Biomedical subjects

Guowang Xu

Publications and source records attributed to Guowang Xu.

At least 19 recordsLinked to original sources

PubMed2026

Column switching liquid chromatography dual mass spectrometry system for simultaneous untargeted metabolomics and targeted exposomics.

Exposome-wide association studies (ExWAS) require the detection of metabolites and exposures with diverse chemical properties across wide concentration ranges, a task that typically demands multiple analytical methods. To address this challenge, we develop an integrated column-switching two-dimensional liquid chromatography-dual mass spectrometry (2DLC-dual-MS) system. This system employs a 2DLC setup to sequentially separate polar and non-polar compounds with log P ranging from -8 to 15. The separated fractions are directed via a three-way valve to a high-resolution MS (HRMS) and a triple quadrupole MS (TQMS), enabling simultaneous untargeted metabolome analysis and targeted quantification of 601 exposures. The method is particularly suited for the concurrent analysis of metabolome and exposome in human blood, where their concentrations typically differ by 2-3 orders of magnitude. In a demonstration application on lung adenocarcinoma ExWAS, the system exhibits good stability over more than 300 consecutive injections for both metabolome and exposome analysis, confirming its robustness for ExWAS applications.

Metabolomics↗

PubMed2026

Comprehensive identification of carboxylic acids by using bromine isotope-based chemical isotope labelling and structure-guided molecular network.

Carboxylic acids (CAs) are important contributors to the flavor quality of sauce-flavor Chinese Baijiu, yet their comprehensive analysis remains challenging due to poor ionization efficiency, weak chromatographic retention, and limited annotation capability. Herein, we developed a workflow for the high-coverage discovery and annotation of CAs in Baijiu by coupling chemical isotope labeling-liquid chromatography-mass spectrometry with a structure-guided molecular network strategy (SGMNS). A bromine-containing derivatization reagent, 1-(3-aminopropyl)-3-bromoquinolin-1-ium bromide (APBQ), was designed and synthesized to exploit the natural isotope distribution of bromine and characteristic MS/MS fragmentation behavior. Following APBQ derivatization, the target CAs showed superior chromatographic retention and favorable analytical performance. Based on isotopic peak pairing in MS1 and diagnostic fragment validation in MS2, 372 potential CA derivatives were discovered from pooled Baijiu samples and 355 of them were validated by diagnostic fragments in MS2 spectra. To address the scarcity of derivatized spectral libraries, SGMNS was employed for annotation using a background network constructed from APBQ-labeled candidates derived from the Expanded Chinese Baijiu Compound Database. The developed method was further applied to profile Baijiu samples, revealing pronounced differences in CA composition across the seven fermentation rounds. Notably, rounds 3 to 5 exhibited the largest numbers of differential CAs. This study provided an effective analytical strategy for large-scale CA profiling, offering new insight into the chemical basis of flavor formation during multi-round fermentation of sauce-flavor Baijiu.

Isotope Labeling↗

PubMed2006

A GC-based metabonomics investigation of type 2 diabetes by organic acids metabolic profile.

"Metabonomics" method requires the development of rapid, advanced analytical tools and GC will play an important role for its special advantage. In this study we show the application of GC-based metabonomics to investigate the control and type 2 diabetes (DM2) patients by urinary organic acids metabolic profile. After peak matching, multivariate statistical analysis methods: principal components analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were used. The results showed that there was a relationship between organic acids metabolic profiles and DM2, and PLS-DA can distinguish the DM2 patients from the control. Five organic acids as potential biomarkers were identified.

Acids↗

PubMed2006

Eicosapentaenoic acid modifies lipid composition in caveolae and induces translocation of endothelial nitric oxide synthase.

