Multiplexed analysis of steroid hormones in human serum using novel microflow tile technology and LC-MS/MS

Profiling of urinary steroids aided by lithium ion adduction-based ultrahigh-performance liquid chromatography-tandem mass spectrometry

RATIONALE

As 3-OH-containing steroids are prone to dehydration by conventional electrospray ionization, reducing detection sensitivity, Li ion adduction-based ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS), developed to prevent dehydration and effectively detect 3-OH steroids, was applied for profiling total and free steroids in urine.

METHODS

Free urinary steroids were isolated directly from urine by solid-phase extraction (SPE) with 80% acetonitrile. The total steroids were prepared by enzymatic treatment of urine with a cocktail of sulfatase and glucronidase, protein precipitation, and separation with the above SPE. In order to detect as many steroid types as possible, UHPLC/MS/MS (Li method) with Li+ solution added after the column was used for analysis in addition to the conventional method of detecting protonated ions (H method). The 13 3-OH steroids and the remaining 16 steroids were quantified by standard curves prepared using product ion transitions derived from [M + Li]+ and MH+ , respectively.

RESULTS

Two groups of human urine, male and female urine, were analyzed. 3-OH steroids could be detected with greater sensitivity using the Li method than the conventional method. The absolute amounts of each steroid were normalized based on creatinine levels. The difference between the male and female groups are clearly attributable to sex steroids.

CONCLUSIONS

Twenty-nine total steroids and 19 free steroids were identified in a limited volume (240 mL) of urine. Of these, 13 3-OH steroids were better detected by Li+ adduction-based UHPLC/MS/MS.

Mass spectrometric-based assessment of the serum kappa to lambda immunoglobulin light chain ratio (κ:λ) in dogs with immunoglobulin secretory diseases

The ratio of κ light chains to λ light chains (κ:λ) in serum is used as a biomarker of immunoglobulin secreting neoplasia in humans but has not been evaluated in dogs. A mass-spectrometry based method for determining the canine serum κ:λ was developed and used to evaluate samples from control dogs, dogs with an infectious aetiology, dogs with secretory plasma cell tumours (sPCT) and dogs with non-secretory B cell neoplasia. A human-targeted immunoturbidometric κ:λ assay and immunofixation using antisera targeting human κ light chain or λ light chain was also performed on all samples. Using whole serum samples, the MS-based κ:λ method identified 5 sPCT as κ-predominant (mean κ:λ = 3.307) and 5 sPCT as λ-predominant (mean κ:λ = 0.023) and documented differences between these groups and all other groups (p < 0.05 for all). The infectious aetiology group had a lower mean κ:λ ratio (mean κ:λ = 0.069) than control samples (mean κ:λ = 0.103, p = 0.035). Similar results were obtained when samples were enriched for proteins between 10 and 50 kDa using size exclusion chromatography, except for the statistical difference between the control and infectious aetiology group. All λ-predominant cases had only anti-human λ light chain labelling by immunofixation. Three κ-predominant cases had only anti-human κ-light chain labelling and the remaining two cases did not label with either antisera by immunofixation. The immunoturbidometric method had high analytical CV% (λ light chain CV = 13%, κ light chain CV = 50%), was unable to measure light chains in 20.5% of samples and did not distinguish groups. The data suggests that the human-targeted immunoturbidometric method would not be diagnostically useful and that the MS-derived serum κ:λ may be a useful biomarker of canine immunoglobulin secretory neoplasia which may have the ability to distinguish neoplasia from infectious causes of immunoglobulin secretion.

Development of Fe3O4/reduced graphene oxide nanocomposite-based dispersive solid-phase extraction for the quantification of five steroid hormones

Aim: An accurate and sensitive analytical method was proposed to detect some steroid hormones in biological samples. Materials & methods: An Fe₃O₄/reduced graphene oxide nanocomposite-based dispersive solid-phase extraction was developed for the effective and simple preconcentration of steroid hormones from human serum samples. Results & conclusion: The nanocomposite was firstly used as adsorbent to simultaneously extract the selected hormones. Limit of detection values for the selected hormones were calculated between 5.5 and 39.2 ng/kg (mass based). An artificial serum sample was used to test the applicability and accuracy of the developed method; percentage recovery results obtained from two different spiked concentrations were found to be in the range of 80.5-99.9%.

Plasma, urine, and stool metabolites in response to dietary rice bran and navy bean supplementation in adults at high-risk for colorectal cancer

Introduction

Dietary intake of whole grains and legumes and adequate physical activity (PA) have been associated with reduced colorectal cancer (CRC) risk. A single-blinded, two-arm, randomized, placebo-controlled pilot trial was implemented to evaluate the impact of a 12-week dietary intervention of rice bran + navy bean supplementation and PA education on metabolite profiles and the gut microbiome among individuals at high risk of CRC.

Methods

Adults (n=20) were randomized 1:1 to dietary intervention or control. All participants received PA education at baseline. Sixteen study foods were prepared with either heat-stabilized rice bran + navy bean powder or Fibersol®-2 as a placebo. Intervention participants consumed 30 g rice bran + 30 g navy bean powder daily; those in the control group consumed 10 g placebo daily. Non-targeted metabolite profiling was performed by UPLC-MS/MS to evaluate plasma, urine, and stool at 0, 6, and 12 weeks. Stool was also analyzed for primary and secondary bile acids (BAs) and short chain fatty acids (SCFAs) by UPLC-MS/MS and microbial community structure via 16S amplicon sequencing. Two-way ANOVA was used to compare differences between groups for metabolites, and mixed models were used to compare differences between groups for BAs, SCFAs, and alpha and beta diversity measures of microbial community structure.

Results

Across biological matrices, the intervention resulted in changes to several amino acid and lipid metabolites, compared to control. There was a 2.33-fold difference in plasma (p<0.001) and a 3.33-fold difference in urine (p=0.008) for the amino acid S-methylcysteine at 12 weeks. Fold-differences to 4-methoxyphenol sulfate in plasma and urine after 6 and 12 weeks (p<0.001) was a novel result from this combined rice bran and navy bean intervention in people. A 2.98-fold difference in plasma (p=0.002) and a 17.74-fold difference in stool (p=0.026) was observed for the lipid octadecenedioylcarnitine at 12 weeks. For stool BAs, 3-oxocholic acid was increased at 12 weeks compared to control within a subset of individuals (mean difference 16.2 ug/uL, p=0.022). No significant differences were observed between groups for stool SCFAs or microbial community structure.

Discussion

Dietary intake of rice bran + navy beans demonstrates beneficial modulation of host and gut microbial metabolism and represents a practical and affordable means of increasing adherence to national guidelines for CRC control and prevention in a high-risk population.

