共查询到20条相似文献,搜索用时 15 毫秒
1.
Peter Pagel Rainer Schubert Hans Uwe Wolf 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2000,746(2):115
We developed sample preparation methods for the detection of various biogenic phenylethylamine derivatives such as 3,4-dihydroxyphenylalanine, and their cyclisation products with aldehydes, i.e., 1,2,3,4-tetrahydroisoquinoline derivatives in blood samples. 1,2,3,4-Tetrahydroisoquinolines are considered to play an essential role as neurotoxic compounds in the pathomechanism of Parkinson’s disease. We used reversed-phase high-performance liquid chromatography with ultraviolet and fluorescence detection for separation and identification. Ultrafiltration, protein precipitation and solid-phase extraction were investigated for purification of blood samples and enrichment of various compounds with a wide range of hydrophilicity and hydrophobicity. Protein precipitation by methanol and perchloric acid is a fast method to separate the analytes from the plasma matrix. A higher yield of the analytes is attained with prior addition of an alkylsulfonic acid giving a fine-grained precipitate. With the addition of ion pairing compounds into the sample it is possible to enrich not only lipophilic compounds such as norharman, tryptamine and melatonin, but also hydrophilic ones such as 3,4-dihydroxyphenylalanine by reversed-phase solid-phase extraction. Ultrafiltration is not useful as a screening method. 相似文献
2.
3.
Rodrigues CM Rinaldo D Sannomiya M dos Santos LC Montoro P Piacente S Pizza C Vilegas W 《Phytochemical analysis : PCA》2008,19(1):17-24
The isolation of polyphenolic compounds from an infusion of the Brazilian plant Davilla elliptica (Dilleniaceae), used as tea by virtue of its digestive properties, is described. An improved preparative HPLC method was used in order to isolate pure polyphenols from the complex mixture. Liquid-liquid extraction and solid-phase extraction were employed to minimise the interference of polymeric compounds and to provide an enriched fraction of the compounds of interest. The identification of the isolated compounds was performed using analytical HPLC as well as direct injection electrospray ionisation ion trap tandem mass spectrometry (ESI-IT-MS/MS). The high flavonoid content suggests that D. elliptica may be a promising source of compounds to produce natural phytomedicines. 相似文献
4.
Thomas P. Davis Charles W. Gehrke Charles W. Gehrke Thomas D. Cunningham Kenneth C. Kuo Klaus O. Gerhardt Harold D. Johnson Charles H. Williams 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1979,162(3):293-310
A remarkably sensitive, simple and selective reversed-phase high-performance liquid chromatographic (HPLC) method has been developed, allowing, for the first time, the direct measurement of histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin and tyramine in a single sample of plasma (2 ml), tissue (0.2 g), or urine. The biogenic amines were modified by pre-column derivatization with o-phthalaldehyde which stabilizes the molecules, aids in extraction, and improves HPLC detection at the nanogram level. To minimize losses during the sampling procedure a careful collection procedure was designed. 相似文献
5.
6.
7.
A simple technique using reverse-phase ion-pair liquid chromatography for measurement of exogenous thiosulfate is described. Accurate measurement of thiosulfate in plasma and urine was permitted by precolumn derivatization with monobromobimane, a substance that readily yields fluorescent compounds upon reaction with a variety of biologically important nucleophiles including glutathione, cysteine, and sulfite. Using an injection volume of 50 microliters, as little as 0.16 nmol of thiosulfate was reliably measured. The interassay precision of the method was reflected by a coefficient of variation of 7.7% while the coefficient of variation for interassay analysis was 2.6%. Recovery of thiosulfate from plasma was 96.9 +/- 3.2% and greater than 98% from urine. The simplicity, sensitivity, and precision of the method make it ideal for the study of thiosulfate and other important nucleophiles in body fluids. 相似文献
8.
9.
