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Biomedical subjects

Q Yu

Publications and source records attributed to Q Yu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evolution of hepatitis C virus genome in chronically infected patients receiving ribavirin monotherapy.

Recent results of clinical trials suggest that combination of interferon and ribavirin exhibits an enhanced antiviral effect in the treatment of chronic hepatitis C. To investigate the effect of ribavirin on hepatitis C virus (HCV) infection, we analysed the evolution of the genetic heterogeneity of HCV in relation to the anti-HCV humoral response in patients treated by ribavirin alone. The study population included 35 patients with liver biopsy proven chronic hepatitis C infected with HCV genotype 1. Among them, 26 were treated with ribavirin for at least 12 months and nine untreated patients served as a control group. Serum samples were analysed before and at 6 and 12 months of therapy. Three regions of the HCV genome, i.e. HVR1, a domain of NS5A including part of the interferon sensitivity determining region (ISDR), and a segment of NS5B, were amplified by RT-PCR using specific primers. The PCR products were then studied using single-strand conformation polymorphism (SSCP) analysis followed by either direct sequencing, or cloning and sequencing. In parallel, the humoral anti-E1 response was studied using an ELISA (Innotest HCV E1Ab, Innogenetics). The results of HCV genome analysis showed no significant effect on the amino acid sequence evolution of the HVR1, NS5A and NS5B regions of HCV. Analysis of a phylogenetic tree from the major quasispecies variants showed the absence of correlation with ribavirin response, and the absence of selection of viral strains during ribavirin treatment. A trend towards a decrease in the anti-E1 Ab response was also observed. Altogether these results suggest that ribavirin may not exhibit a direct antiviral effect, but may trigger a favourable response to interferon by modulating the immune response against HCV.

Amino Acid Sequence↗
PubMed2001

Direct binding of beta-arrestins to two distinct intracellular domains of the delta opioid receptor.

beta-Arrestins regulate opioid receptor-mediated signal transduction and play an important role in opiate-induced analgesia and tolerance/dependence. This study was carried out to measure the direct interaction between beta-arrestins and opioid receptor. Immunoprecipitation experiments demonstrated that beta-arrestin 1 physically interacts with delta opioid receptor (DOR) co-expressed in human embryonic kidney 293 cells in an agonist-enhanced manner and truncation of the carboxyl terminus of DOR partially impairs the interaction. In vitro data from glutathione-S-transferase pull-down assay showed that the carboxyl terminus (CT) and the third intracellular loop (I3L) of DOR are both capable of and either domain is sufficient for binding to beta-arrestin 1 and 2. Surface plasmon resonance determination further revealed that binding of CT and I3L of DOR to beta-arrestin is additive, suggesting these two domains bind at distinctly different sites on beta-arrestin without considerable spatial hindrance. This study demonstrated for the first time the direct binding of beta-arrestins to the two distinct domains, the carboxyl terminus and the third intracellular loop, of DOR.

Amino Acid Sequence↗
PubMed2001

Biosorption and desorption of cadmium(II) by biomass of Laminaria japonica.

Biosorption and desorption properties of cadmium(II) from aqueous solutions by the biomass of marine alga Laminaria japonica were investigated. Results indicated that the uptake capacities were solution pH dependent and a maximum uptake capacity of about 1.3 mmol g-1 (dry weight) was observed at pH 6. The adsorbed cadmium cannot be desorbed by distilled water, but it can be effectively recovered by using acidic or EDTA solutions. The equilibrium isotherms can be described well with the Langmuir adsorption equation. Biomass, pre-treated with calcium solution exhibited a higher (about 30%) uptake capacity and can be easily settled from aqueous solutions. Batch kinetics experiments indicated that more than 90% of the adsorption occurred within 20 minutes of agitation and equilibrium was reached within one hour. Fixed-bed experiments showed similar uptake capacities to those of batch results and sharp breakthrough curves were obtained. This study indicated that the biomass of L. japonica can be used as an efficient biosorbent for the removal and recovery of cadmium(II) from waste water streams.

Adsorption↗
PubMed2001

Negative incidence of Lyme disease-related Borrelia spp. in Alishan, Taiwan.

