bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reference Intervals for Intestinal Disaccharidase Activities Determined from a Non-Reference Population
Authors: Hackenmueller Sarah A , Grenache David G 
Published: July 2018

Abstract

Background
Cutoff activities for diagnosing disaccharidase deficiencies are historical and are difficult to verify from a reference population. The objectives of this study were to validate the utility of historical disaccharidase cutoffs using data from clinical samples and to evaluate the demographics of individuals for whom intestinal disaccharidase testing was performed.

Methods
Results from 14,827 disaccharidase test samples were extracted from the laboratory information system. Data were analyzed by the Hoffman method to calculate a reference interval for each enzyme, and the lower limits were compared to historical cutoffs. The observed frequencies of disaccharidase deficiencies were determined using historic and calculated cutoffs.

Results
The median patient age of the entire data set was 13 years (range &lt;1–88 years), and 45% were male. The cutoffs for lactase, maltase, palatinase, and sucrase were determined to be 10, 100, 9, and 25 U/g protein, respectively. Applying these cutoffs to the data set, 61% had no enzyme deficiencies, 35% were lactase deficient, 11% were maltase deficient, 13% were palatinase deficient, and 13% were sucrase deficient. Pandisaccharidase deficiency was present in 8%.

Conclusions
Disaccharidase testing is most commonly performed in patients &lt;18 years. Lactase deficiency is the most frequently observed single-disaccharidase deficiency. The historical cutoffs for maltase and sucrase were validated. To align with calculated reference intervals, the palatinase cutoff should increase from 5 to 9 U/g protein, and the lactase cutoff should decrease from 15 to 10 U/g protein.
Impact of Integrating Rumke Statistics to Assist with Choosing Between Automated Hematology Analyzer Differentials vs Manual Differentials
Authors: Stephens Laura , Hintz-Prunty Wendy , Bengtsson Hans-Inge , Proudfoot James A , Patel Sandip Pravin , Broome H Elizabeth 
Published: July 2018

Abstract

Background
To optimize precision of nucleated blood cell counting, the clinical laboratory scientist should post the automated differential rather than the manual differential if the former is within the 95% CI of the latter, as determined by the “Rumke statistic.” The objective of this study was to determine the potential impact of real-time, computer-assisted use of Rumke statistics for more judicious use of the automated vs digitally imaged, manual differential.

Methods
Complete blood counts with automated differentials produced by a XE5000™ hematology analyzer (Sysmex) were compared with both the DM96 (CellaVision™ AB) preclassification differentials and the posted reclassified manual differentials, using the Rumke 95% CIs as calculated using the Clopper-Pearson method.

Results
A total of 44.7% of manual differentials had no statistical or clinical justification over the automated differential. In addition, 31.1% of manual differentials had statistical discrepancies between the instrument absolute neutrophil count (IANC) and manual absolute neutrophil count (ANC). Nineteen of these IANC/manual ANC discrepant samples had ANCs below 1500/μL, a decision level for cancer treatment. Holding the IANC when it is less than 2000/μL until after manual smear review would have prevented the posting of any IANC vs manual ANC discrepant results at the 1500/μL ANC decision threshold.

Conclusions
A real-time operator alert concerning the statistical identity of imaging device differentials vs automated differentials could have reduced manual differentials by nearly 45%. Not posting unnecessary manual differentials for the cases with IANC/manual ANC discrepancies would have likely reduced clinical error/confusion.
Are Heart Failure Management Recommendations and Guidelines Followed in Laboratory Medicine in Europe and North America? The Cardiac Marker Guideline Uptake in Europe (CARMAGUE) Study
Authors: Hammerer-Lercher Angelika , Collinson Paul O , Suvisaari Janne , Christenson Robert H , Pulkki Kari , van Dieijen-Visser Marja P , Duff Christopher J , Baum Hannsjörg , Stavljenic-Rukavina Ana , Aakre Kristin M , Langlois Michel R , Stankovic Sanja , Laitinen Paivi 
Published: July 2018

Abstract

Background
The aim of this survey was to investigate how well heart failure (HF) guidelines for use of natriuretic peptides (NPs) have been implemented in laboratory practice in Europe and North America.

Methods
In 2013 and 2014, a web-based questionnaire was distributed via North American and European biochemical societies. Questions covered assay performed, reason for method choice, decision limits for HF, and laboratory accreditation status.

