Tandem Mass Spectrometry Assay Research Articles

A Rapid Dilute-and-Shoot UPLC-MS/MS Assay to Simultaneously Measure 37 Drugs and Related Metabolites in Human Urine for Use in Clinical Pain Management

Monitoring of medication compliance and drug abuse is used by clinicians to increase patient prescription drug compliance and reduce illicit drug abuse and diversion. Despite available immunoassays, chromatography-mass spectrometry-based methods are considered the gold standard for urine drug monitoring owing to higher sensitivities and specificities. Herein, we report a fast, convenient ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay to detect or quantify 37 clinically relevant prescription drugs, drugs of abuse, and related glucuronides and other metabolites in human urine by single diluted sample injection. Analytes consisted of prescription and illicit opioids, benzodiazepines, and drugs of abuse, including parent compounds and glucuronidated and nonglucuronidated metabolites. Urine samples were diluted with water and supplemented with deuterated internal standards without enzymatic hydrolysis, analyte extraction, or sample purification. Analytes were separated by reversed-phase UPLC and quantified by positive-mode electrospray ionization and collision-induced dissociation MS. Assay validation followed Food and Drug Administration bioanalytical guidelines. Total analytical run time was 5.5 min. All analytes demonstrated acceptable inter- and intraassay accuracy, imprecision, and linearity throughout clinically relevant analytical ranges (1-2000 ng/mL, depending on analyte). All analytes demonstrated acceptable selectivity, stability, matrix effects, carryover, and performance compared to national reference laboratory or previously validated in-house methods. A total of 23 and 14 analytes were validated for quantitative and qualitative testing, respectively. A convenient UPLC-MS/MS assay for simultaneously monitoring 37 analytes in human urine was validated for use in pain management testing. Advantages of this multiplex assay include facile sample preparation and higher-throughput definitive detection including glucuronide metabolite quantification.

Applying mass spectrometric methods to study androgen biosynthesis and metabolism in prostate cancer.

Recent development of gas chromatography and liquid chromatography-tandem mass spectrometry (GC-MS/MS, LC-MS/MS) has provided novel tools to define sex steroid concentrations. These new methods overcome several of the problems associated with immunoassays for sex steroids. With the novel MS-based applications we are now able to measure small concentrations of the steroid hormones reliably and with high accuracy in both body fluids and tissue homogenates. The sensitivity of the tandem mass spectrometry assays allows us also for the first time to reliably measure picomolar or even femtomolar concentrations of estrogens and androgens. Furthermore, due to a high sensitivity and specificity of MS technology, we are also able to measure low concentrations of steroid hormones of interest in the presence of pharmacological concentration of other steroids and structurally closely related compounds. Both of these features are essential for multiple preclinical models for prostate cancer. The MS assays are also valuable for the simultaneous measurement of multiple steroids and their metabolites in small sample volumes in serum and tissue biopsies of prostate cancer patients before and after drug interventions. As a result, novel information about steroid hormone synthesis and metabolic pathways in prostate cancer has been obtained. In our recent studies, we have extensively applied a GC-MS/MS method to study androgen biosynthesis and metabolism in VCaP prostate cancer xenografts in mice. In the present review, we shortly summarize some of the benefits of the GC-MS/MS and novel LC-MS/MS assays, and provide examples of their use in defining novel mechanisms of androgen action in prostate cancer.

Postmenopausal Androgen Metabolism and Endometrial Cancer Risk in the Women’s Health Initiative Observational Study

After menopause, several androgens continue to be produced primarily by the adrenal glands; these can be converted into estrogens via aromatization or into androgen metabolites. It is unclear if androgens are associated with endometrial cancer risk independently of their being precursors to estrogens or if alternative metabolic pathways influence risk. We measured prediagnostic serum concentrations of 12 androgens and their metabolites using highly sensitive liquid chromatography-tandem mass spectrometry assays in a nested case-control study of postmenopausal women from the Women's Health Initiative Observational Study (313 endometrial cancer case subjects, 354 matched control subjects). Estrogens were previously assayed. We used conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for endometrial cancer with adjustment for confounders. Compared to the lowest concentrations, the highest levels of adrenal androgens were associated with increased endometrial cancer risk: dehydroepiandrosterone (5th vs 1st quintile: OR = 1.85, 95% CI = 1.06 to 3.25), androstenedione (OR = 2.36, 95% CI = 1.34 to 4.16), and testosterone (OR = 1.91, 95% CI = 1.12 to 3.24). Downstream androgen metabolites were not associated with endometrial cancer. Although increased risks for the parent androgens were still suggested after adjustment for unconjugated estradiol, the associations attenuated, and with the exception of androstenedione, were no longer statistically significant. We also evaluated ratios of estrogens relative to their androgenic precursors; both higher unconjugated estrone:androstenedione and higher unconjugated estradiol:testosterone were associated with increased endometrial cancer risk. We identified increased risks for endometrial cancer with the highest levels of adrenal androgens and high levels of estrogens relative to these androgens. As adrenal androgens can be aromatized to estrogens, this suggests androgens likely influence endometrial carcinogenesis via estrogen metabolism.

