cholesterol ester transfer protein gene Taq IB and -629 C/A polymorphisms in patients with endogenous hypertriglyceridemia in Chinese population].

OBJECTIVE: To investigate the variations of cholesterol ester transfer protein (CETP) gene and its relation to endogenous hypertriglyceridemia (HTG) in Chinese population. METHODS: One hundred and thirty-five endogenous hypertriglyceridemics and 214 healthy subjects from a population of Chinese Han nationality in Chengdu area were studied using restriction fragment length polymorphism (RFLPs) amplified by polymerase chain reaction (PCR). The polymorphic sites studied included Taq IB and -629 C/A polymorphism in CETP gene. RESULTS: The frequencies of B(2) allele at Taq IB site in normal group and HTG group were 0.418 and 0.382, respectively. The frequencies of A allele at -629 C/A site in the two groups were 0.479 and 0.489, respectively. No significant difference between normal control and HTG groups were found in both allele frequency of the two polymorphism. Linkage disequilibrium was observed between Taq IB and -629 C/A polymorphic sites (D'=0.881). In the normal control group, subjects with genotype B(2)B(2) of Taq IB site had a higher serum mean concentration of HDL-C and lower LDL-C when compared with that of genotype B(1)B(1) and B(1)B(2), respectively (both P< 0.05), while those with genotype CC of -629 C/A site had a lower LDL-C level and higher Apo A II level when compared with that of genotype AC (P< 0.01 and P< 0.05, respectively). The changes of the lipid and lipoprotein levels were only observed in normal male subjects when male and female groups were further separated. No significant changes of lipid and lipoprotein levels were observed in both polymorphism in HTG group. Combined genotype analysis of the two sites, subjects with genotype B(2)B(2)CC in normal controls had higher HDL-C levels but lower serum triglyceride (TG) when compared with B(1)B(1)CC. CONCLUSION: These results suggest that Taq IB and -629 C/A polymorphisms in CETP gene are associated with healthy control subjects to some extent in Chinese population, but not with endogenous hypertriglyleridemia in the population group.

Adult↗

PubMed2005

Effect of asymmetric distribution of phospholipids in ghost membrane from rat blood on peroxidation induced by ferrous ion.

This study used rat erythrocyte ghost membrane to investigate the effect of aminophospholipid distribution in biological membranes on oxidative susceptibility. Aminophospholipids, lipid peroxidation, and carbonyl compounds were quantified; plasma membrane structure was examined using atomic force microscopy (AFM) and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Inside-out vesicles (IOVs) had significantly more aminophospholipids and greater lipid peroxidation than right-side-out vesicles (ROVs). Spectrin bands in IOVs disappeared obviously than in ROVs as shown in SDS-PAGE. In both systems vesicle protein size increased significantly with oxidation. Proteins aggregated much more in IOVs than ROVs at 48 h. These observations suggest that IOVs were more susceptible to ferrous ion-induced peroxidation than ROVs and that asymmetric phospholipid distribution affects biomembranes' oxidative susceptibility.

Animals↗

PubMed2005

Spectrophotometric study of fluorescence sensing and selective binding of biochemical substrates by 2,2'-bridged bis(beta-cyclodextrin) and its water-soluble fullerene conjugate.

A bis(beta-cyclodextrin)-fullerene conjugate (3) linked at the secondary hydroxyl side was prepared in a good yield from its precursor N,N'-bis(2-(2-aminoethylamino)ethyl)malonamide-bridged bis(beta-cyclodextrin) (2). Spectrophotomeric studies on the conformation and the inclusion complexation behavior of 3 with a variety of organic and biochemical substrates by means of UV-vis, FT-IR, NMR, fluorescence, and circular dichroism spectroscopy showed that the bis(beta-cyclodextrin)-fullerene conjugate displayed an intramolecular capsule-type conformation in aqueous solution. Because of the multiple binding of bis(beta-cyclodextrin) with substrates, 2 can act as an efficient fluorescence sensor for biochemical substrates, while its fullerene conjugate 3 displays a capability of cleaving DNA under visible-light irradiation.

Benzyl Compounds↗

PubMed2005

Synthesis and structure of cycloruthenated carbonyl complexes and their emission, redox and biological properties.

An interesting series of mononuclear organoruthenium complexes of formulation [Ru(CO)(PPh3)2(ap-R)] (where ap-R = -H, -Cl, -Me, -OMe, -OEt) have been synthesized from the reaction of five 2-(arylazo)phenol ligands with ruthenium(II) precursor [RuH(Cl)(CO)(PPh3)3] in benzene under reflux. The 2-(arylazo)phenolate ligands behave as dianionic tridentate ligand and are coordinated to ruthenium through C, N and O by dissociation of the phenolic and phenyl proton at the ortho position of the phenyl ring forming two five-membered chelate rings. These complexes have been characterized by elemental analysis, FT-IR, 1H NMR and UV-visible spectroscopy. In dichloromethane solution all the metal complexes exhibit characteristic metal-to-ligand charge transfer (MLCT) absorption and emission bands in the visible region. The structures of [Ru(CO)(PPh3)2(ap-H)] and [Ru(CO)(PPh3)2(ap-Cl)] have been determined by X-ray crystallography. Cyclic voltammetric data of all the complexes show a Ru(III)/Ru(II) oxidation and reduction Ru(II)/Ru(I) within the range 0.74-0.84 V and -0.38 to -0.50 V vs saturated calomel electrode (SCE) respectively. The potentials are observed with respect to the electronic nature of substituents (R) in the 2-(arylazo)phenolate ligands. Further, the free ligands and their ruthenium complexes have also been screened for their antibacterial and antifungal activities, which have shown great promise in inhibiting the growth of both gram +ve and gram -ve bacteria Staphylococcus aureus and Escherichia coli and fungus Candida albicans and Aspergillus niger. These results made it desirable to delineate a comparison between free ligands and their complexes.

