Biomedical subjects

Qingyu Wu

Publications and source records attributed to Qingyu Wu.

At least 19 recordsLinked to original sources

PubMed2006

Protective effects of mycosporine-like amino acids of Synechocystis sp. PCC 6803 and their partial characterization.

In this work, mycosporine-like amino acids (MAAs) of Synechocystis sp. PCC 6803 were characterized and were investigated on UV induction and protective ability. High performance liquid chromatographic (HPLC) studies revealed three major compounds in the MAAs. By UV absorption and mass spectra analysis, one of the compounds was tentatively identified as mycosporine-tau (M-tau). One novel compound similar to usujirene was tentatively named as dehydroxylusujirene, and the other novel compound was named as M-343 according to its absorption maximum. In vivo experiments indicated that M-tau was induced by both UV-A and UV-B, while dehydroxylusujirene and M-343 were only induced by UV-A, suggesting that different chromophores were involved in MAAs synthesis in Synechocystis sp. PCC 6803. It was also indicated that M-343 could be photochemically synthesized from some precursors. Under both UV and oxidation stresses, M-343 was more stable than dehydroxylusujirene and M-tau. Considering the reaction with H2O2, M-tau and dehydroxylusujirene might be potential antioxidants in reaction with physiological reactive oxygen species in vivo. In protection experiments, the MAAs exhibited efficient protective ability towards UV-B and H2O2 stresses, with maximal protection rates of 30% and 21.5%, respectively. These results indicate that the MAAs in Synechocystis sp. PCC 6803 act as both UV-screen and antioxidant.

Amino Acids↗

PubMed2006

High quality biodiesel production from a microalga Chlorella protothecoides by heterotrophic growth in fermenters.

The aim of the study was to obtain high quality biodiesel production from a microalga Chlorella protothecoids through the technology of transesterification. The technique of metabolic controlling through heterotrophic growth of C. protothecoides was applied, and the heterotrophic C. protothecoides contained the crude lipid content of 55.2%. To increase the biomass and reduce the cost of alga, corn powder hydrolysate instead of glucose was used as organic carbon source in heterotrophic culture medium in fermenters. The result showed that cell density significantly increased under the heterotrophic condition, and the highest cell concentration reached 15.5 g L(-1). Large amount of microalgal oil was efficiently extracted from the heterotrophic cells by using n-hexane, and then transmuted into biodiesel by acidic transesterification. The biodiesel was characterized by a high heating value of 41 MJ kg(-1), a density of 0.864 kg L(-1), and a viscosity of 5.2 x 10(-4) Pa s (at 40 degrees C). The method has great potential in the industrial production of liquid fuel from microalga.

Biomass↗

PubMed2006

Sorbitol regulates energy transfer from allophycocyanin to the terminal emitter within phycobilisomes in Synechocystis sp.

The effects of sorbitol on energy transfer of phycobilisomes (PBSs) in vivo were investigated in a chlN deletion mutant of Synechocystis sp. PCC 6803. When the mutant was grown in the dark, it contained intact and functional PBSs but essentially no chlorophyll or photosystems. Therefore, the structural and functional changes of the mutant PBSs in vivo can be detected by measurement of low temperature (77 K) and room temperature fluorescence emission spectra. Our results, for the first time, demonstrate that sorbitol decreases the energy transfer from allophycocyanin to the terminal emitter, indicating the site for osmotic regulation of excitation transfer in PBSs.

Chlorophyll↗

PubMed2006

Perivenous application of fibrin glue as external support enhanced adventitial adenovirus transfection in rabbit model.