SUN-LB100 False Elevation of Thyroglobulin by Immunoassay with Negative Thyroglobulin Antibody and Measures Blocking Heterophile Antibody in a Patient Post-thyroidectomy for Papillary Thyroid Cancer; Use of Liquid Chromatography─Tandem Mass Spectrometry

Background: Thyroglobulin (Tg) is a useful tool to monitor residual or recurrent differentiated thyroid cancer in patient post-thyroidectomy. The test is typically performed using immunoassay, which is subject to interference by thyroglobulin antibody (TgAb) and heterophile antibody (HAb). TgAb is routinely checked to validate the test result. Pre-treatment of specimen with HAb blocking agents is adopted to prevent interference by HAb. Clinical Case: A 71-year male had incidental thyroid nodules, leading to discovery of papillary thyroid cancer status post thyroidectomy. There were two sub-centimeter cancer foci, partially encapsulated without capsular or vascular invasion, and surgical margin was clear. It was classified as pT1aNxMx, without clinical evidence of lymph node or distant metastasis. Thyroid remnant ablation was not planned. Measurements of Tg (ng/mL)/TgAb (+ or -) before and after surgery were: Pre-surgery 48.7/ (-); 3M post-surgery 1.7/ (-); 6M post-surgery 450.3/ (-). Tg levels remained markedly elevated up to > 1000 ng/mL with negative TgAb upon repeats and follow-ups. The high Tg levels prompted search for thyroid tissue, either normal or cancerous. Thyroid/Neck thyroid ultrasound didn’t reveal suspicious lesion. Radioactive iodine (RAI) whole body scan showed two foci at thyroid bed, without evidence of ectopic thyroid, node or distant metastasis. The patient received 74.3 mCi I-131 treatment. After RAI treatment, Tg levels remained markedly elevated, ranging from 434.6 to 1232.1 ng/mL, all with negative TgAb. The discrepancy of clinical observations and Tg results suggested false readings of Tg assays. As TgAb had been consistently negative, assay interference by HAb was strongly suspected, but specimen pre-treated with HAb blocking agents yielded similar results. Tg measurement by liquid chromatography─tandem mass spectrometry was performed, and Tg was undetectable, < 0.5 ng/mL, confirming the clinical impression that elevated Tg levels by immunoassay were false regardless negative TgAb and pre-treatment of specimen with HAb blocking agents. Conclusion: Elevated Tg levels by immunoassay can be false even with negative TgAb and pre-treatment of specimen with HAb blocking agents. When Tg levels are inconsistent with clinical findings, Tg measurement by liquid chromatography─tandem mass spectrometry is useful to uncover the false readings before proceeding to extensive work-up and treatment. Reference: (1) Preissner, C., O’Kane, D., Singh, R., Morris, J., Grebe, S. Phantoms in the assay tube: Heterophile antibody interferences in serum thyroglobulin assays. J Clin Endocrinol Metab 2003;88:3069-74 (2) Netzel, B., Grebe, S., Algeciras-Schimnich, A. Usefulness of a thyroglobulin liquid chromatography─tandem mass spectrometry assay for evaluation of suspected heterophile interference. Clin Chem 2014;60:1016-8 Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Clinical utility of an ultrasensitive urinary free cortisol assay by tandem mass spectrometry

Background24 h urinary free cortisol measurement is a clinically important first-line screening test for Cushing’s syndrome (CS). Tandem mass spectrometry (LC-MS/MS) assays have superior sensitivity and specificity compared to immunoassays. Our goal was to improve and validate a LC-MS/MS method to measure urinary free cortisol in both adult and pediatric patients and to characterize its clinical diagnostic performance of CS by chart review. MethodsWe improved a LC-MS/MS method previously reported for urinary free cortisol to be able to measure urinary and salivary cortisol in the same batch for increased efficiency. The sample preparation was by liquid-liquid extraction using dichloromethane followed by stepwise washing with acidic, basic and neutral solutions. The assay’s analytical performance was characterized, and a retrospective patient chart review was conducted to evaluate the assay’s clinical performance in diagnosing CS. ResultsThe LC-MS/MS assay demonstrated enhanced sensitivity and was linear within an analytical measurement range of 10–10,000 ng/dL. Assay accuracy was satisfactory as determined by spike and recovery studies and highly correlated with a reference LC-MS/MS method. The assay’s clinical diagnostic sensitivity and specificity in detecting CS was 96% and 91%, respectively, when compared to a urinary cortisol excretion of at least 50 µg/24 h. ConclusionsThe improved LC-MS/MS method is both sensitive and specific with enhanced analytical performance and clinical diagnostic utility to screen for CS. The clinical diagnostic sensitivity and specificity were superior based on retrospective patient chart review.