Endothelial nitric oxide synthase (eNOS) plays a crucial role in the regulation of a variety of cardiovascular functions. Many studies have shown that dietary n-3 polyunsaturated fatty acids (PUFAs) have beneficial effects on coronary atherosclerosis. However, the mechanisms of n-3 PUFAs regulation in eNOS activation remain unknown. In the present study we investigated the effects of eicosapentaenoic acid (EPA, 20:5 n-3) on subcellular distribution of eNOS and lipid composition of caveolae. We demonstrated for the first time that EPA treatment profoundly altered lipid composition and fatty acyl substitutions of phospholipids in caveolae. We found that caveolin-1 was solely located in caveolae fractions in control cells, and EPA treatment displaced caveolin-1 from caveolae. eNOS was detected in the caveolin-enriched fractions and noncaveolae fractions in control cells. EPA treatment induced the translocation of eNOS from caveolae fractions to soluble fractions. P-eNOS was also distributed in both fractions. After EPA treatment, the level of p-eNOS in each fraction was increased but the distribution of which was unaffected. Moreover, the results of immunofluorescence confirmed that EPA could redistribute caveolin-1 and eNOS in plasma membrane. eNOS activity in HUVEC cells was increased after EPA treatment, which was in a dose dependent manner. And incubation with 50 microM EPA had the maximum effect on eNOS activity. Our results suggested that eNOS translocation was paralleled by a stimulated capacity for NO production in the cells. We found that total Akt and p-Akt were primarily presented in heavy membranes in control cells, and the relative level of p-Akt increased but the distribution did not change after EPA treatment. The distribution of CaM was slightly changed after EPA treatment. Our results indicated that n-3 PUFAs profoundly altered caveolae microenvironment, thereby modifying location and function of proteins in caveolae. EPA-induced alterations of lipid and proteins in caveolae may be an important mechanism in the pathophysiologic process of atherosclerosis.

Blotting, Western↗

PubMed2006

Analysis of Artemisia annua L. volatile oil by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

Artemisia annua L. is an annual herb native of Asia, it has been used for many centuries for the treatment of fever and malaria. In this paper, analysis of the volatile oil of Artemisia annua L. was performed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC x GC-TOF MS). Three hundred and three components were tentatively identified and terpene compounds are the main components of Artemisia annua L. volatile oil. Artemisinic acid is tentatively qualified.

Artemisia annua↗

PubMed2006

Determination of retention indices in constant inlet pressure mode and conversion among different column temperature conditions in comprehensive two-dimensional gas chromatography.

A method to determine the second dimensional real retention time, dead times on both dimensions and retention indices in constant inlet pressure mode was developed in comprehensive two-dimensional gas chromatography. At the same time, the conversion of GC x GC retention indices among different column temperature conditions were also conducted based on some thermodynamics parameters. The calculation accuracies are better than 1.0 retention index unit. Furthermore, a retention index database was developed and used to identify the compounds in a cigarette essential oil sample. It showed that identification by the database was of close agreement with by time-of-flight mass spectrometry, and some isomers could also be distinguished based on the retention index database.

Allergens↗

PubMed2006

Effect of PA-MSHA vaccine on plasma phospholipids metabolic profiling and the ratio of Th2/Th1 cells within immune organ of mouse IgA nephropathy.

Phospholipids as a class of important constituents in the biomembranes have been paid increasing attention in many fields. IgA nephropathy is now generally known to be the most common form of primary glomerulonephritis in the world. However, phospholipids metabolism in IgA nephropathy was not clear. Until recently, there was no effective treatment available for patients with IgA nephropathy. In this paper, effect of PA-MSHA vaccine on plasma phospholipid metabolic profile of mouse IgA nephropathy was investigated using high performance liquid chromatography/mass spectrometry (HPLC/MS) and principal components analysis (PCA). Female Balb/c mice were divided into four groups: model group, control group, PA-MSHA treatment group and medicine control group (dipyridamole+common threewingnut root). The experimental IgA nephropathy model was established by the immunity combination method of oral BSA and injection of SEB. It was found that combination of LC/MS technology with PCA can be successfully applied to phospholipids profile analysis, clearly classify the model group and normal group, and PA-MSHA treatment group is closer to the normal control group than medicine control group. The result showed that Th(2)/Th(1) (=CD(4)(+)CD(30)(+)/CD(4)(+)CD(30)(-)) of the model group is 20.70+/-3.57, which is significantly higher than that of the control group (1.34+/-0.14) (P<0.001). The Th(2)/Th(1) ratio of the PA-MSHA treatment group and the medicine control group are lower than that of the model group (P<0.01). It is suggested that mouse IgA nephropathy has the phospholipids metabolic abnormality, PA-MSHA vaccine cannot only regulate the abnormal phospholipids metabolism mouse with the IgA nephropathy, but also correct the over unbalance of Th(2)/Th(1) proportion.

