Biomedical subjects

Wen-Xin Zheng

Publications and source records attributed to Wen-Xin Zheng.

3 recordsLinked to original sources

PubMed2006

[Determination of artemisinin in Artemisia annuna by HPLC-ELSD].

OBJECTIVE: A HPLC method was first established to determine artemisinin in Artemisia annuna by HPLC-ELSD. Artemisinin in Herba of Artemisia annuna from different places was determined by this new method. METHODS: The method utilized MeOH-H2O (75: 25) as mobile phase with flow rate of 1 ml/min, C18 (250 x 4.6 mm, 5 microm) column. The temperature of detector was 40 degrees C, the pressure of N2 was 3.5 bar, and gain value was 9. RESULTS: The calibration curves were linear within the range of 1 - 5 microg, and the average recovery was 99.33% (RSD = 1.97%). CONCLUSION: The method was rapid, convenient, and accurate. It can be used for the quality control of this herbal medicine.

Antimalarials↗

PubMed2005

Coronavirus phylogeny based on a geometric approach.

A novel coronavirus has been identified as the cause of the outbreak of severe acute respiratory syndrome (SARS). Previous phylogenetic analyses based on sequence alignments show that SARS-CoVs form a new group distantly related to the other three groups of previously characterized coronaviruses. In this paper, a geometric approach based on the Z-curve representation of the whole genome sequence is proposed to analyze the phylogenetic relationships of coronaviruses. The evolutionary distances are obtained through measuring the differences among the three-dimensional Z-curves. The Z-curve is approximately described by its geometric center and the associated three eigenvectors, which indicate the center position and the trend of the Z-curve, respectively. Although some information is lost due to the approximate description of the Z-curve, the phylogenetic tree constructed based on these parameters is consistent with those of previous analyses. The present method has the merits of simplicity and intuitiveness, but it is still in its premature stage. Because the phylogenetic relationships are inferred from the whole genome, instead of some individual genes, the present method represents a new direction of phylogeny study in the post-genome era.

Algorithms↗

PubMed2003

Prediction of proteinase cleavage sites in polyproteins of coronaviruses and its applications in analyzing SARS-CoV genomes.

Recently, we have developed a coronavirus-specific gene-finding system, ZCURVE_CoV 1.0. In this paper, the system is further improved by taking the prediction of cleavage sites of viral proteinases in polyproteins into account. The cleavage sites of the 3C-like proteinase and papain-like proteinase are highly conserved. Based on the method of traditional positional weight matrix trained by the peptides around cleavage sites, the present method also sufficiently considers the length conservation of non-structural proteins cleaved by the 3C-like proteinase and papain-like proteinase to reduce the false positive prediction rate. The improved system, ZCURVE_CoV 2.0, has been run for each of the 24 completely sequenced coronavirus genomes in GenBank. Consequently, all the non-structural proteins in the 24 genomes are accurately predicted. Compared with known annotations, the performance of the present method is satisfactory. The software ZCURVE_CoV 2.0 is freely available at http://tubic.tju.edu.cn/sars/.

Amino Acid Sequence↗