BACKGROUND: Placement of an external support has been reported to prevent intimal hyperplasia of vein grafts. However, it's application limited by potential complications. Peri-adventitial gene delivery is a promising alternative therapy to reduce intimal hyperplasia, but it is limited by low and transient levels of gene transfection. To get more effective inhibition of intimal hyperplasia and to avoid the limitations associated with these two approaches, a study was undertaken to investigate whether mixing adenovirus with fibrin glue may increase the level and prolong the time period of gene expression. METHODS: Right jugular vein to common carotid artery interposition grafting was performed in 36 male New Zealand white rabbits (2.5-3.0 kg) and the animals were divided into four groups: control group (n = 6); fibrin glue group (n = 6); Ad-GAL group (n = 12); fibrin glue/Ad-GAL group (n = 12). Commercially available fibrin glue and adenovirus expressing the gene for beta-galactosidase (Ad-GAL) was applied separately or in mixing around vein grafts. At 7th day and 14th day after implantation, the grafts were harvested to evaluate transfection rate. At 28th day the grafts were harvested for morphometric analysis. RESULTS: Compared with weak staining in 2.1 +/- 0.5% in Ad-GAL alone grafts, a high level of beta-Galactosidase staining was evident in 13.2 +/- 4.6% in fibrin glue/Ad-GAL grafts at 7th day (P < 0.001). At 14th day, almost no staining (0%) was detected in Ad-GAL alone grafts. However, there was still a relative high level staining (6.3 +/- 3.8%) in fibrin glue/Ad-GAL grafts (P < 0.001 versus Ad-GAL alone group). At 28th day, a statistically significantly decrease in neointimal area (0.68 +/- 0.06 mm(2)versus 1.00 +/- 0.08 mm(2), P < 0.05) was shown in fibrin glue grafts compared with unsupported vein grafts (control group). The same statistically significantly difference was also existed in fibrin glue/Ad-GAL group and unsupported group in neointimal area (0.66 +/- 0.07 mm(2), P < 0.05). CONCLUSIONS: A novel method of adventitial gene delivery using fibrin glue as external support is proposed. Fibrin glue may be an ideal candidate for controlled release delivery that would facilitate adventitial gene transfer.

Adenoviridae↗

PubMed2006

Antibodies neutralizing hepsin protease activity do not impact cell growth but inhibit invasion of prostate and ovarian tumor cells in culture.

Hepsin is a type II transmembrane serine protease that is expressed in normal liver, and at lower levels in kidney, pancreas, and testis. Several studies have shown that hepsin mRNA is significantly elevated in most prostate tumors, as well as a significant fraction of ovarian and renal cell carcinomas and hepatomas. Although the overexpression of mRNA in these tumors has been extensively documented, there has been conflicting literature on whether hepsin plays a role in tumor cell growth and progression. Early literature implied a role for hepsin in human tumor cell proliferation, whereas recent studies with a transgenic mouse model for prostate cancer support a role for hepsin in tumor progression and metastases. To evaluate this issue further, we have expressed an activatable form of hepsin, and have generated a set of monoclonal antibodies that neutralize enzyme activity. The neutralizing antibodies inhibit hepsin enzymatic activity in biochemical and cell-based assays. Selected neutralizing and nonneutralizing antibodies were used in cell-based assays with tumor cells to evaluate the effect of antibodies on tumor cell growth and invasion. Neutralizing antibodies failed to inhibit the growth of prostate, ovarian, and hepatoma cell lines in culture. However, potent inhibitory effects of the antibodies were seen on invasion of ovarian and prostate cells in transwell-based invasion assays. These results support a role for hepsin in tumor cell progression but not in primary tumor growth. Consistent with this, immunohistochemical experiments with a mouse monoclonal antibody reveal progressively increased staining of prostate tumors with advanced disease, and in particular, extensive staining of bone metastatic lesions.

Amino Acid Sequence↗

PubMed2005

Corin gene minor allele defined by 2 missense mutations is common in blacks and associated with high blood pressure and hypertension.

