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Biomedical subjects

Yan Liu

Publications and source records attributed to Yan Liu.

At least 235 records · Page 13Linked to original sources
PubMed2005

Preparation of ChIL-2 and IBDV VP2 fusion protein by baculovirus expression system.

This study aims to produce an effective subunit vaccine against infectious bursal disease virus (IBDV). The genes of chicken interleukin-2 (ChIL-2) and IBDV viral protein 2 (VP2) were amplified and fused by splice overlap extension-polymerase chain reaction (SOE-PCR). The fusion gene was digested by EcoR I/Kpn I and inserted into pBacPAK8 vector, resulting in recombinant transfer plasmid pBacPakVP2-IL2. The recombinant plasmid was transfected into Sf-9 cells accompanied with hybrid nuclear polyhedrosis virus (HyNPV) genome DNA and lipofectin. Plaque-purification indicated that we had got the recombinant Hy-VP2-IL2. Fusion protein VP2-IL2 was expressed effectively both in insect cells and bombyx mori. The expression of fusion protein was confirmed by ELISA, SDS-PAGE and Western blotting assay, respectively. This efficient system allows us to meet the need for inexpensive vaccines required by the poultry industry.

Animals↗
PubMed2005

[The influence of several anions on sonoluminescence].

1.1 MHz ultrasound was used to induce sonoluminescence in air-saturated solutions dissolved five kinds of anions in different ranges: NO3-: 0.2-20 mg x L(-1), F- : 4-20 mg x L(-1), Cl- : 5-25 mg x L(-1), HCO3- : 8-30 mgx L(-1), SO4(2-) : 0.4-40 mg x L(-1). It was found that four kinds of the anions, Cl- , NO-, HCO3- and SO4(2-) at the above mentioned concentrations have no influence on sonoluminescence. However, only F- in the range of 4-20 mg x L(-1) can quench the sonoluminescence. The quenching mechanism was analyzed.

Anions↗
PubMed2005

[Screening and cloning of hepatitis C virus non-structural protein 4A interacting protein gene in hepatocytes].

OBJECTIVE: To investigate biological functions of hepatitis C virus (HCV) non-structural protein 4A (NS4A). METHODS: Yeast-two hybrid technique was performed to seek proteins in hepatocytes interacting with HCV NS4A. HCV NS4A bait plasmid was constructed by ligating the NS4A gene with carrier plasmid pGBKT7, then it was transformed into yeast AH109 (alpha type). The transformed yeast cells were amplified and mated with yeast cells Y187 (alpha type) containing liver cDNA library plasmid pACT2 in 2 x YPDA medium. Diploid yeast cells were plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing X-alpha-gal for selection two times. After extracting plasmid from blue colonies, plasmid DNA was transformed into competent E.coli and analyzed by DNA sequencing and bioinformatics methods. RESULTS: Among twenty-two positive colonies there were eleven positive for metallothionein 2A, three for eukaryotic translation elongation factor 1 alpha 1, two for albumin, two for RNA binding motif protein 21, two for myomesin, one for cytochrome C oxidase II, and one for ATPase. CONCLUSIONS: Genes of HCV NS4A interacting proteins in hepatocytes were successfully cloned and the results pave the way for studying the biological functions of NS4A and associated proteins.

Carrier Proteins↗
PubMed2005

[A study of the down-regulation effect of hepatitis B virus pre-protein S2 on inducible nitric oxide synthase gene promoter].

OBJECTIVES: To investigate the regulating effect of HBV pre-S2 protein on iNOS gene promoter and the molecular biological mechanisms of pre-S2 protein in HBV pathogenicity. METHODS: Polymerase chain reaction (PCR) technique was employed to amplify the sequence of iNOS promoter and 3 deletion mutants using HepG2 genomic DNA as the template, and the products were cloned into the pGEM-T vector. The iNOS gene and 3 deletion mutants were cut from T- iNOS by Kpn I and Xho I, and then cloned into pCAT3-Basic. The resulting vectors were named p1-iNOSp, p2-iNOSp, p3-iNOSp, and p4-iNOSp. Each of the reporter vectors was transfected into the HepG2 cell line and cotransfected into HepG2 cells with pcDNA3.1(-)-pre-S2 by FuGENE 6 transfection reagents. The HepG2 cells transfected with pCAT3-Basic were used as a negative control. The activity of CAT in HepG2 cells transfected was detected by an ELISA kit 48 hours after the transfection, which reflected the regulating effect of HBV pre-S2 protein on iNOS gene promoter activity. RESULTS: The expressive vector pcDNA3.1(-)-pre-S2 and report vector pCAT3-iNOSp were constructed and confirmed by restriction enzyme digestion and sequencing. The expression of pcDNA3.1(-)-pre-S2 in HepG2 cells could down-regulate the activity of p1-iNOSp, p3-iNOSp, and the inhibition rate was 54.7% and 79.5%, respectively. The expression of pcDNA3.1(-)-pre-S2 in HepG2 cells had no regulatory effects on p2-iNOSp and p4-iNOSp. CONCLUSION: It is suggested that HBV pre-S2 protein can down-regulate iNOS gene promoter.