Rapidity and Precision of Steroid Hormone Measurement

Steroids are present in all animals and plants, from mammals to prokaryotes. In the medical field, steroids are commonly classified as glucocorticoids, mineralocorticoids, and gonadal steroid hormones. Monitoring of hormones is useful in clinical and research fields for the assessment of physiological changes associated with aging, disease risk, and the diagnostic and therapeutic effects of various diseases. Since the discovery and isolation of steroid hormones, measurement methods for steroid hormones in biological samples have advanced substantially. Although immunoassays (IAs) are widely used in daily practice, mass spectrometry (MS)-based methods have been reported to be more specific. Steroid hormone measurement based on MS is desirable in clinical practice; however, there are several drawbacks, including the purchase and maintenance costs of the MS instrument and the need for specialized training of technicians. In this review, we discuss IA- and MS-based methods currently in use and briefly present the history of steroid hormone measurement. In addition, we describe recent advances in IA- and MS-based methods and future applications and considerations.

Changes in maternal cortisol, cortisol binding globulin and cortisone levels following diagnosis of fetal anomaly

The diagnosis of fetal anomaly can be a major stressor to the expectant mother. Current understanding of the relationship between psychological stress and cortisol in pregnancy is limited. This study examined: (1) differences in the ratio of serum cortisol to cortisol binding globulin (SC/CBG) and cortisone levels among women with and without a diagnosis of fetal anomaly, (2) the association between self-reported stress and cortisol from mid to late pregnancy, and (3) the agreement between two different techniques for analyzing cortisol: liquid chromatography-tandem mass spectrometry (LC-MS/MS) and radioimmunoassay (RIA). Thirty-six pregnant women with a diagnosis of fetal anomaly (study group) and 101 women with healthy pregnancies (comparison group) provided blood samples and completed self-report questionnaires at gestational weeks 18-24 (T1) and 30 (T2). In the comparison group, mean SC/CBG increased from 0.341 nmol/L at T1 to 0.415 at T2 (p < .001), whereas in the study group there was no change (0.342 nmol/L at T1, 0.343 at T2). There was no difference in cortisone levels between the groups at either timepoints. There was a negative association between both depression and traumatic stress at T1, and SC/CBG at T2 (p < .05). There was no association between general distress and SC/CBG. The two methods for analyzing cortisol gave similar results, but with LC-MS/MS showing a lower detection limit than RIA. Increased cortisol with advancing gestational age is expected, thus these findings indicate that under certain conditions of severe stress there may be a suppression of maternal cortisol increase from mid to late gestation. The discrepancy does not seem to be due to differences in the metabolization of cortisol, as indicated by the similar levels of cortisone. Further research is needed in order to understand the potential underlying mechanisms limiting the expression of cortisol in response to certain types of stress in pregnancy.

The impact of extraction protocol on the chemical profile of cannabis extracts from a single cultivar

The last two decades have seen a dramatic shift in cannabis legislation around the world. Cannabis products are now widely available and commercial production and use of phytocannabinoid products is rapidly growing. However, this growth is outpacing the research needed to elucidate the therapeutic efficacy of the myriad of chemical compounds found primarily in the flower of the female cannabis plant. This lack of research and corresponding regulation has resulted in processing methods, products, and terminology that are variable and confusing for consumers. Importantly, the impact of processing methods on the resulting chemical profile of full spectrum cannabis extracts is not well understood. As a first step in addressing this knowledge gap we have utilized a combination of analytical approaches to characterize the broad chemical composition of a single cannabis cultivar that was processed using previously optimized and commonly used commercial extraction protocols including alcoholic solvents and super critical carbon dioxide. Significant variation in the bioactive chemical profile was observed in the extracts resulting from the different protocols demonstrating the need for further research regarding the influence of processing on therapeutic efficacy as well as the importance of labeling in the marketing of multi-component cannabis products.

Fast accurate quantification of salivary cortisol and cortisone in a large-scale clinical stress study by micro-UHPLC-ESI-MS/MS using a surrogate calibrant approach

Cortisol and cortisone are common markers for stress and thus preferentially analyzed in matrices that allow non-invasive sampling such as saliva. Though the major drawback of immunoassays is lack of specificity due to cross reactivities, they are still most commonly used for quantification of steroid hormones. To overcome such problems, sensitive methods based on liquid chromatography-mass spectrometry are becoming more and more accepted as the golden standard for steroid bioanalysis as they achieve accurate quantification at trace levels for multiple analytes in the same run. Along this line, the aim of this study was the development of a new microflow UHPLC-ESI-MS/MS method for the measurement of salivary cortisol and cortisone, which due to its microflow regime provides enhanced sensitivity and is more ecofriendly. The developed method implemented sample preparation by Solid-Phase Extraction (SPE) in a 96-well plate format. Data acquisitions were carried out in MRM (multiple reaction monitoring) mode. The quantitative determination of endogenous compounds in saliva remains a challenge since analyte-free matrix is lacking. Hence, a surrogate calibrant approach with cortisol-d₄ andcortisone-¹³C₃ was applied for the target compounds in the presented method. A number of factors were optimized and the method validated. The lower limit of quantitation (LLOQ) was 72 and 62 pg mL^-1for cortisol and cortisone, respectively. Linear calibration was achieved in the range from 0.062 to 75.5 ng mL^-1for cortisol-d₄ and 0.072 to 44 ng mL^-1forcortisone-¹³C₃. The performance of the method was also evaluated via proficiency test for salivary cortisol. Finally, it was applied successfully to evaluate cortisol and cortisone concentrations in multiple batches in routine clinical stress study samples (4056 total injections with 1983 study samples). Moreover, the instrument performance (in particular retention time variability) within each batch, between different batches and lot-to-lot of 5 investigated capillary columns over time is described. The work documents that micro-UHPLC-ESI-MS/MS is suitable and robust enough to carry out a full clinical study with greater than 1000s of samples over an extended period if adequate internal standards can be used.

Daily Rice Bran Consumption for 6 Months Influences Serum Glucagon-Like Peptide 2 and Metabolite Profiles without Differences in Trace Elements and Heavy Metals in Weaning Nicaraguan Infants at 12 Months of Age

BACKGROUND

Environmental enteric dysfunction (EED) is associated with chronic gut inflammation affecting nutrient absorption and development of children, primarily in low- and middle-income countries. Several studies have shown that rice bran (RB) supplementation provides nutrients and modulates gut inflammation, which may reduce risk for undernutrition.

OBJECTIVE

The aim was to evaluate the effect of daily RB dietary supplementation for 6 mo on serum biomarkers in weaning infants and associated changes in serum and stool metabolites.

METHODS

A 6-mo randomized-controlled dietary intervention was conducted in a cohort of weaning 6-mo-old infants in León, Nicaragua. Anthropometric indices were obtained at 6, 8, and 12 mo. Serum and stool ionomics and metabolomics were completed at the end of the 6-mo intervention using inductively coupled plasma MS and ultra-high performance LC-tandem MS. The ɑ1-acid glycoprotein, C-reactive protein, and glucagon-like peptide 2 (GLP-2) serum EED biomarkers were measured by ELISA.

