Profiling and in vivo Quantification of Proteins by High Resolution Mass Spectrometry: The Example of Goserelin, an Analogue of Luteinizing Hormone-Releasing Hormone

Electrochemical DNA-nano biosensor for the detection of Goserelin as anticancer drug using modified pencil graphite electrode

Goserelin is an effective anticancer drug, but naturally causes several side effects. Hence the determination of this drug in biological samples, plays a key role in evaluating its effects and side effects. The current studies have concentrated on monitoring Goserelin using an easy and quick DNA biosensor for the first time. In this study, copper(II) oxide nanoparticles were created upon the surface of multiwalled carbon nanotubes (CuO/MWCNTs) as a conducting mediator. The modified pencil graphite electrode (ds-DNA/PA/CuO/MWCNTs/PGE) has been modified with the help of polyaniline (PA), ds-DNA, and CuO/MWCNTs nanocomposite. Additionally, the issue with the bio-electroanalytical guanine oxidation signal in relation to ds-DNA at the surface of PA/CuO/MWCNTs/PGE has been examined to determination Goserelin for the first time. It also, established a strong conductive condition to determination Goserelin in nanomolar concentration. Thus, Goserelin's determining, however, has a 0.21 nM detection limit and a 1.0 nM-110.0 µM linear dynamic range according to differential pulse voltammograms (DPV) of ds-DNA/PA/CuO/MWCNTs/PGE. Furthermore, the molecular docking investigation highlighted that Goserelin is able to bind ds-DNA preferentially and supported the findings of the experiments. The determining of Goserelin in real samples has been effectively accomplished in the last phase using ds-DNA/PA/CuO/MWCNTs/PGE.

Measurement of amniotic fluid steroids of midgestation via LC-MS/MS

INTRODUCTION

Analysis of steroids by mass spectrometry (MS) has evolved into a reliable tool for the simultaneous detection of multiple steroids. As amniotic fluid (AF) and fetal serum composition of early pregnancy are closely related, the analysis of AF can yield information on the physiological status of the developing fetus. We evaluated the use of liquid-chromatography tandem mass spectrometry (LC-MS/MS) for AF steroid analysis, including the analysis of its sensitivity and accuracy for gender verification in healthy subjects.

MATERIALS AND METHODS

AF of 78 male and 94 female healthy newborns was analyzed by LC-MS/MS at 16 weeks of gestation. The levels of androstenedione, corticosterone, cortisol, cortisone, deoxycorticosterone, 11-deoxycortisol, dehydroepiandrosterone (DHEA), dehydroepiandrosterone-sulfate (DHEA-S), 17-hydroxyprogesterone, progesterone (17-OHP) and testosterone were measured. Steroid levels were compared to RIA and GC-MS levels of midgestation from the literature. Cross-validated logistic regression was used to obtain statistical predictions of gender at birth from testosterone and the above steroids.

RESULTS

LC-MS/MS analysis of AF steroids yielded comparable results with published GC-MS data. Gender specific differences were found for androstenedione and testosterone concentrations with higher levels in the male fetus. In contrast to published RIA data no gender specific differences were observed for 17-hydroxyprogesterone and dehydroepiandrosterone AF concentrations. Testosterone concentrations yielded highly accurate predictions for male gender at birth. Additional analysis of further steroids did neither increase the accuracy, sensitivity nor specificity of this prediction. The estimated optimal cut-off value for amniotic testosterone level was 0.074 μg/L for healthy male newborns.

CONCLUSIONS

LC-MS/MS is a reliable method for the determination of steroids in amniotic fluid. The determination of testosterone in amniotic fluid by LC-MS/MS in early pregnancy of healthy subjects can be used to offer a reliable prediction of fetal gender at birth.

Combined quantification of corticotropin-releasing hormone, cortisol-to-cortisone ratio and progesterone by liquid chromatography-Tandem mass spectrometry in placental tissue

With mid-gestation the production of placental corticotropin-releasing hormone (CRH) starts to steadily increase. The fetal peptide CRH excerts direct functions at the feto-maternal interface (vasodilatation, timing of birth) via its interaction with progesterone and indirectly ensures maturation and growth of fetal organ systems for delivery by driving fetal cortisol production via its induction of adrenocorticotropic hormone release. This feedback loop is tightly controlled by the amount of enzymatic cortisol/cortisone turnover in the placental syncytiotrophoblast by 11β-hydroxy-steroid dehydrogenase type 2 (11β-HSD2). Traditionally, placental tissue hormones have been quantified by immunological methods (e.g. RIA or ELISA), which have the drawback of possible cross-reactivity and tissue perturbations. Most importantly, it is not possible to quantify CRH and steroid hormones, such as cortisol, cortisone and progesterone together in the same sample with these methods. Hence, we aimed to develop and validate a quantitative mass spectrometry (MS) method for multi-modal quantification of these placental hormones: While CRH was readily detectable throughout the placenta, the placental levels of progesterone and especially cortisol and cortisone were higher at the placental base facing the maternal side. The HPLC-MS/MS procedure showed excellent selectivity and sufficient limit of quantification in placental tissue homogenates to allow for simultaneous detection of CRH, cortisol and cortisone, and progesterone.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the determination of goserelin in rabbit plasma

