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1.
Phytoestrogens (isoflavones and lignans) are of increasing interest due to their potential to prevent certain types of complex diseases. However, epidemiological evidence is needed on the levels of phytoestrogens and their metabolites in foods and biological fluids in relation to risk of these diseases. We report an assay for phytoestrogens which is sensitive, accurate, and uses low volumes of sample. Suitable for epidemiological studies, the assay consists of a simple sample preparation procedure and has been developed for the analysis of five isoflavones (daidzein, O-desmethylangolensin, equol, genistein, and glycitein) and two lignans (enterodiol and enterolactone), which requires only 200 microl of urine and utilizes one solid-phase extraction stage for sample preparation prior to derivatization for GC/MS analysis. Limits of detection were in the region 1.2 ng/ml (enterodiol) to 5.3ng/ml (enterolactone) and the method performed well in the UK Government's Food Standards Agency-sponsored quality assurance scheme for phytoestrogens. For the first time, average levels of all the above phytoestrogens were measured in samples of urine collected from a free living population sample of women. Results show a large range in both the amount and the type of phytoestrogens excreted.  相似文献   

2.
The fine structural motifs of sialic acids, a frequent terminal monosaccharide of glycans, seem to contain essential biological properties. To identify such subtle structural differences, a reliable method was developed for the qualitative and quantitative identification of sialic acids present in different tissues and fluids. This method involved, after liberation of sialic acids by mild acid hydrolysis, their methyl esterification using diazomethane in the presence of methanol and the formation of volatile derivatives using heptafluorobutyric anhydride. The derivatives were analyzed by gas chromatography coupled to mass spectrometry in the electron impact mode. This technique allowed the separation and identification of a large variety of sialic acids, including different O-acylated forms of N-acetyl and N-glycolyl neuraminic acids and of 3-deoxy-D-glycero-D-galacto-nonulosonic acid (Kdn). This method allowed also identifying 8-O-methylated and 8-O-sulfated derivatives, de-N-acetylated neuraminic acid, and 1,7-sialic acid lactones. Compounds present in very complex mixtures could be identified through their fragmentation patterns. Because of the stability of the heptafluorobutyrate derivatives, this method presents important improvements compared to the previous techniques, because it can be frequently applied on very small amounts of crude samples. This methodology will support progress in the field of the biology of sialic acids.  相似文献   

3.
We performed prenatal diagnosis of organic acid disorders using two mass spectrometric methods; gas chromatography mass spectrometry (GC/MS) and tandem mass spectrometry (ESI/MS/MS). Of 28 cases whose amniotic fluid was tested, 11 cases were diagnosed as "affected". All cases whose samples were diagnosed as "unaffected" were confirmed to have no symptoms or abnormalities in urinary organic acid analysis after birth. Of the 11 "affected" cases, two cases were missed by ESI/MS/MS but not by GC/MS. When the stability of metabolites in amniotic fluid was checked, it was found that acylcarnitines degraded in one week at room temperature, whereas organic acids such as methylmalonate or methylcitrate were stable for at least 14 days. Prenatal diagnosis by analysis using simultaneous two or more methods may be more reliable, though attention should be paid to sample transportation conditions.  相似文献   

4.
Abscisic acid and 2-trans-abscisic acid each with three deuterium atoms in the C-3 methyl group, have been synthesized chemically and used as internal standards in selected ion monitoring experiments to establish the endogeneous concentrations of these compounds and their conjugates in turgid and wilted Eucalyptus haemastoma leaves. The analytical procedure used GC/CIMS(methane) to detect the methyl esters of abscisic acid, 2-trans-abscisic acid and their deuterated internal standards. A three-fold increase in the concentration of abscisic acid occurred on wilting and the amounts of 2-trans-abscisic acid and conjugates of both compounds were determined.  相似文献   

