PubMed Health⌕ Search

Biomedical subjects

Guowang Xu

Publications and source records attributed to Guowang Xu.

At least 55 records · Page 3Linked to original sources
PubMed2004

Discrimination of Type 2 diabetic patients from healthy controls by using metabonomics method based on their serum fatty acid profiles.

Metabonomics, the study of metabolites and their roles in various disease states, is a novel methodology arising from the post-genomics era. This methodology has been applied in many fields, including work in cardiovascular research and drug toxicology. In this study, metabonomics method was employed to the diagnosis of Type 2 diabetes mellitus (DM2) based on serum lipid metabolites. The results suggested that serum fatty acid profiles determined by capillary gas chromatography combined with pattern recognition analysis of the data might provide an effective approach to the discrimination of Type 2 diabetic patients from healthy controls. And the applications of pattern recognition methods have improved the sensitivity and specificity greatly.

Case-Control Studies↗
PubMed2004

Diagnosis of liver cancer using HPLC-based metabonomics avoiding false-positive result from hepatitis and hepatocirrhosis diseases.

Metabonomics, the study of metabolites and their roles in various disease states, is a novel methodology arising from the post-genomics era. This methodology has been applied in many fields. Current metabonomics practice has relied on mass spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) to analyze metabolites. In this study, a novel approach of using high-performance liquid chromatography (HPLC) in conjunction with developed software was employed. Using the principal components analysis method (PCA), all (113) peaks of urinary metabolites with a cis-diol structure from patients with hepatitis and hepatocirrhosis were compared to those from liver cancer patients. The results showed that the metabonomics-PCA method might be useful to differentiate between patients with hepatocirrhosis and hepatitis from patients with liver cancer while lowering false-positive rate. These findings also suggest that a subset of the urinary nucleosides identified with metabonomics correlate better with cancer diagnosis than the traditional single tumor marker alpha-fetoprotein (AFP).

Chromatography, High Pressure Liquid↗
PubMed2004

Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

Gas chromatography-mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to assign the components from GC x GC-TOF-MS analysis. The distributions of aliphatic hydrocarbons and aromatics were also investigated. Over 100 isoprenoid hydrocarbons were detected, including carotene degradation products, phytadiene isomers and carbocyclic diterpenoids. A total of 1800 hydrocarbons were tentatively identified, including aliphatic hydrocarbons, aromatics, and isoprenoid hydrocarbons. The identified hydrocarbons by GC x GC-TOF-MS were far more than those by GC-MS.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

Analysis of coenzyme Q(10) in human plasma by column-switching liquid chromatography.

A new method of determining coenzyme Q10 in human plasma was developed based on column-switching high performance liquid chromatography (HPLC). CoQ10 was quantitatively extracted into 1-propanol with a fast one-step extraction procedure, after centrifugation, the supernatant was cleaned on an octadecyl-bonded silica column and then transferred to reversed-phase column by a column-switching valve. Determination of CoQ10 was performed on a reversed-phase analytical column with ultraviolet detection at 275 nm and the mobile phase containing 10% (v/v) isopropanol in methanol at a flow-rate of 1.5 ml/min. The sensitivity of this method allows the detection of 0.1 microg/ml CoQ10 in plasma (S/N=3). The linearity between the concentration and peak height is from 0.05 to 20 mg/l. The reproducibility (R.S.D.%) of the method is less than 2% (within day) and less than 3% (between day), the average recovery is 100.9 + 2.1%, it takes only 30 min to complete an analysis procedure, suitable for the determination of CoQ10 in human plasma especially for batch analysis in clinical laboratories. Finally, the method was applied to determine the plasma CoQ10 levels in healthy subjects, hyperthyroid and hypothyroid patients.

Chromatography, High Pressure Liquid↗
PubMed2004

Application of comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry in the analysis of volatile oil of traditional Chinese medicines.

This paper reports comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF MS) analysis of Pogostemon cablin Benth (Cablin Parchouli) volatile oil. The suitable column system and operation conditions were chosen on the basis of the properties of composition of the volatile oil. One-dimensional gas chromatography (ID-GC) and GC x GC, GC-MS and GC x GC-TOF MS were compared under appropriate conditions, and the enhanced sensitivity and superior resolution of GC x GC were demonstrated. 394 components were tentatively identified by GC x GC-TOF MS.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

Detection of K-ras exon 1 mutations by constant denaturant capillary electrophoresis.

Among various mutation detection methods, constant denaturant capillary electrophoresis (CDCE) is one of the most common techniques for rapid identification of known or unknown mutations. In this report, a CDCE analysis method with homemade linear polyacrylamide (LPA) kit was developed on ABI 310 genetic analyzer, the effect and relationship of various denaturing factors in CDCE analysis were investigated and K-ras gene mutations of 31 coloerctal cancer patients were detected. Results indicate that, with the increase of chemical danaturant concentration, the optimum temperature was lowered, and when the concentration of urea (formamide) was higher than 7 M (40%), the homoduplex and heteroduplex of mutant samples were separated with difficulty. Detection results of K-ras gene in colorectal samples indicated that mutations were present in eight (26%) of 31 patients; most mutations were localized in codon 12, which is thought to be a critical step and plays an important role in human colorectal carcinogenesisas.