Down-Regulation↗
PubMed2005

In vitro expression and antibody preparation of black carp (Mylopharyngodon piceus) GH.

The cDNA fragment encoding the mature polypeptide of growth hormone (GH) for the black carp (Mylopharyngodon piceus) was PCR amplified and subcloned into pET-28a. The recombinant expression plasmid pET-bcGH was transformed into E.coli BL21(DE3) and fusion polypeptide containing a 6xHis-tag at the N-terminus was expressed after IPTG induction. The fusion protein band of 23 kDa or so showed immunoreactivity to the polyclonal antibody aganist grass carp GH. The recombinant GH for black carp was purified by affinity chromatography and dialysis. Using the fusion protein as an antigen, through the modified immunization method, the polyclonal antiserum to black carp GH was obtained. Immunochemistry results showed that the antiserum could detect the antigen as low as 4 ng. The protein of 21 kDa in black carp pituitary protein extracts and blood serum could be detected by western blot analysis in which polyclonal antiserum to black carp GH was used as the primary antibody. All these results showed that the polyclonal antiserum against black carp GH was not only effective but also highly specific.

Animals↗
PubMed2005

[Screening and cloning of hepatitis C virus non-structural protein 4B interacting protein gene in hepatocytes].

OBJECTIVE: To investigate biological functions of non-structural protein 4B (NS4B) of hepatitis C virus (HCV), yeast-two hybrid technique was performed to seek proteins in hepatocytes interacting with HCV NS4B. METHODS: HCV NS4B bait plasmid was constructed by ligating the NS4B gene with carrier plasmid pGBKT7 and transformed into yeast cells AH109 (type alpha). The transformed yeast cells were amplified and mated with yeast cells Y187 (alpha type) containing liver cDNA library plasmid pACT2 in 2 x YPDA medium. Diploid yeast cells were plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-alpha-gal for selecting two times. After extracting plasmid from blue colonies, plasmid DNA was transformed into competent Escherichia coli and analysed by DNA sequencing and bioinformatics. RESULTS: Five genes in eight positive colonies were obtained. There were one NADH dehydrogenase subunit 3, one cytochrome c oxidase subunit III, one retinol binding protein 4, one reticulon 3-A (RTN3) and one fibrinogen gamma polypeptide (FGG). CONCLUSION: Genes of HCV NS4B interacting proteins in hepatocytes were successfully cloned and the results paved the way for studying the biological functions of NS4B and associated proteins.

Blotting, Western↗
PubMed2005

[In vitro and in vivo pharmaceutical behaviors of lycopene microcapsules].

AIM: To evaluate in vitro release of lycopene microcapsules. Pharmacokinetic parameters of lycopene microcapsule and lycopene powder as reference were estimated after a single dose of oral administration to dogs. The relationship between in vitro dissolution and in vivo absorption was investigated. METHODS: The content of lycopene in the release medium was determined by UV spectroscopy method. Health hybrid male dogs were used as experiment subjects and lycopene powder used as standard to estimate the pharmacokinetics of lycopene microcapsules. HPLC method was used to assay the concentration of lycopene in dog plasma. Pharmacokinetics parameters were estimated by 3P87 program. The drug release percentage in stimulated intestinal fluid was compared with the absorption at a given time point. RESULTS: The release profiles of lycopene from microcapsule showed that the lycopene gelatin microcapsule exhibited enteric property. The pharmacokinetics parameters estimated after oral administration of lycopene powder and lycopene microcapsule in a single dose of 2.5 mg x kg(-1) body weight to dogs were 7.30 h, 15.06 h for T1/2alpha; 28.10 h, 46.76 h for T1/2beta; 22.32 h, 41.03 h for T(max); 1.67 microg x h x L(-1), 2.08 microg x h x L(-1) for AUC(0-infinity), respectively. The concentration-time curves could be fitted to a two-compartment model for both the lycopene powder and the lycopene microcapsule analyzed by 3P87 program. The relationship between in vitro dissolution and in vivo absorption was found to have good correlation (r = 0. 981 9) was found. CONCLUSION: It could be concluded that lycopene microcapsule was a sustained release dosage form. The result of release in vitro could be used to predict the absorption in vivo.