To investigate the prevalence of Lyme disease-related Borrelia species, wild rodents were captured around Yushan National Park and Alishan Forest Recreation Area Park in Taiwan 2,000 to 3,000 meters above sea level. Borrelia was not isolated from 67 small mammals of 7 species. Sera from rodents showed no positive reactivity against whole cell antigens of B. garinii, B. afzelii or B. valaisiana by ELISA. These results suggested that Lyme disease is not endemic to the Alishan area.

Animals↗
PubMed2001

Identification of critical elements in the tRNA acceptor stem and T(Psi)C loop necessary for human immunodeficiency virus type 1 infectivity.

A mutant human immunodeficiency virus type 1 (HIV-1) with a primer binding site (PBS) complementary to yeast tRNA(Phe) (psHIV-Phe), which relies on exogenous yeast tRNA(Phe) as reverse transcription primer, was used to investigate elements in the tRNA acceptor stem and T(Psi)C stem-loop required for the tRNA primer selection and use in HIV-1 replication. tRNA(Phe) mutants with two- or four-nucleotide deletions in the 3' end retained the capacity to complement replication of psHIV-Phe. tRNA(Phe) mutants with an extended 5' end had reduced capacity for complementation, which could be restored by extension of the 3' end of these tRNA(Phe) mutants with sequences complementary to the HIV-1 U5 region. Further analysis of mutations in the acceptor stem of tRNA(Phe) suggested that an intact acceptor stem RNA structure is important for complementation. Analysis of single-nucleotide changes in the T(Psi)C stem-loop of tRNA(Phe) revealed an unexpected, essential role of this region for rescue of psHIV-Phe.

Binding Sites↗
PubMed2001

Analysis of SM22alpha-deficient mice reveals unanticipated insights into smooth muscle cell differentiation and function.

SM22alpha is a 22-kDa smooth muscle cell (SMC) lineage-restricted protein that physically associates with cytoskeletal actin filament bundles in contractile SMCs. To examine the function of SM22alpha, gene targeting was used to generate SM22alpha-deficient (SM22(-/-LacZ)) mice. The gene targeting strategy employed resulted in insertion of the bacterial lacZ reporter gene at the SM22alpha initiation codon, permitting precise analysis of the temporal and spatial pattern of SM22alpha transcriptional activation in the developing mouse. Northern and Western blot analyses confirmed that the gene targeting strategy resulted in a null mutation. Histological analysis of SM22(+/-LacZ) embryos revealed detectable beta-galactosidase activity in the unturned embryonic day 8.0 embryo in the layer of cells surrounding the paired dorsal aortae concomitant with its expression in the primitive heart tube, cephalic mesenchyme, and yolk sac vasculature. Subsequently, during postnatal development, beta-galactosidase activity was observed exclusively in arterial, venous, and visceral SMCs. SM22alpha-deficient mice are viable and fertile. Their blood pressure and heart rate do not differ significantly from their control SM22alpha(+/-) and SM22alpha(+/+) littermates. The vasculature and SMC-containing tissues of SM22alpha-deficient mice develop normally and appear to be histologically and ultrastructurally similar to those of their control littermates. Taken together, these data demonstrate that SM22alpha is not required for basal homeostatic functions mediated by vascular and visceral SMCs in the developing mouse. These data also suggest that signaling pathways that regulate SMC specification and differentiation from local mesenchyme are activated earlier in the angiogenic program than previously recognized.

Animals↗
PubMed2001

The ASK1 gene regulates B function gene expression in cooperation with UFO and LEAFY in Arabidopsis.

