Commutability assessment of new standard reference materials (SRMs) for determining serum total 25-hydroxyvitamin D using ligand binding and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays.

Commutability is where the measurement response for a reference material (RM) is the same as for an individual patient sample with the same concentration of analyte measured using two or more measurement systems. Assessment of commutability is essential when the RM is used in a calibration hierarchy or to ensure that clinical measurements are comparable across different measurement procedures and at different times. The commutability of three new Standard Reference Materials (SRMs) for determining serum total 25-hydroxyvitamin D [25(OH)D], defined as the sum of 25-hydroxyvitamin D [25(OH)D] and 25-hydroxyvitamin D [25(OH)D], was assessed through an interlaboratory study.

Determination of 24,25-dihydroxyvitamin D in Vitamin D External Quality Assessment Scheme samples using a reference measurement procedure.

Ninety archived human serum samples from the Vitamin D External Quality Assessment Scheme (DEQAS) were analyzed using a reference measurement procedure (RMP) based on isotope dilution liquid chromatography - tandem mass spectrometry (ID LC-MS/MS) for the determination of 24,25-dihydroxyvitamin D [24,25(OH)D]. These 24,25(OH)D results, in conjunction with concentration values assigned using RMPs for 25-hydroxyvitamin D [25(OH)D] and 25-hydroxyvitamin D [25(OH)D], provide a valuable resource for assessing the accuracy of measurements for 24,25(OH)D and for investigating the relationship between 24,25(OH)D and 25(OH)D. Results for 24,25(OH)D using the RMP were compared to DEQAS consensus values demonstrating that the consensus values were not sufficient to assess the accuracy of measurements among different laboratories and methods.

The postprandial secretion of peptide YY and in obesity is differentially increased after gastric bypass versus sleeve gastrectomy.

Objectives: Peptide tyrosine tyrosine (PYY) exists as two species, PYY and PYY , with distinct effects on insulin secretion and appetite regulation. The detailed effects of bariatric surgery on PYY and PYY secretion are not known as previous studies have used nonspecific immunoassays to measure total PYY. Our objective was to characterize the effect of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on fasting and postprandial PYY and PYY secretion using a newly developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay.

Late-night salivary cortisol and cortisone should be the initial screening test for Cushing's syndrome.

Endogenous Cushing's syndrome (CS) poses considerable diagnostic challenges. Although late-night salivary cortisol (LNSC) is recommended as a first-line screening investigation, it remains the least widely used test in many countries. The combined measurement of LNSC and late-night salivary cortisone (LNS cortisone) has shown to further improve diagnostic accuracy.

Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 - Part 2 ligand binding assays - impact of 25-hydroxyvitamin D and 24R,25-dihydroxyvitamin D on assay performance.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of ligand binding assays (Part 2) for the determination of serum total 25-hydroxyvitamin D [25(OH)D]. Fifty single-donor samples were assigned target values for concentrations of 25-hydroxyvitamin D [25(OH)D], 25-hydroxyvitamin D [25(OH)D], 3-epi-25-hydroxyvitamin D [3-epi-25(OH)D], and 24R,25-dihydroxyvitamin D [24R,25(OH)D] using isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 2 includes results from 17 laboratories using 32 ligand binding assays.

Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 - Part 1 liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays - impact of 3-epi-25-hydroxyvitamin D on assay performance.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays used for the determination of serum total 25-hydroxyvitamin D (25(OH)D), which is the sum of 25-hydroxyvitamin D (25(OH)D) and 25-hydroxyvitamin D (25(OH)D). A set of 50 single-donor samples was assigned target values for concentrations of 25(OH)D, 25(OH)D, 3-epi-25-hydroxyvitamin D (3-epi-25(OH)D), and 24R,25-dihydroxyvitamin D (24R,25(OH)D) using isotope dilution liquid chromatography - tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 1 includes results from 14 laboratories using 14 custom LC-MS/MS assays.

Vitamin D Supplementation and Sunlight Exposure on Serum Vitamin D Concentrations in 2 Parallel, Double-Blind, Randomized, Placebo-Controlled Trials.