5.
Currently available radioimmunoassay methods for estradiol in serum lack sufficient sensitivity and precision to monitor estradiol levels in patients placed on third generation aromatase inhibitors. We recently validated a gas chromatography/tandem mass spectrometry assay (GC/MS/MS) for estradiol and determined estrogen levels in normal post-menopausal women and in women with breast cancer before and during administration of aromatase inhibitors. Validation of the GC/MS/MS assay in human plasma and human serum included determination of assay sensitivity (<0.63 pg/ml), precision (all CVs less than 17.8%), recovery (98-103%), and linearity of recovery (R=0.998). Levels of estradiol were lower when assayed by GC/MS/MS compared to RIA under all conditions (7.26+/-4.82 pg/ml versus 11.9+12.0 pg/ml in normal post-menopausal women; 5.88+/-3.43 pg/ml versus 13.8+/-7.5 pg/ml in breast cancer patients prior to treatment; and<0.63 pg/ml versus 5.8+/-4.1 pg/ml during aromatase inhibitor therapy). Fifty-five women treated either with atamestane/toremiphene or letrozole/placebo were monitored for estradiol levels at 4, 8 and 12 weeks of therapy. The mean levels of estradiol during aromatase inhibitor therapy was 5.8+/-4.1 pg/ml as measured by RIA and <0.63 pg/ml by GC/MS/MS. The degree of suppression with the aromatase inhibitors as detected by RIA was 58% versus >89% by GC/MS. These results suggest that most RIA methods detect cross-reacting estrogen metabolites and yield higher measured levels than GC/MS/MS. Several pharmacological and clinical considerations suggest that GC/MS/MS should become the preferred method for monitoring aromatase inhibitor therapy.  相似文献   

6.
Oral sodium phenylbutyrate (SPB) is currently under investigation as a histone deacetylation (HDAC) inhibitor in Huntington disease (HD). Ongoing studies indicate that symptoms related to HD genetic abnormalities decrease with SPB therapy. In a recently reported safety and tolerability study of SPB in HD, we analyzed overall chromatographic patterns from a method that employs gradient liquid chromatography with series electrochemical array, ultraviolet (UV), and fluorescence (LCECA/UV/F) for measuring SPB and its metabolite phenylacetate (PA). We found that plasma and urine from SPB-treated patients yielded individual-specific patterns of approximately 20 metabolites that may provide a means for the selection of subjects for extended trials of SPB. The structural identification of these metabolites is of critical importance because their characterization will facilitate understanding the mechanisms of drug action and possible side effects. We have now developed an iterative process with LCECA, parallel LCECA/LCMS, and high-performance tandem MS for metabolite characterization. Here we report the details of this method and its use for identification of 10 plasma and urinary metabolites in treated subjects, including indole species in urine that are not themselves metabolites of SPB. Thus, this approach contributes to understanding metabolic pathways that differ among HD patients being treated with SPB.  相似文献   

7.
We have studied rapid and simple sugar mapping using liquid chromatography/electrospray ionization mass spectrometry (LC/MS) equipped with a graphitized carbon column. The oligosaccharide mixture was separated on the basis of the sequence, branching structure, and linkage, and each oligosaccharide was characterized based on its molecular mass. In this study we demonstrated the usefulness of capillary LC/MS (CapLC/MS) and capillary liquid chromatography/tandem mass spectrometry (CapLC/MS/MS) as sensitive means for accomplishing the structural analysis of oligosaccharides in a low-abundance glycoprotein. The carbohydrate heterogeneity and molecular mass information of each oligosaccharide can be readily obtained from CapLC/MS of a small amount of glycoprotein. CapLC/MS/MS provided b-ion series, which is informative with regard to monosaccharide sequence. Exoglycosidase digestion followed by CapLC/MS elucidated a carbohydrate residue linkage. Using this method, we characterized N-linked oligosaccharides in hepatocyte growth factor produced in mouse myeloma NS0 cells as the complex-type bi-, tri-, and tetraantennary terminated with N-glycolylneuraminic acids and alpha-linked galactose residues. Sugar mapping with CapLC/MS and CapLC/MS/MS is useful for monitoring glycosylation patterns and for structural analysis of carbohydrates in a low-abundance glycoprotein and thus will become a powerful tool in biological, pharmaceutical, and clinical studies.  相似文献   