Acrylic Resins↗
PubMed2004

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection.

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360 degrees C) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.

Journal Article↗
PubMed2004

Characterization of cigarette smoke condensates by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS). Part 2: basic fraction.

Cigarette smoke condensate is a complex chemical matrix. Analysis of nitrogen-containing compounds present therein is very difficult because of the limitation of the peak capacity of conventional one-dimensional chromatography. Extensive and laborious sample preparation is frequently required or selective detectors are frequently used. In this study, the basic fraction of mainstream cigarette smoke condensate has been investigated by using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS). Auto data processing by TOFMS software combined with manual identification was used to assign the components. 377 nitrogen-containing compounds, including 155 pyridine derivatives, 104 quinoline/isoquinoine derivatives, and 56 pyrazine derivatives were tentatively identified. By selecting appropriate unique masses and in the light of the component positions in the structured chromatogram, alkyl-substituted pyridines, pyrazines, and quinolines/isoquinolines were separately shown and further validated. The peaks of eight individual positional isomers of two-carbon-substituted pyridines and thirteen positional isomers of methyl-substituted quinolines/isoquinolines were further confirmed, based on linear incremental retention behavior in combination with TOFMS and the structured chromatogram of GC x GC.

Journal Article↗
PubMed2004

Fluorescent-based single-strand conformation polymorphism/heteroduplex capillary electrophoretic mutation analysis of the P53 gene.

Fluorescent-based single-strand conformation polymorphism (F-SSCP) analysis with capillary electrophoresis (CE) is the most common method for the detection of mutation because of its high sensitivity and resolution. In this study, we prepared an inexpensive linear polyacrylamide (LPA), and successfully applied it to CE-SSCP analysis and tandem CE-SSCP/heteroduplex analysis (HA) of the P53 gene on an ABI capillary genetic analyzer. A comparison of the sieving capabilities of a homemade LPA and commercial polydimethylacrylamide (PDMA) demonstrates that the homemade LPA has a higher resolution, a shorter analysis time, and is more suitable for tandem SSCP/HA than commercial PDMA. To show the usefulness, mutations of P53 gene exon 7 - 8 in 37 tumor samples were investigated by using homemade LPA. The results indicate that 10 mutations were found in 9 of 37 cases; the majority of P53 mutations were missense mutations, and 70% were located in exon 7, which plays an important role in neoplastic progression in human tumorigenesis.

Acrylic Resins↗
PubMed2004

[Distribution of sulfur-containing compounds in the gasoline range petroleum products].

A capillary gas chromatography coupled with sulfur chemiluminescence detection (GC-SCD) method has been developed for detailed analysis and group-type characterization of sulfur compounds in gasoline range petroleum products. Chemical treatment of the samples was carried out using selective reactions for group-type classification of compounds. A total of 107 sulfur compounds were tentatively classified and identified based on standard substances and retention rule. The relative standard deviations (RSDs) of retention times were no more than 0.25%. The quantitative analysis on major sulfur compounds and total sulfur was carried out based on the linear response of sulfur chemiluminescence detector and the internal standard method. The recoveries were in the range of 96% - 115%. For the sulfur-containing compounds whose concentration exceeded 7 mg/kg, the RSDs of the determination were less than 8.9%. Various types of gasoline were analyzed and their sulfur distributions were investigated using the developed method. The results show that the method can be used to separate, identify and quantitate sulfur-containing compounds.

Chromatography, Gas↗
PubMed2004

[Characterization and quantitative determination of diesel fractions by comprehensive two-dimensional gas chromatography/time of flight mass spectrometry].

Comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GC x GC/TOFMS) has been applied for the analysis of diesel fractions. Two GC x GC methods are suggested. One is applied for exhaustive characterization and the other is used for the fast separation and quantitation of groups. No sample cleaning-up was required for both methods. Besides hydrocarbon compounds, the distributions of sulfur compounds and nitrogen compounds in a catalytic cracked diesel oil were investigated using the developed method. A total of 27 nitrogen compounds (including indole, alkyl indoles, carbazole and alkyl carbazoles) and 42 sulfur compounds (including benzothiophene, alkyl benzothiophenes, dibenzothiophene and alkyl dibenzothiophenes) were identified based on TOFMS and retention index. Quantitative determination of non-aromatics, mono-, di- and tri-aromatics of four diesel oils has been performed. The results are in good agreement with those from ASTM D2425 method.

Chromatography, Gas↗
PubMed2004

[Determination of curcumin in urine by capillary electrophoresis].