A rapid and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the determination of goserelin in rabbit plasma. Various parameters affecting plasma sample preparation, LC separation, and MS/MS detection were investigated, and optimized conditions were identified. Acidified plasma samples were applied to Oasis((R)) HLB solid-phase extraction (SPE) cartridges. Extracted samples were evaporated under a stream of nitrogen and then reconstituted with 100microL mobile phase A. The separation was achieved on a Capcell-Pak C18 (2.0mmx150mm, 5microm, AQ type) column with a gradient elution of solvent A (0.05% acetic acid in deionized water/acetonitrile=85/15; v/v) and solvent B (acetonitrile) at a flow rate of 250microL/min. The LC-MS/MS system was equipped with an electrospray ion source operating in positive ion mode. Multiple-reaction monitoring (MRM) of the precursor-product ion transitions consisted of m/z 635.7-->m/z 607.5 for goserelin and m/z 424.0-->m/z 292.1 for cephapirin (internal standard). The proposed method was validated by assessing specificity, linearity, limit of quantification (LOQ), intra- and inter-day precision and accuracy, recovery, and stability. Linear calibration curves were obtained in the concentration range of 0.1-20ng/mL (the correlation coefficients were above 0.99). The LOQ of the method was 0.1ng/mL. Results obtained from the validation study of goserelin showed good accuracy and precision at concentrations of 0.1, 1, 5, 10, and 20ng/mL. The validated method was successfully applied to a pharmacokinetic study of goserelin after a single subcutaneous injection of 3.6mg of goserelin in healthy white rabbits.

Simultaneous Quantification of Ghrelin and Desacyl-Ghrelin by Liquid Chromatography–Tandem Mass Spectrometry in Plasma, Serum, and Cell Supernatants

Background: A sensitive method specific for ghrelins is needed for investigations of this gastrointestinal peptide. Our aim was to develop and validate a quantitative mass spectrometry (MS) method to measure ghrelin and desacyl-ghrelin simultaneously.

Methods: After deproteinization by precipitation, we performed reversed-phase separation with a rapid 2-column online extraction design coupled to a quadrupole mass spectrometer for electrospray ionization MS detection. Chromatography was performed on a C18 monolithic column, with ammonium acetate buffer/methanol as the mobile phase and a chromatographic run time of 6 min/sample. The 4-fold–charged ions were used for multiple reaction monitoring experiments.

Results: The method was linear with injections of 0.01–10 ng. Limits of detection and quantification were 0.02 and 0.07 μg/L for ghrelin, respectively, and 0.03 and 0.35 μg/L for desacyl-ghrelin. Intra- and interday imprecision (CVs) were 9%–4% and 12%–6% at concentrations of 0.33–5.93 μg/L for ghrelin, respectively, and 16%–6% and 15%–8% at concentrations of 1.12–10.02 μg/L for desacyl-ghrelin. The mean (SD) recoveries in plasma of added ghrelin and desacyl-ghrelin were 95.8% (12%) and 101% (1.2%), respectively. Using kinetic modeling, we determined the mean (SD) periods of half-change (t1/2) of ghrelin to be 156 (16) min in EDTA plasma and 49 (1) min in Li-heparin plasma. Bland–Altman analysis showed that the median differences between EIA and liquid chromatography–tandem mass spectrometry (MS/MS) for desacyl-ghrelin were −40% for plasma/serum samples and 85% for cell supernatants and for ghrelin were 6% for enriched plasma samples and 44% for cell supernatants.

Conclusion: Our HPLC-MS/MS procedure has excellent selectivity and sufficient limit of quantification to allow the monitoring of concentration–time profiles in biological matrices.

Absolute quantification of Atlantic salmon and rainbow trout vitellogenin by the 'signature peptide' approach using electrospray ionization QqToF tandem mass spectrometry

In this work, we present a simple method for absolute quantification of plasma vitellogenin from both rainbow trout and Atlantic salmon. Plasma samples obtained from control and beta-estradiol induced fish were digested with trypsin. A characteristic 'signature peptide' was selected and analyzed by high performance liquid chromatography (HPLC) coupled to an electrospray quadrupole-time-of-flight tandem mass spectrometer, using a deuterated homolog peptide as an internal standard. The hybrid tandem mass spectrometer was operated in a 'pseudo' selected reaction-monitoring mode in which three diagnostic product ions were monitored for identification and quantification purposes. The reproducibility (coefficient of variation approximately 5%) and sensitivity (limit of quantification (LOQ) of 0.009 mg/ml) achieved by this simple assay allow it to be considered as an alternative to immunological assays.

Global Differential Non-Gel Proteomics by Quantitative and Stable Labeling of Tryptic Peptides with Oxygen-18

We describe a protocol for quantitative labeling of tryptic peptides with oxygen-18. Proteins are first digested in natural water with trypsin, the pH is then lowered to 4.5 and the mixture is dried. Oxygen-18 water is added and two oxygen-18 atoms are incorporated at the peptides' carboxyl termini. Trypsin is finally inactivated by cysteine alkylation under denaturing conditions, which blocks oxygen back-exchange. The general value of this labeling strategy for differential proteomics is illustrated by the analysis and identification of several couples of differently labeled amino terminal peptides isolated from a human platelet proteome by a previously described chromatographic procedure.