8.
A method utilizing thermospray high-performance liquid chromatography/mass spectrometry for the separation and direct analysis of carnitine, acetylcarnitine, and propionylcarnitine is described. On-column analysis of mixtures of the acylcarnitines with their corresponding stable, isotope-labeled analogs at nanomolar concentrations has indicated that isotope dilution assays can be applied towards the analysis of carnitine and short-chain acylcarnitines present in biological samples.  相似文献   

9.
An important component of proteomic research is the high-throughput discovery of novel proteins and protein–protein interactions that control molecular events that contribute to critical cellular functions and human disease. The interactions of proteins are essential for cellular functions. Identifying perturbation of normal cellular protein interactions is vital for understanding the disease process and intervening to control the disease. A second area of proteomics research is the discovery of proteins that will serve as biomarkers for the early detection, diagnosis and drug treatment response for specific diseases. These studies have been referred to as clinical proteomics. To discover biomarkers, proteomics research employs the quantitative comparison of peptide and protein expression in body fluids and tissues from diseased individuals (case) versus normal individuals (control). Methods that couple 2D capillary liquid chromatography (LC) and tandem mass spectrometry (MS/MS) analysis have greatly facilitated this discovery science. Coupling 2D-LC/MS/MS analysis with automated genome-assisted spectra interpretation allows a direct, high-throughput and high-sensitivity identification of thousands of individual proteins from complex biological samples. The systematic comparison of experimental conditions and controls allows protein function or disease states to be modeled. This review discusses the different purification and quantification strategies that have been developed and used in combination with 2D-LC/MS/MS and computational analysis to examine regulatory protein networks and clinical samples.  相似文献   

10.
Ethyl glucuronide (EtG) has been shown to be a suitable marker of excessive alcohol consumption. Determination of EtG in hair samples may help to differentiate social drinkers from alcoholics, and this testing can be widely used in forensic science, treatment programs, workplaces, military bases as well as driving ability test to provide legal proof of drinking. A method for determination of EtG in hair samples using large volume injection-gas chromatography-tandem mass spectrometry (LVI-GC/MS/MS) was developed and validated. Hair samples (in 1 mL deionized water) were ultrasonicated for 1h and incubated overnight; these samples were then deproteinated to remove impurities and derivatisated with 15 μL of pyridine and 30 μL of BSTFA. EtG was detected using GC/MS/MS in multiple-reaction monitoring mode. This method exhibited good linearity: y=0.0036 x+0.0437, R2=0.9993, the limit of detection and the limit of quantification were 5 pg/mg and 10 pg/mg, respectively. The extraction recoveries were more than 60%, and the inter-day and intra-day relative standard deviations (RSD) were less than 15%. This method has been applied to the analysis of EtG in hair samples from 21 Chinese subjects. The results for samples obtained from all of those who were teetotallers were negative, and the results for the other 15 samples ranged from 10 to 78 pg/mg, except for one negative sample. These data are the basis for interpretation of alcohol abuse.  相似文献   

