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Biomedical subjects

Qi Liu

Publications and source records attributed to Qi Liu.

At least 73 records · Page 4Linked to original sources
PubMed2004

[Study on the molecular epidemiology of hantaviruse carried by hosts in northern suburb of Beijing].

OBJECTIVE: To investigate hantanvirus infection of captured rodents in Haidian district and Changping district of Beijing and to type hantavirus using molecular technique. METHODS: The captured mice were classified and the density of distribution was calculated. Reverse transcription-polymerase chain reaction (RT-PCR) technique was used to amplify the partial M fragnments of hantaviruse. Several representative positive samples were sequenced and analysed by ClustalX (5.0) and DNAClub software. RESULTS: A total of 414 animals were captured, among which Battus norvegicus was the dominant group. In Haidian district, the median infection rates with hantavirus were 13.14% in Battus norvegicus and 0 in Mus musculus Linnaeus. In Changping district, the average infection rates were 17.46% in Battus norvegicus and 3.57% in Mus musculus Linnaeus. Nucleotide sequences analysis showed that the virus detected all belonged to SEO-type. They clustered with Z37 virus and could be branched into 2 different subclades. CONCLUSION: The major hosts of hantavirus in Haidian and Changping district were Battus norvegicus and the epidemic strains in the two districts of Beijing were genotyped as SEO-type. Nucleotide sequence and deduced amino acid sequence from different rodents were highly homologous, while nucleotide mutation had also been observed. Further studies are required to explore the possible virus sequence mutation.

Animals↗
PubMed2004

[Construction and identification of expressing siRNA plasmid against human augmenter of liver regeneration].

OBJECTIVES: To detect whether there is an expression of human augmenter of liver regeneration (hALR) in HepG2 cells. To develop a kind of RNAi that specifically targets human augmenter of liver regeneration by synthesizing small interfering RNA (siRNA) in vivo, and to assess the inhibitory effect of this siRNA on hALR expression. METHODS: The expression of hALR in HepG2 cells was observed with immunocytochemistry. The RNAi plasmid pSIALR-A and the unrelated control plasmid pSIALR-B were transfected into HepG2 cells. Forty-eight hours after transfection, the protein level of hALR was measured with immunocytochemistry; meanwhile, the reverse transcription PCR (RT-PCR) was performed to detect the expression of hALR mRNA. RESULTS: hALR was expressed by HepG2 cells. siRNA plasmid pSIALR-A, which targets the cDNA of hALR and the unrelated control plasmid pSIALR-B, was successfully constructed. Both immunocytochemistry and RT-PCR showed that pSIALR-A inhibited the expression of hALR in HepG2 cells significantly, compared with that of pSIALR-B. CONCLUSION: The results showed that the small interfering RNA targeting hALR suppresses the expression of hALR in a sequence-specific manner

Base Sequence↗
PubMed2004

Preliminary analysis of CDK2 sequence and its nuclear import.

We constructed the plasmids encoding enhanced green fluorescent protein (EGFP)-tagged wild type cyclin-dependent kinase 2(CDK2) (pEGFP-CDK2) and CDK2 deletion mutants (pEGFP-CDK2N and pEGFP-CDK2C, lacking the last C-terminal and the first N-terminal 97 amino acids of CDK2, respectively) and transfected them into HeLa cell line and CHO cell line. After synchronization, green fluorescent signals were detected mainly in nucleus of the cells transfected with pEGFP-CDK2 and predominantly in cytoplasm of the cells transfected with the two mutant CDK2 constructs. Our results suggested that there were no nuclear-import signals in CDK2 and that CDK2 nuclear import might be mediated by association with other proteins through the three-dimensional structure formed by amino acids including those from the N- and C-terminal regions of CDK2.

Active Transport, Cell Nucleus↗
PubMed2004

[A system for testing alternating frequency properties of body fluid and tissues].

The electric properties of biotic tissues are of importance to our understanding biotic substances even life. But the measurement taken in this aspect is different from the measurement of ordinary materials, we need a special testing instrument for living substances. In order to understand the alternating frequency properties of body fluid and tissues in detail, we have developed an electricity characteristic testing system, which is more proper for testing living substances. This system adopts advanced measuring method and expert circuit. As the measure and the control core, the single chip processor is used. This system has wide frequency range and wide impedance testing range, much more adapted objects, and it is dependable, more precise and intelligent. The application of this system in practical testing has obtained optimal results.