The Arabidopsis floral regulatory genes APETALA3 (AP3) and PISTILLATA (PI) are required for the B function according to the ABC model for floral organ identity. AP3 and PI expression are positively regulated by the LEAFY (LFY) and UNUSUAL FLORAL ORGANS (UFO) genes. UFO encodes an F-box protein, and we have shown previously that UFO genetically interacts with the ASK1 gene encoding a SKP1 homologue; both the F-box containing protein and SKP1 are subunits of ubiquitin ligases. We show here that the ask1-1 mutation can enhance the floral phenotypes of weak lfy and ap3 mutants; therefore, like UFO, ASK1 also interacts with LFY and AP3 genetically. Furthermore, our results from RNA in situ hybridizations indicate that ASK1 regulates early AP3 and PI expression. These results support the idea that UFO and ASK1 together positively regulate AP3 and PI expression. We propose that the UFO and ASK1 proteins are components of a ubiquitin ligase that mediates the proteolysis of a repressor of AP3 and PI expression. Our genetic studies also indicate that ASK1 and UFO play a role in regulating the number of floral organ primordia, and we discuss possible mechanisms for such a regulation.

Arabidopsis↗
PubMed2001

M13 sequencing.

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Autoradiography↗
PubMed2001

[Study on the relationship between methylenetetrahydrofolate reductase gene C677T mutation and coronary heart disease].

OBJECTIVE: To investigate whether methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism is linked with coronary heart disease (CHD). METHODS: Transmission/disequilibrium test(TDT), sib transmission/disequilibrium test(STDT), and sibship disequilibrium test(SDT) were used. Forty-five CHD pedigrees with at least one CHD patient in the first degree relatives of probands were recruited from Oct. 1998 to Feb. 1999. Among those recruited were 21, 2 and 22 pedigrees with the genotypes of both parents known, one parental genotype unknown and both unknown, respectively. MTHFR genotype was measured by PCR-RFLP technique. RESULTS: Neither the TDT for 23 nuclear families with at least one parental genotype known or the STDT and SDT for 40 sibships found significant difference between the transmitted and untransmitted MTHFR gene 677T allele distributions. CONCLUSION: The above results suggest that MTHFR gene 677T allele is probably not linked with CHD in Chinese population.

Coronary Disease↗
PubMed2001

The recruitment of Fas-associated death domain/caspase-8 in Ras-induced apoptosis.

Oncogenic Ras induces cells to undergo apoptosis after inhibition of protein kinase C (PKC) activity. The integration of differential signaling pathways is required for full execution of apoptosis. In this study, we used Jurkat as well as Fas/FADD-defective cell lines expressing v-ras to determine the upstream elements required for activation of the caspase cascade in PKC/Ras-mediated apoptosis. During this Ras-induced apoptotic process, caspase-8 was activated, possibly through its binding to Fas-associated death domain (FADD), in Jurkat/ras and Jurkat/Fas(m)/ras cells but not in Jurkat/FADD(m)/ras cells. c-Jun NH(2)-terminal kinase (JNK) was activated in all three cell lines expressing ras in response to apoptotic stimulation. Suppression of JNK by dn-JNK1 blocked the interaction of FADD and caspase-8 and partially protected Jurkat/ras and Jurkat/Fas(m)/ras cells from apoptosis. However, dn-JNK1 had no effect on PKC/Ras-induced apoptosis in Jurkat/FADD(m)/ras cells. The results indicate that FADD/caspase-8 signaling is involved in PKC/Ras-mediated apoptosis, and JNK may be an upstream effector of caspase activation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

[Bioaccumulation mechanism of red tide alga Prorocentrum micans for heavy metal ions].

Pollution of heavy metal from industrial wastewater is a worldwide environmental problem. Biosorption is an effective technology for the treatment of low concentration industrial wastewater. The purpose of this study was to evaluate the heavy metal uptake capacities of the biomass of marine red tide Prorocentrum micans. All red tide biomass used in this study were obtained from cultivation in our lab. Batch experimental results showed that living and non-living biomass of P. micans killed by CH2O were similar setting property for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+. This study indicated that biomass of P. micans has a high capacities for above six heavy metal and the kinetics under the conditions studied were relatively fast. About 90% of the biosorption occurred within 10 min and an equilibrium was reached in 30 min. The Biosorption capacities for heavy metal ions were strongly dependent on pH of the solution, and higher capacities were obtained at pH around 5 and higher. Bonding and FIR of P. micans polysaccharide obtained by the hot water method for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+ was also studied. The study indicated that -OH and -CONH2 groups were active center of biosorption.

Adsorption↗
PubMed2000

Microfluidic tectonics: a comprehensive construction platform for microfluidic systems.