RESULTS

Twenty-four infants in the control group and 23 in the RB group successfully completed the 6-mo dietary intervention with 90% dietary compliance. RB participants had higher concentrations of GLP-2 as compared with control participants at 12 mo [median (IQR): 743.53 (380.54) pg/mL vs. 592.50 (223.59) pg/mL; P = 0.04]. Metabolite profiles showed significant fold differences of 39 serum metabolites and 44 stool metabolites from infants consuming RB compared with control, and with significant metabolic pathway enrichment scores of 4.7 for the tryptophan metabolic pathway, 5.7 for polyamine metabolism, and 5.7 for the fatty acid/acylcholine metabolic pathway in the RB group. No differences were detected in serum and stool trace elements or heavy metals following daily RB intake for 6 mo.

CONCLUSIONS

RB consumption influences a suite of metabolites associated with growth promotion and development, while also supporting nutrient absorption as measured by changes in serum GLP-2 in Nicaraguan infants. This clinical trial was registered at https://clinicaltrials.gov as NCT02615886.

Quantitation of six steroid hormones by ultra-performance liquid chromatography-tandem mass spectrometry in plasma and prefrontal cortex samples from rats with chronic unpredictable mild stress-induced depression

Steroid hormones such as glucocorticoids and their metabolites are closely related to mental diseases and neuroendocrine diseases. Quantitative analysis of these substances will help in understanding their roles in related research fields. In this study, an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to detect the concentration of corticosterone (CORT) and its metabolites, progesterone (PROG) and testosterone in rat plasma and prefrontal cortex (PFC), and was applied to investigate the changes in hormones in rats with depression induced by chronic unpredictable mild stress (CUMS). The method was shown to be linear in the quantitation range for all analytes. Intra- and inter-day accuracy and precision were between 80% and 120%. Furthermore, we found that the level of CORT in plasma and PFC increased, whereas that of 11-dehydrocorticosterone (11-DHCORT) as well as the ratio of 11-DHCORT and CORT declined in rats with CUMS-induced depression. The trends of these changes in central PFC and peripheral plasma were consistent. In conclusion, this study successfully established an UPLC-MS/MS method for simultaneous measurement of CORT and its metabolites, PROG and testosterone in rat plasma and PFC, and applied it to rats with depression. The method could be further applied to the research of depression and diseases related to these steroid hormones.

Comprehensive Evaluation of Metabolites and Minerals in 6 Microgreen Species and the Influence of Maturity

BACKGROUND

Microgreens are the young leafy greens of many vegetables, herbs, grains, and flowers with potential to promote human health and sustainably diversify the global food system. For successful further integration into the global food system and evaluation of their health impacts, it is critical to elucidate and optimize their nutritional quality.

OBJECTIVES

We aimed to comprehensively evaluate the metabolite and mineral contents of 6 microgreen species, and the influence of maturity on their contents.

METHODS

Plant species evaluated were from the Brassicaceae (arugula, broccoli, and red cabbage), Amaranthaceae (red beet and red amaranth), and Fabaceae (pea) plant families. Nontargeted metabolomics and ionomics analyses were performed to examine the metabolites and minerals, respectively, in each microgreen species and its mature counterpart.

RESULTS

Nontargeted metabolomics analysis detected 3321 compounds, 1263 of which were annotated and included nutrients and bioactive compounds. Ionomics analysis detected and quantified 26 minerals including macrominerals, trace minerals, ultratrace minerals, and other metals. Principal component analysis indicated that microgreens have distinct metabolite and mineral profiles compared with one another and with their mature counterparts. Several compounds were higher (P  < 0.05; fold change ≥2) in microgreens compared with their mature counterparts, whereas some were not different or lower. In many cases, compounds that were higher in microgreens compared with the mature counterpart were also unique to that microgreen species.

CONCLUSIONS

These data provide evidence for the nutritional quality of microgreens, and can inform future research and development aimed at characterizing and optimizing microgreen nutritional quality and health impacts.

Liquid chromatography-mass spectrometry applications for quantification of endogenous sex hormones

Liquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17-β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography-mass spectrometry. LC-MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high-resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC-MS/MS steroid hormone analysis captured in the literature over the last decade.

Longitudinal Multi-omics Reveals Subset-Specific Mechanisms Underlying Irritable Bowel Syndrome

The gut microbiome has been implicated in multiple human chronic gastrointestinal (GI) disorders. Determining its mechanistic role in disease has been difficult due to apparent disconnects between animal and human studies and lack of an integrated multi-omics view of disease-specific physiological changes. We integrated longitudinal multi-omics data from the gut microbiome, metabolome, host epigenome, and transcriptome in the context of irritable bowel syndrome (IBS) host physiology. We identified IBS subtype-specific and symptom-related variation in microbial composition and function. A subset of identified changes in microbial metabolites correspond to host physiological mechanisms that are relevant to IBS. By integrating multiple data layers, we identified purine metabolism as a novel host-microbial metabolic pathway in IBS with translational potential. Our study highlights the importance of longitudinal sampling and integrating complementary multi-omics data to identify functional mechanisms that can serve as therapeutic targets in a comprehensive treatment strategy for chronic GI diseases. VIDEO ABSTRACT.

Non-invasive Drug Monitoring of β-Lactam Antibiotics Using Sweat Analysis-A Pilot Study

Background: Antimicrobial resistance is a major challenge in treating infectious diseases. Therapeutic drug monitoring (TDM) can optimize and personalize antibiotic treatment. Previously, antibiotic concentrations in tissues were extrapolated from skin blister studies, but sweat analyses for TDM have not been conducted. Objective: To investigate the potential of sweat analysis as a non-invasive, rapid, and potential bedside TDM method. Methods: We analyzed sweat and blood samples from 13 in-house patients treated with intravenous cefepime, imipenem, or flucloxacillin. For cefepime treatment, full pharmacokinetic sampling was performed (five subsequent sweat samples every 2 h) using ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. The ClinicalTrials.gov registration number is NCT03678142. Results: In this study, we demonstrated for the first time that flucloxacillin, imipenem, and cefepime are detectable in sweat. Antibiotic concentration changes over time demonstrated comparable (age-adjusted) dynamics in the blood and sweat of patients treated with cefepime. Patients treated with standard flucloxacillin dosage showed the highest mean antibiotic concentration in sweat. Conclusions: Our results provide a proof-of-concept that sweat analysis could potentially serve as a non-invasive, rapid, and reliable method to measure antibiotic concentration and as a surrogate marker for tissue penetration. If combined with smart biosensors, sweat analysis may potentially serve as the first lab-independent, non-invasive antibiotic TDM method.