Body Composition↗
PubMed2003

Distribution of Pb(II) species in aqueous solutions.

Turbidity and zeta potential measurements were made on solid precipitates formed after raising the pH of a 10(-3) mol/l lead nitrate aqueous solutions containing 10(-2) mol/l KCl with KOH. Distribution diagrams of Pb(II) species in aqueous solutions at a total Pb(II) concentration of 10(-3) mol/l and 10(-2) mol/l KCl was constructed to explain the results. Several solubility products for solid Pb(OH)(2) were found from the literature and used to construct the diagrams. It was observed that distribution diagrams constructed using a solubility product of 1.43x10(-20) explained the experimental results better than those with other reported solubility products.

Journal Article↗
PubMed2003

Synthesis, photophysical properties, and nucleic acid binding of phenanthridinium derivatives based on ethidium.

A series of substituted phenanthridine derivatives has been synthesized by converting the amines at the 3- and 8-positions of ethidium bromide into guanidine, pyrrole, urea, and various substituted ureas. The resulting derivatives exhibit unique spectral properties that change upon binding nucleic acids. The compounds were analyzed for their ability to inhibit the HIV-1 Rev-Rev Response Element (RRE) interaction, as well as for their affinity to calf thymus DNA. One derivative (3,8-bis-urea-ethylenediamine-5-ethyl-6-phenylphenanthridinium trifuroracetate) has an enhanced affinity and specificity for HIV-1 RRE as compared to ethidium bromide. These results indicate that the nucleic acid affinity and specificity of an intercalating agent can be tuned by synthetic modification of its exocyclic amines.

Animals↗
PubMed2003

RNA-ligand interactions: affinity and specificity of aminoglycoside dimers and acridine conjugates to the HIV-1 Rev response element.

Semisynthetic aminoglycoside derivatives may provide a means to selectively target viral RNA sites, including the HIV-1 Rev response element (RRE). The design, synthesis, and evaluation of derivatives based upon neomycin B, kanamycin A, and tobramycin conjugates of 9-aminoacridine are presented. To evaluate the importance of the acridine moiety, a series of dimeric aminoglycosides as well as unmodified "monomeric" aminoglycosides have also been evaluated for their nucleic acid affinity and specificity. Fluorescence-based binding assays that use ethidium bromide or Rev peptide displacement are used to quantify the affinities of these compounds to various nucleic acids, including the RRE, tRNA, and duplex DNA. All the modified aminoglycosides exhibit a high affinity for the Rev binding site on the RRE (K(d) <or= 10 nM), but few compounds have a high specificity for the RRE. Compared to the acridine conjugates, the dimeric and unmodified aminoglycosides exhibit good RNA over DNA selectivity, but show little differentiation between different RNA molecules. Neomycin-based derivatives consistently have the highest RNA and DNA affinities, but the lowest RRE specificity. To optimize these derivatives for RRE specificity, a series of neomycin-acridine conjugates with variable linker lengths were synthesized and evaluated. The neo-acridine conjugate with the shortest linker length has the optimal RRE specificity. Duplex DNA, on the other hand, prefers the acridine conjugate with the longest linker length, and duplex RNA (poly r[A]-r[U]) has the highest affinity for the conjugate with an intermediate linker length. Compared to neomycin B, the derivatives based upon tobramycin and kanamycin A have slightly lower RRE affinities, but better RRE specificities. These results illustrate how the binding affinity and specificity of aminoglycoside intercalator conjugates can be tuned by optimizing the linker length and by changing the identity of the aminoglycoside moiety. These results also indicate that many aminoglycoside-based ligands are capable of high-affinity binding of RNA, but achieving high site specificity remains a challenging objective.

Acridines↗
PubMed2003

A HMM-based method to predict the transmembrane regions of beta-barrel membrane proteins.

A novel method is developed to model and predict the transmembrane regions of beta-barrel membrane proteins. It is based on a Hidden Markov model (HMM) with architecture obeying those proteins' construction principles. The HMM is trained and tested on a non-redundant set of 11 beta-barrel membrane proteins known to date at atomic resolution with a jack-knife procedure. As a result, the method correctly locates 97% of 172 transmembrane beta-strands. Out of the 11 proteins, the barrel size for ten proteins and the overall topology for seven proteins are correctly predicted. Additionally, it successfully assigns the entire topology for two new beta-barrel membrane proteins that have no significant sequence homology to the 11 proteins. Predicted topology for two candidates for beta-barrel structure of the outer mitochondrial membrane is also presented in the paper.