Xiao Qing Gu Bronwyn Fryirs Laurence E. Mather 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,719(1-2)
Chiral separation of rac-bupivacaine extracted from blood was achieved with similar limits of detection but using a much simpler sample preparation than reported previously. The simple one-step sample preparation devised was highly robust and efficient and allowed a very high throughput of samples. The high-performance liquid chromatography (HPLC) conditions used gave baseline separation of the enantiomers with high sensitivity. R-(+)-bupivacaine and S-(−)-bupivacaine blood concentrations were determined using a chiral stationary phase (AGP, ChromTech) with diode array detection at 220 nm; this wavelength produced a stable baseline allowing semi-automated analysis. Sample preparation involved addition of internal standard (diphenhydramine), basification of blood, extraction with n-hexane, concentration of the extract to dryness and reconstitution in 0.002 M phosphoric acid. At rac-bupivacaine concentrations of 0.5, 5 and 50 μg/ml in blood, assay accuracy as estimated by coefficients of variation (C.V.s), were 3.3, 1.4, and 1.6%, respectively, for R-(+)-bupivacaine and 3.7, 2.0 and 1.5%, respectively, for S-(−)-bupivacaine. Using 0.6-ml samples, the estimated limits of detection for R-(+)-bupivacaine and S-(−)-bupivacaine were both 15 ng/ml of blood. Calibration curves (n=188) were linear from 0.1 to 50 μg/ml with all correlation coefficients being greater than 0.99. This semi-automated method was applied to studies involving whole body pharmacokinetics with intravenous doses ranging from 12.5 to 350 mg and regional myocardial pharmacokinetics with coronary arterial doses ranging from 2.5 to 12.5 mg. These studies generated approximately 12 000 blood samples. 相似文献
10.
Nitric oxide (NO) is a janus faced chemical messenger, which, in the recent years, has been the focus of neurobiologists for its involvement in neurodegenerative disorders in particular, Parkinson's disease (PD). Nitric oxide synthase, the key enzyme involved in NO production exists in three known isoforms. The neuronal and inducible isoforms have been implicated in the pathogenesis of PD. These enzymes are subject to complex expressional and functional regulation involving mRNA diversity, phosphorylation and protein interaction. In the recent years, mRNA diversity and polymorphisms have been identified in the NOS isoforms. Some of these genetic variations have been associated with PD, indicating an etiological role for the NOS genes. This review mainly focuses on the NOS genes - their differential regulation and genetic heterogeneity, highlighting their significance in the pathobiology of PD. 相似文献
11.
Separating individual compounds by HPLC represents an effective method for the detection and quantification of phenolic compounds and has been widely utilised. However, phlorotannins are commonly quantified using colorimetric methods, as the total amount of the whole compound group. In the present paper the separation of a set of individual soluble phlorotannins from the phenolic crude extract of Fucus vesiculosus was achieved by HPLC with UV photodiode array detection. Different gradient programs for reversed- and normal-phase HPLC methods were developed and tested. Normal-phase (NP) conditions with a silica stationary phase and a mobile phase with a linear gradient of increasing polarity were found to separate 16 individual components of the phenolic extract. The suitability of the NP-HPLC method for mass spectrometric application was preliminarily tested. Sample preparation was found to be a critical step in the analysis owing to the rapid oxidation of phlorotannins; ascorbic acid was used as an antioxidant. 相似文献
12.
Parkinson’s disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra (SN). The present study was designed to examine the therapeutic effect of hydrogen sulfide (H2S, a novel biological gas) on PD. The endogenous H2S level was markedly reduced in the SN in a 6‐hydroxydopamine (6‐OHDA)‐induced PD rat model. Systemic administration of NaHS (an H2S donor) dramatically reversed the progression of movement dysfunction, loss of tyrosine‐hydroxylase positive neurons in the SN and the elevated malondialdehyde level in injured striatum in the 6‐OHDA‐induced PD model. H2S specifically inhibited 6‐OHDA evoked NADPH oxidase activation and oxygen consumption. Similarly, administration of NaHS also prevented the development of PD induced by rotenone. NaHS treatment inhibited microglial activation in the SN and accumulation of pro‐inflammatory factors (e.g. TNF‐α and nitric oxide) in the striatum via NF‐κB pathway. Moreover, significantly less neurotoxicity was found in neurons treated with the conditioned medium from microglia incubated with both NaHS and rotenone compared to that with rotenone only, suggesting that the therapeutic effect of NaHS was, at least partially, secondary to its suppression of microglial activation. In summary, we demonstrate for the first time that H2S may serve as a neuroprotectant to treat and prevent neurotoxin‐induced neurodegeneration via multiple mechanisms including anti‐oxidative stress, anti‐inflammation and metabolic inhibition and therefore has potential therapeutic value for treatment of PD. 相似文献
13.
Vidmantas A. Raisys Patrick N. Friel Patricia R. Graaff Kent E. Opheim Alan J. Wilensky 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,183(4)
A one-step method for extraction of diazepam, nordiazepam, and internal standard into toluene is followed by chromatographic separation and detection with either dual-wavelength high-performance liquid chromatography or electron-capture gas—liquid chromatography. Agreement between the two methods was excellent for diazepam (r = 0.99, n = 38) and good for nordiazepam (r = 0.96, n = 79) over a concentration range that included subtherapeutic, therapeutic, and toxic plasma levels. 相似文献
14.