Anti-Infective Agents↗

PubMed2005

Aerobic granulation for organic carbon and nitrogen removal in alternating aerobic-anaerobic sequencing batch reactor.

Microbial granules with excellent settle-ability were successfully developed at different ammonium-N loadings in four sequencing batch reactors run under alternating aerobic-anaerobic conditions. Results showed that heterotrophic, nitrifying and denitrifying populations could co-exist in the microbial granules. The activity of denitrifying bacteria was highly determined by the availability of external carbon source in the anaerobic phase. Complete denitrification was achieved with supply of external carbon source, whereas only partial denitrification occurred with no addition of external carbon source. This study shows that microbial granules cultivated under the alternating aerobic-anaerobic condition could efficiently remove organic carbon and completely convert ammonia to nitrogen gas. A new generation of microbial granules-based bioreactor for organics and nitrogen removal can be envisaged.

Aerobiosis↗

PubMed2005

Diastereomeric molecular recognition and binding behavior of bile acids by L/D-tryptophan-modified beta-cyclodextrins.

[reaction: see text] Binding behavior of L- and D-tryptophan-modified beta-cyclodextrins (L/D-Trp-beta-CD) (1 and 2) with four bile acids, i.e., cholate (CA), deoxycholate (DCA), glycocholate (GCA), and taurocholate (TCA), has been investigated by fluorescence, circular dichroism, and 2D-NMR spectroscopies and fluorescence lifetime measurement, as well as isothermal titration microcalorimetry. From the induced circular dichroism (ICD) and 2D NMR spectra, it is deduced that the D-Trp moiety of 2 attached to beta-CD is more deeply self-included in the cavity than that of the antipodal L-Trp moiety of 1, indicating appreciably enantioselective binding of the chiral sidearm by beta-CD. Interestingly, the original difference in conformation between 1 and 2 led to quite a large difference in affinity toward DCA, giving 3.3 times higher binding ability for 2 than for 1. Thermodynamically, the inclusion complexation of 1 and 2 with bile acids was entirely driven by favorable enthalpy change (DeltaH degrees) with accompanying negative entropy change (DeltaS degrees). The stronger binding of bile acids by L/D-Trp-beta-CD is attributable to higher enthalpic gains. The combined use of the calorimetric and NMR ROESY spectral examinations revealed the correlation between the thermodynamic parameters and the role of sidearm conformation in modified beta-cyclodextrins.

Bile Acids and Salts↗

PubMed2005

Migration of intravenously grafted mesenchymal stem cells to injured heart in rats.

The present study aimed to determine the role of tissue injury in migration of mesenchymal stem cells (MSCs) intravenously transplanted into heart and to establish experimental basis for improving stem cell therapy in its targeting and effectiveness. MSCs were isolated from bone marrow of male Sprague-Dawley rats and purified by density centrifuge and adhered to the culture plate in vitro. Female rats were divided randomly into four groups. Myocardial ischemia (MI) transplanted group received MSCs infusion through tail vein 3 h after MI and compared with sham-operated group or normal group with MSCs infusion, or control group received culture medium infusion. MI was created in female rats by ligating the left anterior descending coronary artery. The heart was harvested 1 week and 8 weeks after transplantation. The characteristics of migration of MSCs to heart were detected with expression of sry gene of Y chromosome by using fluorescence in situ hybridization (FISH). Ultrastructural changes of the ischemic myocardium of the recipient rats were observed by transmission electron microscope (TEM). One week or 8 weeks after transplantation, sry positive cells were observed in the cardiac tissue in both of MI transplanted group and sham-operated group, the number of sry positive cells being significantly higher in MI transplanted group (P<0.01). No significant difference was found in the number of sry positive cells between 1 week and 8 weeks after transplantation. No sry positive cells were observed in the hearts of control and normal group. In addition, the ultrastructure of some cells located in the peri-infarct area of MI rats with MSCs transplantation was similar to that of MSCs cultured in vitro. These results indicate that MSCs are capable of migrating towards ischemic myocardium in vivo and the fastigium of migration might appear around 1 week after MI. The tissue injury and its degree play an important role in the migration of MSCs.

Animals↗

PubMed2005

The oncoprotein gankyrin negatively regulates both p53 and RB by enhancing proteasomal degradation.

