Biomedical subjects

Xing Lü

Publications and source records attributed to Xing Lü.

8 recordsLinked to original sources

PubMed2006

Radiation-induced changes in gene expression involve recruitment of existing messenger RNAs to and away from polysomes.

Although ionizing radiation has been shown to influence gene transcription, little is known about the effects of radiation on gene translational efficiency. To obtain a genome-wide perspective of the effects of radiation on gene translation, microarray analysis was done on polysome-bound RNA isolated from irradiated human brain tumor cells; to allow for a comparison with the effects of radiation on transcription, microarray analysis was also done using total RNA. The number of genes whose translational activity was modified by radiation was approximately 10-fold greater than those whose transcription was affected. The radiation-induced change in a gene's translational activity was shown to involve the recruitment of existing mRNAs to and away from polysomes. Moreover, the change in a gene's translational activity after irradiation correlated with changes in the level of its corresponding protein. These data suggest that radiation modifies gene expression primarily at the level of translation. In contrast to transcriptional changes, there was considerable overlap in the genes affected at the translational level among brain tumor cell lines and normal astrocytes. Thus, the radiation-induced translational control of a subset of mRNAs seems to be a fundamental component of cellular radioresponse.

Astrocytes↗

PubMed2005

[CCD-array detection-flow injection analysis of oligomeric: proanthocyanidins in health food].

A flow-injection-CCD array detection spectrophotometry for the determination of oligomeric proanthocyanidin (OPC) in health foods was developed in the present paper, based on the reaction that OPC can form red anthocyanidin in hydrochloric acid medium with ferric ion as a catalytic agent. The absorption spectrum of OPC was scanned and the absorbance at 545 nm was determined by flow injection with CCD-array detector. The influencing factors of the chromogenic reaction and parameters of the flow injection analysis were optimized. There is a good linear relationship between the absorbances and the concentrations of OPC in the range of 0.010-0.20 mg x mL(-1). The detection limit of the method was 5 microg x mL(-1). The recoveries were 82.47%-98.18% with the relative standard deviation (RSD) of 1.5%-4.9%. The proposed method is sensitive, accurate and rapid with the sampling frequency of 10 samples-h(-1) and suitable for the determination of OPC in the health food.

Flow Injection Analysis↗

PubMed2004

Microarray analysis in clinical oncology: pre-clinical optimization using needle core biopsies from xenograft tumors.

BACKGROUND: DNA microarray profiling performed on clinical tissue specimens can potentially provide significant information regarding human cancer biology. Biopsy cores, the typical source of human tumor tissue, however, generally provide very small amounts of RNA (0.3-15 microg). RNA amplification is a common method used to increase the amount of material available for hybridization experiments. Using human xenograft tissue, we sought to address the following three questions: 1) is amplified RNA representative of the original RNA profile? 2) what is the minimum amount of total RNA required to perform a representative amplification? 3) are the direct and indirect methods of labeling the hybridization probe equivalent? METHODS: Total RNA was extracted from human xenograft tissue and amplified using a linear amplification process. RNA was labeled and hybridized, and the resulting images yielded data that was extracted into two categories using the mAdb system: "all genes" and "outliers". Scatter plots were generated for each slide and Pearson Coefficients of correlation were obtained. RESULTS: Results show that the amplification of 5 microg of total RNA yields a Pearson Correlation Coefficient of 0.752 (N = 6,987 genes) between the amplified and total RNA samples. We subsequently determined that amplification of 0.5 microg of total RNA generated a similar Pearson Correlation Coefficient as compared to the corresponding original RNA sample. Similarly, sixty-nine percent of total RNA outliers were detected with 5 microg of amplified starting RNA, and 55% of outliers were detected with 0.5 microg of starting RNA. However, amplification of 0.05 microg of starting RNA resulted in a loss of fidelity (Pearson Coefficient 0.669 between amplified and original samples, 44% outlier concordance). In these studies the direct or indirect methods of probe labeling yielded similar results. Finally, we examined whether RNA obtained from needle core biopsies of human tumor xenografts, amplified and indirectly labeled, would generate representative array profiles compared to larger excisional biopsy material. In this analysis correlation coefficients were obtained ranging from 0.750-0.834 between U251 biopsy cores and excised tumors, and 0.812-0.846 between DU145 biopsy cores and excised tumors. CONCLUSION: These data suggest that needle core biopsies can be used as reliable tissue samples for tumor microarray analysis after linear amplification and either indirect or direct labeling of the starting RNA.

Animals↗

PubMed2004

Genotype and allele frequency of the variable number tandem repeat polymorphism in the VNTR6-1st of the of human telomerase reverse transcriptase (hTERT) gene in Chinese population.