Animals↗

PubMed2006

Determination of monoamines in urine by capillary electrophoresis with field-amplified sample stacking and amperometric detection.

A simple, rapid and low-cost method using capillary electrophoresis coupled with field-amplified sample stacking and electrochemical detection was developed for the separation and determination of monoamines. In this present work, a systematic study of the parameters (pH value and concentration of electrophoretic buffer, composition of sample solvent, injection voltage and time) affecting separation and on-line concentration of monoamines has been performed enabling the detection sensitivity of these monoamines to be improved by 5,000 times compared with the conventional electrokinetic injection. This developed method was applied to the direct analysis of these monoamines in human urine without off-line sample preconcentration. Due to the requirement for urine dilution to minimize the detrimental effects of high salt on analyte stacking, the real sensitivity improvement is about 50-fold when applying the optimized method to urine samples. In order to quantitate these monoamines accurately, internal standard calibration curves were constructed with standard monoamines in presence of salt with similar concentration as in human urine. In the method validation, the calibration curves were linear over a range of 1.0 x 10(-9) to 2.5 x 10(-8) mol/L for each monoamine and the limits of detection (signal to noise ratio of 3) for these monoamines were in the sub-nmol/L concentration range (6.0 x 10(-10) mol/L).

Catecholamines↗

PubMed2006

Simultaneous analysis of microsatellite instability and loss of heterozygosity by capillary electrophoresis with a homemade kit.

Microsatellite instability (MSI) and loss of heterozygosity (LOH), the alteration in length and strength of short tandem repeat sequences are an important molecular characteristic of many human tumors. MSI and LOH analysis has become an attractive method for diagnostic and tumor research purposes. A method for the simultaneous analysis of MSI and LOH at the five microsatellite loci (BAT-26, D17S261, D3S1283, D2S123 and D3S1611) was developed employing a cheap homemade kit to replace the expensive commercial kit on ABI 310 capillary genetic analyzer. After studying the effect of temperature and urea denaturant on microsatellite analysis, 8 mol/L urea and 60 degrees C were selected for assessing accurately fragment size of microsatellite alleles. Based on this method, 52 sporadic gastric cancers were screened, and MSI and LOH, at least one locus was observed in 15 of 52 (28.8%) patients. Moreover, it is found that a statistically significant association exists between MSI and LOH and tumor-differentiated level.

Base Sequence↗

PubMed2006

Methylation analysis of hMLH1 gene promoter by a bisulfite-sensitive single-strand conformation polymorphism-capillary electrophoresis method.

DNA methylation is an important epigenetic modification that alters transcription in those genes containing CpG islands. In this report, a novel DNA methylation analysis method was developed employing bisulfite-single strand conformation polymorphism combined with capillary electrophoresis (bisulfite-SSCP-CE). During the bisulfite treatment of genomic DNA, a high concentration of sodium bisulfite (4.8 mol/L) was preferred in order to shorten reaction time and minimize template degradation. The methylated and unmethylated ssDNA of hMLH1 promoter were simultaneously separated under the optimized CE conditions, including 6% SLPA with 10% glycerol as sieving medium, 25 degrees C as separation temperature and 12 kV as running voltage. The heterogeneous methylation of hMLH1 promoter was identified in 13 of 64 colorectal cancer patients. Moreover, hMLH1 promoter methylation had a significant relationship with protein expression loss and increased with the age of patients. Our results indicated that DNA methylation analysis for a large number of clinical samples would be facilitated by use of the bisulfite-SSCP-CE method.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Rapid detection of Staphylococcus aureus by a combination of monoclonal antibody-coated latex and capillary electrophoresis.

The rapid detection of pathogenic bacteria is extremely important in biotechnology and clinical diagnosis. CE has been utilized in the field of bacterial analysis for many years, but to some extent, simultaneous separation and identification of certain microbes from complex samples by CE coupled with UV detector is still a challenge. In this paper, we propose a new strategy for rapid separation and identification of Staphylococcus aureus (S. aureus) in bacterial mixtures by means of specific mAb-coated latex coupled with CZE. An appropriate set of conditions that selectively isolated S. aureus from the microorganisms Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae were established. S. aureus could be differentiated from the others by unique peaks in the electropherograms. The validity was also confirmed by LIF with antibodies specific to both the latex and the microbial cells. The LOD is as low as 9.0 x 10(5) colony forming unit/mL. We have also utilized this technology to identify S. aureus in a stool sample coming from a healthy volunteer spiked successfully with S. aureus. This CZE-UV technique can be applied to rapid diagnosis of enteritis caused by S. aureus or other bacterial control-related fields needing rapid identification of target pathogens from microbial mixtures. In theory, this method is suitable for the detection of any bacterium as long as corresponding bacterium-specific antibody-coated latex is available.