A rapid, simple and sensitive liquid chromatography tandem mass spectrometry assay to determine amoxicillin concentrations in biological matrix of little volume

To assess pharmacokinetics of amoxicillin (AMX) in mice, limitations such as a small sampling volume and low drug concentrations have to be addressed. Similar challenges are faced in a clinical framework, e.g. for therapeutic drug monitoring in neonates or small-scale in vitro investigations. An assay enabling quantification of small sample volumes but still at very low concentrations covering a broad concentration range is thus needed.A simple, rapid and highly sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and successfully validated for quantification of AMX in mouse serum according to European Medicines Agency guidelines. Sample preparation enabled the use of only 10 μL of serum, which is 5-fold less than comparable assays and allows to reduce the number of mice used in pharmacokinetic studies. After protein precipitation with 40 μL chilled methanol and dilution of the supernatant with water, the sample was injected into the LC system on a Poroshell 120 Phenyl Hexyl column (2.1 × 100 mm, 2.7 μm). Chromatographic separation was achieved using a gradient method consisting of acetonitrile and ultra-pure water, both with 0.1% (V/V) formic acid. Positive electrospray ionisation in multiple reaction monitoring mode was used for detection and quantification of AMX. Application to murine study samples demonstrated the reliability of the developed method being accurate and precise with a quantification range from 0.01 to 10 μg/mL. The assay is easily transferable due to a simple sample preparation and confirmed stability of AMX under various applied conditions.

Deciphering the role of N‐terminal methylation in modulating yeast protein function including the multitasking stress response protein, Hsp31

The first cytosolic N‐terminal methyltransferase identified in yeast, Tae1, recognizes mainly a protein N‐terminal motif sequence of M‐X‐P‐K. This conserved sequence motif is found in multiple proteins including ribosomal proteins, histones and small heat shock proteins across species. The human homolog of Tae1, N‐terminal methyltransferase 1 (NTMT1/NRMT1) has important functions in cell division by regulating RCC1 and centromere proteins such as CENP‐A and is implicated as a cancer target. Although these studies have been informative, the biological function of alpha N‐terminal methylation in yeast and human remains largely unknown. Our research is directed at unravelling the role of N‐terminal methylation in regulating yeast protein function and is currently focused on Hsp31, a multifunctional chaperone and enzyme involved in oxidative stress response. We are also investigating N‐terminal methylation on a proteome‐wide basis.Immuno‐detection and tandem mass spectrometry (MS/MS) assay with overexpressed Hsp31‐ MORF or physiologically expressed Hsp31‐GFP purified from WT and Tae1 deficiency strains demonstrated that Hsp31‐MORF is methylated at the first alanine (initial methionine is efficiently removed by a native methionine aminopeptidase) after the protein is synthesized. We also observed that the methylation types are exclusively mono‐ or di‐ methylation, with no tri‐methylated species observed. This is the first demonstration that the Hsp31 chaperone protein is N‐terminally methylated. Interestingly, methylation of Hsp31 was decreased but not completely eliminated in Tae1 deficient strains. This is the first evidence of such an overlapping methyltransferase activity which suggests the presence of another enzyme with N‐terminal methyltransferase activity. It unclear how the biological function of Hsp31 is affected by methylation and the difference between mono‐/di‐ methylation and tri‐methylation. We also verified N‐terminal methylation on other potential Tae1 substrates by MS/MS, including Hsp33 and a xylose and arabinose reductase. We conclude that N‐terminal methylation occurs with diverse substrates and that yeast is an excellent model to probe the function of this post‐translational modification. Further investigation is ongoing to determine if and how N‐terminal methylation modulates Hsp31 functions using site‐directed mutagenesis and biological activity assays.Support or Funding InformationFunding: Purdue University MCMP Research Enhancement grantThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Extended diagnosis of purine and pyrimidine disorders from urine: LC MS/MS assay development and clinical validation.