Animals↗
PubMed2003

Identification of beta-barrel membrane proteins based on amino acid composition properties and predicted secondary structure.

Unlike all-helices membrane proteins, beta-barrel membrane proteins can not be successfully discriminated from other proteins, especially from all-beta soluble proteins. This paper performs an analysis on the amino acid composition in membrane parts of 12 beta-barrel membrane proteins versus beta-strands of 79 all-beta soluble proteins. The average and variance of the amino acid composition in these two classes are calculated. Amino acids such as Gly, Asn, Val that are most likely associated with classification are selected based on Fishers discriminant ratio. A linear classifier built with these selected amino acids composition in observed beta-strands achieves 100% classification accuracy for 12 membrane proteins and 79 soluble proteins in a four-fold cross-validation experiment. Since at present the accuracy of secondary structure prediction is quite high, a promising method to identify beta-barrel membrane proteins is presented based on the linear classifier coupled with predicted secondary structure. Applied to 241 beta-barrel membrane proteins and 3855 soluble proteins with various structures, the method achieves 85.48% (206/241) sensitivity and 92.53% specificity (3567/3855).

Amino Acids↗
PubMed2003

[Expression of rat augmenter of liver regeneration in pichia pastoris and evaluation of its bioactivity in vitro].

OBJECTIVES: To construct yeast expression plasmid of rat augmenter of liver regeneration (rALR), express it in GS115, and examine its bioactivity in vitro. METHODS: With PCR and genetic recombination techniques, the gene fragment of rALR was amplified from recombinant plasmid pcDNA3.1-rALR, and the recombinant plasmid pPIC9K-rALR was constructed. The recombinant plasmid pPIC9K-rALR was transducted into GS115 by electroporation after identified with endonuclease digestion and PCR amplification. The target protein was expressed by GS115 under the induction of 0.5% methanol. The recombinant rALR (rrALR) was purified with ultrafiltration after demonstrated by 15% SDS-PAGE and western blot. The effects of rrALR on the proliferation of QGY, HepG2 cells and primary rat hepatocytes in vitro were evaluated by 3H-TdR intake method. RESULTS: Recombinant plasmid pPIC9K-rALR was identified by restriction digestion and PCR methods. The rrALR as a secretive protein was successfully expressed in GS115. Its molecular weight, 1.5x10(4), was in correspondence with theoretic value. The rrALR could bind with the polyclonal antibody against human ALR in western blot, which demonstrated that there was cross-antigenicity between human and rat ALR. The high qualitative rrALR was obtained through ultrafiltration. Among the experimental concentrations, the rrALR could stimulate the proliferations of QGY and HepG2 cells in a dose-dependent manner in vitro, but had little effect on the proliferation of primary rat hepatocytes in vitro. CONCLUSIONS: The rrALR as a secretive protein is expressed in GS115 efficiently. The rrALR can stimulate the proliferations of QGY and HepG2 cells in a dose-dependent manner in vitro, but had no effect on primary rat hepatocytes, which demonstrates that there exists different receptors on the normal hepatocytes and hepatocarcinoma cells. There are cross-bioactivity and cross-antigenicity between human and rat ALR.

Animals↗
PubMed2003

[Clinical value of MR cholangiopancreatography combining with dynamic enhanced MRI in the detection of cholangiocarcinoma].

OBJECTIVES: To evaluate the clinical value of breath-hold magnetic resonance cholangiopancreatography (MRCP) combining with dynamic enhanced MRI in the diagnosis of cholangiocarcinoma. METHODS: MRCP findings of 88 cholangiocarcinoma patients proved surgically and pathologically were analyzed retrospectively. RESULTS: MRCP examination succeeded in all the 88 patients and the pancreaticobiliary ducts were shown satisfactorily. The accuracy of MRCP in the location of both hilar and extrahepatic cholangiocarcinoma was 100%, and the accuracy of detecting hilar and extrahepatic cholangiocarcinoma were 100% and 52.2%, respectively. Combining with dynamic enhanced MRI, the detecting accuracy of extrahepatic cholangiocarcinoma improved to 91.3%. CONCLUSIONS: MRCP examination has a high successful rate and can accurately determine the location of hilar and extrahepatic cholangiocarcinoma, and the accuracy of qualitative diagnosis for the former two is high. Combining with dynamic enhanced MRI, the specificity of determining extrahepatic cholangiocarcinoma is also high.

