Biomedical subjects

Yong-Heng Zhao

Publications and source records attributed to Yong-Heng Zhao.

6 recordsLinked to original sources

PubMed2006

Construction of the recombinant adenovirus vector carrying antisense multidrug resistance gene.

BACKGROUND: Multidrug resistance proteins serve as transporters for chemical drugs in human malignancies. The objective of this study was to construct a homologous recombinant adenovirus carrying a reversal fragment of multidrug resistance gene 1 (mdr1) gene cDNA sequence. METHODS: The fragment of the mdr1 gene from the plasmid pHaMDR1-1 carrying the whole human mdr1 cDNA sequence was inserted reversely into the shuttle plasmid pAdTrack-CMV of adenoviral vector system AdEasy. The homologous recombination process was taken place in E. coli BJ5183 with the backbone plasmid pAdEasy-1. After packaging in 293 cells, recombinant adenoviral plasmid was generated. The recombinant adenoviral plasmid was identified by polymerase chain reaction (PCR), restriction endonucleases digest, DNA sequence analysis and fluorescence microscopic photograph, respectively. RESULTS: The recombinant adenovirus pAdEasy-GFP-ASmdr1 was successfully constructed and identified by PCR, restriction digest, and sequencing with strong green fluorescence expression in fluorescence microscopic photograph. CONCLUSIONS: The recombinant adenoviral mdr1 vector would introduce the antisense mdr1 gene into the human multidrug resistance hepatocellular cell line effectively, which would provide an experimental basis to study the multidrug resistance in human hepatocellular carcinoma.

Adenoviridae↗

PubMed2006

[A method for auto-extraction of spectral lines based on convolution type of wavelet packet transformation].

The important astrophysical information is hidden in spectral lines of astronomical spectra. The presen paper presents a method for auto-extraction of spectral lines based on convolution type of wavelet packet. This method consists of four main steps: First, the observed spectra are transformed by convolution type of wavelet packet with 4th scale. Then, the noise with coefficients of the 4th scale is eliminated by the local correlation algorithm and threshold in the wavelet packet domain. After that, middle and high frequency coefficients are selected to reconstruct the feature of the spectral lines. Finally, with the reconstructed feature of the spectral lines, spectral lines in observed spectra are searched. The results of our experiments, which include the spectral lines of stars, normal galaxies and active galaxies, show that the method can robustly and accurately extract the spectral lines. The method was applied to extract the SDSS spectral lines and compute the redshifts with those lines. By comparing the redshifts with those given by SDSS, the extraction has proven successful and practical.

English Abstract↗

PubMed2006

[A method for obtaining redshifts of quasars based on wavelet multi-scaling feature matching].

The LAMOST project, the world's largest sky survey project being implemented in China, is expected to obtain 10(5) quasar spectra. The main objective of the present article is to explore methods that can be used to estimate the redshifts of quasar spectra from LAMOST. Firstly, the features of the broad emission lines are extracted from the quasar spectra to overcome the disadvantage of low signal-to-noise ratio. Then the redshifts of quasar spectra can be estimated by using the multi-scaling feature matching. The experiment with the 15, 715 quasars from the SDSS DR2 shows that the correct rate of redshift estimated by the method is 95.13% within an error range of 0. 02. This method was designed to obtain the redshifts of quasar spectra with relative flux and a low signal-to-noise ratio, which is applicable to the LAMOST data and helps to study quasars and the large-scale structure of the universe etc.

English Abstract↗

PubMed2005

[Wavelet transform zero-crossing method for auto-extraction of spectral lines].

Wavelet transform method is used in this paper. The authors firstly studied the properties of spectral lines in the wavelet domain. By introducing the items of up-zero-crossings and down-zero-crossings, the authors concluded that absorption lines and emission lines correspond to different kinds of zero-crossings. Therefore the authors presented a new wavelet transform zero-crossing method for the extraction of spectral lines and the normalization of continuum spectra. The useful spectral lines can be obtained together with the continuum spectra. The extraction of spectral lines in this paper is a direct method, which avoids the errors caused during the process of noise reduction. The experiments both on stars and nearby galaxies show that our method can be used to accurately extract the spectral lines, which is helpful to the computation of characteristic parameters and the automatic classification of spectra based on spectral lines.

Algorithms↗

PubMed2005

[Construction of recombinant adeno-associated virus vectors carrying double gene of antisense multidrug resistance-associated protein and antisense multidrug resistance].

OBJECTIVE: To construct a recombinant adeno-associated virus vectors carrying double gene of antisense multidrug resistance-associated protein (MRP) and antisense multidrug resistance (MDR1) for use in studying the gene therapy to reverse the multidrug resistance (MDR) in hepatocellular carcinoma (HCC). METHODS: The 500 bp fragment (mrp) of MRP cDNA 5' region and the 600 bp fragment (mdr1) of MDR1 cDNA 5' region were amplified through polymerase chain reaction (PCR), and then they were linked to a combined gene fragment (mrp+mdrl) by overlapping technique. The combined gene fragment(mrp+mdrl) was cloned reversely into the multiple cloning site (MCS) of the expression plasmid pAAV-IRES-hrGFP in AAV Helper-Free System to construct the recombinant expression plasmid pAAV-IRES-hrGFP-(mrp + mdr1)AS. The packaging cell line (HEK 293 cell) was co-transfected with the pAAV-IRES-hrGFP-(mrp+mdr1)AS together with the control plasmid pAAV-RC and pHelper in AAV Helper-Free System by means of lipofectamine. The recombinant adeno-associated virus vector : rAAV2-(mrp+mdr1)AS carrying the double gene of antisense multidrug resistance-associated protein (MRP)and antisense multidrug resistance (MDR1) was packaged. Then the viral titer was checked by GFP. RESULTS: The recombinant adeno-associated virus vector : rAAV2-(mrp + mdr1)AS carrying antisense MRP and antisense MDR1 was constructed successfully, the strong green fluorescence was observed in HEK 293 cells under a fluorescence microscope. The viral titer was 2.5 X 10(6) efu/ml. CONCLUSION: The rAAV2-(mrp+mdr1)AS thus constructed could introduce the antisense MRP and antisense MDR1 into the human drug-resistant hepatocellular cell line effectively, which might provide a sound basis for the mechanisms and reversal methods of the multidrug resistance in HCC.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

[Non-parameter estimation algorithm to determine stellar effective temperature].

The effective temperature of a star is one of the most important parameters, which determine the continuum and spectral lines in the stellar spectrum. A non-parameter estimation algorithm is proposed to estimate the stellar effective temperature in the present paper. Firstly, the spectrum data is processed by principal component analysis(PCA), then, an estimating model based on a Gaussian kernel function is set up using the PCA data and their temperatures. Experiments were carried out to verify the efficiency, and numerical robustness of the algorithm is also tested.

English Abstract↗