Biomedical subjects

Yu-Kui Zhang

Publications and source records attributed to Yu-Kui Zhang.

7 recordsLinked to original sources

PubMed2006

Octyl-functionalized hybrid silica monolithic column for reversed-phase capillary electrochromatography.

Hybrid silica monolithic stationary phase functionalized with octyl groups was synthesized by a two-step acid/base-catalyzed hydrolysis/co-condensation of tetraethoxysilane (TEOS) and n-octyltriethoxysilane (C(8)-TEOS). The influences of determining factors in the sol-gel process such as the monomer ratio and water content on the monolith formation were systematically investigated. An increase in the TEOS/C(8)-TEOS ratio in the polymerization mixture shifted the pore size distribution towards smaller pore diameter with larger pore volume. The optimal TEOS/C(8)-TEOS volume ratio was found to be 90/50, under which condition the median pore diameter of the monolith was around 1.0 microm with pore volume of 3.25 cm(3)/g. The chromatographic characteristics of the monolithic column prepared with the optimized fabrication condition were studied. Some aromatic compounds including alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs) and phenols were successfully separated on the octyl-functionalized silica monolithic column with high column efficiency up to 180,000 plates/m.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2006

[HLA-DQA1 genotyping by using oligonucleotide microarrays].

In order to fabricate the HLA-DQA1 genotyping chip and develop an integrated, parallel technical platform to type HLA system, a pair of primers and a set of probes were designed according to the sequences of HLA-DQA1 exon 2, where the polymorphism is concentrated. The oligonucleotide chip was made with the methods developed in our laboratory. The target DNA was asymmetrically amplified with the labeled sense primer. The signals were scanned and analyzed after the hybridization between microarray and PCR product. The allele types of the samples were identified. The result was verified by the standard DNA and DNA sequencing. The results showed that the genotyping was successfully carried out in 50 standard DNA samples and 50 clinical samples. Among them, results of the 50 standard DNA samples matched their templates. In the other 50 samples, results of the randomly selected 10 matched their sequencing results except that two of them got the incompletely result. In reproducible tests, the signal reappear rate was 95%. It is concluded that HLA-DQA1 genotyping by using our array system is simple and convenient with satisfied accuracy and reproducibility.

Genotype↗

PubMed2005

Mutations of mitochondrial 12S rRNA in gastric carcinoma and their significance.

AIM: To detect the variations of mitochondrial 12S rRNA in patients with gastric carcinoma, and to study their significance and the relationship between these variations and the genesis of gastric carcinoma. METHODS: PCR amplified mitochondrial 12S rRNA of 44 samples including 22 from gastric carcinoma tissues and 22 from adjacent normal tissues, was detected by direct DNA sequencing. Then laser capture microdissection technique (LCM) was used to separate the cancerous cells and dysplasia cells with specific mutations. Denaturing high performance liquid chromatography (DHPLC) plus allele-specific PCR (AS-PCR), nest-PCR and polyacrylamide gel electrophoresis (PAGE) were used to further evaluate this mutant property and quantitative difference of mutant type between cancerous and dysplasia cells. Finally, RNAdraw biosoft was used to analyze the RNA secondary structure of mutant-type 12S rRNA. RESULTS: Compared with Mitomap database, some new variations were found, among which np652 G insertion and np716 T-G transversion were found only in cancerous tissues. There was a statistic difference in the frequency of 12S rRNA variation between intestinal type (12/17, 70.59%) and diffusive type (5/17, 29.41%) of gastric carcinoma (P<0.05). DHPLC analysis showed that 12S rRNA np652 G insertion and np716 T-G transversion were heteroplasmic mutations. The frequency of 12S rRNA variation in cancerous cells was higher than that in dysplasia cells (P<0.01). 12S rRNA np652 G insertion showed obviously negative effects on the stability of 12S rRNA secondary structure, while others such as T-G transversion did not. CONCLUSION: The mutations of mitochondrial 12S rRNA may be associated with the occurrence of intestinal-type gastric carcinoma. Most variations exist both in gastric carcinomas and in normal tissues, and they might not be the characteristics of tumors. However, np652 G insertion and np716 T-G transversion may possess some molecular significance in gastric carcinogenesis. During the process from normality to dysplasia, then to carcinoma, 12S rRNA tends to convert from homoplasmy (wild type) to heteroplasmy, then to homoplasmy (mutant type, np717 T-G).

Base Sequence↗

PubMed2005

[Expression of tobacco SKP1 gene induced by oligochitosan].

Oligochitosan is an effective inductor for plant resistance. To understand the induced resistance mechanism, mRNA differential display was used to isolate genes from Nicotiana tabacum var. Samsun NN and four enhanced-expression gene fragments were obtained and were reamplified. The reamplified products of appropriate size were isolated and purified before they were subcloned into PMD18-T vector. The results of plasmids digestion by EcoRI and HindIII and analysis of reverse Northern blot indicated that the expression of the four genes was enhanced by oligochitosan induction. Sequence and homology analysis show that they share 82% identity in nucleotide sequence with Nicotiana benthamiana SKP1 gene. Because the SKP1 protein as the core component of SCF (ubiquitin ligase enzyme E3) is relevant to plant resistance to virus, so these results suggested that oligochitosan can induce plant resistance and its mechanism may be relevant to ubiquitination.