The effects of neurectomy and hibernation on bone properties and the endocannabinoid system in marmots (Marmota flaviventris)

Hibernators have adapted a physiological mechanism allowing them to undergo long periods of inactivity without experiencing bone loss. However, the biological mechanisms that prevent bone loss are unknown. Previous studies found meaningful changes, between active and hibernating marmots, in the endocannabinoid system of many tissues, including bone. Cannabinoid receptors (CB1 and CB2) have divergent localization in bone. CB1 is predominately found on sympathetic nerve terminals, while CB2 is more abundant on bone cells and their progenitors. This study aimed to determine the contribution of innervation on endocannabinoid regulation of bone properties in hibernating (during torpor) and non-hibernating yellow-bellied marmots. Neurectomy, a model for disuse osteoporosis, was performed unilaterally in both hibernating and active marmots. Endocannabinoid concentrations were measured in bone marrow, cortical, and trabecular regions from fourth metatarsals of both hindlimbs using microflow chromatography-tandem quadrupole mass spectrometry. Trabecular bone architectural properties of fifth metatarsals were evaluated using micro-computed tomography. There were ligand-specific increases with neurectomy in active, but not hibernating, marmots. Trabecular bone architectural properties were not affected by neurectomy during hibernation, but did show some minor negative changes in active marmots. These findings suggest protection from bone loss in hibernating rodents is peripherally rather than centrally regulated. Furthermore, findings suggest even active marmots with normal metabolism are partially protected from disuse induced bone loss compared to laboratory rodents. Understanding the mechanism hibernators use to maintain bone density may guide development for novel bone loss prevention therapies.

Single-Dose Pharmacokinetics and Preliminary Safety Assessment with Use of CBD-Rich Hemp Nutraceutical in Healthy Dogs and Cats

The use of CBD-rich hemp products is becoming popular among pet owners with no long-term safety data related to consumption in adult dogs and cats. The purpose of this study was to determine the single-dose oral pharmacokinetics of CBD, and to provide a preliminary assessment of safety and adverse effects during 12-week administration using a hemp-based product in healthy dogs and cats. Eight of each species were provided a 2 mg/kg total CBD concentration orally twice daily for 12 weeks with screening of single-dose pharmacokinetics in six of each species. Pharmacokinetics revealed a mean maximum concentration (Cmax) of 301 ng/mL and 43 ng/mL, area under the curve (AUC) of 1297 ng-h/mL and 164 ng-h/mL, and time to maximal concentration (Tmax) of 1.4 h and 2 h, for dogs and cats, respectively. Serum chemistry and CBC results showed no clinically significant alterations, however one cat showed a persistent rise in alanine aminotransferase (ALT) above the reference range for the duration of the trial. In healthy dogs and cats, an oral CBD-rich hemp supplement administered every 12 h was not detrimental based on CBC or biochemistry values. Cats do appear to absorb or eliminate CBD differently than dogs, showing lower serum concentrations and adverse effects of excessive licking and head-shaking during oil administration.

Recent Advances and Challenges in Steroid Metabolomics for Biomarker Discovery

BACKGROUND

Steroid hormones belong to a group of low-molecular weight compounds which are responsible for maintenance of various body functions, thus, their accurate assessment is crucial for evaluation of biosynthetic defects. The development of reliable methods allowing disease diagnosis is essential to improve early detection of various disorders connected with altered steroidogenesis. Currently, the field of metabolomics offers several improvements in terms of sensitivity and specificity of the diagnostic methods when opposed to classical diagnostic approaches. The combination of hyphenated techniques and pattern recognition methods allows to carry out a comprehensive assessment of the slightest alterations in steroid metabolic pathways and can be applied as a tool for biomarker discovery.

METHODS

We have performed an extensive literature search applying various bibliographic databases for peer-reviewed articles concentrating on the applications of hyphenated techniques and pattern recognition methods incorporated into the steroid metabolomic approach for biomarker discovery.

RESULTS

The review discusses strengths, challenges and recent developments in steroidbased metabolomics. We present methods of sample collection and preparation, methods of separation and detection of steroid hormones in biological material, data analysis, and interpretation as well as examples of applications of steroid metabolomics for biomarker discovery (cancer, mental and central nervous system disorders, endocrine diseases, monitoring of drug therapy and doping control).

CONCLUSION

Information presented in this review will be valuable to anyone interested in the application of metabolomics for biomarker discovery with a special emphasis on disorders of steroid hormone synthesis and metabolism.

Impact of Wearing and Washing/Drying of Permethrin-Treated Clothing on Their Contact Irritancy and Toxicity for Nymphal Ixodes scapularis (Acari: Ixodidae) Ticks

Permethrin-treated clothing is available as consumer products to prevent bites by tick and insect pests. We used bioassays to examine the impact of wearing and washing/drying of permethrin-treated shirts, pants, and socks, and wearing of treated shoes, on their contact irritancy and toxicity for nymphal Ixodes scapularis Say (Acari: Ixodidae) ticks, the primary vectors in the eastern United States of the causative agents of Lyme disease, human anaplasmosis, and human babesiosis. Pristine permethrin-treated clothing displayed strong contact irritancy and toxicity toward I. scapularis nymphs, with 0-30% of ticks across clothing types and tick sources displaying normal movement 1 h after forced contact for 30-120 s with treated textile. Following 16 d of wear and 16 rounds of machine washing and drying, we recorded reduced concentrations (by 50-90%) of permethrin, compared with pristine treated clothing, from shirts, pants, and socks. This loss of permethrin was associated with reduced contact irritancy and toxicity for ticks after forced contact with worn and washed/dried treated clothing: 31-67% of ticks displayed normal movement 1 h after contact. Nevertheless, the worn and washed/dried treated clothing was still superior to nontreated textile, for which 90-100% of ticks displayed normal movement. Treated shoes, which were worn but not washed, remained as toxic to the ticks as pristine treated shoes. We caution that these laboratory bioassay results should not be interpreted as being directly indicative of the outcome of using washed/worn permethrin-treated clothing in daily life. Although wear and washing/drying did reduce the irritancy and toxicity of permethrin-treated clothing for I. scapularis nymphs more than we had expected, the remaining effect might still reduce the risk of tick bites in a real-life scenario.

