Biomedical subjects

Yu Zhao

Publications and source records attributed to Yu Zhao.

At least 55 records · Page 3Linked to original sources

PubMed2006

Synthesis and antioxidant evaluation of novel silybin analogues.

In this work, we evaluated the antioxidant properties of the eight novel silybin analogues for their capacity to scavenge free radicals including superoxide anion radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in vitro. Compound 7d demonstrated an excellent antioxidant effect in scavenging superoxide anion free radical with an IC50 value of 26.5 microM, while the IC50 of quercetin (the reference compound) was 38.1 microM. Compounds 7b, 7e, 7h showed certain scavenging activities for both types of free radicals.

Anions↗

PubMed2006

Fine-structure analysis of ribosomal protein gene transcription.

The ribosomal protein genes of Saccharomyces cerevisiae, responsible for nearly 40% of the polymerase II transcription initiation events, are characterized by the constitutive tight binding of the transcription factor Rap1. Rap1 binds at many places in the yeast genome, including glycolytic enzyme genes, the silent MAT loci, and telomeres, its specificity arising from specific cofactors recruited at the appropriate genes. At the ribosomal protein genes two such cofactors have recently been identified as Fhl1 and Ifh1. We have now characterized the interaction of these factors at a bidirectional ribosomal protein promoter by replacing the Rap1 sites with LexA operator sites. LexA-Gal4(AD) drives active transcription at this modified promoter, although not always at the correct initiation site. Tethering Rap1 to the promoter neither drives transcription nor recruits Fhl1 or Ifh1, showing that Rap1 function requires direct DNA binding. Tethering Fhl1 also fails to activate transcription, even though it does recruit Ifh1, suggesting that Fhl1 does more than simply provide a platform for Ifh1. Tethering Ifh1 to the promoter leads to low-level transcription, at the correct initiation sites. Remarkably, activation by tethered LexA-Gal4(AD) is strongly reduced when TOR kinase is inhibited by rapamycin. Thus, TOR can act independently of Fhl1/Ifh1 at ribosomal protein promoters. We also show that, in our strain background, the response of ribosomal protein promoters to TOR inhibition is independent of the Ifh1-related protein Crf1, indicating that the role of this corepressor is strain specific. Fine-structure chromatin mapping of several ribosomal protein promoters revealed that histones are essentially absent from the Rap1 sites, while Fhl1 and Ifh1 are coincident with each other but distinct from Rap1.

Bacterial Proteins↗

PubMed2006

[Levels of serum interleukin-15 and the expression of T-helper lymphocyte subsets in peripheral blood of children with juvenile rheumatoid arthritis].

OBJECTIVE: To study the changes of serum interleukin-15 (IL-15) levels and the expression of CD4(+)T (T-helper lymphocyte) subsets CD4(+)CD45RA(+) and CD4(+)CD45RO(+) in peripheral blood of children with juvenile rheumatoid arthritis (JRA). METHODS: The serum concentration of IL-15 was detected using ELISA in 39 children with JRA. The expressions of CD4(+)CD45RA(+)T and CD4(+)CD45RO(+)T in peripheral blood were detected by flow cytometry in 24 out of the 39 patients with JRA. Twenty-six age and sex-matched healthy children were used as the Control group. RESULTS: The mean serum IL-15 level in JRA patients was significantly higher than that in controls (1.37 +/- 0.98 pg/mL vs 0.96 +/- 0.41 pg/mL, P <0.05). Among the 39 JRA patients, the serum IL-15 level in 17 patients with systemic JRA increased remarkably (P < 0.01), but not in patients with the other two types of JRA, the oligoarthritis and polyarthritis (n=13, n=9, respectively), compared with that in controls. The mean serum IL-15 level of the JRA patients was significantly reduced after conventional treatment (P < 0.01). The serum IL-15 level in JRA patients positively correlated with white blood cell count (r=0.347, P <0.05) and C reactive protein (r=0.452, P < 0.01) but not with the erythrocyte sedimentation rate. The patients with high serum IL-15 levels (> or = medium level 1.73 pg/mL) had higher expression of CD4(+)CD45RO(+)T than those with low serum IL-15 levels (< medium level) (16.29 +/- 5.46% vs 11.75 +/- 3.15 %, P < 0.05). CONCLUSIONS: The serum IL-15 levels in JRA patients increased significantly. An increased IL-15 level can transform CD45RA into CD45RO in peripheral blood of patients with JRA, and then result in T lymphocyte activation and mediate the immunopathological impairment. IL-15 may be used a marker for the evaluation of severity of JRA.