Base Sequence↗

PubMed2003

Variations of mitochondrial D-loop region plus downstream gene 1 2S rRNA-tRNA(phe) and gastric carcinomas.

AIM: To explore the instabilities, polymorphisms and other variations of mitochondrial D-loop region and downstream gene 12S rRNA-tRNA(phe) in gastric cancers, and to study their relationship with gastric cancer. METHODS: Three adjacent regions (D-loop, tRNA(phe) and 12S rRNA) were detected for instabilities, polymorphisms and other variations via PCR amplification followed by direct DNA sequencing in 22 matched gastric cancerous tissues and para-cancerous normal tissues. RESULTS: PolyC or (CA) (n) instabilities were detected in 13/22(59.1 %) gastric cancers and 9/22(40.9 %) in the control (P>0.05). There existed 2/12(16.7 %) and 6/10(60 %) alterations of 12S rRNA-tRNA(phe) in well differentiated gastric cancers and poorly differentiated ones, respectively (P<0.05). Some new variations were found, among which np 318 and np 321 C-T transitions in D-loop region were two of the five bases for H-strand replication primer. np 523 AC-deletion and np 527 C-T transition occurred at mtTF1 binding site (mtTFBS), which were associated with the transcription of downstream mitochondrial genome. Seven samples showed the np 16 182 polyC instabilities, five of which simultaneously showed np 16 189 T-C transitions. CONCLUSION: There is no statistic significance of instabilities and polymorphisms in mitochondrial D-loop region between gastric cancerous and para-cancerous normal tissues, which suggests that the instability might relate to heredity or be dependent on aging. There is a significant correlation between differentiation degree of gastric cancer and variant frequencies of 12S rRNA-tRNA(phe). The poorly differentiated gastric cancers are more prone to 12S rRNA-tRNA(phe) variations, or gastric cancers with 12S rRNA-tRNA(phe) variations are more likely to be poorly differentiated. np 16 189 T-C transition may be one of the important reasons for polyC instability in gastric cancer.

Base Sequence↗

PubMed2003

[Optimization of cDNA microarray fabrication].

To optimize and screen the most suitable target gene length,concentration and printing solution in cDNA microarray, housekeeping genes, such as beta actin and GAPDH, were selected as targets and hepatitis B virus gene as negative control. The RT-PCR primers that spanned at least one intron and whose products were at between 189 bp and 1078 bp were designed with primer premier 5.0, so did the hepatitis B virus gene PCR primer. After polymerase chain reaction, the products were purified with ethanol and dissolved in 3xSSC, 50% DMSO and 0.5 mol/L carbonate buffer(pH=9.0)respectively. The concentrations of target genes were adjusted at 0.5 microg/microL, 1.0 microg/microL and 1.5 microg/microL. The hybridization signals had a good specificity. No signal showed in either negative control (HBV) or blank control (printing solution only). There was no significant difference in target gene lengths. The P value of beta actin (189 bp,491 bp,974 bp) and GAPDH (227 bp,552 bp,1078 bp) was 0.378 and 0.866 respectively. There was no significant difference among concentrations(P=0.648),too. However, the higher the concentration was, the stronger the signals would be. Among the three kinds of printing solution, 50% DMSO was the best (P=0.0001), while the other two had no difference by multi-comparison (P=0.142). The target gene at length between 200 bp and 1000 bp has got the same hybridization signals.50% DMSO printing solution and the target gene concentration of 0.5 microg/microl are suitable for good hybridization.

English Abstract↗

PubMed2002

[Preparation of low electroosmotic flow monolithic capillary column and the investigation on its properties].

Monolithic columns of capillary electrochromatography (CEC) with low electroosmotic flow (EOF) have been prepared by in-situ polymerization of butylmethacrylate and ethylene dimethacrylate, without any charged groups existed in the reaction mixture. The good reproducibility of the columns has been proved no matter if they are prepared in the same or different batches. Besides the traditional ternary porogenic mixture of 1-propanol, 1,4-butanediol and water, a binary porogenic mixture with only alcohols has also been adopted. In comparing with the ternary porogenic mixture, the design of binary mixture allows fine control of pore diameter and the formation of specific surface of the monolithic polymers. The effects of composition and ratio of porogenic reagents on EOF of the column systems have also been shown. The pore properties and EOF of monolithic columns with different porogenic mixtures were investigated. The results of scanning-electron micrograph show that the continuous beds were quite different from each other, while the proportions of 1-propanol were the same under these two situations. In addition, the Joule heat effect of such columns has been studied by varying the inner diameter of capillary columns. The effect of length of capillary on the EOF was also studied. Under the conditions of high pH and high concentrations of organic solvents, low EOF was obtained to satisfy different needs from the diversified separation modes. Through the separation of acidic compounds, monolithic columns with low EOF have shown potentialities in the analysis of charged samples.

English Abstract↗