Background and aimsInborn errors of purine and pyrimidine metabolism are a diverse group of disorders with possible serious or life-threatening symptoms. They may be associated with neurological symptoms, renal stone disease or immunodeficiency. However, the clinical presentation can be nonspecific and mild so that a number of cases may be missed. Previously published assays lacked detection of certain diagnostically important biomarkers, including SAICAr, AICAr, beta-ureidoisobutyric acid, 2,8-dihydroxyadenine and orotidine, necessitating the use of separate assays for their detection. Moreover, the limited sensitivity for some analytes in earlier assays may have hampered the reliable detection of mild cases. Therefore, we aimed to develop a liquid chromatography–tandem mass spectrometry (LC-MS/MS) assay that allows the simultaneous and sensitive detection of an extended range of purine and pyrimidine biomarkers in urine.MethodsThe assay was developed and validated using LC-MS/MS and clinically tested by analyzing ERNDIM Diagnostic Proficiency Testing (DPT) samples and further specimens from patients with various purine and pyrimidine disorders.ResultsReliable determination of 27 analytes including SAICAr, AICAr, beta-ureidoisobutyric acid, 2,8-dihydroxyadenine and orotidine was achieved in urine following a simple sample preparation. The method clearly distinguished pathological and normal samples and differentiated between purine and pyrimidine defects in all clinical specimens.ConclusionsA LC-MS/MS assay allowing the simultaneous, sensitive and reliable diagnosis of an extended range of purine and pyrimidine disorders has been developed. The validated method has successfully been tested using ERNDIM Diagnostic Proficiency Testing (DPT) samples and further clinical specimens from patients with various purine and pyrimidine disorders. Sample preparation is simple and assay duration is short, facilitating an easier inclusion of the assay into the diagnostic procedures.

Selective enrichment and quantification of okadaic acid in shellfish using an immunomagnetic-bead-based liquid chromatography with tandem mass spectrometry assay.

Okadaic acid is a marine biotoxin that primarily occurs in shellfish and can cause diarrheic shellfish poisoning in humans. When analyzing biological samples using liquid chromatography with tandem mass spectrometry, the presence of complex matrices is a major issue. Thus, it is crucial to selectively and simply extract the target analyte from samples and minimize matrix effects simultaneously. To meet this need, an immunomagnetic-bead-based liquid chromatography with tandem mass spectrometry method was developed to detect okadaic acid in shellfish. Magnetic beads bound to monoclonal antibody against okadaic acid were used as affinity probes to specifically enrich okadaic acid in samples, which effectively eliminated matrix effects. A magnetic separator was used to aggregate and separate magnetic particles from sample matrices, and methanol was used to elute okadaic acid from the magnetic beads. Standard solution prepared with methanol was employed directly for quantitative analysis. Several experimental conditions were optimized to improve performance. The method is of interest as a rapid (10min) sample clean-up and selective enrichment tool, and it showed good linearity and sensitivity, with reported limits of detection and quantitation of 3 and 10 μg/kg, respectively. Fifty-three shellfish samples from an aquatic products market were tested using this method, and four samples positive for okadaic acid were found.

Pharmacokinetic-Guided Therapeutic Dose Monitoring (TDM) of Busulfan Reduces Relapse of Non-Hodgkin Lymphoma (NHL) Patients Undergoing Autologous Stem Cell Transplantation (ASCT)

Introduction Busulfan (Bu) is integral to many preparative regimens for hematopoietic stem cell transplantation but its metabolism is variable and unpredictable. At our institution, Bu was administered with fixed weight-based dosing (WBD) for NHL patients (pts) undergoing ASCT until 2014 when we initiated a prospective clinical trial (NCT01959477) with pharmacokinetic (PK)-guided therapeutic dose monitoring (TDM) of Bu with cyclophosphamide (Cy) and etoposide (VP16). We subsequently adopted this practice as a standard for all NHL pts. Here, we compare outcomes of NHL pts who received ASCT with WBD vs. PK-directed TDM. Methods We collected clinical features and outcomes of 336 adult NHL pts who underwent ASCT with Bu/Cy/VP16 using WBD (n=258) from 1/2007-12/2013 or TDM from 5/2014-12/2017 (n=78) excluding mantle cell lymphoma. For WBD, Bu was given at 2.8 mg/kg q24 hours on day -9 to -6. For TDM, plasma Bu concentration was serially determined via an in-house liquid chromatography–tandem mass spectrometry (LC–MS/MS) assay as previously described and externally validated. Bu area under the curve (AUC) after first dose was calculated for each pt and used to adjust subsequent doses to target a daily AUC of 4500 μM-minute. Results Baseline features of WBD and TDM pts were similar, although more TDM pts received plerixafor for stem cell mobilization and TDM pts were more often categorized as having a complete remission (CR) prior to ASCT (Table), likely due to more use of PET scan. To adjust for differences, propensity-matched cohorts of WBD and TDM pts were also studied (Table). 36% of TDM pts had increases and 41% had decreases in Bu dose. As shown in the Figure, 24 months after ASCT, relapse was significantly lower with TDM vs. WBD (19% vs. 38%, P = 0.004) and relapse-free survival (RFS) was also improved (69% vs. 55%, P = 0.038). Overall survival (OS) did not differ between WBD and TDM cohorts, likely due to subsequent therapy at the time of relapse. Propensity matched cohorts displayed similar patterns of outcomes. For pts in CR at time of ASCT, RFS did not differ between WBD and TDM (P = 0.79) whereas RFS was improved for pts in Conclusion Compared to WBD, PK-directed TDM of Bu safely reduces relapse when used in combination with Cy + VP16 for NHL pts undergoing ASCT, particularly for pts in