Administration, Oral↗
PubMed2005

[Cloning, expression and preparation of polyclonal antibody for IBDV non-structure protein gene].

Infectious bursal disease virus (IBDV) VP5 gene was amplified and cloned into an N-terminal GST-Tag fusion expression vector, pGEX-4T-2, which was controlled by T7 promoter. The sequencing result showed that the VP5 gene was composed of 438 base pairs, and coded 145 amino acids. High VP5 product was expressed in E. coli BL21 induced by IPTG, and the GST-VP5 fusion protein existed in inclusion. High titer anti-VP5 serum was also prepared in New Zealand rabbit immunized with purified fusion protein inclusion. These results gave a basis for further research for VP5 function in IBDV replication and pathogenicity, which also paved the way for developing VP5 gene deleted IBDV live vaccine.

Animals↗
PubMed2005

[Dynamics of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan].

The total flux and concentration of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan were measured from July 2002 to July 2003. The results showed that the TOC input by precipitation was 41.80 kg x hm(-2) x yr(-1), while its output by surface runoff and groundwater (soil solution at 50 cm depth) was 17.54 and 1.80 kg x hm(-2) x yr(-1), respectively. The difference between input and output was 22.46 kg x hm(-2) x yr(-1), indicating that the ecosystem TOC was in positive balance. The monthly variation of TOC flux in hydrological processes was very similar to that in precipitation. The mean TOC concentration in precipitation was 3.64 mg x L(-1), while that in throughfall and stemflow increased 6.10 and 7.39 times after rain passed through the tree canopies and barks. The mean TOC concentration in surface runoff and in soil solution at 25 and 50 cm depths was 12.72, 7.905 and 3.06 mg x L(-1), respectively. The monthly TOC concentration in throughfall and stemflow had a similar changing tendency, showing an increase at the beginning of growth season (March), a decrease after September, and a little increase in December. The TOC concentration in runoff was much higher during high precipitation months. No obvious monthly variation was observed in soil solution TOC concentration (25 and 50 cm below the surface). Stemflow TOC concentration differed greatly between different tree species. The TOC concentration in precipitation, throughfall, and soil solution (25 and 50 cm depths) decreased with increasing precipitation, and no significant relationship existed between the TOC concentrations in stemflow, surface runoff and precipitation. The TOC concentrations in the hydrological processes fluctuated with precipitation intensity, except for that in stemflow and soil solutions.

Carbon↗
PubMed2005

[Clinical and laboratory characteristics of anti-soluble liver antigen/liver-pancreas (SLA/LP) autoantibody positive liver disease patients].

OBJECTIVE: To analyze the clinical and laboratory features of anti-soluble liver antigen/liver-pancreas (SLA/LP) autoantibody positive patients with abnormal liver functions. METHODS: From July 1999 to August 2004, 4928 serum samples from patients with abnormal liver functions (ALT >40 U/L) were collected. A series of autoantibody examinations were carried out. Clinical manifestations and laboratory findings of 8 patients with anti-SLA/LP autoantibody positive were reviewed. RESULTS: Among the 5500 serum samples, 8 cases (6 females and 2 males) with positive anti-SLA/LP autoantibodies were found with complete clinical information. The age of the patients was (27-76) years old. The case histories were from 2 years to 10 years. Of the 8 patients, 6 cases had liver cirrhosis and HBsAg-negative and anti-HCV-negative, active, 1 case had liver cirrhosis with HBsAg-positive, but HBVDNA negative; 1 case had liver cirrhosis and anti-HCV positive, but HCV RNA negative. The 8 cases were all ANA positive with titers of 31:320. Four cases were AMA positive and 2 among these 4 cases were M2 positive. The most frequent symptoms were fatigue, anorexia, nausea, jaundice, abdominal distention and edema of lower limbs. All patients had high hypergammaglobulinemia. CONCLUSION: Anti-SLA/LP autoantibody was at a low detection rate in the study with females in preponderance, Clinical and laboratory characteristics of the 8 cases were consistent with those of the autoimmune hepatitis (AIH). Testing for anti-SLA autoantibodies helps in the diagnosis of AIH in many patients who may otherwise be misdiagnosed.

Adult↗
PubMed2005

[A cephalometric study on Twin-block appliance for treatment of early skeletal Class II malocclusion].