Antibodies, Bacterial↗

PubMed2006

Urinary profiling investigation of metabolites with cis-diol structure from cancer patients based on UPLC-MS and HPLC-MS as well as multivariate statistical analysis.

Nucleosides are an important class of metabolites and have been investigated as potential tumor biomarkers. A method based on ultra peerformance liquid chromatography (UPLC)-TOF MS was developed to analyze urinary nucleosides and other metabolites with cis-diol structure to distinguish between cancer patients and healthy persons and compare the results with those obtained by HPLC. The data showed that the UPLC method used about one third of the time required by HPLC and achieved a much better chromatographic resolution and increased sensitivity, the number of peaks detected by UV being 79 and 94 for HPLC and UPLC, respectively. With UPLC-TOF MS, more information was obtained about metabolites, the separation of cancer patients from healthy persons was significantly improved, and more potential biomarkers were found. The method based on UPLC-TOF MS is a powerful technique for the study of metabolite profiles.

Adult↗

PubMed2006

Study of the phase I and phase II metabolism of nephrotoxin aristolochic acid by liquid chromatography/tandem mass spectrometry.

Prolonged exposure to aristolochic acid (AA) was shown to pose rapid progressive renal fibrosis in Belgian women in a slimming regime in the early 1990s. AA was also demonstrated to be strong carcinogen in rats. The carcinogenicity of AA is generally believed to be related to the nitro-reduction of AA, in which the aristolactam-nitriumion ion with a delocalized positive charge is the ultimate carcinogen. In this study, the phase I and phase II metabolism of AA was investigated by using an in vitro system with rat liver S9 and an in vivo animal study with Sprague-Dawley rats. AA was found to have been undergone hydroxylation, lactam formation, and desnitro and desmethyl transformations. Three conjugated metabolites of AA, namely the N- and O-glucuronides of aristolactams, were detected directly in pre-concentrated urine sample, with no acid hydrolysis or enzymatic digestion. Structural elucidation of the metabolites was performed by using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The results indicated that N-glucuronidation was the major phase II metabolic pathway for the aristolactams formed by AA after their nitro-reduction.

Aerobiosis↗

PubMed2006

Rapid characterization of the sucrose esters from oriental tobacco using liquid chromatography/ion trap mass spectrometry.

Sucrose esters (SEs) from oriental tobacco are normally characterized by gas chromatography/mass spectrometry (GC/MS) after a long saponification and derivatization procedure. To simplify the process, a rapid method has been developed by using liquid chromatography coupled with electrospray ion trap mass spectrometry (LC/ESI-MSn). Using the characteristic fragmentation behavior of abundant SEs identified by GC/MS after purification by gel permeation chromatography (GPC) from cuticular waxes of green oriental tobacco leaf, two types of SEs from green and cured oriental tobacco were identified by MSn analysis. The first is one of three types reported formerly and has 13 SE homologues. However, the presence of unsaturation in one of the acyl substituents of this first type gave rise to a new series with three homologues. The other was found to be a new type and had three homologues. The proposed method enables the rapid and sensitive characterization of SEs from oriental tobacco.

Arylsulfonates↗

PubMed2006

Effect of docosahexaenoic acid on interleukin-2 receptor signaling pathway in lipid rafts.