Background: Vitamin D concentrations are a function of sunlight exposure and dietary intake. However, current dietary vitamin D recommendations do not consider differences in country-specific sunlight availability or spontaneous individual exposure.

Objectives: We aimed to investigate the effects of vitamin D supplementation and sunlight exposure on vitamin D concentrations in Brazilian women living in high compared with low latitudes.

Clinical Evaluation of Assays for Plasma Renin Activity and Aldosterone Measurement by Liquid Chromatography-Tandem Mass Spectrometry.

Background: Aldosterone and renin are pivotal hormones in the regulation of salt and water homeostasis and blood pressure. Measurement of renin and aldosterone in serum/plasma is essential for the investigation of primary hyperaldosteronism (PA) and monitoring of glucocorticoid replacement therapy.

Methods: We report 2 LC-MS/MS methods developed to measure aldosterone and plasma renin activity (PRA).

The relationship between vitamin D status, intake and exercise performance in UK University-level athletes and healthy inactive controls.

The potential ergogenic effects of vitamin D (vitD) in high performing athletes has received considerable attention in the literature and media. However, little is known about non-supplemented university athletes and students residing at a higher latitude. This study aimed to investigate the effects of vitD (biochemical status and dietary intake) on exercise performance in UK university athletes and sedentary students.

Seasonal variation in vitamin D status, bone health and athletic performance in competitive university student athletes: a longitudinal study.

Vitamin D deficiency has been commonly reported in elite athletes, but the vitamin D status of UK university athletes in different training environments remains unknown. The present study aimed to determine any seasonal changes in vitamin D status among indoor and outdoor athletes, and whether there was any relationship between vitamin D status and indices of physical performance and bone health. A group of forty-seven university athletes (indoor 22, outdoor 25) were tested during autumn and spring for serum vitamin D status, bone health and physical performance parameters.

Pre-clinical activity of combined LSD1 and mTORC1 inhibition in MLL-translocated acute myeloid leukaemia.

The histone demethylase lysine-specific demethylase 1 (LSD1 or KDM1A) has emerged as a candidate therapeutic target in acute myeloid leukaemia (AML); tranylcypromine-derivative inhibitors induce loss of clonogenic activity and promote differentiation, in particular in the MLL-translocated molecular subtype of AML. In AML, the use of drugs in combination often delivers superior clinical activity. To identify genes and cellular pathways that collaborate with LSD1 to maintain the leukaemic phenotype, and which could be targeted by combination therapies, we performed a genome-wide CRISPR-Cas9 dropout screen.

Enhancer Activation by Pharmacologic Displacement of LSD1 from GFI1 Induces Differentiation in Acute Myeloid Leukemia.

Pharmacologic inhibition of LSD1 promotes blast cell differentiation in acute myeloid leukemia (AML) with MLL translocations. The assumption has been that differentiation is induced through blockade of LSD1's histone demethylase activity. However, we observed that rapid, extensive, drug-induced changes in transcription occurred without genome-wide accumulation of the histone modifications targeted for demethylation by LSD1 at sites of LSD1 binding and that a demethylase-defective mutant rescued LSD1 knockdown AML cells as efficiently as wild-type protein.

Derepression of the Iroquois Homeodomain Transcription Factor Gene IRX3 Confers Differentiation Block in Acute Leukemia.

The Iroquois homeodomain transcription factor gene IRX3 is expressed in the developing nervous system, limb buds, and heart, and transcript levels specify obesity risk in humans. We now report a functional role for IRX3 in human acute leukemia. Although transcript levels are very low in normal human bone marrow cells, high IRX3 expression is found in ∼30% of patients with acute myeloid leukemia (AML), ∼50% with T-acute lymphoblastic leukemia, and ∼20% with B-acute lymphoblastic leukemia, frequently in association with high-level HOXA gene expression.

Redefining the stress cortisol response to surgery.

Background: Cortisol levels rise with the physiological stress of surgery. Previous studies have used older, less-specific assays, have not differentiated by severity or only studied procedures of a defined type. The aim of this study was to examine this phenomenon in surgeries of varying severity using a widely used cortisol immunoassay.

