Environmental contaminants, sex hormones and SHBG in an elderly population.

Introduction: Effects of environmental contaminants (ECs) on endocrine systems have been reported, but few studies assessed associations between ECs and sex hormones (SH) in elderly. Aim of this study was to investigate whether blood concentrations of four classes of ECs were associated with SH concentrations in elderly.

Methods: Samples from participants of the cross-sectional population-based Prospective Investigation of the Vasculature in Uppsala Seniors study (PIVUS, 70-year-old men and women, n = 1016) were analyzed using validated mass spectrometry-based methods for SH (testosterone (T), dihydrotestosterone (DHT), estrone and estradiol (E2)); 23 persistent organic pollutants (POPs); 8 perfluoroalkyl substances (PFAS); 4 phthalates and 11 metals.

Glycosylation Profiling of the Neoplastic Biomarker Alpha Fetoprotein through Intact Mass Protein Analysis.

Elevated serum alpha-fetoprotein (AFP) can be observed in liver cirrhosis and hepatocellular carcinoma (HCC). The glycosylation patterns of AFP have been shown to differentiate these conditions, with AFP glycoforms with core fucosylation (AFP-L3) serving as a malignancy risk predictor for HCC. We have developed a method to detect endogenously present AFP proteoforms and to quantify the relative abundance of AFP-L3 glycoforms (AFP-L3%) in serum samples.

The plasma free fraction of 25-hydroxyvitamin D is not strongly associated with 25-hydroxyvitamin D clearance in kidney disease patients and controls.

Circulating 25-hydroxyvitamin D [25(OH)D] concentration is used to monitor vitamin D status. Plasma protein binding may influence the 25(OH)D dose-response to vitamin D treatment through a direct relationship between the plasma unbound ("free") fraction and clearance of 25(OH)D. We previously evaluated 25(OH)D clearance in relation to kidney function using intravenous administration of deuterium labeled 25(OH)D.

LC-MS/MS Method for High-Throughput Analysis of Methylmalonic Acid in Serum, Plasma, and Urine: Method for Analyzing Isomers Without Chromatographic Separation.

Measurement of methylmalonic acid (MMA) plays an important role in the diagnosis of vitamin B deficiency. Vitamin B is an essential cofactor for the enzymatic carbon rearrangement of methylmalonyl-CoA (MMA-CoA) to succinyl-CoA (SA-CoA), and the lack of vitamin B leads to elevated concentrations of MMA. Measurement of MMA in biological samples is complicated because of the presence of succinic acid (SA), isomer of MMA.

LC-MS/MS Method for Measurement of Thiopurine Nucleotides (TN) in Erythrocytes and Association of TN Concentrations With TPMT Enzyme Activity.

Monitoring concentrations of thiopurine metabolites is used clinically to prevent adverse effects in patients on thiopurine drug therapy. We developed a LC-MS/MS method for the quantification of 6-thioguanine (6-TG) and 6-methylmercaptopurine (6-MMP) in red blood cells (RBCs). This method utilizes an automated cell washer for RBC separation from whole blood samples and washing of the separated RBCs.

Endogenous sex hormones, aromatase activity and lung cancer risk in postmenopausal never-smoking women.

Although reproductive factors have been repeatedly associated with lung cancer risk, no study to date has directly evaluated the relationship with endogenous sex hormones nor with aromatase activity in postmenopausal never-smoking women. A case-control study of 397 incident lung cancer cases and their individually matched controls, nested within the Shanghai Women's Health Study, was conducted among postmenopausal women who were lifetime never smokers. Prediagnostic concentrations of sex hormones was quantitated using LC-MS/MS assays in plasma.

Clinical Utility and Analytical Aspects of Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods.

Background: The free hormone (FH) hypothesis states that hormone action and the corresponding biological effects are mediated by the unbound (free) fraction of hormone in circulation. The in vivo relationship between protein-bound and FH is complex and dynamic. In most individuals, measurement of total hormone (TH) is usually adequate to reflect the hormone status; however, certain physiological conditions and/or medications can affect protein binding and alter FH concentration.

A high sensitivity LC-MS/MS method for measurement of 3-methoxytyramine in plasma and associations between 3-methoxytyramine, metanephrines, and dopamine.

Introduction: Diagnosis of pheochromocytoma and paraganglioma (PPGL) is aided by the measurement of metanephrine (MN) and normetanephrine (NMN). Research suggests that 3-methoxytyramine (3MT), a dopamine (DA) metabolite, may serve as a biomarker of metastasis in patients with paraganglioma. Considering the very low endogenous plasma 3MT concentrations (<0.

Concentrations of nine endogenous steroid hormones in 70-year-old men and women.