11.
Although, 1,3-butadiene is a known human carcinogen emitted from mobile sources, little is known about traffic-related human exposure to this toxicant. This pilot study was designed to characterize traffic-related environmental exposure to 1,3-butadiene and evaluate its urinary mercapturic acids as biomarkers of exposure in these settings. Personal air samples and multiple urine samples were collected on two separate occasions from three groups of individuals that differed by spatial proximity as well as intensity of traffic: (i) toll collectors, (ii) urban-weekday and (iii) suburban-weekend group. Air samples were analyzed using thermal desorption followed by GC/MS and urine samples were analyzed using isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) for two mercapturic acids of 1,3-butadiene: monohydroxy-3-butenyl mercapturic acid (MHBMA) and 1,2-dihydroxybutyl mercapturic acid (DHBMA). Exposure differed between groups (p<0.05) with median values of 2.38, 1.62 and 0.88 microg/m(3) for toll collectors, the urban-weekday group and the suburban-weekend group, respectively. A refined ID-LC-MS/MS method enabled detection of MHBMA, previously detected only in occupational settings, with high frequency. MHBMA and DHBMA were detected in 95 and 100% of urine samples at levels (mean+/-S.D.) of 9.7+/-9.5, 6.0+/-4.3 and 6.8+/-2.6 ng/mL for MHBMA and 378+/-196, 258+/-133 and 306+/-242 ng/mL for DHBMA for the three different groups, respectively. Mean biomarker levels were higher among the toll collectors compared to the other two groups, however, the differences were not statistically significant (p>0.05). This study is the first to evaluate 1,3-butadiene biomarkers for subtle differences in environmental exposures. However, additional research will be required to ascertain whether the lack of statistical association observed here is real or attributable to unexpectedly small differences in exposure between groups (<1 microg/m(3)), non-specificity of the biomarker at low exposure, and/or small sample size.  相似文献   

12.
《Free radical research》2013,47(10):1233-1238
Abstract

The lipid peroxidation product 4-hydroxynonenal (HNE) is a biomarker of oxidative stress which is essentially involved in the pathophysiology of many diseases. The analysis of HNE is challenging because this aldehyde is extremely reactive and thus unstable. Hence, we adopted a gas chromatography–mass spectrometry (GC–MS) method based on derivatization of HNE with pentafluorobenzylhydroxylamine–HCl followed by trimethylsilylation to trimethylsilyl ethers. Ions representative for a negative ion chemical ionization mode were recorded at m/z = 152 for HNE and at m/z = 162 for the deuterated analogon (HNE-d11) as internal standard. This excellent stable and precise GC–MS method was carefully validated for HNE, and showed good linearity (r2 = 0.998), and high specificity and sensitivity. Within-day precisions were 4.4–6.1% and between-day precisions were 5.2–10.2%. Accuracies were between 99% and 104% for the whole calibration range (2.5–250 nmol/L) of HNE.

To examine the versatility of this modified GC–MS method, we analyzed HNE in ethylenediaminetetraacetic acid (EDTA) plasma in a well-defined collective of migraine patients; recently published. The results underline our former observations that women with migraine are afflicted with increased levels of HNE. Patients with thyroidal dysfunction showed no significant HNE alterations. This was confirmed by normal HNE EDTA plasma levels in hyper- und hypothyroid Sprague-Dawley rats.

Taken together, the GC–MS method presented herein is of excellent quality to record oxidative stress-related bioactive HNE levels. This is important for a reorientation of oxidative stress analytics in other human diseases first of atherosclerosis and cancer.  相似文献   

13.
Partial acid hydrolysis and methanolysis released disaccharides and disaccharide methylglycosides from the glycoproteins, ovomucoid and porcine gastric mucin in amounts of 0.5--7 microgram disaccharide per mg of glycoprotein. These disaccharides were fractionated by gas chromatography as the trimethylsilyl (Me3Si) derivatives. The composition of recovered disaccharides has been determined by hydrolysis and rechromatography of the Me3Si monosaccharides. The intersaccharide linkages of the disaccharides have been determined by electron impact mass spectrometry. This simple and rapid method can give structural information on small glycoprotein samples.  相似文献   