Recent studies have shown that polyunsaturated fatty acids (PUFA) regulated the functions of membrane receptors in T cells and suppressed T cell -mediated immune responses. But the molecular mechanisms of immune regulation are not yet elucidated. Lipid rafts are plasma membrane microdomains, in which many receptors localized. The purpose of this study was to investigate the effect of DHA on IL-2R signaling pathway in lipid rafts. We isolated lipid rafts by discontinuous sucrose density gradient ultracentrifugation, and found that DHA could change the composition of lipid rafts and alter the distribution of key molecules of IL-2R signaling pathway, which transferred from lipid rafts to detergent-soluble membrane fractions. These results revealed that DHA treatment increased the proportion of polyunsaturated fatty acids especially n-3 polyunsaturated fatty acids in lipid rafts and changed the lipid environment of membrane microdomains in T cells. Compared with controls, DHA changed the localization of IL-2R, STAT5a and STAT5b in lipid rafts and suppressed the expression of JAK1, JAK3 and tyrosine phosphotyrosine in soluble membrane fractions. Summarily, this study concluded the effects of DHA on IL-2R signaling pathway in lipid rafts and explained the regulation of PUFAs in T cell-mediated immune responses.

Docosahexaenoic Acids↗

PubMed2006

Study on gender difference based on metabolites in urine by ultra high performance liquid chromatography/time of flight mass spectrometry.

Metabolites in urine can illustrate the physical condition of an individual as a whole. Ultra high performance liquid chromatography/time of flight mass spectrometry (UPLC/TOF-MS) is a relative new technique for the separation of complex samples. The aim of this study is to assess the feasibility of metabonomics in gender difference in unrestricted conditions, i.e. for healthy volunteers there are no strict controls such as food, life style and the collection of urine samples. In this work, 31 spontaneous urine samples were collected and analyzed by using UPLC/TOF-MS. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models were tested and compared in samples classification. The gender discrimination was highly improved and some gender related biomarkers were found by PLS-DA. These preliminary results suggested that UPLC/MS-based approaches coupled with pattern recognition show promise for metabonomics.

Chromatography, High Pressure Liquid↗

PubMed2006

High performance liquid chromatography-mass spectrometry for metabonomics: potential biomarkers for acute deterioration of liver function in chronic hepatitis B.

Metabonomics methods have been successfully applied to the drug discovery, toxicology, phytochemistry, and clinical fields. Here, we report a self-developed metabonomics platform which is based on high performance liquid chromatography-mass spectrometry (HPLC-MS) technique and applied to the investigation of acute deterioration of liver function in chronic hepatitis B to find the potential biomarkers. Sera from 50 healthy persons and 37 patients with acute deterioration of liver function in chronic hepatitis B were analyzed by HPLC-MS after removal of proteins. After de-noise, peak detection and peak alignment, the data of metabolites were fed to partial least squares discriminant analysis (PLS-DA) to find the potential biomarkers. According to the corresponding tandem mass results, several potential biomarkers were identified: Lysophosphatidyl Choline (LPC) C18:0, LPC C16:0, LPC C18:1, LPC C18:2, and glycochenodeoxycholic acid (GCDCA) (or its isomer glycodeoxycholic acid (GDCA)). On the basis of the relevant literature and pathway databases, the biological significance of the present study is discussed.

Adult↗

PubMed2006

Metabonomics study of intestinal fistulas based on ultraperformance liquid chromatography coupled with Q-TOF mass spectrometry (UPLC/Q-TOF MS).

Ultraperformance liquid chromatography coupled with Q-TOF mass spectrometry (UPLC/Q-TOF MS) is an effective and sensitive analytical tool. A UPLC/Q-TOF MS-based metabonomics technique was employed to investigate sera from 40 patients with intestinal fistula and 17 healthy volunteers in an effort to find potential biomarkers of the disease and reveal their pathophysiological changes. After the UPLC/Q-TOF analysis, the retention time and m/z data pair for each peak were detected. Partial least squares discriminant analysis (PLS-DA) and coefficient of correlation analysis were used for marker selection and identification. According to the data, nine potential biomarkers were identified: glycochenodeoxycholic acid, glycocholic [corrected] acid, taurochenodexycholic acid, taurodeoxycholic acid, and two kinds of lysophosphatidyl choline (C16:0 and C18:2) were found with increased concentrations in the patients, and phenylalanine, tryptophan, and carnitine were found with decreased concentrations in the patients. The results suggested that a subclinical hepatic injury and abnormal metabolism of two essential amino acids (phenylalanine and tryptophan), and a key compound of fatty acid synthesis and beta-oxidation (carnitine), occurred in the fistula patients. This work demonstrates the utility of metabonomics as a top-down systems biology tool for understanding clinical problems.

Biomarkers↗