Development and validation of an assay for quantifying budesonide in dried blood spots collected from extremely low gestational age neonates

Budesonide is a potential therapeutic option for the prevention of bronchopulmonary dysplasia in mechanically ventilated premature neonates. The dose and concentrations of budesonide that drive effective prophylaxis are unknown, due in part to the difficulty in obtaining serial blood samples from this fragile population. Of primary concern is the limited total blood volume available for collection for the purposes of a pharmacokinetic study. Dried blood spots (DBS), which require the collection of <200 μL whole blood to fill an entire card, are an attractive low-blood volume alternative to traditional venipuncture sampling. We describe a simple and sensitive method for determining budesonide concentrations in DBS using an ultra-high-performance liquid chromatography – tandem mass spectrometry assay. Budesonide was liberated from a single 6 mm punch using a basified methyl tert-butyl ether extraction procedure. The assay was determined to be accurate and precise in the dynamic range of 1 to 50 ng/mL. The validated assay was then successfully applied to DBS collected as part of a multi-center, dose-escalation study of budesonide administered in surfactant via intra-tracheal instillation to premature neonates between 23 and 28 weeks gestational age. These findings show that DBS are a useful technique for collecting pharmacokinetic samples in premature neonates and other pediatric populations.

Determination of Ganciclovir and Acyclovir in Human Serum using Liquid Chromatography-Tandem Mass Spectrometry

Abstract OBJECTIVES: Currently there is no data about a liquid chromatography tandem mass spectrometry (LC-MS/MS) assay including ganciclovir and acyclovir using stable-isotopically labeled internal standards. METHODS: LC-MS/MS assay for measurement of ganciclovir and acyclovir using deuterated standards: ganciclovir-[2H5] and acyclovir-[2H4] was developed. The selectivity and sensitivity, linearity, accuracy and precision, recovery, matrix effect, stability, total process efficiency, carry-over and dilution integrity were validated based on EMA and FDA guidelines. RESULTS: The retention time for ganciclovir was 1.1 min and for acyclovir 1.35 min. Calibration curves were linear over a range of 0.1 to 20 mg/L and the correlation coefficient (R2) was 0.99912 for ganciclovir and 0.99945 for acyclovir. The calculated accuracy was –2.0% to 3.1% for ganciclovir and –1.0% to 6.4% for acyclovir. Within-day precision ranged from 1.8% to 6.6% for ganciclovir and 1.6 % to 6.5% for acyclovir and between-day precision 0% to 9.6% for ganciclovir and 0% to 7.9% for acyclovir. CONCLUSIONS: A rapid and validated LC-MS/MS method was developed for measurement of ganciclovir and acyclovir in human serum which can be used in routine patient care and clinical research.

Association of Plasma Ceramides With Myocardial Perfusion in Patients With Coronary Artery Disease Undergoing Stress Myocardial Perfusion Scintigraphy.

Objective- It is known that specific plasma ceramides are associated with stress-induced reversible myocardial perfusion defects in patients with established or suspected coronary artery disease undergoing myocardial perfusion scintigraphy (MPS). However, it is currently uncertain whether plasma ceramides are also associated with reduced poststress myocardial perfusion in these patients. Approach and Results- We measured 6 previously identified high-risk plasma ceramide species (ceramide [d18:1/16:0], ceramide [d18:1/18:0], ceramide [d18:1/20:0], ceramide [d18:1/22:0], ceramide [d18:1/24:0], and ceramide [d18:1/24:1]) in 167 consecutive patients with established or suspected coronary artery disease undergoing stress MPS for clinical indications. Plasma ceramides were measured by a targeted liquid chromatography-tandem mass spectrometry assay both at baseline and after MPS. Multivariable linear regression analysis was undertaken to examine the associations (standardized B coefficients) between plasma ceramides and the percentage of poststress myocardial perfusion after adjustment for multiple cardiovascular risk factors. Seventy-eight patients had stress-induced myocardial ischemia on MPS (mainly located in the anteroapical wall). Of the 6 measured plasma ceramides, higher levels of basal ceramide (d18:1/18:0; B=-0.182; P=0.019), ceramide (d18:1/20:0; B=-0.224; P=0.004), ceramide (d18:1/22:0; B=-0.163; P=0.035), and ceramide (d18:1/24:1; B=-0.20; P=0.010) were associated with lower poststress anteroapical wall perfusion. Notably, these significant associations persisted even after adjustment for conventional cardiovascular risk factors, previous coronary artery disease, electrocardiographic left bundle branch block, left ventricular ejection fraction and type of stress testing. Similar results were observed for poststress plasma ceramides. Conclusions- Higher circulating levels of specific ceramides, both at baseline and after stress, were independently associated with lower poststress anteroapical wall perfusion in patients with suspected or established coronary artery disease referred for clinically indicated MPS.