Adolescent↗

PubMed2006

[Studies on the preparation and characterization of immobilized neutral protease by carboxymethyl chitosan microsphere].

AS1. 398 neutral protease was immobilized onto carboxymethyl chitosan with glutaraldehyde as cross-linking agent. The effects of pH, time of cross-linking, amount of cross-linking agent and the ratio of enzyme to carrier on the activity of the immobilized enzyme were demonstrated, and the optimum immobilization condition of AS1. 398 neutral protease was established. Also studied was the characterization of immobilized enzyme,including pH, temperature, Km and the stability of storage.

Bacterial Proteins↗

PubMed2006

[Biomechanical study of restorations of medial-occlusal cavities of endodontically treated premolars].

OBJECTIVE: To compare the different restorations of endodontically treated premolars, and to choose the best method. METHODS: 10 pairs of symmetry maxillary first premolars were collected from 10 patients, and randomly divided into 2 groups. Every pair received different treatment accordingly. The test group was set up the medial-occlusal cavities model under the same standard. The 10 pairs teeth were test by instron 4302 universal test machine in speed of 1.00 mm/min until broken up and the top load was recorded. The load angle was 45 degree to the long axis of the teeth, as the load was pointed to the middle of the lingual surface on the buccal cusp. The records were analyzed by paired samples t test. RESULTS: Based on the medial-occlusal cavities, the fracture strength of the full crowned teeth was lower than the full natural teeth, and the fracture strength of the post-crowned teeth was higher than the full natural teeth. CONCLUSION: From the point of biomechanics, the different trauma of the endodontically treated teeth fits to different restorations. The medial-occlusion cavities fit the post-crown restoration mostly.

Bicuspid↗

PubMed2006

[Hepatitis E virus of different genotypes contains multiple-type antigenic epitopes].

Monoclonal antibodies (McAbs) were prepared against a recombinant protein p166Us derived from US-1 strain of hepatitis E virus (HEV). The immune reactivity of the McAbs to seven p166s derived from different genotypes and subtypes of HEV, which included p166Bur (genotype I a), p166Pak (genotype I b), p166Mor (genotype I c), p166Mex (genotype II), p166Us (genotype III), p166Nz (swine HEV, genotype III) and p166Chn (genotype IV), was tested by an indirect enzyme-linked immunosorbent assay (ELISA) and a Western blotting assay. The immunological relationship between the McAbs and native HEV particles or anti-HEV positive serum samples was analyzed by an antigen-competitive or antibody-competitive ELISA. Totally, six McAb-producible hybridoma cell lines, designated by the name of 4D3, 2E3, 11E11, 12H5, 3A3 and 1F1 respectively, were cloned and obtained in this study. The McAb of 4D3 could react to all of the seven p166 recombinant proteins. This kind of reaction could be inhibited by each of 4 genotypes of native HEV particles or anti-HEV positive serum samples. The McAbs produced by 2E3, 11E11 and 12H5 reacted to p166Us, p166Nz and p166Chn, but did not react to p166Bur, p166Pak, p166Mor and p166Mex. The reaction of McAb of 2E3, as an example of the McAbs of 2E3, 11E11 and 12H5, could be only inhibited by genotype III and IV HEV or anti-HEV positive serum. The McAb of 3A3 could bind to p166Us as well as p166Nz. The McAb produced by 1F1 was reactive to the p166Us only. However, neither of I , II , IV genotype HEV particles or antisera could inhibit both of their reactions to p166Us. The data as mentioned above suggested that there are multiple-type antigenic epitopes such as genotype I, II, III and IV common, III and IV common, and III specific epitopes within HEV ORF2 encoded p166 proteins of different genotypes and subtypes of HEV. Moreover, the antigenic epitopes on recombinant protein p166s and these on native HEV particles possess identical immunological characteristics.

Animals↗

PubMed2006

[Extraction and salting-out purification of alpha-galactosidase and beta-glucosidase from fresh roots of Rehmannia glutinosa].