The major component of the plant curcuma longa (a widely cultivated tropical plant in Asia and Central America) is curcumin. Curcumin has been reported to have very strong anti-inflammatory, anti-carcinogenic, anti-oxidant, antiallergic, anti-bacterial, and anti-tumor activities. Little is known about the absorption, distribution, and metabolism of curcumin in human beings. The first step in in vivo physiological and pharmacokinetic studies is to develop a method to measure curcumin in body fluid. A rapid capillary electrophoretic (CE) method with diode array detection was established for the determination of curcumin in human urine. It could be rapidly determined within 2.5 min. The optimized experimental conditions were as follows: 15 mmol/L Na2B4O7 as buffer, applied voltage 20 kV, temperature 25 degrees C and detection wavelength 262 nm. The method has been validated and shows good performance with respect to selectivity, reproducibility and limit of detection. Curcumin had good linearity in the range of 10 - 300 mg/L, and the recoveries of curcumin added in urine were more than 96.3% with relative standard deviations (RSDs) less than 2.3%. The method is sensitive, fast and accurate and can be used to determine curcumin in urine.

Curcuma↗
PubMed2003

Determination of sulfur-containing compounds in diesel oils by comprehensive two-dimensional gas chromatography with a sulfur chemiluminescence detector.

This article reports an analytical method for separating, identifying and quantitating sulfur-containing compounds and their groups in diesel oils (170-400 degrees C) using comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. The identification of target compounds and their groups was based on standard substances, the group separation feature and tile-effect of comprehensive two-dimensional gas chromatography. The quantitative analysis on major sulfur compounds and total sulfur was carried out based on the linear response of sulfur chemiluminescence detector and the internal standards method. The results of total sulfur determination in the samples were compared with those from ASTM D 4294 standard method, the R.S.D. percentage were <6.02%, correctness of this method can meet the industrial requirement. To the end, the method developed was used to investigate the sulfur-containing compounds in different diesel oils, the result shows that the distribution of sulfur-containing compounds in diesel oils from different process units are apparently different. The sulfur compounds in fluid catalytic cracking (FCC), residuum fluid catalytic cracking (RFCC) diesel oils mainly exist in the form of alkyl-substituted dibenzothiophenes that add up to about 40-50% of the total sulfur, while this number is only 6-8 and 20-28% in visbreaking (VB) and delayed-coking (DC) diesel oils, respectively.

Chromatography, Gas↗
PubMed2003

Simultaneous genotyping of multiplex single nucleotide polymorphisms of the K-ras gene with a home-made kit.

Accurate and fast genotyping of single nucleotide polymorphisms (SNPs) is important in the human genome project. Here an automated fluorescent method that can rapidly and accurately genotype multiplex known SNPs was developed by using a homemade kit, which has lower cost but higher resolution than commercial kit. With this method, oncogene K-ras was investigated, four known SNPs of K-ras gene exon 1 in 31 coloerctal cancer patients were detected. Results indicate that mutations were present in 8(26%) of 31 patients, and most mutations were localized in codon 12. The presence of these mutations is thought to be a critical step and plays an important role in human colorectal carcinogenesisas.

Base Sequence↗
PubMed2003

Analysis of cigarette smoke condensates by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry I acidic fraction.

Cigarette smoke condensate is a complex chemical matrix, and analysis of its components is very difficult because of the limitation of the peak capacity and sensitivity of conventional chromatography and the extensive and laborious sample preparation that is frequently required. In this study, the acidic fraction of mainstream cigarette smoke condensate has been investigated by using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOFMS). Different column systems were tested and compared under proper GCxGC/TOFMS conditions. Auto data processing by TOFMS software combined with manual identification was used to assign the components. Over 1000 compounds, with S/N > or = 100, including 139 organic acids and over 150 phenols were tentatively identified by the developed method.

Journal Article↗
PubMed2003

A single-strand conformation polymorphism method by capillary electrophoresis with laser-induced fluorescence for detection of the T1151A mutation in hMLH1 gene.

Mutation of hMLH1 gene plays an important role in human tumorigenesis. A highly sensitive single-strand conformation polymorphism (SSCP) method for detection of the T1151A mutation in exon 12 of the hMLH1 gene was for the first time developed employing laser-induced fluorescence capillary electrophoresis (LIF-CE). Effects of the concentration of linear polyacrylamide solution, running temperature, running voltage and the addition of glycerol on SSCP analysis were investigated, and the optimum separation conditions were defined. Thirty colorectal cancer patients and eight lung cancer patients were screened and the T1151A mutation was found in four of them. Based on CE-sequencing the mutation was further confirmed. To our knowledge, this is for the first time that the T1151A mutation is found in lung cancer. Our method is simple, rapid, and highly sensitive and is well suited to the analysis of large numbers of clinical samples.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Determination of trace RA by capillary electrophoresis-solid-phase microextraction with direct UV detection.

A new method of offline solid-phase microextraction coupled with capillary electrophoresis (CE) [in an uncoated capillary using borax and boric acid in acetonitrile-water (40:60) as the running buffer] with UV detection at 254 nm is presented and used for direct determination of trace biomedically important retinoic acid (RA) without any derivation. As low as 138 ng/mL RA in aqueous solution can be determined using CE with UV detection with a concentration factor of 19.6 times.

Electrophoresis, Capillary↗