BACKGROUND: The natriuretic peptide system contributes to blood pressure regulation. Atrial and brain natriuretic peptides are cleaved into smaller biologically active molecules by corin, a transmembrane serine protease expressed in cardiomyocytes. METHOD AND RESULTS: This genotype-phenotype genetic association study included replication samples and genomic control to correct for population stratification. Sequencing of the human corin gene identified 2 nonsynonymous, nonconservative single nucleotide polymorphisms (Q568P and T555I) in near-complete linkage disequilibrium, thus describing a single minor I555 (P568) corin gene allele. This allele was present in the heterozygote state in &12% of blacks but was extremely rare in whites (<0.5% were homozygous for the minor allele). In our primary population sample, the Dallas Heart Study, after adjustment for potential confounders, including population stratification, the corin I555 (P568) allele remained independently associated with increased risk for prevalent hypertension (odds ratio, 1.63; 95% CI, 1.11 to 2.38; P=0.013). The corin I555 (P568) allele also was associated with higher systolic blood pressure in subjects not using antihypertensive medication in unadjusted (133.7+/-20.7 versus 129.4+/-17.4 mm Hg; P=0.029) and adjusted (132.5+/-1.6 versus 128.9+/-0.6 mm Hg; P=0.029) analyses. The independent association of the minor corin allele with increased risk for prevalent hypertension was confirmed in the Multi-Ethnic Study of Atherosclerosis (odds ratio, 1.50; 95% CI, 1.09 to 2.06; P=0.014). In addition, the association of the minor corin I555 (P568) allele with higher systolic blood pressure was confirmed in adjusted analysis in the Chicago Genetics of Hypertension Study (125.8+/-1.9 versus 121.4+/-0.7 mm Hg; P=0.03). CONCLUSIONS: The corin I555 (P568) allele is common in blacks and is associated with higher blood pressure and an increased risk for prevalent hypertension.

Adult↗

PubMed2005

Serine proteases and cardiac function.

The serine proteases of the trypsin superfamily are versatile enzymes involved in a variety of biological processes. In the cardiovascular system, the importance of these enzymes in blood coagulation, platelet activation, fibrinolysis, and thrombosis has been well established. Recent studies have shown that trypin-like serine proteases are also important in maintaining cardiac function and contribute to heart-related disease processes. In this review, we describe the biological function of corin, tissue kallikrein, chymase and urokinase and discuss their roles in cardiovascular diseases such as hypertension, cardiac hypertrophy, heart failure, and aneurysm.

Animals↗

PubMed2005

Biodiesel production from heterotrophic microalgal oil.

The present study introduced an integrated method for the production of biodiesel from microalgal oil. Heterotrophic growth of Chlorella protothecoides resulted in the accumulation of high lipid content (55%) in cells. Large amount of microalgal oil was efficiently extracted from these heterotrophic cells by using n-hexane. Biodiesel comparable to conventional diesel was obtained from heterotrophic microalgal oil by acidic transesterification. The best process combination was 100% catalyst quantity (based on oil weight) with 56:1 molar ratio of methanol to oil at temperature of 30 degrees C, which reduced product specific gravity from an initial value of 0.912 to a final value of 0.8637 in about 4h of reaction time. The results suggested that the new process, which combined bioengineering and transesterification, was a feasible and effective method for the production of high quality biodiesel from microalgal oil.

Biotechnology↗

PubMed2005

Expression and oxidative stress tolerance studies of glutaredoxin from cyanobacterium Synechocystis sp. PCC 6803 in Escherichia coli.

Glutaredoxin (Grx), which has been found widely in bacteria, plant, and mammalian cells, is an electron carrier for ribonucleotide reductase and a general glutathione-disulfide reductase of importance for redox regulation. The open reading frame designated ssr2061 from cyanobacterium Synechocystis sp. PCC 6803 was found as a homologous gene coding for Grx. The amino acid sequence deduced from ssr2061 shares high identity with that of Grxs from other organisms. In the present study, the protein of Grx2061 encoded by ssr2061 was successfully overexpressed as soluble fraction in Escherichia coli BL21 (DE3). The recombinant protein was purified to near homogenity by two steps involving immobilized metal affinity chromatography and gel filtration chromatography with a yield of 22% and a specific activity of 41.5 micromol NADPH oxidized per milligram of protein in the 2-hydroxyethyl disulfide assay. The pET-2061 transformed Escherichia coli cells showed higher Grx activity and tolerance to H(2)O(2) mediated growth inhibition compared to cells transformed with the vector alone. This suggests that overexpression of Grx from Synechocystis sp. PCC 6803 may provide protection to E. coli cells against oxidative stress mediated by H(2)O(2).