Objectives: Circulating concentrations of endogenous steroids have systemic implications on health in elderly. However, population-based age- and ethnicity-specific data are scarce. The aim was to report sex-specific plasma concentrations of endogenous sex and adrenal steroids in elderly Swedish Caucasians, to examine the impact of BMI and to present concentrations in apparently healthy subjects.

Development and Clinical Evaluation of a High-Throughput LC-MS/MS Assay for Vitamin B6 in Human Plasma and Serum.

Background: Pyridoxal 5'-phosphate (PLP) is the primary circulatory form of vitamin B6, an essential cofactor for numerous biochemical enzymatic reactions. Conventional PLP analysis using high-performance liquid chromatography (HPLC) with fluorescence requires derivatization and long injection-to-injection time. Development of high-throughput LC-MS/MS assays is desirable.

Developmental low-dose exposure to bisphenol A induces chronic inflammation, bone marrow fibrosis and reduces bone stiffness in female rat offspring only.

Background: Developmental exposure to low doses of the endocrine disruptor bisphenol A (BPA) is known to alter bone tissue in young rodents, although how bone tissue is affected in aged animals is not well known. We have recently shown that low-dose developmental exposure to BPA increases procollagen type I N-terminal propeptide (P1NP) levels, a peptide formed during type 1 collagen synthesis, in plasma of 5-week-old female rat offspring while male offspring showed reduced bone size.

Objective: To analyze offspring bone phenotype at 52 weeks of age and clarify whether the BPA-induced increase in P1NP levels at 5 weeks is an early sign of bone marrow fibrosis development.

Association of PTHrP levels in CSF with Alzheimer's disease biomarkers.

Background: Parathyroid hormone-related protein (PTHrP) is involved in intracellular calcium regulation, neural cell proliferation and synaptic transmission. To date, no studies have been performed to evaluate the potential of PTHrP concentrations in cerebrospinal fluid (CSF) as a biomarker of brain pathophysiology. In this study we evaluated the association between CSF concentrations of PTHrP with the core CSF biomarkers of Alzheimer's disease (AD).

Parathyroid hormone related protein concentration in human serum and CSF correlates with age.

Background: Parathyroid Hormone-Related Protein (PTHrP) is involved in intracellular calcium (Ca) regulation, and has been demonstrated to participate in regulation of Ca in brain cells, activation of neurons, and modulation of pain. However, there are conflicting reports regarding the presence of PTHrP in CSF.

Design And Methods: PTHrP and Ca were quantified in paired CSF and serum samples using mass spectrometry-based methods.

An exploratory study Evaluating the impact of opioid and non-opioid pain medications on serum/plasma free testosterone and free estradiol concentrations.

Chronic use of opioid medications has been reported to cause altered sexual function. It is not known if non-opioid pain medications have similar effects. Assessment of this effect through the measurement of concentrations of free hormones is limited.

Altered adrenal and gonadal steroids biosynthesis in patients with burn injury.

Introduction: Burn injury inevitably leads to changes in the endogenous production of cytokines, as well as adrenal and gonadal steroids. Previous studies have reported gender-related differences in outcome following burn injury, which suggests that gonadal steroids may play a role. The aim of this study was to assess alterations in concentration of endogenous steroids in patients with burn injury.

Recommendations for the Generation, Quantification, Storage, and Handling of Peptides Used for Mass Spectrometry-Based Assays.

Background: For many years, basic and clinical researchers have taken advantage of the analytical sensitivity and specificity afforded by mass spectrometry in the measurement of proteins. Clinical laboratories are now beginning to deploy these work flows as well. For assays that use proteolysis to generate peptides for protein quantification and characterization, synthetic stable isotope-labeled internal standard peptides are of central importance.

Direct Measurement of Free Estradiol in Human Serum and Plasma by Equilibrium Dialysis-Liquid Chromatography-Tandem Mass Spectrometry.

We describe a direct method of measurement of free estradiol using equilibrium dialysis followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum aliquots and internal standards are extracted by liquid-liquid extraction using methyl-tert-butyl ether (MTBE) followed by derivatization with dansyl chloride. An API 5500 mass spectrometer operated in positive electrospray mode is used for detection.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for analysis of endogenous steroids in the luteal phase and early pregnancy in dogs: a pilot study.

Background: Blood samples from dogs are often limited in volume, only allowing few steroids to be quantified with immunoassays. In addition, immunoassays may be compromised by interferences such as anti-reagent antibodies. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can be used for the simultaneous quantitation of several steroids.

Mass spectrometry methods measured androgen and estrogen concentrations during pregnancy and in newborns of mothers with polycystic ovary syndrome.

Objective: Little is known about the aetiology of polycystic ovary syndrome (PCOS). Some suggest that elevated maternal androgens during gestation play a causative role. This implies placental passage of androgens during pregnancy.