A microfluidic platform for the construction of microscale components and autonomous systems is presented. The platform combines liquid-phase photopolymerization, lithography, and laminar flow to allow the creation of complex and autonomous microfluidic systems. The fabrication of channels, actuators, valves, sensors, and systems is demonstrated. Construction times can be as short as 10 min, providing ultrarapid prototyping of microfluidic systems.

Journal Article↗
PubMed2000

Essential regions of the tRNA primer required for HIV-1 infectivity.

Human immunodeficiency virus (HIV), like all retroviruses, requires a cellular tRNA as a primer for initiation of reverse transcription. In a previous study, we demonstrated that an HIV-1 with a primer binding site complementary to yeast tRNA(Phe) (psHIV-Phe) was not infectious unless yeast tRNA(Phe) was supplied in trans. This unique in vivo complementation system has now been used to define the elements of the tRNA required for HIV-1 replication. Mutant tRNA(Phe) with deletions in TPsiC stem-loop, anticodon stem-loop or D stem-loop of the tRNA were generated and assessed for the capacity to rescue psHIV-Phe. Mutant tRNA(Phe) with disrupted TPsiC stem-loop did not rescue psHIV-Phe. In contrast, a mutant tRNA(Phe) without the D stem-loop was fully functional for the rescue. The tRNA anticodon stem-loop region was found to be important for efficient complementation. The results of our studies demonstrate for the first time the importance of specific structural and sequence elements of the tRNA primer for HIV-1 reverse transcription and define new targets for interruption of HIV-1 replication.

Base Sequence↗
PubMed2000

Stabilization of neoclassical tearing modes by an externally applied static helical field.

The effect of a static helical magnetic field on the nonlinear growth of the neoclassical tearing mode (NTM) is investigated. The NTM is found to be stabilized by an externally applied helical field of a different helicity if the field magnitude is sufficiently large, suggesting a very simple method for stabilizing the NTM. The mechanism responsible for this stabilization is the decreased fundamental harmonic pressure perturbation of the NTM in the presence of the helical field.

Journal Article↗
PubMed2000

Hypoxia augments conversion of big-endothelin-1 and endothelin ET(B) receptor-mediated actions in rat lungs.

We have examined the effect of endothelin-1, sarafotoxin-6C, big-endothelin-1 and other agents on perfused lungs from chronically hypoxic rats. Increases in pulmonary perfusion pressure induced by big-endothelin-1, endothelin-1, phenylephrine and potassium chloride were enhanced in hypoxic lungs, while the constrictor action of sarafotoxin-6C was not increased. When basal pulmonary perfusion pressure was raised, low doses of endothelin-1 and sarafotoxin-6C produced decreases in pulmonary perfusion pressure which were significantly greater in chronically hypoxic lungs, whereas responses to sodium nitroprusside were unchanged. Endothelin ET(B) receptor-mediated bronchoconstrictor responses were also potentiated in hypoxic lungs, whereas responses to carbachol were not. In hypoxic lungs, conversion of big-endothelin-1 to endothelin-1 was significantly increased. These data provide evidence for a generalised increase in vasomotor activity in chronically hypoxic lungs, and a more selective increase in endothelin ET(B) receptor-mediated vasodilator and bronchoconstrictor responses. Hypoxia also augments the conversion of big-endothelin-1 to endothelin-1.

Animals↗
PubMed2000

Complete suppression of neoclassical tearing modes with current drive at the electron-cyclotron-resonance frequency in ASDEX upgrade tokamak

Noninductive current drive has been performed in the tokamak ASDEX upgrade by injection of radiofrequency waves at the second harmonic of the electron-cyclotron frequency in order to suppress unwanted disturbances of the magnetic-field configuration. The current has been driven parallel [co-electron cyclotron current drive (ECCD)] and antiparallel (counter-ECCD) to the plasma current to compare the effect of heating with direct current drive in the magnetic island. For the first time it has been shown experimentally that total stabilization of neoclassical tearing modes is possible with co-ECCD. The experiments verify the role of direct current drive as opposed to local heating.

Journal Article↗