Search results for "Plasma samples"
showing 10 items of 18 documents
Multicentric study of the effect of pre-analytical variables in the quality of plasma samples stored in biobanks using different complementary proteo…
2016
12 páginas, 7 figuras.-- Jesús Mateos ... et al.
Validated HPLC-UV detection method for the simultaneous determination of ceftolozane and tazobactam in human plasma
2018
Aim: A simple, rapid, economical and sensitive HPLC-UV method was developed for the simultaneous quantification of ceftolozane and tazobactam in plasma samples. Methodology: After deproteinization followed by a liquid–liquid back-extraction, the compounds were separated on a C18 column (150 mm × 4.6 mm, 5 μm) with UV-visible detection at 220 nm. The mobile phase consisted of acetonitrile and potassium dihydrogenphosphate buffer at pH 3.0 (8:92, v/v), delivered isocratically at a flow rate of 1.0 ml/min and at a column oven temperature of 30°C. Cefepime was used as an internal standard. Results: Linearity was achieved in the concentration range of 0.50–100.00 μg/ml for ceftolozane and 0.25–…
Ultra-Performance Liquid Chromatography-Ion Mobility Separation-Quadruple Time-of-Flight MS (UHPLC-IMS-QTOF MS) Metabolomics for Short-Term Biomarker…
2020
A major problem with dietary assessments is their subjective nature. Untargeted metabolomics and new technologies can shed light on this issue and provide a more complete picture of dietary intake by measuring the profile of metabolites in biological samples. Oranges are one of the most consumed fruits in the world, and therefore one of the most studied for their properties. The aim of this work was the application of untargeted metabolomics approach with the novel combination of ion mobility separation coupled to high resolution mass spectrometry (IMS-HRMS) and study the advantages that this technique can bring to the area of dietary biomarker discovery, with the specific case of biomarker…
Oxyphytosterols are present in plasma of healthy human subjects
2004
The oxidised derivatives of phytosterols (oxyphytosterols) were identified in plasma samples from thirteen healthy human volunteers, using MS. All the samples contained noticeable quantities of (24R)-5b,6b-epoxy-24-ethylcholestan-3b-ol (b-epoxysitostanol) and (24R)-ethylcholestan-3b,5a,6b-triol (sitostanetriol) and also trace levels of (24R)-5a,6a-epoxy-24-ethylcholestan-3b-ol (a-epoxysitostanol), (24R)-methylcholestan-3b,5a,6b-triol (campestanetriol) and (24R)-ethylch olest-5-en-3b-ol-7-one(7-ketositosterol). The amounts of these oxyphytosterols in plasma varied from 4·8 to 57·2 ng/ml. There are two possibilities concerning the origin of these compounds. First, they could come from the sma…
Detection of gastric atrophy by circulating pepsinogens: A comparison of three assays.
2017
Background Circulating levels of pepsinogens have been used in high gastric cancer-risk Asian and European populations to triage endoscopic evaluation for more severe pathology. There are different analytic methods with uncertain correlations. We therefore compared diagnostic performance of three commonly used pepsinogen assays to detect histologically confirmed gastric atrophy. Methods We tested plasma samples from adult patients with (n=50) and without (n=755) moderate or severe gastric corpus atrophy, as determined histologically by consensus of three expert pathologists. A single laboratory measured pepsinogens I (PgI) and II (PgII) using commercially available assays: two ELISA assays …
Short-term treadmill running as a model for studying cell-free DNA kinetics in vivo.
2011
BACKGROUND Increased plasma concentrations of cell-free DNA (cf-DNA) are considered a hallmark of various clinical conditions. Despite intensive research in this field, limited data are available concerning the time course of release and clearance of cf-DNA in vivo. METHODS We extracted cf-DNA from plasma samples taken before and immediately after a 10-km cross-country run, and from samples taken before, immediately after, and 30 min after exhaustive short-term treadmill exercise. The contribution of nuclear (nDNA) and mitochondrial DNA (mtDNA) was measured by quantitative real-time PCR. The incremental treadmill exercise setup was exploited to delineate the precise sequencing and timing o…
Pepsinogen testing for evaluation of the success of Helicobacter pylori eradication at 4 weeks after completion of therapy.
2014
Background and objective: Pepsinogen levels in plasma are increased by inflammation in the gastric mucosa, including inflammation resulting from Helicobacter pylori infection. A decrease in pepsinogen II level has been suggested as a reliable marker to confirm the successful eradication of infection. The aim of our study was to evaluate the potential role of pepsinogens I and II, gastrin-17 and H. pylori antibodies in confirming successful eradication. Material and methods: Altogether 42 patients (25 women, 17 men), mean age 45 years (range 23–74), were enrolled. Pepsinogens I and II, gastrin-17 and H. pylori IgG antibodies were measured in plasma samples using an ELISA test (Biohit, Oyj., …
A preliminary study on the stability of benzodiazepines in blood and plasma stored at 4 degrees C.
1997
An approach to determine the stability of benzodiazepines and some of their metabolites (n = 13) by means of a routinely applied gas chromatographic method using electron capture detection was made in this preliminary study. Validation data of the method are given. Spiked blood and plasma samples were stored at 4 degrees C and analysed at selected times up to 240 days. The concentrations of all analytes had decreased to at least 60% of the original levels at the end of the observation period. A clear pattern of breakdown could not be established. The data obtained suggest that results from long-term stored samples should be interpreted cautiously. Further investigations concerning the stabi…
Infrared biospectroscopy for a fast qualitative evaluation of sample preparation in metabolomics.
2014
Liquid chromatography-mass spectrometry (LC-MS) has been increasingly used in biomedicine to study the dynamic metabolomic responses of biological systems under different physiological or pathological conditions. To obtain an integrated snapshot of the system, metabolomic methods in biomedicine typically analyze biofluids (e.g. plasma) that require clean-up before being injected into LC-MS systems. However, high resolution LC-MS is costly in terms of resources required for sample and data analysis and care must be taken to prevent chemical (e.g. ion suppression) or statistical artifacts. Because of that, the effect of sample preparation on the metabolomic profile during metabolomic method d…
Development and validation of a micellar liquid chromatographic method to determine three antitumorals in plasma
2017
Aim: A micellar liquid chromatographic method to determine several anticancer drugs (pazopanib, dabrafenib and regorafenib) in plasma was developed and validated by the guidelines of the EMA. Experimental: Plasma samples were directly injected, after a 1/5-dilution in a micellar solution. The drugs were resolved in <18 min using a C18 column. The mobile phase was an aqueous solution of 0.12 M SDS – 2% 1-pentanol, buffered at pH 7. The detection was performed by absorbance at 260 nm. Results: The values of the main validation parameters were: LOD (0.1–1 mg/l), calibration range (0.2–2 to 80 mg/l), accuracy (-12.5 to +11.7%) and precision (<11.9%). Conclusion: The procedure was conduct…