Torsten Binscheck Hartmut Meyer Hans Herbert Wellhöner 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,675(2):287
A quantitative, highly sensitive HPLC-based method for the direct measurement of azathioprine is described, introducing a newly synthesized 9-methyl derivative of this immunosuppressant as internal standard in combination with isocartic HPLC and UV-absorbance measurement at 285 nm. Analysis was performed on a RP18 select B column with acetonitrile-0.01 M potassium phosphate buffer (12:88, v/v) at pH 2.3 as mobile phase. Results of precision analysis from serum samples spiked with 3.125, 12.5, and 25 ng azathioprine, respectively, were (mean±S.D.): 3.148±0.259 ng (8.22%), 12.594±0.571 ng (4.53%), and 25.016±0.658 ng (2.63%) with C.V. values in parentheses for n=5. The accuracy of the assay ranged from −7.6 to 0.7% (expressed as % bias) tested on five consecutive days. The limit of quantification was at 2.5±0.256 ng (C.V. 10.25%), thus allowing drug monitoring in long-term patients. The method can also be used to evaluate individual pharmacokinetic parameters of a single patient, as well as for drug monitoring of a cohort of patients who suffer from azathioprine-induced symptoms of toxicity. An example of the pharmacokinetic behaviour in an individual is given in this paper. 相似文献
15.
16.
Susan E. Barrow A.A. Taylor E.C. Horning M.G. Horning 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,181(2):219-226
A procedure for the separation and isolation of the urinary metabolites of quinidine and quinine by reversed-phase high-performance liquid chromatography is described. Nine metabolites of quinidine and eight metabolites of quinine were detected in the urine of male Sprague-Dawley rats after a single dose of quinidine or quinine (50 mg kg?1). Following extraction from urine, the metabolites were separated on either an analytical or a semi-preparative reversed-phase column by gradient elution. After isolation and derivatization, the metabolites were analyzed by gas chromatography and gas chromatography—mass spectrometry. 相似文献
17.
Evandro Fioretti Anna Maria Eleuteri Mauro Angeletti Franca Ascoli 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,617(2)
A reversed-phase high-performance liquid chromatographic method for the determination and quantitative recovery of fully active aprotinin (the basic pancreatic trypsin inhibitor or Kunitz inhibitor) and aprotinin-like inhibitors in amounts down to 0.5 μg is reported. The method, which allows separation of aprotinin isoinhibitors characterized by small differences in the primary structure with respect to aprotinin itself, appears to be suitable for the quantitation and identification of aprotinin-like inhibitors in human biological fluids, in which they appear to be present at very low levels. 相似文献
18.
19.
Xiao‐Bing Gao Katherine V. Yao Hongling Du John D. Elsworth Hugh S. Taylor 《Journal of cellular and molecular medicine》2011,15(4):747-755
Parkinson’s disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons. Adult human endometrial derived stem cells (HEDSC), a readily obtainable type of mesenchymal stem‐like cell, were used to generate dopaminergic cells and for transplantation. Cells expressing CD90, platelet derived growth factor (PDGF)‐Rβ and CD146 but not CD45 or CD31 were differentiated in vitro into dopaminergic neurons that exhibited axon projections, pyramidal cell bodies and dendritic projections that recapitulate synapse formation; these cells also expressed the neural marker nestin and tyrosine hydroxylase, the rate‐limiting enzyme in dopamine synthesis. Whole cell patch clamp recording identified G‐protein coupled inwardly rectifying potassium current 2 channels characteristic of central neurons. A 1‐methyl 4‐phenyl 1,2,3,6‐tetrahydro pyridine induced animal model of PD was used to demonstrate the ability of labelled HEDSC to engraft, migrate to the site of lesion, differentiate in vivo and significantly increase striatal dopamine and dopamine metabolite concentrations. HEDSC are a highly inducible source of allogenic stem cells that rescue dopamine concentrations in an immunocompetent PD mouse model. 相似文献
20.
《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1995,667(1):179-184
A simple and sensitive HPLC method is described for the determination of the nitrobenzodiazepines, nitrazepam, flunitrazepam and clonazepam and their respective 7-amino metabolites in post-mortem blood. Using a single-step extraction the nitrobenzodiazepines were recovered from 0.5 ml of blood using butyl chloride. The solvent was evaporated to dryness and the reconstituted residue injected onto an HPLC system. Separation was achieved using a phenyl-bonded reversed-phase column with an acetonitrile-phosphate buffer mobile phase. Ultraviolet detection (240 nm) was used for quantitation. A linear response was observed between 0.01 and 0.60 mg/l. Assay precision between and within assays was less than 20% for all analytes. The limits of detection ranged from 0.001 to 0.008 mg/l with a limit of quantitation of 0.01 mg/l for all analytes. 相似文献