PURPOSE: To investigate the dentofacial morphological changes and the indication of Twin-block appliance for treatment of skeletal Class II malocclusion. METHODS: Twenty-one patients (5 degrees < ANB < 10 degrees , 12 males,9 females) were recruited with an average age of 11.5 years.Lateral headfilm were performed for each patient before and after treatment with Twin-block appliance. Fifteen cephalometrics parameters were selected and measurement was performed. Paired t test and multiple regression analysis were used for statistical analysis. RESULTS: After treatment SNB(degrees), (L1-MP) (degrees), (Co-Go) (mm),(Go-Gn) (mm),(Co-Gn) (mm),(Sn-A'-UL) (degrees), (LL-B'-Pos) (degrees) increased significantly(P<0.05) ; ANB(degrees), WITS, OJ(mm), (U1-SN)(degrees), (UL-E line)(mm), (LL-E line)(mm) decreased significantly(P<0.05). ANB(<) and (U1-SN)(<) before treatment were significantly related to reduction in overjet (y=-37.14+0.43 ANB+0.36 (U1-SN), r(2)=0.62); SNA( degrees ) and SNB( degrees ) before treatment were significantly related to reduction in (UL-E line) (mm) (y=-5.37+0.44SNA-0.37SNB, r(2)=0.53); (U1-SN) (degrees) and (L1-MP)(degrees) before treatment were significantly related to reduction in( LL-E line) (mm) (y=-7.65+0.18 (U1-SN )-0.09 (L1-MP), r(2)=0.58). CONCLUSION: Twin-block appliance can be used successfully for early treatment of skeletal Class II malocclusion. It is more indicated for patients with retruded mandible , more labially inclined upper incisors and more upright lower incisors.

Cephalometry↗
PubMed2005

[Research on swallowable camera-capsules of gastrointestinal wireless endoscope].

The swallowable camera-capsule,described in the aper, 11 mm in diameter and 30 mm in length , contains a CMOS image sensor, an optical system, a battery, a light source, a transmitter, a antenna and so on. The CMOS image sensor and its driving circuit can be miniaturized with MEMS technology. Image signal can be transmitted by analog or digital way. Image signal can be wirelessly transmitted through serial data interface. Finally, the processing technics of the capsule's crust is introduced.

Capsule Endoscopes↗
PubMed2005

[The influence of topical application of insulin on the formation of basement membrane in scalded rats].

OBJECTIVE: To investigate the influence of topical application of insulin on the formation of basement membrane (BM) in rats with deep partial thickness scald. METHODS: Ninety-six SD rats were inflicted with deep partial thickness scald on the back and were randomized into A group (n = 48, with subcutaneous injection of 2 ml of isotonic saline on the 1 post scald day (PSD)) and B group (n = 48, with subcutaneous injection of 0.1 U of insulin and 2 ml of isotonic saline on the 1 PSD). The rats received the treatment every other day until wound re-epithelization completed. Then the rats were sacrificed on 2, 3, 4, 5, 6, 10, 14 PSD, and on the day when the wound re-epithelialized completely. The skin samples of 1 cm in width were harvested at the edge of the wound for reticular fiber staining and for morphological observation of the wound BM with transmission electron microscope. The expression of laminin-5 mRNA and laminin in keratinocyte was determined by RT-PCR and Western blotting, respectively. RESULTS: Integrated and continuous structure of the basement membrane was observed in B group. Laminin-5 mRNA expression was much higher in B group than that in A group on 10 and 14 PSD (P < 0.05 or P < 0.01). Laminin-5 mRNA expression was decreased in both groups when epithelialization completed. But the Laminin-5 protein expression on 14 PSD and the day of epithelization (56 +/- 8, 101 +/- 13) was obviously higher in B group than that in A group (39 +/- 5, 73 +/- 16), (P < 0.05). CONCLUSION: Subcutaneous injection of 0.1 U insulin beneath the scald wound is beneficial to the acceleration of the wound re-epithelialization process, and to the improvement of the wound healing quality.

Animals↗
PubMed2005

[Multi-institutional randomized controlled clinical trial on China made 4-demethoxydaunokrubicin (IDA) in the treatment of acute leukemia].