Results
There were 442 European Union and 91 North American participating laboratories with response rates of 50% and 64% from major or university hospitals, respectively. NP measurements were offered in 67% of European Union and 58% of North American respondents. N-terminal pro–B-type natriuretic peptide (NT-proBNP) was most widely used in Europe (68%) and B-type natriuretic peptide (BNP) was more commonly used (58%) in North America. The most frequent reason for use of a specific assay was the availability of instruments that measure either NT-proBNP (51%) or BNP (67%). For diagnosis of acute HF, NT-proBNP decision limits were diverse; age-dependent limits based on the 2012 European Society of Cardiology (ESC) recommendations were used in only 17% of European sites and 26% of North American sites. For BNP, the guideline-recommended acute HF decision limit of 100 ng/L was better adhered to in Europe (48%) and North America (57%). Surprisingly, similar decision limits were stated for acute and chronic HF by &gt;50% of respondents.

Conclusions
NP measurement for HF diagnosis was available in &gt;50% of responding laboratories. However, guideline recommended cutoff values for both acute and chronic HF were still implemented in &lt;30% of participating medical centers.
Serum Free Light Chain (FLC) Analysis: A Guiding Light in Monoclonal Gammopathy Management
Authors: Jenner Ellen L , Evans Josie A R , Harding Stephen J 
Published: July 2018

Abstract

Background
Monoclonal free light chains (FLCs) were first reported by Dr. Henry Bence Jones over 150 years ago in the urine of patients with multiple myeloma. Now established as important tumor markers, they aid not only in the diagnosis of monoclonal gammopathies but also in their clinical management by indicating the response to treatment and persistence of residual disease.

Content
A particular focus over the past 15 years has been on the replacement of urine with serum analysis for monoclonal FLC measurement. Because of the limited sensitivity and practical constraints of urine assessment, a combination of serum electrophoresis and serum FLC analysis has been adopted by many laboratories as a first-line screen for patients with a suspected monoclonal gammopathy. Early myeloma diagnosis may translate into improved clinical outcomes, and a new study, iStopMM, is underway to ascertain the benefit of population-wide screening protocols for early detection of the disease in its asymptomatic phase. Laboratory algorithms that include measurement of both monoclonal intact immunoglobulins and FLCs are important for assessing possible changes in myelomic clones in response to treatment, and recent data from Intergroupe Francophone du Myelome trials validate serum FLC as a clinically relevant disease biomarker. Whether sensitive serum techniques such as FLC analysis can be used to guide the use of more invasive procedures for detection of minimal residual disease is the subject of emerging studies.

Summary
Here we review the current and evolving utility of serum FLC measurements for the management of patients with monoclonal gammopathies.
Assessment of Two Rapid Assays for Diagnostic Capability to Accurately Identify Infection by Treponema pallidum
Authors: Constantine Niel T , Sill Anne M , Gudesblat Elizabeth , Paulus Samantha , Saleh Ahmed 
Published: July 2018

Abstract

Background
Rapid, point-of-care tests that accurately identify syphilis are gaining popularity and offer several advantages over classic tests.

Methods
The SD Bioline Syphilis 3.0 and the Chembio DPP Syphilis Screen and Confirm Assay (CB) were assessed using 1283 samples that had been characterized by reference tests. The challenge samples included 5 commercial panels (seroconversion, mixed-titer), archived samples, fresh samples, and a dilution series. Both tests detect specific anti-treponemal antibodies, and the CB additionally detects antibodies to a non-treponemal (NT) component. The evaluation was used to determine performance indices and compare with those cited by the manufacturers.

Results
When assessing reactivity to treponemal, the sensitivities for the 2 tests were 98.3% and 93.2%, with specificities of 100% and 99.4%, respectively. For both tests, precision, whole blood testing, and high-temperature testing produced perfect results, and there were no invalid results. Comparisons of 2 different lots of each test indicated excellent concordance (100% and 99.5%), and reproducibility was 100% and 98.0%, respectively. For the CB, the sensitivity for the NT component was between 65.3% and 80.9%, but increased to 98.5% with samples having a rapid plasma regain (RPR) titer of ≥8. The specificity for NT was found to be 100%, and the reading of results visually and when using a battery-operated reader indicated a concordance for all challenges of 95%–100%.

Conclusions
Both rapid tests produced impressive results for the detection of antibodies to treponemal for all challenges and exceeded, met, or closely approached the performance characteristics as cited by the manufacturers.
N-Terminal Pro–B-Type Natriuretic Peptide (NT-proBNP) Immunoreactivity Is Reduced After 6 Years of Storage at −70 °C
Authors: Wee Tracee , Tang Mila , Zrno Ilinka , Hamilton Jonah , Holmes Daniel T 
Published: July 2018

Abstract

Background
Clinical trial samples may be stored frozen for prolonged periods before analysis, which can reduce the immunoreactivity of numerous analytes, particularly peptides. We sought to determine the effect of 6 years of frozen storage on serum N-terminal pro–B-type natriuretic peptide (NT-proBNP).