Adaptation, Physiological↗

PubMed2005

Hypertension in mice lacking the proatrial natriuretic peptide convertase corin.

Atrial natriuretic peptide (ANP) is a cardiac hormone that regulates blood pressure. In cardiomyocytes, the hormone is synthesized as a precursor, proatrial natriuretic peptide (pro-ANP), which is proteolytically converted to active ANP. Corin is a cardiac transmembrane serine protease that has been shown to process pro-ANP in vitro, but its physiological importance had not been established. Here, we show that corin-deficient (Cor-/-) mice develop normally during embryogenesis and survive to postnatal life. Cor-/- mice have elevated levels of pro-ANP but no detectable levels of ANP as compared with WT littermates. Infusion of an active recombinant soluble corin transiently restores pro-ANP conversion, resulting in the release of circulating biologically active ANP. Using radiotelemetry to assess blood pressure, we find that Cor-/- mice have spontaneous hypertension as compared with WT mice, and it is enhanced after dietary salt loading. Pregnant Cor-/- mice demonstrate late-gestation proteinuria and enhanced high blood pressure during pregnancy. In addition, Cor-/- mice exhibit cardiac hypertrophy resulting in a mild decline in cardiac function later in life. Thus, our data establish corin as the physiological pro-ANP convertase and indicate that corin deficiency may contribute to hypertensive heart disease.

Animals↗

PubMed2005

Single gene retrieval from thermally degraded DNA.

To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen (especially heat) are both crucial factors influencing DNA degradation. The heat influence, mainly represented by temperature and heating time, affects the DNA degradation via DNA depurination followed by cleavage of nearby phosphodiesters. The heating time influence is temperature-dependent. By reactive oxygen species (ROS) scavenging and 1,3-diphenyl-isobenzofuran (DPBF) bleaching experiments the influence of oxygen on DNA thermal degradation was shown to occur via a singlet oxygen pathway. A comparative study of the thermal degradation of cellular DNA and isolated DNA showed that cellular lipids can aggravate DNA thermal degradation. These results confirm the possibility of gene amplification from thermally degraded DNA. They can be used to evaluate the feasibility of the retrieval of single gene from ancient remains.

Air↗

PubMed2005

In vitro DNA-binding properties of a manganese response regulator (ManR) from Anabaena sp.

ManR of Anabaena sp. PCC 7120 is a manganese response regulator. Two ManR molecules bind to the specific DNA sequences at the same time, which was demonstrated by our previous results. From size exclusion chromatography, ManR exits as monomer in solution. Therefore, cooperative interactions of ManR-ManR play a role in DNA binding of the ManR, suggesting that ManR molecules bind co-operatively to DNA. When serial deletions of N-terminal of the ManR were also carried out the mutant proteins, ManRC111, ManRC130 and ManRC158, had completely lost the in DNA binding activity. Mutants ManRC 196, ManRC206, ManRC221 and ManRC230, however, could specifically bind to DNA, indicating that the amino acid residues between Val16 and Ile78 of the N-terminal of ManR are necessary for the DNA binding activity of C-terminal domain.

Amino Acid Substitution↗

PubMed2005

Surgical treatment of giant coronary artery aneurysm.

OBJECTIVE: Giant coronary artery aneurysm is an extremely uncommon disease. Most previous reports have involved only single cases. This report describes 6 patients with giant coronary artery aneurysm, examines its causes, and aims to establish the optimal surgical strategies for this exceptional and rare pathology. METHODS: From July 1996 to October 2004, a total of 30,268 patients underwent heart surgery at Fuwai Hospital in Beijing. Among these, 6 patients had giant coronary artery aneurysm diagnosed and underwent operation. Various surgical strategies were used for the operations of these 6 patients, such as coronary artery aneurysm resection, coronary artery reconstruction, and concomitant coronary bypass. Additional procedures, such as fistula closure, aortic valve replacement, aortoplasty, and embolectomy, were done at same time for the patients with complications of coronary fistula, aortic valve insufficiency, or thrombus. Patients were followed up from 8 to 87 months, with a mean of 48 months. Doppler echocardiography, ultrafast computed tomography, and 3-dimensional aerial image studies were performed during follow-up. RESULTS: Five of these six cases were found combined with coronary artery fistula, and the cause for these giant coronary artery aneurysms was congenital. The remaining case was caused by atherosclerosis. After surgery, all patients recovered uneventfully, without in-hospital mortality. None died during the follow-up, nor did any have recurrence of the symptoms or giant coronary artery aneurysm. CONCLUSION: Giant coronary artery aneurysm is a rare entity that is commonly caused by congenital malformation and combined with other cardiac anomalies. An optimal surgical operation should be based on the specific cardiac anomaly of the individual patient.