Gonadotropin-releasing hormone agonist in premenopausal women does not alter hypothalamic-pituitary-adrenal axis response to corticotropin-releasing hormone

Sex hormones appear to play a role in the regulation of hypothalamic-pituitary-adrenal (HPA) axis activity. The objective was to isolate the effects of estradiol (E₂) on central activation of the HPA axis. We hypothesized that the HPA axis response to corticotropin-releasing hormone (CRH) under dexamethasone (Dex) suppression would be exaggerated in response to chronic ovarian hormone suppression and that physiologic E₂ add-back would mitigate this response. Thirty premenopausal women underwent 20 wk of gonadotropin-releasing hormone agonist therapy (GnRH_AG) and transdermal E₂ (0.075 mg per day, GnRH_AG + E₂, n = 15) or placebo (PL) patch (GnRH_AG + PL, n = 15). Women in the GnRH_AG + PL and GnRH_AG + E₂ groups were of similar age (38 (SD 5) yr vs. 36 (SD 7) yr) and body mass index (27 (SD 6) kg/m² vs. 27 (SD 6) kg/m²). Serum E₂ changed differently between the groups ( P = 0.01); it decreased in response to GnRH_AG + PL (77.9 ± 17.4 to 23.2 ± 2.6 pg/ml; P = 0.008) and did not change in response to GnRH_AG + E₂ (70.6 ± 12.4 to 105 ± 30.4 pg/ml; P = 0.36). The incremental area under the curve (AUC_INC) responses to CRH were different between the groups for total cortisol ( P = 0.03) and cortisone ( P = 0.04) but not serum adrenocorticotropic hormone (ACTH) ( P = 0.28). When examining within-group changes, GnRH_AG + PL did not alter the HPA axis response to Dex/CRH, but GnRH_AG + E₂ decreased the AUC_INC for ACTH (AUC_INC, 1,623 ± 257 to 1,211 ± 236 pg/ml·min, P = 0.004), cortisone (1,795 ± 367 to 1,090 ± 281 ng/ml·min, P = 0.009), and total cortisol (7,008 ± 1,387 to 3,893 ± 1,090 ng/ml·min, P = 0.02). Suppression of ovarian hormones by GnRH_AG therapy for 20 wk did not exaggerate the HPA axis response to CRH, but physiologic E₂ add-back reduced HPA axis activity compared with preintervention levels.

Pharmacokinetics, Safety, and Clinical Efficacy of Cannabidiol Treatment in Osteoarthritic Dogs

Objectives: The objectives of this study were to determine basic oral pharmacokinetics, and assess safety and analgesic efficacy of a cannabidiol (CBD) based oil in dogs with osteoarthritis (OA).

Methods: Single-dose pharmacokinetics was performed using two different doses of CBD enriched (2 and 8 mg/kg) oil. Thereafter, a randomized placebo-controlled, veterinarian, and owner blinded, cross-over study was conducted. Dogs received each of two treatments: CBD oil (2 mg/kg) or placebo oil every 12 h. Each treatment lasted for 4 weeks with a 2-week washout period. Baseline veterinary assessment and owner questionnaires were completed before initiating each treatment and at weeks 2 and 4. Hematology, serum chemistry and physical examinations were performed at each visit. A mixed model analysis, analyzing the change from enrollment baseline for all other time points was utilized for all variables of interest, with a p ≤ 0.05 defined as significant.

Results: Pharmacokinetics revealed an elimination half-life of 4.2 h at both doses and no observable side effects. Clinically, canine brief pain inventory and Hudson activity scores showed a significant decrease in pain and increase in activity (p < 0.01) with CBD oil. Veterinary assessment showed decreased pain during CBD treatment (p < 0.02). No side effects were reported by owners, however, serum chemistry showed an increase in alkaline phosphatase during CBD treatment (p < 0.01).

Clinical significance: This pharmacokinetic and clinical study suggests that 2 mg/kg of CBD twice daily can help increase comfort and activity in dogs with OA.

The evolution of methods for urinary steroid metabolomics in clinical investigations particularly in childhood

The metabolites of cortisol, and the intermediates in the pathways from cholesterol to cortisol and the adrenal sex steroids can be analysed in a single separation of steroids by gas chromatography (GC) coupled to MS to give a urinary steroid profile (USP). Steroids individually and in profile are now commonly measured in plasma by liquid chromatography (LC) coupled with MS/MS. The steroid conjugates in urine can be determined after hydrolysis and derivative formation and for the first time without hydrolysis using GC-MS, GC-MS/MS and liquid chromatography with mass spectrometry (LC-MS/MS). The evolution of the technology, practicalities and clinical applications are examined in this review. The patterns and quantities of steroids changes through childhood. Information can be obtained on production rates, from which children with steroid excess and deficiency states can be recognised when presenting with obesity, adrenarche, adrenal suppression, hypertension, adrenal tumours, intersex condition and early puberty, as examples. Genetic defects in steroid production and action can be detected by abnormalities from the GC-MS of steroids in urine. New mechanisms of steroid synthesis and metabolism have been recognised through steroid profiling. GC with tandem mass spectrometry (GC-MS/MS) has been used for the tentative identification of unknown steroids in urine from newborn infants with congenital adrenal hyperplasia. Suggestions are made as to areas for future research and for future applications of steroid profiling. As routine hospital laboratories become more familiar with the problems of chromatographic and MS analysis they can consider steroid profiling in their test repertoire although with LC-MS/MS of urinary steroids this is unlikely to become a routine test because of the availability, cost and purity of the internal standards and the complexity of data interpretation. Steroid profiling with quantitative analysis by mass spectrometry (MS) after chromatography now provides the most versatile of tests of adrenal function in childhood.

Seasonal Changes in Endocannabinoid Concentrations between Active and Hibernating Marmots (Marmota flaviventris)

Hibernation is a naturally occurring model for studying diseases such as obesity and osteoporosis. Hibernators, marmots (Marmota flaviventris) among them, are able to nearly double their body mass by increasing fat stores prior to hibernation without the negative consequences of obesity. They are also physically inactive for extended periods of time without experiencing negative effects on the skeleton. The endocannabinoid system is involved in modulating neural signaling, circannual rhythms, behavior, appetite, thermogenesis, and bone and energy metabolism. These systems are also altered to maintain homeostasis during hibernation. This study aims to better understand the involvement of the endocannabinoid system in the regulation of physiological processes during hibernation by quantifying the seasonal variation of endocannabinoids and endocannabinoid-like ligands in both active and hibernating marmots. We hypothesized that there would be significant changes in endocannabinoid concentrations at the tissue level in marmots between active and hibernating states. Concentrations were measured in brain, serum, brown adipose tissue, white adipose tissue, bone marrow, cortical bone, and trabecular bone using microflow chromatography coupled with tandem quadrupole mass spectrometry. Significant changes were found, such as a 30-fold decrease in 2-arachidonoyl glycerol (2-AG) in cortical bone during hibernation. Many endocannabinoid and endocannabinoid-like ligands decreased in brown adipose tissue, white adipose tissue, and cortical bone, while several ligands increased in bone marrow. This result supports our hypothesis and suggests the possibility of a peripherally controlled shift in energy metabolism, reduction in bone metabolism, and suppression of the immune system during hibernation.