Adult↗
PubMed2003

[Determination of danshensu in urine and its pharmacokinetics in human].

AIM: To determine Danshensu in urine and study its pharmacokinetics in human. METHODS: A solid phase extraction-HPLC method was used for determination of Danshensu in urine of human. HPLC separation is performed on a Shim-pack CLC-ODS column (150 mm x 6.0 mm ID, 5 microns) with a mobile phase composed of acetonitrile -0.01 mol.L-1 KH2PO4 (adjusted to pH 2.8 with phosphoric acid). The flow rate was 1.0 mL.min-1 and the UV detector was set at 280 nm. The linear range of Danshensu was 0.2-50 mg.L-1 (r = 0.9999), and its limit of detection was 1.5 ng. The mean recovery was 99.4% (RSD = 2.9%). RESULTS: The pharmacokinetics of Danshensu after p.o. administration of two kinds of pharmaceutical preparations containing Danshen (with 20 mg of Danshensu) were investigated in 6 healthy human volunteers by determining the Danshensu in urine samples. The elimination half lives (T1/2) of Danshensu after p.o. administration of compound granule preparation A and decoction of Danshen were (0.92 +/- 0.16) h and (0.94 +/- 0.21) h, respectively. Their excretions of Danshensu in urine were (6.2 +/- 2.8)% and (14 +/- 4)% of the dose in 8 hours, respectively. CONCLUSION: Under normal doses, Danshensu can be eliminated from kidney. There is no evident difference on elimination half lives of Danshensu after p.o. administration of the two doses, but the excretions of Danshensu by urine after p.o. administration of compound granule preparation A were lower than that of decoction of Danshen.

Adult↗
PubMed2002

RNase E levels in Escherichia coli are controlled by a complex regulatory system that involves transcription of the rne gene from three promoters.

The rne gene of Escherichia coli encodes RNase E, an essential endoribonuclease that is involved in both mRNA decay and rRNA processing. Here we present evidence that the gene is transcribed from three promoters: p1, p2 and p3. The p2 and p3 promoters map 34 and 145 nt upstream from the previously characterized rne promoter, p1, generating unusually long 5' UTRs of 395 and 506 nt respectively. Based on promoter-lacZ transcriptional fusions, p1 is a more efficient promoter than either p2 or p3. Low copy number or single copy number vectors carrying rne transcribed from either p1, p2 or p3 alone complement the rne 1018::bla deletion mutation at 30 degrees C, 37 degrees C and 44 degrees C. However, normal autoregulation requires the presence of all three promoters. A comparison among intracellular levels of RNase E, the half-lives of the rpsO, rpsT and rne mRNAs, and growth rates, indicates that the cell contains a considerable excess of RNase E protein. In addition, when the rne transcript is stabilized at low RNase E levels, it is not efficiently translated.

5' Untranslated Regions↗
PubMed2002

Wedge osteotomies of the radius for Kienböck's disease: a biomechanical analysis.

We compared changes in lunate cortical strain with an applied physiologic load by altering radial inclination to simulate opening and closing wedge osteotomies of the distal radius. Nineteen fresh-frozen cadaver arms were mounted in neutral position and tested under axial compression at a physiologic load by means of a repeated-measures design. Principal compressive strains were measured with rosette strain gauges mounted on the lunate's palmar and dorsal cortices. Distal radius osteotomy and custom external fixator allowed for altering radial inclination in progressive 3 degrees increments both by increasing and decreasing radial inclination in each specimen. Maximum principal strain was recorded for each inclination increment and compared with control. Comparison of all data showed a 26% decrease on lunate cortical strain for the radial opening wedge osteotomy and a 24% increase for the radial closing wedge osteotomy. This difference was statistically significant. No significant differences were found between individual angular increments (3 degrees to 15 degrees). The radial opening wedge osteotomy was more effective than the radial closing wedge osteotomy at diminishing lunate strain. The results validate the biomechanical effectiveness of this extra-articular osteotomy, which is intended to minimize alteration of ulnar variation.

Analysis of Variance↗