Adult↗

PubMed2005

Purification and characterization of two small heat shock proteins from Anabaena sp. PCC 7120.

Two small heat shock proteins (sHsps), Hsp17.8 and Hsp17.1, were identified in the cyanobacterium Anabaena sp. PCC 7120. Recombinant Hsp17.8 and Hsp17.1 were overexpressed in Escherichia coli and characterized here. Hsp17.8 was purified by sequential chromatography on DEAE-Sepharose and Superose 6 10/300 column, and Hsp17.1 was purified by Superose 6 10/300 column in 4M urea. Size exclusion chromatography demonstrated that both purified proteins form large oligomers approximately 420kDa and 410kDa, respectively. Both Hsp17.8 and Hsp17.1 showed chaperone-like activity to protect citrate synthase (CS) from thermal aggregation at 43 degrees C. Furthermore, both proteins were found to form complexes with denatured CS at 45 degrees C. Our study also demonstrated that despite a high degree of sequence homology and similar subunit size, Hsp17.1 showed higher hydrophobicity indicated by 8-anilino-1-naphthalene sulfonate fluorescence and thus greater chaperone-like activity. This is the first report of characterization and comparison of an sHsp system containing two chaperones in cyanobacteria.

Anabaena↗

PubMed2004

Characterization of a small molecule PAI-1 inhibitor, ZK4044.

Plasminogen activator inhibitor-1 (PAI-1) is a key negative regulator of the fibrinolytic system. In animal studies, inhibition of PAI-1 activity prevents arterial and venous thrombosis, indicating that PAI-1 inhibitors may be used as a new class of antithrombotics. In this study, we characterize a small molecule PAI-1 inhibitor, ZK4044, which was identified by high throughput screening and chemically optimized. In a chromogenic substrate-based urokinse (uPA)/PAI-1 assay and a tissue-type plasminogen activator (tPA)-mediated clot lysis assay, ZK4044 inhibited human PAI-1 activity with IC50 values of 644+/-255 and 100+/-90 nM, respectively. ZK4044 had no detectable inhibitory activity toward other serpins such as antithrombin III, alpha1-antitrypsin and alpha2-antiplasmin, indicating that ZK4044 is a specific PAI-1 inhibitor. ZK4044 was shown to bind directly to PAI-1 and prevent the binding of PAI-1 to tPA in a dose-dependent manner in surface plasmon resonance Biacore-based experiments. ZK4044 also prevented PAI-1/tPA complex formation, as analyzed by SDS/PAGE. ZK4044 had little effect on elastase-mediated cleavage of active PAI-1, indicating that the primary mode of action of ZK4044 is most likely to directly block the PAI-1/tPA interaction rather than to convert active PAI-1 to latent PAI-1. In the chromogenic substrate-based uPA/PAI-1 assay, ZK4044 was approximately 2-fold less potent against a mutant PAI-1 (14B-1), which contains four mutations at N150H, K154T, Q319L and M354I, compared with wild-type PAI-1, suggesting that the ZK4044 binding site on the surface of PAI-1 is close to these mutant residues. Together, our data show that ZK4044 represents a new class of small molecule PAI-1 inhibitors with anti-thrombotic potential.

Aniline Compounds↗

PubMed2004

Identification of domain structures in the propeptide of corin essential for the processing of proatrial natriuretic peptide.

