Mass spectrometry and its evolving role in assessing tissue specific steroid metabolism

Glucocorticoid hormones play vital roles in regulating diverse biological processes in health and disease. Tissue levels are regulated by enzymes which activate and inactivate hormones. The enzyme, 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), in particular, has been identified as a potential drug target; inhibiting this enzyme attenuates glucocorticoid action by lowering local levels of active hormone. A variety of mass spectrometric approaches have been developed to characterize this enzyme in vivo. Endogenous glucocorticoids and their metabolites can be profiled in urine by GC–MS and circulating steroids are now more commonly quantified by liquid chromatography tandem mass spectrometry. Tracer dilution studies have allowed rates of generation of glucocorticoids by the enzyme to be distinguished from hormone generated directly by the adrenal glands and, in combination with arterio-venous (AV) sampling, rates of production by specific tissues have been quantified. This has allowed the contribution of liver, adipose, muscle and brain to cortisol production in metabolic disease and hence prioritized drug targets. Most recently MS imaging in combination with on-tissue derivatization has been developed to profile oxo-steroids in tissue sections, allowing molecular maps to be generated across complex tissues, where regional functions are important. The review provides a synopsis of how measurement of steroids by MS has evolved with technological advances and this has provided insight into the dynamic turnover of glucocorticoids in vivo, highlighting the milestones that have advanced the field and identifying the remaining challenges for researchers, in terms of analytical chemistry and endocrine physiology and biochemistry.

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Development and Pharmacokinetics Study of Antifungal Peptide Nanoliposomes by Liquid Chromatography-tandem Mass Spectrometry

Current Pharmaceutical Analysis ◽

10.2174/1573412914666180307155328 ◽

2019 ◽

Vol 15 (4) ◽

pp. 312-318

Author(s):

Shuoye Yang

Keyword(s):

Mass Spectrometry ◽

Biological Properties ◽

Pharmacokinetic Property ◽

Antifungal Peptide ◽

Simple Liquid ◽

Physico Chemical ◽

Liquid Chromatography Tandem Mass ◽

Pegylated Lipids

Background: The therapeutic ability and application of antifungal peptide (APs) are limited by their physico-chemical and biological properties, the nano-liposomal encapsulation would improve the in vivo circulation and stability. </P><P> Objective: To develop a long-circulating liposomal delivery systems encapsulated APs-CGA-N12 with PEGylated lipids and cholesterol, and investigated through in vivo pharmacokinetics. Methods: The liposomes were prepared and characterized, a rapid and simple liquid chromatographytandem mass spectrometry (LC-MS/MS) assay was developed for the determination of antifungal peptide in vivo, the pharmacokinetic characteristics of APs liposomes were evaluated in rats. Results: Liposomes had a large, unilamellar structure, particle size and Zeta potential ranged from 160 to 185 nm and -0.55 to 1.1 mV, respectively. The results indicated that the plasma concentration of peptides in reference solutions rapidly declined after intravenous administration, whereas the liposomeencapsulated ones showed slower elimination. The AUC(0-∞) was increased by 3.0-fold in liposomes in comparison with standard solution (20 mg·kg-1), the half-life (T1/2) was 1.6- and 1.5-fold higher compared to the reference groups of 20 and 40 mg·kg-1, respectively. Conclusion: Therefore, it could be concluded that liposomal encapsulation effectively improved the bioavailability and pharmacokinetic property of antifungal peptides.

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RNA-Centric Approaches to Profile the RNA–Protein Interaction Landscape on Selected RNAs

Non-Coding RNA ◽

10.3390/ncrna7010011 ◽

2021 ◽

Vol 7 (1) ◽

pp. 11 ◽

Cited By ~ 1

Author(s):

André P. Gerber

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Regulatory Networks ◽

Rna Binding ◽

Rna Binding Proteins ◽

Protein Complexes ◽

Cell Protein ◽

Transcriptional Regulatory Networks ◽

Technological Advances

RNA–protein interactions frame post-transcriptional regulatory networks and modulate transcription and epigenetics. While the technological advances in RNA sequencing have significantly expanded the repertoire of RNAs, recently developed biochemical approaches combined with sensitive mass-spectrometry have revealed hundreds of previously unrecognized and potentially novel RNA-binding proteins. Nevertheless, a major challenge remains to understand how the thousands of RNA molecules and their interacting proteins assemble and control the fate of each individual RNA in a cell. Here, I review recent methodological advances to approach this problem through systematic identification of proteins that interact with particular RNAs in living cells. Thereby, a specific focus is given to in vivo approaches that involve crosslinking of RNA–protein interactions through ultraviolet irradiation or treatment of cells with chemicals, followed by capture of the RNA under study with antisense-oligonucleotides and identification of bound proteins with mass-spectrometry. Several recent studies defining interactomes of long non-coding RNAs, viral RNAs, as well as mRNAs are highlighted, and short reference is given to recent in-cell protein labeling techniques. These recent experimental improvements could open the door for broader applications and to study the remodeling of RNA–protein complexes upon different environmental cues and in disease.

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Bile Acids Quantification by Liquid Chromatography–Tandem Mass Spectrometry: Method Validation, Reference Range, and Interference Study

Diagnostics ◽

10.3390/diagnostics10070462 ◽

2020 ◽

Vol 10 (7) ◽

pp. 462 ◽

Cited By ~ 2

Author(s):

Elisa Danese ◽

Davide Negrini ◽

Mairi Pucci ◽

Simone De Nitto ◽

Davide Ambrogi ◽

...

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Healthy Subjects ◽

Reference Range ◽

Tandem Mass ◽

Chromatography Tandem Mass Spectrometry ◽

Liquid Chromatography Tandem Mass ◽

Interference Study

Bile acids (BA) play a pivotal role in cholesterol metabolism. Their blood concentration has also been proposed as new prognostic and diagnostic indicator of hepatobiliary, intestinal, and cardiovascular disease. Liquid chromatography tandem mass spectrometry (LC–MS/MS) currently represents the gold standard for analysis of BA profile in biological samples. We report here development and validation of a LC–MS/MS technique for simultaneously quantifying 15 BA species in serum samples. We also established a reference range for adult healthy subjects (n = 130) and performed a preliminary evaluation of in vitro and in vivo interference. The method displayed good linearity, with high regression coefficients (>0.99) over a range of 5 ng/mL (lower limit of quantification, LLOQ) and 5000 ng/mL for all analytes tested. The accuracies were between 85–115%. Both intra- and inter-assay imprecision was <10%. The recoveries ranged between 92–110%. Each of the tested BA species (assessed on three concentrations) were stable for 15 days at room temperature, 4 °C, and −20 °C. The in vitro study did not reveal any interference from triglycerides, bilirubin, or cell-free hemoglobin. The in vivo interference study showed that pools obtained from hyper-cholesterolemic patients and hyper-bilirubinemic patients due to post-hepatic jaundice for benign cholestasis, cholangiocarcinoma and pancreatic head tumors had clearly distinct patterns of BA concentrations compared with a pool obtained from samples of healthy subjects. In conclusion, this study proposes a new suitable candidate method for identification and quantitation of BA in biological samples and provides new insight into a number of variables that should be taken into account when investigating pathophysiological changes of BA in human diseases.

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