OBJECTIVE: To extract and preliminarily purify alpha-galactosidase and beta-glucosidase from the fresh roots of Rehmannia glutinosa. METHODS: With the enzyme activity as a criterion, the best procedure of extraction was selected though orthogonal design method, and the desired saturation of ammonium sulfate in two-step salting-out was settled by gradient sedimentation of root extract according to enzyme activity and protein content. RESULTS: Temperature and solvent volume affect the extraction of alpha-galactosidase significantly, while solvent type to beta-glucosidase. Therefore the procedure for extracting two enzymes was decided as mixing comminuted fresh root with 3 times phosphate buffer, and placing the mixture in refrigeratory at 4 degrees C for 4 hours, and then obtaining the enzyme liquid by centrifuging at 4 degrees C. 30% and 60% saturation was defined as the lower and upper point for two-step ammonium sulfate salting-out of the two enzymes. CONCLUSION: alpha-Galactosidase and beta-glucosidase exist in the fresh roots, and can be preliminarily purified through two-step salting-out.

Molecular Weight↗

PubMed2006

[IEMAD (modified MIME) therapy for refractory or relapsed non-Hodgkin's lymphoma].

The study was aimed to evaluate the effect of IEMAD (modified MIME) composed of isofosfamide, VM26 or VP16, methotrexate, cytarabine, dexamethasone or methylprednisolone, in treatment of refractory or relapsed non-Hodgkin's lymphoma. Twenty-five patients with refractory or relapsed non-Hodgkin's lymphoma (11 refractory NHL patients, 14 relapsed NHL patients) were treated with IEMAD regimen. The results showed that the complete remission rate was 24.0% (6/25) and the partial remission rate was 28.0%, having an overall response rate of 52%. The median survival duration was 13 months and the median duration of progression-free survival was 8 months. The most frequent complications were gastrointestinal complaint (nausea, vomiting etc.) and myelosuppression. No treatment related mortality was found. It is concluded that the IEMAD (modified MIME) regimen may be a safe and effective regimen that can be used in treatment of patients with refractory or relapsed non-Hodgkin's lymphoma who did not respond to other regimens.

Adolescent↗

PubMed2006

[Study on preparation of the pH sensitive hydroxyethyl chitin/poly (acrylic acid) hydrogel and its drug release property].

Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine.

Acrylates↗

PubMed2006

[Rapid analysis of antiepileptic drugs in human plasma by micellar electrokinetic capillary chromatography].

AIM: To develop a rapid and feasible method based on micellar electrokinetic capillary chromatography (MECC) for the simultaneous determination of antiepileptic drugs (AEDs)--phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), primidone (PRM) and clonazepam (CZP) in human plasma. METHODS: Several factors that impact the separation of AEDs with MECC were investigated, such as concentration of sodium dodecyl sulfate (SDS), buffer compositions, pH, organic modifier, internal diameter and temperature, and an optimized MECC running condition was obtained the running buffer consisted of 8 mmol x L(-1) phosphate, 3 mmol x L(-1) sodium tetraborate, and 50 mmol x L(-1) sodium dodecylsulfate (SDS) (pH 8.0), containing acetonitrile (ACN) (18%) as organic modifier. Detection at 210 nm, run at 25 kV at 30 degrees C in a untreated fused silica capillary (50/45.5 cm length, 50 microm ID). RESULTS: The reproducibility of both migration time and relative peak area with MECC analysis were appropriate for the intra- and inter-assay coefficients. The evaluated drugs concentration intervals of PRM 1.0-40.0 microg x mL(-1), PB 1.0-60.0 microg x mL(-1), PHT 1.0-40.0 microg x mL(-1), CBZ 1.0-40.0 microg x mL(-1), CZP 0.2-8.0 microg x mL(-1) were linear with correlation coefficients higher than 0.999 1, and coefficients of the variation of the points of the calibration curve lower than 10%. The recoveries of AEDs varied from 80.0% to 100.0%, depending on the drug, with coefficients of the variation lower than 10.0%. CONCLUSION: The MECC technique is showed to be rapid, simple, efficient and low cost when applied to monitoring therapeutic drugs in patient treated with a combination of PHT and other AEDs such as hepatic enzyme-inducing agents.