Assessment of Patient Medication Adherence, Medical Record Accuracy, and Medication Blood Concentrations for Prescription and Over-the-Counter Medications

ImportanceInaccurate medication records and poor medication adherence result in incomplete knowledge of therapy for patients.ObjectiveTo study accuracy of medical records and patient adherence by measuring blood concentrations of medications.Design, Setting, and ParticipantsThis cross-sectional study validated a serum-based liquid chromatography–tandem mass spectrometry assay to simultaneously quantify 263 medications used for acute and chronic conditions. The assay panel was applied to 3 clinical patient cohorts: residual serum from 1000 randomly selected samples sent for routine clinical chemistry testing between April 8 and October 6, 2015 (residuals cohort), 50 prospectively enrolled patients in a gastroenterology clinic between March 1 and March 15, 2016, who were prescribed more than 5 medications (gastroenterology care cohort), and a convenience cohort of 296 patients with hypertension who sought care in an emergency department (ED care cohort) between July 1, 2012, and April 25, 2013. Integrated data analysis of the cohorts was performed from August 22 to November 29, 2017.Main Outcomes and MeasuresMedication serum concentrations, electronic health record medication lists, and predicted drug interactions.ResultsOf the 1346 total samples, 1000 came from the residuals cohort (640 women and 360 men; median age, 60 years [interquartile range (IQR), 44-71 years]), 50 from the gastroenterology care cohort (30 women and 20 men; median age, 66 years [IQR, 62-70 years]), and 296 from the ED care cohort (160 women and 136 men; median age, 59 years [IQR, 52-66 years]). Median medication adherence, defined as the subset of detected medications from the prescription record, was 83% (IQR, 50%-100%) in the residuals cohort, 100% (IQR, 84%-100%) in the gastroenterology care cohort, and 78% (IQR, 57%-100%) in the ED care cohort. Patients adherent to 1 medication were more often adherent to other medications. Among patients prescribed 3 medications or more, there were no significant associations between medication adherence and sex or number of prescribed medications, and there was a modest association between adherence and age. By comparing detected vs prescribed medications, we detected a median of 0 (IQR, 0-2) medications per patient that were not listed in the electronic health record in the residuals cohort, 1 (IQR, 0-2) medication per patient that was not listed in the electronic health record in the gastroenterology care cohort, and 1 (IQR, 0-2) medication per patient that was not listed in the electronic health record in the ED care cohort. A total of 435 patients (43.5%) in the residuals cohort had no discrepancy between the electronic health record and detected medication lists, 22 patients (44.0%) in the gastroenterology care cohort had no discrepancy between the electronic health record and detected medication lists, and 41 patients (13.9%) in the ED care cohort had no discrepancy between the electronic health record and detected medication lists. Half of adverse drug reaction alerts occurred among medications detected without prescription.Conclusions and RelevanceComprehensive medication monitoring offers promise to improve adherence, the accuracy of medical records, and the safety for patients with polypharmacy.

Close correlation between hyperandrogenism and insulin resistance in women with polycystic ovary syndrome—Based on liquid chromatography with tandem mass spectrometry measurements

To investigate the correlation between hyperandrogenism (HA) and insulin resistance (IR) in women with polycystic ovary syndrome (PCOS) by measuring serum total testosterone (TT) using a liquid chromatography and tandem mass spectrometry assay (LC-MS/MS). This cohort study included 332 patients with PCOS, 63 patients with IR and 276 with controls. TT levels were measured by LC-MS/MS and chemiluminescent immunoassay (CLIA); glucose and insulin levels were determined by an oral glucose tolerance test (OGTT). Compared with CLIA, LC-MS/MS differentiated more cases with high TT levels among the non-PCOS subjects with IR In patients with PCOS, LC-MS/MS-based TT levels or a combination with the mFG score detected a significantly higher incidence of HA in subjects with IR identified by hyperinsulinemia (HIN), HOMA-IR or impaired fasting glucose (IFG) than in those without IR Conversely, the IR rates demonstrated by HIN, HOMA-IR, or IFG were remarkably higher in the LC-MS/MS-defined high TT subgroup than in the normal TT subgroup. However, the CLIA platform could not discern a difference in HA incidence between IR and non-IR subgroups or in IR rate between high and normal TT populations. ROC curves also proved that HIN, HOMA-IR, and IFG were positive contributors to HA as measured by LC-MS/MS CONCLUSIONS: The correlation between HA and IR has always been underestimated, partly owing to the less accurate methods previously used to measure TT. HIN, HOMA-IR, and IFG are likely to contribute to the development of HA from a clinical perspective.

Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry Assay for Determination of Endogenous GHB and GHB-Glucuronide in Nails

Background: The short chain fatty acid gamma-hydroxybutyric acid (GHB) is a precursor, and the metabolite of gamma-aminobutyric acid is commonly used as an illegal recreational drug of abuse. Methods: An ultra-high-performance liquid chromatography tandem mass spectrometry was developed and validated for endogenous GHB and its glucuronide in nails, to complement hair in forensic contexts for a retrospective detection of psychotropic drugs consumption. Results: GHB endogenous values for children and adolescents, adult females, and adult males in fingernails ranged from 0.3 to 3.0, 3.2, and 3.8 ng/mg, respectively, and toenails values ranged from 0.3 to 1.8, 2.0, and 2.4 ng/mg, respectively. In the three different groups, values of GHB in fingernails were statistically higher than those in toenails. GHB glucuronide could only be detected in finger nails with values ranging from 0.08 to 0.233, 0.252 and 0.243 in children and adolescents, adult females and adult males, respectively. Conclusions: The validated method was efficaciously applied to real finger and toe nails specimens from a population of males and females non GHB consumers. A preliminary cut-off of 5.0 ng/mg nail for endogenous GHB and 0.5 ng/mg for endogenous GHB-Gluc in the general population was proposed.

Detection of Infantile Batten Disease by Tandem Mass Spectrometry Assay of PPT1 Enzyme Activity in Dried Blood Spots.

A new tandem mass spectrometry (MS/MS)-based approach for measurement of the enzymatic activity of palmitoyl protein thioesterase I (PPT1) in dried blood spots (DBS) is presented. Deficiency in this enzyme leads to infantile neuronal ceroid lipofuscinosis (INCL, Infantile Batten disease, CLN1). The assay could distinguish between 80 healthy newborns and three previously diagnosed INCL patients. Unlike the fluorimetric PPT1 assay, the MS/MS assay does not require recombinant β-glucosidase. Furthermore, the assay could be easily combined with a TPP1 enzyme assay (for CLN2 disease) and can be potentially multiplexed with a large panel of additional lysosomal enzyme assays by MS/MS for newborn screening and postscreening analysis.

Measurement of Cortisol and Testosterone in Athletes: Accuracy of Liquid Chromatography-Tandem Mass Spectrometry Assays for Cortisol and Testosterone Measurement in Whole-Blood Microspecimens.

Fragala, MS, Goldman, SM, Goldman, MM, Bi, C, Colletti, JD, Arent, SM, Walker, AJ, and Clarke, NJ. Measurement of cortisol and testosterone in athletes: Accuracy of LC-MS/MS assays for cortisol and testosterone measurement in whole-blood microspecimens. J Strength Cond Res 32(9): 2425-2434, 2018-Biomarker monitoring provides insight into athletes' training tolerance but is limited by the need for office-based specimen collection. To facilitate self-collection during training, we developed liquid chromatography-tandem mass spectrometry-based tests that measure circulating total cortisol and testosterone using a finger stick volumetric absorptive microsampler. Here, we describe the analytical validation of these tests. Forty-six Division I athletes (18-22 years, 30 women, 16 men) provided a 20-µL finger stick microspecimen and a 5-ml venous blood specimen from the forearm; the venous blood sample was analyzed using both normal volume serum analysis and analysis of dried whole blood (from the microsampler). Liquid chromatography-tandem mass spectrometry on standard serum specimens obtained by venipuncture yielded total cortisol levels of 26.2 ± 11.6 µg·dl (women and men), and total testosterone levels of 37 ± 17 ng·dl in women and 564 ± 171 ng·dl in men. Analytical measurement ranges of the microspecimen assay were 0.3-440 µg·dl (CV <9%) for cortisol and 15 to 20,000 ng·dl (CV <9%) for testosterone. Deming regression and Pearson correlation indicated good test accuracy for the microspecimen tests compared with venipuncture tests for cortisol (y = 0.98x + 1.34, 95% CI of slope = 0.83-1.14; r = 0.92, p < 0.0001) and testosterone (y = 1.06x - 0.01, 95% CI of slope = 0.99-1.14; r = 0.99, p < 0.0001). Similarly, high agreement was observed between finger stick and venous microspecimens for cortisol (y = 1.00x + 0.65, 95% CI of slope = 0.9-1.11; r = 0.96, p < 0.001) and testosterone (y = 0.97x + 2.75, 95% CI of slope = 0.9-1.03; r = 0.99, p < 0.001). These findings suggest the viability of finger stick collection whole-blood microspecimens for assessment of total cortisol and testosterone in athletes.