Metabolomics and Ionomics of Potato Tuber Reveals an Influence of Cultivar and Market Class on Human Nutrients and Bioactive Compounds

Potato (Solanum tuberosum L.) is an important global food crop that contains phytochemicals with demonstrated effects on human health. Understanding sources of chemical variation of potato tuber can inform breeding for improved health attributes of the cooked food. Here, a comprehensive metabolomics (UPLC- and GC-MS) and ionomics (ICP-MS) analysis of raw and cooked potato tuber was performed on 60 unique potato genotypes that span 5 market classes including russet, red, yellow, chip, and specialty potatoes. The analyses detected 2,656 compounds that included known bioactives (43 compounds), nutrients (42), lipids (76), and 23 metals. Most nutrients and bioactives were partially degraded during cooking (44 out of 85; 52%), however genotypes with high quantities of bioactives remained highest in the cooked tuber. Chemical variation was influenced by genotype and market class. Specifically, ~53% of all detected compounds from cooked potato varied among market class and 40% varied by genotype. The most notable metabolite profiles were observed in yellow-flesh potato which had higher levels of carotenoids and specialty potatoes which had the higher levels of chlorogenic acid as compared to the other market classes. Variation in several molecules with known association to health was observed among market classes and included vitamins (e.g., pyridoxal, ~2-fold variation), bioactives (e.g., chlorogenic acid, ~40-fold variation), medicinals (e.g., kukoamines, ~6-fold variation), and minerals (e.g., calcium, iron, molybdenum, ~2-fold variation). Furthermore, more metabolite variation was observed within market class than among market class (e.g., α-tocopherol, ~1-fold variation among market class vs. ~3-fold variation within market class). Taken together, the analysis characterized significant metabolite and mineral variation in raw and cooked potato tuber, and support the potential to breed new cultivars for improved health traits.

Pregnenolone-progesterone-allopregnanolone pathway as a potential therapeutic target in first-episode antipsychotic-naïve patients with schizophrenia

Neurosteroids are both endogenous and exogenous steroids that rapidly alter neuronal excitability through interactions with ligand-gated ion channels and other cell surface receptors. They are originated from cholesterol and have important implications for schizophrenia (SZ) pathophysiology and treatment strategies. Specifically, pregnenolone (PREG), progesterone (PROG) and allopregnanolone (ALLO) exhibit similar psychotropic properties. Using enzyme immunoassay, we compared the neurosteroids in PREG downstream pathways in plasma between healthy controls (HC, n = 43) and first-episode antipsychotic-naïve patients with SZ (FEAN-SZ, n = 53) before antipsychotic drug (APD) treatment. Comparisons were also made particularly along PREG-PROG-ALLO pathway in the same FEAN-SZ patients across multiple time points following initiation of treatment for 12 months (m). Firstly, at baseline, levels of PREG were significantly higher and those of ALLO were lower in FEAN-SZ than in HC, whereas PROG, cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were not different. Consequently, the molar ratios of ALLO/PREG and ALLO/PROG in FEAN-SZ were significantly reduced. Secondly, in response to APD at 1 month, ALLO levels in FEAN-SZ were markedly elevated, whereas PREG and PROG levels decreased. Thirdly, among FEAN-SZ, lower levels of PROG (reflecting higher conversion to ALLO) at baseline may predict better therapeutic outcome after 1 month of APD treatment. These findings point to the perturbations of the PREG-PROG-ALLO pathway early in psychosis, and further study of this pathway may inform alternative and innovative therapeutic targets for SZ.

Simultaneous Determination of Seven Neuroactive Steroids Associated with Depression in Rat Plasma and Brain by High Performance Liquid Chromatography-Tandem Mass Spectrometry

Sensitive and specific biomarkers are required for the diagnosis and treatment of depression because the existing diagnostic criteria are subjective and could produce false positives or negatives. Some endogenous neuroactive steroids that have shown either antidepressant effects or concentration changes in individuals with depression could provide potential biomarkers. In this study, a simple and specific method was developed to simultaneously determine seven endogenous neuroactive steroids in biological samples: cortisone, cortisol, dehydroepiandrosterone, estradiol, progesterone, pregnenolone, and testosterone. After liquid-liquid extraction, chromatographic separation was achieved on a C18 column with gradient elution using water-methanol at a flow rate of 300 μL min(-1). Detection and quantitation were performed by tandem mass spectrometry with atmospheric pressure chemical ionization and selected reaction monitoring. Plasma and brain neuroactive steroid levels were then determined in control rats and rats exposed to forced swimming, a classical rodent model of depression. The results showed that the plasma concentrations of testosterone, pregnenolone, and progesterone significantly increased in rats exposed to the forced swimming test. In contrast, brain homogenate levels of cortisol, estradiol, and progesterone decreased, while pregnenolone levels were elevated in this model of depression. In conclusion, a new method to quantify neuroactive steroids was successfully developed and applied to their investigation in rat plasma and brain. The findings of this study indicated that plasma testosterone, pregnenolone, and progesterone levels could provide potential biomarkers for the diagnosis and treatment of depression.

Simultaneous determination of thirteen different steroid hormones using micro UHPLC-MS/MS with on-line SPE system

Ultratrace analysis of sample components requires excellent analytical performance in terms of limits of quantitation (LOQ). Micro UHPLC coupled to sensitive tandem mass spectrometry provides state of the art solution for such analytical problems. Using on-line SPE with column switching on a micro UHPLC-MS/MS system allowed to decrease LOQ without any complex sample preparation protocol. The presented method is capable of reaching satisfactory low LOQ values for analysis of thirteen different steroid molecules from human plasma without the most commonly used off-line SPE or compound derivatization. Steroids were determined by using two simple sample preparation methods, based on lower and higher plasma steroid concentrations. In the first method, higher analyte concentrations were directly determined after protein precipitation with methanol. The organic phase obtained from the precipitation was diluted with water and directly injected into the LC-MS system. In the second method, low steroid levels were determined by concentrating the organic phase after steroid extraction. In this case, analytes were extracted with ethyl acetate and reconstituted in 90/10 water/acetonitrile following evaporation to dryness. This step provided much lower LOQs, outperforming previously published values. The method has been validated and subsequently applied to clinical laboratory measurement.

Model of Chronic Equine Endometritis Involving a Pseudomonas aeruginosa Biofilm

Bacteria in a biofilm community have increased tolerance to antimicrobial therapy. To characterize the role of biofilms in equine endometritis, six mares were inoculated with lux-engineered Pseudomonas aeruginosa strains isolated from equine uterine infections. Following establishment of infection, the horses were euthanized and the endometrial surfaces were imaged for luminescence to localize adherent lux-labeled bacteria. Samples from the endometrium were collected for cytology, histopathology, carbohydrate analysis, and expression of inflammatory cytokine genes. Tissue-adherent bacteria were present in focal areas between endometrial folds (6/6 mares). The Pel exopolysaccharide (biofilm matrix component) and cyclic di-GMP (biofilm-regulatory molecule) were detected in 6/6 mares and 5/6 mares, respectively, from endometrial samples with tissue-adherent bacteria (P < 0.05). A greater incidence (P < 0.05) of Pel exopolysaccharide was present in samples fixed with Bouin's solution (18/18) than in buffered formalin (0/18), indicating that Bouin's solution is more appropriate for detecting bacteria adherent to the endometrium. There were no differences (P > 0.05) in the number of inflammatory cells in the endometrium between areas with and without tissue-adherent bacteria. Neutrophils were decreased (P < 0.05) in areas surrounding tissue-adherent bacteria compared to those in areas free of adherent bacteria. Gene expression of interleukin-10, an immune-modulatory cytokine, was significantly (P < 0.05) increased in areas of tissue-adherent bacteria compared to that in endometrium absent of biofilm. These findings indicate that P. aeruginosa produces a biofilm in the uterus and that the host immune response is modulated focally around areas with biofilm, but inflammation within the tissue is similar in areas with and without biofilm matrix. Future studies will focus on therapeutic options for elimination of bacterial biofilm in the equine uterus.