Anticonvulsants↗

PubMed2006

[Role of calcium signal in apoptosis and protective mechanism of colon cancer cell line SW480 in response to 5-aminolevulinic acid-photodynamic therapy].

BACKGROUND & OBJECTIVE: Photodynamic therapy (PDT) for tumors is based on the tumor-selective accumulation of a photosensitizer, followed by irradiation with visible light, which induces cell death and apoptosis. As an important second messenger, free calcium is involved in the regulation of several cellular processes. However, the role of calcium signal in the cells after PDT is less clear. This study was to explore the role of calcium signal in apoptosis and protective mechanism of colon cancer cell line SW480 in response to 5-aminolevulinic acid (ALA)-PDT. METHODS: SW480 cells were divided into control group, light group, ALA group, and ALA-PDT group. Cell apoptosis was detected by TUNEL assay. The changes of intracellular Ca(2+) concentration were observed by confocal laser scanning microscopy (CLSM). Intracellular cAMP and cGMP concentrations were detected by radioimmunoassay. The expression of calmodulin in SW480 cells was detected by reverse transcription-polymerase chain reaction (RT-PCR). The expression of protein products and phosphorylated protein products of MEK and ERK1/2 was detected by Western blot. RESULTS: Apoptosis indexes of SW480 cells at 30 min and 60 min after PDT were (25.26+/-5.04)% and (50.45+/-7.85)%, respectively. CLSM revealed that intracellular Ca(2+) concentration was 100.00+/-19.83 at 10 min after PDT, but 185.40+/-18.90 at 20 min after PDT (P<0.01). cAMP concentration of ALA-PDT group was (3.215+/-0.245) pmol/L at 30 min after irradiation, which was significantly higher than those of other groups (P<0.001). The relative contents of CaM gene of ALA-PDT group at 30, 60 and 90 min after PDT were significantly higher than those of control group, light group, and ALA group (12.60+/-1.84, 11.39+/-1.13, and 12.77+/-1.35 vs. 3.97+/-0.29, 4.28+/-0.39, and 4.51+/-0.44, P<0.001). ERK pathway of SW480 cells was activated after ALA-PDT. CONCLUSIONS: Calcium signal plays an important role in ALA-PDT-induced apoptosis of SW480 cells, and can induce protective mechanism of SW480 cells by activating ERK pathway.

Aminolevulinic Acid↗

PubMed2006

[Id4 gene methylation for detection of minimal residual disease in acute leukemia].

OBJECTIVE: To evaluate the possibility of Id4 gene promoter methylation as a biomarker for minimal residual disease (MRD) detection in acute leukemia. METHODS: Methylation specific-PCR technique was used to detect Id4 gene methylation in samples with different percentages of leukemia cells from leukemia cell line and bone marrows from leukemia patients in complete remission (CR). RESULTS: Id4 gene methylation could be detected in samples containing 1% or lower leukemia cells. Frequency of Id4 gene methylation in acute lymphoblastic leukemia (ALL) patients in CR was 64.3% being higher than that in acute myeloid leukemia (AML) patients in CR. In 14 ALL patients with Id4 gene methylation, 8 relapsed in 12 months, while only one relapsed in 9 patients without Id4 gene methylation. In 8 AML patients with Id4 gene methylation, 5 relapsed in 12 months, while two relapsed in 20 AML patients with Id4 gene methylation. CONCLUSION: Id4 gene promoter methylation is a candidate of biomarker for MRD detection in acute leukemias.

Acute Disease↗

PubMed2006

A novel locus for X-linked retinitis pigmentosa.

INTRODUCTION: Retinitis pigmentosa (RP) is the most prevalent group of inherited retinopathies and demonstrates considerable clinical and genetic heterogeneity, with wide variations in disease severity, progression, and gene involvement. We studied a large family with RP to determine the pattern of inheritance and to identify the disease-causing gene/locus. MATERIALS AND METHODS: Ophthalmic examination was performed on 35 family members to identify affected individuals and carriers and to characterise the disease phenotype. Genetic linkage analysis was performed using short tandem repeat (STR) polymorphic markers encompassing the known loci for Xlinked RP (xlRP) including RP2, RP3, RP6, RP23, and RP24. Mutation screening was performed by direct sequencing of PCR-amplified genomic DNA of the RP2 and RPGR genes of the affected individuals. RESULTS: A highly penetrant, X-linked form of RP was observed in this family. Age of onset was from 5 to 8 years and visual acuity ranged from 20/25 in children to light perception in older adults. Linkage analysis and direct sequencing showed that no known loci/genes were associated with the phenotype in this kindred. CONCLUSION: A novel disease gene locus/loci is responsible for the xlRP phenotype in this family.