14.
A rapid method for measuring 3-methylhistidine (3MH) in rat and human urine with higher sensitivity and precision than any previously reported method is described using internal standard [1-(13)C]3MH (M+1) and negative chemical ionization (NCI) gas chromatography/mass spectrometry (GC/MS). Internal standard [1-(13)C]3MH (M+1) was added to rat and human urine samples, hydrolyzed, and absorbed onto cation exchange columns. The column eluent was dried and derivatized for GC/MS analysis. Quantification of 3MH levels was accomplished by monitoring the m/z 204 fragment. The m/z 204 fragment was chosen due to the fragment's abundance and stability as determined by analysis of [methyl-(2)H(3), (18)O(2)]3MH (M+7) and [methyl-(13)C]3MH (M+1) fragmentation patterns under NCI conditions. This method shows excellent linearity (0.9989) over the range studied (0-0.5 mol), high recovery (95.9%), and low coefficient of variation (4.7%). The described method is sensitive enough to detect 6.8 pmol amount of urinary 3MH with a precision of 9.1%. The in vivo utility of this method to quantify urinary 3MH was tested in a burn injury rat model and on urine specimens from pediatric burn patients. Data obtained from the urine of burn-injured rats and pediatric burn patients match previously reported trends and validate the in vivo utility of this method.  相似文献   

15.
Sediment in urine may contain low-molecular-weight compounds that should be included in the analysis. To date, no systematic investigation has addressed this issue. We investigated three primary factors that influence the extraction efficiency of metabolites during preparation of urine samples for metabolomic research: centrifugation, pH, and extraction solvents. Obtained with the use of gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) technique and principal component analysis (PCA), our results indicate that (1) conventional centrifugation causes an apparent loss of some metabolites, indicating that urine samples for metabolomic research should not be centrifuged before procedures are undertaken to recover the metabolites; (2) pH adjustment has a large impact on the recovery of metabolites and is therefore not encouraged; (3) with design of experiment analysis, methanol and water yield the optimal extraction efficiency. Differences between rat and human urine were observed and are discussed. Ninety-nine metabolites identified in rat and human urine are presented. An efficient protocol is proposed for the pretreatment of urine samples.  相似文献   

16.
Several microbial volatile organic compounds (MVOCs) that can serve as potential chemical markers for microbial contamination in tobacco have been identified. Four different fungal species, Aspergillus niger (AN), A. ornatus (AO), Pencillium chrysogenum (PC) and Rhizopus stolonifer (RS), commonly reported in moldy tobacco were cultured and screened for MVOCs. Because the MVOCs emitted by a microbial species are substrate specific, the fungal strains were separately grown on potato dextrose agar (PDA) and tobacco products. MVOCs from the mold cultures grown on PDA and tobacco products were extracted using closed-loop stripping analysis (CLSA) and identified by gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). Some of the prominent tobacco mold markers identified by this method include: 1-octen-3-ol; 2-octen-1-ol; 2-methyl-1-butanol; 3-methyl-1-butanol; 1-octene and 2-pentanone. In particular, 1-octen-3-ol was detected in all the mold cultures and moldy tobacco samples analyzed. Olfactory evaluation of 1-octen-3-ol indicated a characteristic musty odor and the odor threshold was determined to be approximately 200 ng/ml. The limits of detection for 1-octen-3-ol using GC/TOF-MS and GC/mass selective detector (MSD) in the full-scan mode and selected ion monitoring (SIM) mode were investigated. The CLSA-GC/TOF-MS demonstrates a fast, sensitive and semi-quantitative analytical technique for screening tobacco materials for the presence of mold via chemical markers of microbial contamination.  相似文献   

17.
A new sensitive and specific method using liquid chromatography/tandem mass spectrometry for determination of bryostatin 1 was developed and validated. Sample pretreatment involved a double liquid-liquid extraction step with a mixture of acetonitrile/n-butyl chloride (1/4, v/v). Separation of the compound of interest, including the internal standard paclitaxel, was achieved on a Waters X-Terra C18 (50 x 2.1 mm i.d., 3.5 microm) analytical column with acetonitrile/water mobile phase (80:20, v/v) containing 0.1% formic acid using isocratic flow at 0.15 mL/min for 13 min. The analytes of interest were monitored by tandem mass spectrometry with electrospray positive ionization. The linear calibration curves were generated over the range of 50-2000 pg/mL with values for the coefficient of determination of >0.99. The values for both within-day and between-day precision and accuracy were <15%. This method was used to characterize the plasma pharmacokinetics of bryostatin 1 at doses of 20 microg/m2) to optimize treatment with this agent.  相似文献   