The variable number of tandem repeat (VNTR) polymorphism in the intron 6 of the human telomerase reverse transcriptase(hTERT) was investigated. Seven alleles of 18, 20, 21, 22, 23, 26 and 35 repeats of the 36 bp VNTR6-1st and 14 genotypes were identified among 210 unrelated healthy Chinese individuals (Han people) living in Beijing. The 20, 22 and 35 repeats were the most frequent alleles which accounted for 94.76% of the total alleles observed. The allele frequency of the Chinese population showed no difference with that of the Korea population living in Pusan except for allele of 35 repeats. But the 5' flanking region of VNTR6-1st polymorphic sequence of the Chinese population included a 53-bp insert compared with that of korea population except for some alleles of 22 repeats.

Alleles↗

PubMed2004

Transcriptional signature of flavopiridol-induced tumor cell death.

Flavopiridol has been shown to inhibit the proliferation of a variety of human tumor cells and is currently undergoing clinical evaluation in cancer treatment. Although the antiproliferative effect of flavopiridol has been attributed to the inhibition of cyclin-dependent kinases 2 and 4, recent reports indicate that the mechanism responsible for the cell death induced by this agent is more complex. To provide insight into the molecular processes mediating flavopiridol-induced cytotoxicity and to investigate the availability of markers indicative of its activity, we have applied cDNA microarray technology. Gene expression profiles were determined for four human tumor cell lines (prostate carcinomas PC3 and DU145 and gliomas SF359 and U251) following exposure to selected concentrations of flavopiridol. Treatment of these cell lines with a concentration of flavopiridol sufficient to reduce survival to 10% resulted in the identification of a set of 209 genes, the expression of which were altered in each of the cell lines. This common set of 209 gene expression changes suggested that flavopiridol-induced cell death can be defined in terms of a specific transcriptome. The flavopiridol death transcriptome consisted primarily of down-regulated genes; however, there were also a significant number of genes with increased expression. Whereas causal relationships were not established, these data suggest molecular events/processes that may be associated with flavopiridol-induced tumor cell death. Moreover, the identification of a set of gene expression changes in four human tumor cell lines suggests that such a transcriptome may be applicable to investigations of flavopiridol pharmacodynamics.

Antineoplastic Agents↗

PubMed2003

[Isolation and characterization of a novel radiation-resistant rod-shaped bacterium].

A novel radiation-resistant bacterium was isolated from soil of lake bank in Beijing. The bacterium produced orange-pigmented colonies and formed rod-shaped cells that stained gram negative alike the Deinobacter grandis previously described by Japan's scientist. It was found with electron microscopy that the isolate is of 0.6 microm - 1.6 microm size and has a 30-40 nm thickness of cell wall, being slightly larger and thicker than the Deinobacter grandis. There was a difference in the concentration and molecule weight of catalase between the isolate and the Deincoccus radiodurans R1. The deoxyribonucleic acid guanine plus cytosine (G + C) base ratio was 70.7 mol%. 16S RNA gene sequencing also showed that this rod-shaped bacterium possessed a high homology with the Deinobacter grandis, suggesting that it might be classified into the genus Deinobacter and constitute a new species in this genus.

Bacterial Proteins↗

PubMed2002

[A short tandem repeat polymorphism in the inducible nitric oxide synthase gene in Chinese population].

Polymorphism of the (CCTTT)n repeat, a short tandem repeats (STR) located in promoter region of the inducible nitric oxide synthase (iNOS) gene, was analyzed in a total of 316 Chinese healthy subjects. Twelve alleles and forty-nine genotypes were identified. Three alleles that had not been reported previously, namely 17-repeats, 18-repeats and 19-repeats, were found in Chinese population. Mendelian inheritance of the allele in a family composed of three generations was determined. Some of the observed allele frequency of this STR locus in Chinese differed significantly from that of Caucasians in England.

Adolescent↗

PubMed2000

Deinococcus radiodurans CatB Gene Cloning and Expression in Escherichia coli.

A 1 611 bp length complete coding sequence of the catalase (Cat) was obtained through bioimformatical analysis of the database of D.radiodurans genome, and then was amplified from D. radiodurans genomic DNA by polymerase chain reaction. The amplified gene was cloned into pKK223-3 vector and transformed into E.coli UM2, a Cat-deficient mutant. Staining of non-denaturing polyacrylamide gels for Cat activity demonstrated that pKK223-3 insert encoded a Cat that co-migrated with the CatB found in D.radiodurans cell lysates. Expression of CatB gene from D.radiodurans in E.coli UM2 restored the resistance to H(2)O(2) at low concentrations.

Journal Article↗