Interlaboratory Comparison for the Determination of 24,25-Dihydroxyvitamin D₃ in Human Serum Using Liquid Chromatography with Tandem Mass Spectrometry.

Six laboratories associated with the Vitamin D Standardization Program (VDSP) participated in an interlaboratory comparison of LC with tandem MS (MS/MS) methods for the determination of 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] in human serum. The laboratories analyzed two different serum-based Standard Reference Materials (SRMs) intended for use in the determination of 25-hydroxyvitamin D and 30 samples from the Vitamin D External Quality Assessment Scheme (DEQAS). All laboratory methods for 24,25(OH)2D3 were based on isotope dilution LC-MS/MS; three of the methods used derivatization of the vitamin D metabolites before LC-MS/MS.

Clinical roles in clinical biochemistry: a national survey of practice in the UK.

Background Using an online survey, we collected data to present a picture of how clinical authorization is performed in the UK. Methods A 21-question survey was uploaded to www.surveymonkey.

Prednisolone Replacement Therapy Mimics the Circadian Rhythm More Closely Than Other Glucocorticoids.

Background: This study examined the pharmacokinetic profile of prednisolone.

Methods: Using a newly developed ultra-performance liquid chromatography MS/MS method, prednisolone profiles in healthy volunteers and patients with adrenal insufficiency already treated with prednisolone were prospectively analyzed in a tertiary center.

Results: Twelve prednisolone day curves were analyzed.

Frequent Derepression of the Mesenchymal Transcription Factor Gene FOXC1 in Acute Myeloid Leukemia.

Through in silico and other analyses, we identified FOXC1 as expressed in at least 20% of human AML cases, but not in normal hematopoietic populations. FOXC1 expression in AML was almost exclusively associated with expression of the HOXA/B locus. Functional experiments demonstrated that FOXC1 contributes to a block in monocyte/macrophage differentiation and enhances clonogenic potential.

Screening for mutations in 17β-hydroxysteroid dehydrogenase and androgen receptor in women presenting with partially virilised 46,XY disorders of sex development.

Context And Objective: The precise diagnosis of partially virilised women with 46,XY disorders of sex development (DSD) is often obscure. In practice, this group often comes under the poorly defined, clinically based label of partial androgen insensitivity syndrome (PAIS). In a previous study, we found that 5α-reductase 2 (SRD5A2) mutations occurred in 43% of women in this subgroup.

Performance evaluation of Sanger sequencing for the diagnosis of primary hyperoxaluria and comparison with targeted next generation sequencing.

Definitive diagnosis of primary hyperoxaluria (PH) currently utilizes sequential Sanger sequencing of the AGXT, GRPHR, and HOGA1 genes but efficacy is unproven. This analysis is time-consuming, relatively expensive, and delays in diagnosis and inappropriate treatment can occur if not pursued early in the diagnostic work-up. We reviewed testing outcomes of Sanger sequencing in 200 consecutive patient samples referred for analysis.

Reversible inhibitors of LSD1 as therapeutic agents in acute myeloid leukemia: clinical significance and progress to date.

In the 10 years since the discovery of lysine-specific demethylase 1 (LSD1), this epigenetic eraser has emerged as an important target of interest in oncology. More specifically, research has demonstrated that it plays an essential role in the self-renewal of leukemic stem cells in acute myeloid leukemia (AML). This review will cover clinical aspects of AML, the role of epigenetics in the disease, and discuss the research that led to the first irreversible inhibitors of LSD1 entering clinical trials for the treatment of AML in 2014.

Isolation and enrichment of Stro-1 immunoselected mesenchymal stem cells from adult human bone marrow.

The availability of mesenchymal stem cells (MSCs) or skeletal stem cells (SSCs) is vital to many of the tissue engineering strategies currently being developed for repairing bone and cartilage. One difficulty with using this cell population is that SSCs represent only a small fraction of the cells available from an individual patient's bone marrow sample, typically less than 1 in 10,000. Therefore, methods have been devised to enrich the proportion of MSCs obtained from a bone marrow sample using hybridoma cell lines to generate antibodies to cell surface antigens specific for MSCs.