Quantification of steroid hormones in human serum by liquid chromatography-high resolution tandem mass spectrometry

A limited specificity is inherent to immunoassays for steroid hormone analysis. To improve selectivity mass spectrometric analysis of steroid hormones by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been introduced in the clinical laboratory over the past years usually with low mass resolution triple-quadrupole instruments or more recently by high resolution mass spectrometry (HR-MS). Here we introduce liquid chromatography-high resolution tandem mass spectrometry (LC-MS/HR-MS) to further increase selectivity of steroid hormone quantification. Application of HR-MS demonstrates an enhanced selectivity compared to low mass resolution. Separation of isobaric interferences reduces background noise and avoids overestimation. Samples were prepared by automated liquid-liquid extraction with MTBE. The LC-MS/HR-MS method using a quadrupole-Orbitrap analyzer includes eight steroid hormones i.e. androstenedione, corticosterone, cortisol, cortisone, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, and testosterone. It has a run-time of 5.3min and was validated according to the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) guidelines. For most of the analytes coefficient of variation were 10% or lower and LOQs were determined significantly below 1ng/ml. Full product ion spectra including accurate masses substantiate compound identification by matching their masses and ratios with authentic standards. In summary, quantification of steroid hormones by LC-MS/HR-MS is applicable for clinical diagnostics and holds also promise for highly selective quantification of other small molecules.

Endogenous glucocorticoid analysis by liquid chromatography-tandem mass spectrometry in routine clinical laboratories

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical technique that offers exceptional selectivity and sensitivity. Used optimally, LC-MS/MS provides accurate and precise results for a wide range of analytes at concentrations that are difficult to quantitate with other methodologies. Its implementation into routine clinical biochemistry laboratories has revolutionised our ability to analyse small molecules such as glucocorticoids. Whereas immunoassays can suffer from matrix effects and cross-reactivity due to interactions with structural analogues, the selectivity offered by LC-MS/MS has largely overcome these limitations. As many clinical guidelines are now beginning to acknowledge the importance of the methodology used to provide results, the advantages associated with LC-MS/MS are gaining wider recognition. With their integral role in both the diagnosis and management of hypo- and hyperadrenal disorders, coupled with their widespread pharmacological use, the accurate measurement of glucocorticoids is fundamental to effective patient care. Here, we provide an up-to-date review of the LC-MS/MS techniques used to successfully measure endogenous glucocorticoids, particular reference is made to serum, urine and salivary cortisol.

Quantitative bottom up analysis of infliximab in serum using protein A purification and integrated μLC-electrospray chip IonKey MS/MS technology

Background: TNO Triskelion has applied its general workflow for the development of quantitative LC–MS methods for proteins in biological matrices to the quantification of infliximab in rat serum using bottom up μLC–MS/MS. Results/methodology: The general workflow consists of sample purification, analyte processing and LC–MS analysis. In the development of a quantitative μLC–MS/MS method for infliximab in rat serum the analyte processing part and the LC–MS part were optimized, in order to meet the different sample requirements of μLC–MS as compared with UPLC–MS. Using the optimized μLC–MS/MS method the LOQ was 75 ng/ml. Conclusion: The present study showed that it is possible to gain sensitivity when going to smaller scale LC–MS (UPLC–MS to μLC–MS). Due to the combination of a modified sample preparation approach and the application of μLC–MS a lower LOQ could be achieved for infliximab compared with a previously developed UPLC–MS method.

Microfluidic Organ/Body-on-a-Chip Devices at the Convergence of Biology and Microengineering

Recent advances in biomedical technologies are mostly related to the convergence of biology with microengineering. For instance, microfluidic devices are now commonly found in most research centers, clinics and hospitals, contributing to more accurate studies and therapies as powerful tools for drug delivery, monitoring of specific analytes, and medical diagnostics. Most remarkably, integration of cellularized constructs within microengineered platforms has enabled the recapitulation of the physiological and pathological conditions of complex tissues and organs. The so-called “organ-on-a-chip” technology, which represents a new avenue in the field of advanced in vitro models, with the potential to revolutionize current approaches to drug screening and toxicology studies. This review aims to highlight recent advances of microfluidic-based devices towards a body-on-a-chip concept, exploring their technology and broad applications in the biomedical field.

Bioanalytical validation for simultaneous quantification of non-aromatic steroids in follicular fluid from cattle via ESI-LC-MS/MS

The family of steroid hormones is quite attractive for the approach of phenotype monitoring in farm animals. Therefore, we developed a new protocol for the quantitative analysis of natural steroids in follicular fluid from dairy cows. The corresponding steroid profile, which consists of progesterone, corticosterone, hydrocortisone, testosterone, and androstenedione covering three distinct steroid classes, was determined by LC/MS. Quantification is achieved by use of steroid standards diluted in steroid-free follicular fluid as calibrators. Thus, the new protocol does not require deuterated standards. In order to correct for conditional performance of the analytical system we have used dexamethasone as an internal standard. The method was validated according to EMA guidelines. Within- and between-day variations were below 20% for most parameters assessed. All steroids assessed had lower limits of quantification in the range of 2.1 to 4.4ng/ml. We have established a simple and sensitive analytical system in order to step towards a broader and cost-efficient phenotyping analysis in follicular fluid from dairy cows.

Integration of microfluidic LC with HRMS for the analysis of analytes in biofluids: past, present and future

Capillary LC (cLC) coupled to MS has the potential to improve detection limits, address limited sample volumes and allow multiple analyses from one sample. This is particularly attractive in areas where ultrahigh assay sensitivity, low limits of detection and small sample volumes are becoming commonplace. However, implementation of cLC–MS in the bioanalytical–drug metabolism area had been hampered by the lack of commercial instrumentation and the need for experts to operate the system. Recent advances in microfabricated devices such as chip-cube and ion-key technologies offer the potential for true implementation of cLC in the modern laboratory including the benefits of the combination of this type of separation with high-resolution MS.

Molecular effects of supraphysiological doses of doping agents on health

Supraphysiological doses of doping agents, such as T/DHT and GH/IGF-1, affect cellular pathways associated with apoptosis and inflammation.