18.
Recent developments in combined separations with mass spectrometry for sensitive and high-throughput proteomic analyses are reviewed herein. These developments primarily involve high-efficiency (separation peak capacities of ~103) nanoscale liquid chromatography (flow rates extending down to approximately 20 nl/min at optimal liquid mobile-phase separation linear velocities through narrow packed capillaries) in combination with advanced mass spectrometry and in particular, high-sensitivity and high-resolution Fourier transform ion cyclotron resonance mass spectrometry. Such approaches enable analysis of low nanogram level proteomic samples (i.e., nanoscale proteomics) with individual protein identification sensitivity at the low zeptomole level. The resultant protein measurement dynamic range can approach 106 for nanogram-sized proteomic samples, while more abundant proteins can be detected from subpicogram-sized (total) proteome samples. These qualities provide the foundation for proteomics studies of single or small populations of cells. The instrumental robustness required for automation and providing high-quality routine performance nanoscale proteomic analyses is also discussed.  相似文献   

19.
The Aconitum alkaloids aconitine, mesaconitine, and hypaconitine are the main toxic components in a commonly used traditional Chinese herbal medicine Fu Zi. To provide guidelines for the safe use of this medicine, metabolic changes in Wistar rats caused by these compounds were investigated by means of integrated analysis of two metabonomic approaches: 1H nuclear magnetic resonance (NMR) and gas chromatography/time-of-flight mass spectrometry (GC/TOF–MS). Rats were given a single dose of aconitine, mesaconitine, hypaconitine, or vehicle. The largest metabolic changes were observed 6 h after treatment. Every group receiving a dose had higher urine concentrations of glucose, acetate, dimethylglycine, succinate, and alanine and had lower concentrations of creatinine, citrate, 2-oxoglutarate, N-acetylated metabolites, and trimethylamine-N-oxide (TMAO) than did the control group. These results may reflect the perturbation of renal tubular function within the first 24 h after treatment. The results also revealed a larger perturbation of metabolic profiles in the aconitine group than in the mesaconitine and hypaconitine groups, illustrating how these alkaloids exhibit different toxicities. An analysis of plasma samples collected 7 days postdose showed that there were higher levels of lactate, alanine, and lipids along with lower levels of glucose, β-hydroxybutyrate, and creatine in the plasma of the aconitine and mesaconitine groups than there were in the control and hypaconitine groups. The GC/TOF–MS data from the plasma samples showed that the number of metabolites, with significant changes or with a tendency to change, in the aconitine and mesaconitine groups were dissimilar, suggesting a possible difference in the acute toxicity mechanisms of these alkaloids.  相似文献   

20.
Our primary focus in this research was to identify and characterize its bioactive compounds for potential therapeutic use. Twenty-seven metabolites of Polygonum orientale were identified using LC-QTOF tandem mass spectrometry. Interestingly, P. orientale extracts included several highly oxygenated flavonoids were isolated from P. orientale by column chromatography. 13C NMR data of highly oxygenated flavonoids (1–7) are reported here for the first time. In addition, nitric oxide, 1,1-diphenyl-2-picrylhydrazyl, and water-soluble tetrazolium salt assays were carried out on the isolated compounds to investigate their anti-inflammatory, anti-oxidant, and neuroprotective activities, respectively. Compounds 1, 2, 3, 5, 7, and 8 significantly attenuated lipopolysaccharide-stimulated NO production in BV2 cells without affecting cell viability. Compounds 9–12 exhibited significant antioxidant activity, while compounds 8, 9, and 12 exhibited protective effects against glutamate-induced neurotoxicity in HT22 cells. Our results indicate that P. orientale is a promising source of natural agents for the potential treatment of inflammation and neurodegenerative diseases.  相似文献   

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