Ubiquitin-dependent proteolysis mediates selective destruction of various cell cycle regulators, transcription factors and tumor suppressors. Gankyrin, a seven ankyrin-repeat protein, was originally identified as an oncoprotein commonly overexpressed in hepatocellular carcinomas and independently as a protein associated with the 19S regulatory complex of the 26S proteasome. Gankyrin also binds to CDK4 and the tumor suppressor RB, and accelerates phosphorylation and proteasomal degradation of RB. Recently, we have shown that gankyrin has an anti-apoptotic activity in cells exposed to DNA-damaging agents. Gankyrin binds to MDM2, a major E3 ubiquitin ligase for p53, and increases ubiquitylation and degradation of p53. Gankyrin increases activities of CDK4 and MDM2, and facilitates targeting of polyubiquitylated proteins to the 26S proteasome. Furthermore, inhibition of gankyrin induces apoptosis in cancer cells. Therefore, gankyrin is a promising target for potential anticancer therapeutic agents.

Animals↗

PubMed2005

Low temperature protects mammalian cells from apoptosis initiated by various stimuli in vitro.

Mild hypothermia shows protective effects on patients with brain damage and cardiac arrest. To elucidate the molecular mechanisms underlying these effects, we examined the effects of low temperature (32 degrees C) on cells exposed to a variety of stress in vitro. We found that 32 degrees C suppressed induction of apoptosis by cytotoxic stimuli such as adriamycin, etoposide, thapsigargin, NaCl, H(2)O(2), and anti-Fas antibody. In adriamycin-treated BALB/3T3 cells, the down-shift in temperature from 37 degrees C to 32 degrees C increased the Bcl-xL protein level and decreased the mRNA level of Puma and mitochondrial translocation of Bax, suppressing caspase-9-mediated apoptosis. Furthermore, the protein level and stability of p53 were decreased, and its nuclear export was increased concomitant with Mdm2 mRNA upregulation. The low temperature effect was not observed in p53(-/-)/Mdm2(-/-) mouse embryonic fibroblasts, suggesting that the effect is mediated by suppression of the p53 pathway. In contrast, while thapsigargin-induced apoptosis was suppressed by the low temperature, no effect on the p53 protein level was observed. Furthermore, the survival rate of p53(-/-)/Mdm2(-/-) cells exposed to thapsigargin was increased when cultured at 32 degrees C compared with 37 degrees C. In conclusion, mild hypothermia protects cells from a variety of stress by p53-dependent and p53-independent mechanisms.

Animals↗

PubMed2005

Investigation on the mechanism of crystallization of soluble protein in the presence of nonionic surfactant.

The mechanism of crystallization of soluble, globular protein (lysozyme) in the presence of nonionic surfactant C8E4 (tetraoxyethylene glycol monooctyl ether) was examined using both static and dynamic light scattering. The interprotein interaction was found to be attractive in solution conditions that yielded crystals and repulsive in the noncrystallizing solution conditions. The validity of the second virial coefficient as a criterion for predicting protein crystallization could be established even in the presence of nonionic surfactants. Our experiments indicate that the origin of the change in interactions can be attributed to the adsorption of nonionic surfactant monomers on soluble proteins, which is generally assumed to be the case with only membrane proteins. This adsorption screens the hydrophobic attractive force and enhances the hydration and electrostatic repulsive forces between protein molecules. Thus at low surfactant concentration, the effective protein-protein interaction remains repulsive. Large surfactant concentrations promote protein crystallization, possibly due to the attractive depletion force caused by the intervening free surfactant micelles.

Binding Sites↗

PubMed2005

Functional recovery after rhesus monkey spinal cord injury by transplantation of bone marrow mesenchymal-stem cell-derived neurons.

BACKGROUND: The treatment of spinal cord injury is still a challenge. This study aimed at evaluating the therapeutical effectiveness of neurons derived form mesenchymal stem cells (MSCs) for spinal cord injury. METHODS: In this study, rhesus MSCs were isolated and induced by cryptotanshinone in vitro and then a process of RT-PCR was used to detect the expression of glutamic acid decarboxylase (GAD) gene. The induced MSCs were tagged with Hoechst 33342 and injected into the injury site of rhesus spinal cord made by the modified Allen method. Following that, behavior analysis was made after 1 week, 1 month, 2 months and 3 months. After 3 months, true blue chloride retrograde tracing study was also used to evaluate the re-establishment of axons pathway and the hematoxylin-eosin (HE) staining and immunohistochemistry were performed after the animals had been killed. RESULTS: In this study, the expression of mRNA of GAD gene could be found in the induced MSCs but not in primitive MSCs and immunohistochemistry could also confirm that rhesus MSCs could be induced and differentiated into neurons. Behavior analysis showed that the experimental animals restored the function of spinal cord up to grade 2-3 of Tarlov classification. Retrograde tracing study showed that true blue chollide could be found in the rostral thoracic spinal cords, red nucleus and sensory-motor cortex. CONCLUSIONS: These results suggest that the transplantation is safe and effective.

Animals↗