Corin is a type II transmembrane serine protease and functions as the proatrial natriuretic peptide (pro-ANP) convertase in the heart. In the extracellular region of corin, there are two frizzled-like cysteine-rich domains, eight low density lipoprotein receptor (LDLR) repeats, a macrophage scavenger receptor-like domain, and a trypsin-like protease domain at the C terminus. To examine the functional importance of the domain structures in the propeptide of corin for pro-ANP processing, we constructed a soluble corin, EKshortCorin, that consists of only the protease domain and contains an enterokinase (EK) recognition sequence at the conserved activation cleavage site. After being activated by EK, EKshortCorin exhibited catalytic activity toward chromogenic substrates but failed to cleave pro-ANP, indicating that certain domain structures in the propeptide are required for pro-ANP processing. We then constructed a series of corin deletion mutants and studied their functions in pro-ANP processing. Compared with that of the full-length corin, a corin mutant lacking frizzled 1 domain exhibited approximately 40% activity, whereas corin mutants lacking single LDLR repeat 1, 2, 3, or 4 had approximately 49, approximately 12, approximately 53, and approximately 77% activity, respectively. We also made corin mutants with a single mutation at a conserved Asp residue that coordinates Ca(2+)-binding in LDLR repeats 1, 2, 3, or 4 (D300Y, D336Y, D373Y, and D410Y) and showed that these mutants had approximately 25, approximately 11, approximately 16, and approximately 82% pro-ANP processing activity, respectively. Our results indicate that frizzled 1 domain and LDLR repeats 1-4 are important structural elements for corin to recognize its physiological substrate, pro-ANP.

Amino Acid Sequence↗

PubMed2004

Upregulation of corin gene expression in hypertrophic cardiomyocytes and failing myocardium.

High levels of plasma atrial natriuretic peptides (ANP) are associated with pathological conditions such as congestive heart failure (CHF). Recently, we have identified a cardiac serine protease, corin, that is the pro-ANP convertase. In this study, we examined the regulation of corin gene expression in cultured hypertrophic cardiomyocytes and in the left ventricular (LV) myocardium of a rat model of heart failure. Quantitative RT-PCR analysis showed that both corin and ANP mRNA levels were significantly increased in phenylephrine (PE)-stimulated rat neonatal cardiomyocytes in culture. The increase in corin mRNA correlated closely with the increase in cell size and ANP mRNA expression in the PE-treated cells (r = 0.95, P < 0.01; r = 0.92, P < 0.01, respectively). The PE-treated cardiomyocytes had an increased activity in converting recombinant human pro-ANP to biologically active ANP, as determined by a pro-ANP processing assay and a cell-based cGMP assay. In a rat model of heart failure induced by ligation of the left coronary artery, corin mRNA expression in the noninfarcted LV myocardium was significantly higher than that of control heart tissues from sham-operated animals, when examined by Northern blot analysis and RT-PCR at 8 wk. These results indicate that the corin gene is upregulated in hypertrophic cardiomyocytes and failing myocardium. Increased corin expression may contribute to elevation of ANP in the setting of cardiac hypertrophy and heart failure.

Animals↗

PubMed2004

High yield bio-oil production from fast pyrolysis by metabolic controlling of Chlorella protothecoides.

The use of renewable energy sources is becoming increasingly necessary to mitigate global warming. Recently much research has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuels. This paper reports an approach for increasing the yield of bio-oil production from fast pyrolysis after manipulating the metabolic pathway in microalgae through heterotrophic growth. The yield of bio-oil (57.9%) produced from heterotrophic Chlorella protothecoides cells was 3.4 times higher than from autotrophic cells by fast pyrolysis. The bio-oil was characterized by a much lower oxygen content, with a higher heating value (41 MJ kg(-1)), a lower density (0.92 kg l(-1)), and lower viscosity (0.02 Pas) compared to those of bio-oil from autotrophic cells and wood. These properties are comparable to fossil oil. The research could contribute to the creation of a system to produce energy from microalgae, and also could have great commercial potential for liquid fuel production.

Chlorella↗