Adolescent↗

PubMed2006

[Research progress in Laggera medicinal plants].

This paper reviewed the worldwide research progresses of the genus Laggera both on phytochemical and pharmacological work in the past few decades. The main secondary metabolites of this genus are proved to be sesquitepenoids, flavonoids and phenolic acids. Phamacological investigations revealed that the certain extracts of some Laggera species possess significant bioactivities on anti-inflammation, anti-tumor and anti-viral infection. This review afforded the comprehensive description of the active components as to provide useful references to elucidate their historical clinical application on upper respiratory infection, influenza, parotitis, and recurrent herpes viral infection.

Animals↗

PubMed2006

[Advances in caffeoylquinic acid research].

This paper reviewed updated research progresses of caffeoylquinic acids both in phytochemical and pharmacological aspects. The resources, distribution as well as the chemical structures of monocaffeoylquinic acids, dicaffeoylquinic acids, tricaffeoylquinic acids and multicaffeoylquinic acids are conclusively analyzed. The reviewed pharmacological investigations indicated that the caffeoylquinic acids exhibited significant activities such as anti-oxidation, anti-inflammation, enzyme inhibition, hypatoprotective and anti-PAF effects. The broad distribution and the remarkably pharmacological activities of these natural phenolic acids indicated their potential in the discovery and development of new natural drugs.

Animals↗

PubMed2006

[Studies on the chemical constituents in herb of Ranunculus japonicus].

OBJECTIVE: To isolate and determine the chemical constituents from Ranunculus japonicus. METHOD: Compounds were isolated by column chromatography, and identified by MS, NMR data. RESULT: Nine compounds were obtained andelucidated as scoparone (1), tricin (2), protocatechuic acid (3), luteolin (4), anemonin (5), scopoletin (6), 5-hydroxy-6, 7-dimethoxyflavone (7), 5-hydroxy-7, 8-dimethoxyflavone (8), ternatolide (9), respectively. CONCLUSION: Compounds 1-9 were isolated from R. japonicus for the first time while compounds 7, 8 were separated from Ranunculus genus first time.

Coumarins↗

PubMed2006

[Study on supension culture and quantitative determination of total ginsenosides from the crown gall of Panax quinquefolium].

The influences of different cultural node on the crown gall culture of Panax quinquefolium and its ginsenosides contents were studied. The faster growth rate was obtained in suspension culture. And the dry weight (DW) of crown gall and the accumulation of total ginsenoside content reached 0. 776 g DW/flask and 19.4 mg/flask, which were 111% and 64% higher than solid culture, respectively. The results also indicated that the utilization (by percentage) of sucrose was 91.8%. The investigation provided useful information for following researches on fermentation culture and large-scale production of ginsenosides.

Carbon↗

PubMed2006

[The significance of DNA-binding inhibitor 4 promoter methylation status in acute leukemia].

OBJECTIVE: To investigate the relationship between promoter methylation of inhibitor of DNA binding 4 (Id4) gene and acute leukemia. METHODS: We detected the status of promoter methylation of Id4 gene in peripheral blood, peripheral blood stem cell transplantation (PBSC) and bone marrow samples from health donors, bone marrow cells from leukemia patients and leukemia cell lines with MS-PCR methods. RESULTS: The frequency of Id4 promoter methylation was 21/25 in acute myeloid leukemia (84%), 12/14 in acute lymphoblastic leukemia (86%), 8/8 in relapse acute leukemias and 2/2 in leukemia cell lines whereas no methylation was detected in peripheral blood, PBSC and bone marrow samples from healthy donors. In addition, Hek937 cell line was unmethylated. CONCLUSION: Id4 promoter methylation was detected only in acute leukemia patients and leukemia cell lines and it might play a role in leukemia genesis.

DNA Methylation↗