Lab-on-a-Chip hyphenation with mass spectrometry: strategies for bioanalytical applications

The Lab-on-a-Chip concept aims at miniaturizing laboratory processes to enable automation and/or parallelization via microfluidic chips that are capable of handling minute sample volumes. Mass spectrometry is nowadays the detection method of choice, because of its selectivity, sensitivity and wide application range. We review the most interesting examples over the last two-and-a-half years where the two techniques were used for bioanalytical applications. Furthermore, we discuss the merits and limitations of such hyphenated systems. We inventorize the reported applications and approaches. We see an ongoing trend towards chip-based liquid chromatography-mass spectrometry usage and small volume analysis applications, particularly in the field of proteomics where bottom-up approaches profit from chip-based technologies and hyphenation with complex cell cultures.

Quantitation of human peptides and proteins via MS: review of analytically validated assays

Since the development of monoclonal antibodies in the 1970s, antibody-based assays have been used for the quantitation of proteins and peptides and, today, they are the most widely used technology in routine laboratory medicine and bioanalysis. However, in the last couple of decades, liquid chromatography-mass spectrometry/mass spectrometry (LC–MS/MS) techniques have been adopted in the quantitation of small molecules, and more recently have made significant contributions in the quantitation of proteins and peptides. In this article, we will review clinical MS-based assays for endogenous peptides, proteins, and therapeutic antibodies, for which validated methods exist. We will also cover the measurement of protein turnover and the unique solutions that MS can offer in this field.

Clinical applications of LC-MS sex steroid assays: evolution of methodologies in the 21st century

PURPOSE OF REVIEW

The purpose of this review is to summarize why and how liquid chromatography tandem mass spectrometry (LC-MS/MS) is increasingly replacing other methodologies for the measurement of sex steroids.

RECENT FINDINGS

Measurement of sex steroids, particularly testosterone and estradiol, is important for diagnosis or management of a host of conditions (e.g. disorders of puberty, hypogonadism, polycystic ovary syndrome, amenorrhea, and tumors of ovary, testes, breast and prostate). Historically, metabolites of testosterone and estradiol were measured as ketosteroids in urine using colorimetric assays that lacked sensitivity and specificity due to endogenous and exogenous interferences. Extracted competitive manual radio-immunoassays provided improved, but still imperfect, specificity, and offered increased sensitivity. As testing demand increased, they were displaced by automated immunoassays. These offered better throughput and precision, but suffered worse specificity problems. Moreover, agreement between different immunoassays has often been poor and they are all compromised by a limited dynamic measurement range. To overcome these problems, LC-MS/MS methods have been developed and validated for quantitation of sex steroids. These methods reduce interferences, provide better specificity, improve dynamic range, and reduce between-method bias.

SUMMARY

Endocrine Society and Urology Society guidelines have highlighted the limitations of the immunoassays for sex steroids and have provided convincing evidence that mass spectrometric methods are preferable for measurement of sex steroid hormones. In this review, we describe LC-MS/MS methods for measurement of testosterone and estradiol.

Microwave-assisted derivatization: application to steroid profiling by gas chromatography/mass spectrometry

Gas chromatography-mass spectrometry (GC-MS) remains as the gold-standard technique for the study of the steroid metabolome. A main limitation is the need of performing a derivatization step since incubation with strong silylations agents for long periods of time (usually 16 h) is required for the derivatization of hindered hydroxyls present in some steroids of interest. In the present work, a rapid, simple and reproducible microwave-assisted derivatization method was developed. In the method, 36 steroids already treated with methoxyamine (2% in pyridine) were silylated with 50 μl of N-trimethylsilylimidazole by using microwave irradiation, and the formed methyloxime-trimethylsilyl derivatives were analyzed by GC-MS. Microwave power and derivatization time silylation conditions were optimized being the optimum conditions 600 W and 3 min respectively. In order to evaluate the usefulness of this technique, the urine steroid profiles for 20 healthy individuals were analyzed. The results of a comparison of microwave irradiation with the classical heating protocol showed similar derivatization yields, thus suggesting that microwave-assisted silylation is a valid tool for the rapid steroid metabolome study.

17-Hydroxyprogesterone in children, adolescents and adults

17-Hydroxyprogesterone (17-OHP) is an intermediate steroid in the adrenal biosynthetic pathway from cholesterol to cortisol and is the substrate for steroid 21-hydroxylase. An inherited deficiency of 21-hydroxylase leads to greatly increased serum concentrations of 17-OHP, while the absence of cortisol synthesis causes an increase in adrenocorticotrophic hormone. The classical congenital adrenal hyperplasia (CAH) presents usually with virilisation of a girl at birth. Affected boys and girls can have renal salt loss within a few days if aldosterone production is also compromised. Diagnosis can be delayed in boys. A non-classical form of congenital adrenal hyperplasia (NC-CAH) presents later in life usually with androgen excess. Moderately raised or normal 17-OHP concentrations can be seen basally but, if normal and clinical suspicion is high, an ACTH stimulation test will show 17-OHP concentrations (typically >30 nmol/L) above the normal response. NC-CAH is more likely to be detected clinically in females and may be asymptomatic particularly in males until families are investigated. The prevalence of NC-CAH in women with androgen excess can be up to 9% according to ethnic background and genotype. Mutations in the 21-hydroxylase genes in NC-CAH can be found that have less deleterious effects on enzyme activity. Other less-common defects in enzymes of cortisol synthesis can be associated with moderately elevated 17-OHP. Precocious puberty, acne, hirsutism and subfertility are the commonest features of hyperandrogenism. 17-OHP is a diagnostic marker for CAH but opinions differ on the role of 17OHP or androstenedione in monitoring treatment with renin in the salt losing form. This review considers the utility of 17-OHP measurements in children, adolescents and adults.

Simultaneous determination of cortisol and cortisone from human serum by liquid chromatography-tandem mass spectrometry

A fast, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and then the levels of cortisol and cortisone from sera of healthy adults were determined by the LC-MS/MS method. One hundred μ L of serum sample was directly extracted by adding 2 mL ethyl acetate, followed by chromatographic separation on a C18 column with a mobile phase consisting of 5 mM ammonium acetate and methanol (25 : 75, v/v). The precision, accuracy, and average recovery of the method were 1.5-5.3%, 95.4-102.5%, and 96.4% for cortisol, and 1.9-6.0%, 89.2-98.8%, and 79.9% for cortisone, respectively. The method was linear from 1.0 to 500.0 ng/mL (r(2) = 0.999) for cortisol and 2.5 to 100.0 ng/mL (r(2) = 0.998) for cortisone. The limits of detection (LOD) and quantification (LOQ) were 0.2 and 1.0 ng/mL for cortisol, and 1.0 and 2.5 ng/mL for cortisone, respectively. The average cortisol concentration (133.9 ± 63.7 ng/mL) of samples collected between 9:00 and 11:00 a.m. was higher approximately 4.4 times than that of cortisone (30.5 ± 10.7 ng/mL) (P < 0.0001). The average cortisone/cortisol ratio was 0.225. Therefore, the LC-MS/MS method may be useful for the diagnosis of some adrenal diseases and the assessment of 11 β -hydroxysteroid dehydrogenase (11 β -HSD) activity in clinical laboratories.