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Biomedical subjects

Jicun Ren

Publications and source records attributed to Jicun Ren.

24 records · Page 2Linked to original sources
PubMed2004

Detection of C677T mutation in methylenetetrahydrofolate reductase gene by denaturing high performance liquid chromatography.

In this paper, we described an assay for the detection of the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene using denaturing high-performance liquid chromatography (DHPLC). The conditions for DHPLC analysis were systematically investigated based on a general HPLC instrument (Prostar VARIAN). A 225 bp DNA fragment covering the 677 site of MTHFR gene was amplified by PCR technology using the purified DNA from whole blood or whole blood as template DNA. PCR products were directly injected without the need for purification. The C677T mutation could be clearly distinguished by DHPLC technology. Our data demonstrated that DHPLC was a powerful and alternative tool for detection of genetic variants and single-nucleotide polymorphisms to electrophoresis technology.

Base Sequence↗
PubMed2004

Ultraviolet sealing and poly(dimethylacrylamide) modification for poly(dimethylsiloxane)/glass microchips.

Simple sealing methods for poly(dimethylsiloxane) (PDMS)/glass-based capillary electrophoresis (CE) microchips by UV irradiation are described. Further, we examined the possibility to modify the inner surface of separation channels, using polymethylacrylamide (PDMA) as a dynamic coating reagent. The surface properties of native PDMS, UV-irradiated PDMS, and PDMA-coated PDMS were systematically studied by atomic force microscopy (AFM), infrared absorption by attenuated total reflection infrared (ATR-IR) spectroscopy, and contact angle measurement. We found that PDMA forms a stable coating on PDMS and glass surfaces, eliminating the nonhomogeneous electroosmotic flow (EOF) in channels on PDMS/glass microchips, and improving the hydrophilicity of PDMS surfaces. Mixtures of flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and fluorescein were separated in 35 s using PDMA-coated PDMS/glass microchips. A high efficiency of theoretical plates with at least 1365 (105 000 N/m) and a good reproducibility with relative standard deviations (RSD) below 4% in five successive separations were achieved.

Acrylamides↗
PubMed2004

A new quantitative method for circulating DNA level in human serum by capillary zone electrophoresis with laser-induced fluorescence detection.

We present a method for the quantification of circulating DNA in serum by capillary zone electrophoresis (CZE) with laser-induced fluorescence detection (LIF). The serum was digested by proteinase to release free DNA. SYBR Gold was utilized as DNA intercalating dye, fluorescein as internal standard (ISTD). CZE-LIF was applied for the separation and quantification of total circulating DNA. Good linearity (R = 0.9992) in the low range of DNA concentrations (0.5-40 ng/mL) and a detection limit of 0.5 ng/mL for DNA (S/N = 3) were obtained. Our data demonstrated that CZE-LIF system has a good linearity with excellent sensitivity and satisfactory reproducibility in the quantification of circulating DNA in serum. This method was successfully used for the quantification of circulating DNA levels in serum. We observed that the circulating DNA levels in certain cancer patients were significantly higher than that in healthy individuals. Compared to current methods, our protocol does not need the extraction of DNA from serum. Our preliminary results have illustrated that CZE-LIF system is simple, rapid, and sensitive, and it is well suitable for large-scale quantification of circulating DNA levels in clinical diagnosis.

Adult↗
PubMed2004

High-throughput DNA analysis by microchip electrophoresis.

DNA analysis plays a great role in genetic and medical research, and clinical diagnosis of inherited diseases and particular cancers. Development of new methods for high throughput DNA analysis is necessitated with incoming of post human genome era. A new powerful analytical technology, called microchip capillary electrophoresis (MCE), can be integrated with some experimental units and is characterized by high-speed, small sample and reagent requirements and high-throughput. This new technology, which has been applied successfully to the separation of DNA fragments, analysis of polymerase chain reaction (PCR) products, DNA sequencing, and mutation detection, for example, will become an attractive alternative to conventional methods such as slab gel electrophoresis, Southern blotting and Northern blotting for DNA analysis. This review is focused on some basic issues about DNA analysis by MCE, such as fabrication methods for microchips, detection system and separation schemes, and several key applications are summarized.

DNA↗
PubMed2002

Uracil in human DNA from subjects with normal and impaired folate status as determined by high-performance liquid chromatography-tandem mass spectrometry.

A sensitive and selective method for determination of the uracil content in human DNA was first developed on the basis of high-performance liquid chromatography-tandem mass spectrometry. Uracil was excised from DNA using uracil DNA glycosylase. The released uracil was derivatized with 4-bromomethyl-7-methoxycoumarin, thereby forming bis-N,N'-(4-methylene-7-methoxycoumaryl)-uracil (uracil-MMC). 15N2-Uracil was used as an internal standard. The analytes were separated on an Adsorbsphere XL ODS column. A SCIEX API III tandem mass spectrometer equipped with a turbo ion-spray interface was used as the detector. Multiple reaction monitoring using the parent --> product ion combinations of m/z 489 --> 232 and 491 --> 233 were used to detect uracil-MMC and the internal standard, respectively. The detection limit for this assay is <1.0 x 10(-10) mol/L uracil, and the linearity is from 1.0 x 10(-10) to 2.5 x 10(-6) mol/L. The method was used for determination of uracil in human DNA. Our data show that the uracil levels in human DNA isolated from peripheral white blood cells did not differ between subjects with folate deficiency and subjects with normal red cell folate levels.

Base Composition↗