OBJECTIVE: To evaluate the efficacy and safety of IDA (Haizheng Parmacy, China) in the treatment of acute leukemia. METHODS: A multi-institutional single-blind randomized controlled clinical trial was carried out. A total of 155 newly diagnosed patients with AML and ALL were enrolled. The patients were randomly divided into two groups, one was given IDA (n = 77) and the other given zevodas (Pharnacia & Upjohn, n = 78) for comparison. RESULTS: All the patients enrolled in this trial were eligible for assessment of side effects, and 129 patients for evaluation of overall response rate. In patients treated with IDA vs zevodas, the overall response rate (OR) was 78.1% vs 76.9%, CR was 68.8% vs 67.7%; in AML patients, OR was 82.4% vs 71.8%, and CR was 76.5% vs 64.1%; in ALL patients, OR was 80.0% vs 81.8%, and CR was 68.0% vs 68.2%. There was no sitatistically significant difference in hematologic and non-hematologic toxicities between the two groups. CONCLUSION: The efficacy of IDA in the treatment of acute leukemia is comparable to that of zevodas. Both have similar toxic side effects.

Adolescent↗
PubMed2004

Kruppel-like factor 4 abrogates myocardin-induced activation of smooth muscle gene expression.

Platelet-derived growth factor BB (PDGF-BB) has been shown to be an extremely potent negative regulator of smooth muscle cell (SMC) differentiation. Moreover, previous studies have demonstrated that the Kruppel-like transcription factor (KLF) 4 potently represses the expression of multiple SMC genes. However, the mechanisms whereby KLF4 suppresses SMC gene expression are not known, nor is it clear whether KLF4 contributes to PDGF-BB-induced down-regulation of SMC genes. The goals of the present studies were to determine the molecular mechanisms by which KLF4 represses expression of SMC genes and whether it contributes to PDGF-BB-induced suppression of these genes. Results demonstrated that KLF4 markedly repressed both myocardin-induced activation of SMC genes and expression of myocardin. KLF4 was rapidly up-regulated in PDGF-BB-treated, cultured SMC, and a small interfering RNA to KLF4 partially blocked PDGF-BB-induced SMC gene repression. Both PDGF-BB and KLF4 markedly reduced serum response factor binding to CArG containing regions within intact chromatin. Finally, KLF4, which is normally not expressed in differentiated SMC in vivo, was rapidly up-regulated in vivo in response to vascular injury. Taken together, results indicate that KLF4 represses SMC genes by both down-regulating myocardin expression and preventing serum response factor/myocardin from associating with SMC gene promoters, and suggest that KLF4 may be a key effector of PDGF-BB and injury-induced phenotypic switching of SMC.

3T3 Cells↗
PubMed2004

Electrochemical impedance behavior of DNA biosensor based on colloidal Ag and bilayer two-dimensional sol-gel as matrices.

A novel method for fabrication of DNA biosensors has been developed by means of self-assembling colloidal Ag (Ag) to a thiol-containing sol-gel network. The thiol groups of 3-mercaptopropyltrimethoxysilane (MPTS) serve as binding sites for the covalent attachment to gold electrode surface. Then the one-dimensional network of silane unites (1dMPTS) was combined together into a two-dimensional sol-gel network (2dMPTS) by dipping into aqueous NaOH. The second silane layer (B2dMPTS) was formed by immersing electrodes back into the MPTS solution overnight, and then the Ag nanoparticles were chemisorbed onto the thiol groups of the second silane layer. Finally, the mercapto oligonucleotide was self-assembled onto the surface via the Ag nanoparticles. The modified process was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). In addition, we utilized the impedance spectroscopy as a platform for DNA sensing assay. The factors influencing the performance of the resulting biosensor were studied in detail. The linear range of the biosensor was from 8.0 x 10(-9) to 1.0 x 10(-6) M with a detection limit of 4.0 x 10(-9) M at 3sigma. In addition, the experiment results indicate that oligonucleotide immobilized on this way exhibits a good sensitivity and selectivity, high stability and a long-term maintenance of bioactivity.

Binding Sites↗
PubMed2004

Novel potentiometry immunoassay with amplified sensitivity for diphtheria antigen based on Nafion, colloidal Ag and polyvinyl butyral as matrixes.

A novel potentiometry immunoassay with amplified sensitivity has been developed for the detection of diphtheria antigen (Diph) via immobilizing diphtheria antibody (anti-Diph) on a platinum electrode based on Nafion, colloidal Ag (Ag), and polyvinyl butyral (PVB) as matrixes in this study. The modified procedure was further characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The influence and factors influencing the performance of resulting immunosensor were studied in detail. The resulting immunosensor exhibited sigmoid curve with log Diph concentrations, high sensitivity (51.4 mV/decade), wide linear range from 8 to 800 ng ml(-1) with a detection limit of 1.5 ng ml(-1), rapid potentiometric response (<3 min) and long-term stability (>6 months). Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme-linked immunosorbent assays (ELISAs) method, implying a promising alternative approach for detecting diphtheria antigen in the clinical diagnosis.

Antigens↗