Development and full validation of a liquid chromatography-tandem mass spectrometry method for determination of carbinoxamine in beagle plasma and its application to a pharmacokinetic study

Carbinoxamine maleate is an antihistamine drug with mild sedation effects, which is used to treat seasonal and perennial allergic rhinitis clinically. In order to optimize drug therapy, reduce drug accumulation, lessen the frequency of adverse effects and facilitate clinical research, a high performance liquid chromatography tandem mass spectrometry assay was firstly established and fully validated for the quantitative admeasurements of carbinoxamine. After extraction with ethyl acetate, the chromatographic separation was implemented on a C18 column (Hypersil GOLD, 100 mm × 2.1 mm, 3.0 μm) using gradient elution with water (containing 0.1% formic acid) and methanol at the flow rate of 0.4 mL/min. The analytes were measured under multiple reactions monitoring (MRM) mode with m/z 291.2 → 202.1 for carbinoxamine and m/z 285.0 → 193.2 for diazepam (IS) using electrospray ionization source (ESI) in the positive ion mode. A satisfactory linearity was obtained over the wide extent of 0.1–100.0 ng/mL (r > 0.99). Inter- and intra-day precision and accuracy of the assay were favorably accorded with the currently recognized limits (< 8.9%). The mean extraction recoveries for carbinoxamine ranged from 74.00% to 86.4%. The pharmacokinetic characteristics of carbinoxamine were subsequently evaluated in beagles. Following intragastric administration (0.534 mL/kg), carbinoxamine possessed a large apparent volume of distribution of the central compartment (Vc = 1005.7 ± 945.9 L/kg), oral clearance (Cl = 112.446 ± 53.249 L/h/kg), and a relatively long absorption time (Tmax = 2.38 ± 1.00 h). This analytical method with adequate sensitivity was applicable to pharmacokinetic study and could monitor concentrations of carbinoxamine in beagle plasma. Moreover, the methodology could be used for further bioequivalence determination and addressing metabolism associated with the drug.

Effects of Cyclic Fatty Acid Monomers from Heated Vegetable Oil on Markers of Inflammation and Oxidative Stress in Male Wistar Rats.

This study assesses the effects of cyclic fatty acid monomers (CFAM) from heated vegetable oils on oxidative stress and inflammation. Wistar rats were fed either of these four diets for 28 days: canola oil (CO), canola oil and 0.5% CFAM (CC), soybean oil (SO), and soybean oil and 0.5% CFAM (SC). Markers of oxidative stress and inflammation were determined by micro liquid chromatography tandem mass spectrometry (micro-LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) kits, respectively. Analysis of variance (ANOVA) for a 2 × 2 factorial design was performed to determine the CFAM and oil effects and interactions between these two factors at P ≤ 0.05. For significant interactions, a post hoc multiple comparison test was performed, i.e., Tukey HSD (honest significant difference) test. CFAM induced higher plasma levels of 15-F2t-IsoP (CC, 396 ± 43 ng/mL, SC, 465 ± 75 ng/mL vs CO, 261 ± 23 ng/mL and SO, 288 ± 35 ng/mL, P < 0.05). Rats fed the SC diet had higher plasma 2,3-dinor-15-F2t-IsoP (SC, 145 ± 9 ng/mL vs CC, 84 ± 8 ng/mL, CO, 12 ± 1 ng/mL, and SO, 12 ± 1 ng/mL, P < 0.05), urinary 2,3-dinor-15-F2t-IsoP (SC, 117 ± 12 ng/mL vs CC, 67 ± 13 ng/mL, CO, 15 ± 2 ng/mL, and SO, 18 ± 4 ng/mL, P < 0.05), and plasma IL-6 (SC, 57 ± 10 pg/mL vs CC, 48 ± 11 pg/mL, CO, 46 ± 9 pg/mL, and SO, 44 ± 4 pg/mL, P < 0.05) than the other three diet groups. These results indicate that CFAM increased the levels of markers of oxidative stress, and those effects are exacerbated by a CFAM-high-linoleic acid diet.