Methods
NT-proBNP was measured from serum samples taken from 99 different patients enrolled in the CanPREDDICT study after &lt;1 year of storage at −70 °C using the Roche first-generation NT-proBNP assay on an e411 instrument. Separate aliquots of the same samples were analyzed after an additional 6 years of storage at −70 °C using the Roche second-generation assay on an e601 instrument.

Results
The median NT-proBNP immunoreactivity for the first measurement was 572 pg/mL (interquartile range [IQR] 205–1606, range 49–12820), while after an additional 6 years of storage at −70 °C, this value decreased to 526 pg/mL (IQR 181–1338, range 18–12880), resulting in a median percent difference of −7% (IQR −10.6% to −3.4%, P &lt; 0.001).

Conclusions
We report findings consistent with trends seen in previous work but have investigated the effect of a much longer storage period. Larger percent decreases in NT-proBNP reaching statistical significance are seen, although the median difference is still &lt;10%.
Practical LC-MS/MS Method for 5-Hydroxyindoleacetic Acid in Urine
Authors: Clark Zlatuse D , Cutler Jeaneah M , Frank Elizabeth L 
Published: July 2018

Abstract

Background
Serotonin, an endogenous biogenic amine found in enterochromaffin cells of the gastrointestinal tract, is produced in excess by carcinoid tumors. The primary urinary metabolite of serotonin, 5-hydroxyindoleacetic acid (5-HIAA), is used in the diagnosis and management of carcinoid disease. This study describes the development and validation of a dilute-and-shoot LC-MS/MS method for the measurement of 5-HIAA in urine.

Methods
Samples were prepared by dilution in a 96-well format using an automated liquid handler. Chromatographic isolation of the analyte was achieved using a reversed-phase analytical column. A triple quadrupole mass spectrometer with electrospray ionization in positive mode was used for detection and quantification. Data were acquired by multiple reaction monitoring. Two transitions, quantifier (192.1/146.1) and qualifier (192.1/118.1), were monitored for the analyte and its stable isotope–labeled internal standard [5-hydroxyindole-4,6,7-d3-3-acetic-2,2-d2 acid (5-HIAA-d5)]. Chromatography was designed to elute the analyte outside of major suppression zones.

Results
Injection-to-injection time was 4 min. The method was validated for linearity, limit of quantification, accuracy, and imprecision. The analytical measurement range was 0.5–100 mg/L. Coefficients of variation for within-run, between-day, and total imprecision ranged from 0.8% to 5.4%. The method produced accurate 5-HIAA concentrations and correlated well (R = 0.9876) with a comparison HPLC method. Matrix effects were evaluated by post-column infusion of urine samples. An analytical specificity study of endogenous compounds, vitamins, medications, and drugs showed minimal interference.

Conclusions
A simple, inexpensive LC-MS/MS method was developed for measurement of 5-HIAA in urine. Results from the assay can be used clinically to assess carcinoid tumors.
Routine Supercritical Fluid Chromatography Tandem Mass Spectrometry Method for Determination of Vitamin K1 Extracted from Serum with a 96-Well Solid-Phase Extraction Method
Authors: Sandvik Trude Athammer , Husa Asgeir , Buchmann Marie , Lundanes Elsa 
Published: July 2018

Abstract

Background
The concentration of vitamin K1 in serum or plasma is the most common index for assessing vitamin K status. The aim of this study was to develop and validate a rapid and reliable routine method for quantifying vitamin K1 above 0.1 ng/mL. Semi-automation of a simple sample preparation with fast analysis by supercritical fluid chromatography–tandem mass spectrometry (SFC-MS/MS) was exploited.

Methods
Vitamin K1 was extracted from 250-μL serum samples by the use of protein precipitation and reversed-phase solid-phase extraction (SPE) in 96-well plates and quantified by SFC on a 2.1 × 100 mm Torus 1-Aminoanthracene (1-AA) column in 3.8 min with electrospray ionization—tandem mass spectrometry (MS/MS) detection.

Results
This method shows good linearity in the concentration range of 0.1–50 ng/mL with a correlation coefficient of R 2 &gt;0.999. Imprecision was satisfactory, with repeatability and reproducibility &lt;10% CV. The lower limit of the measuring interval was 0.1 ng/mL, and no systematic bias was observed for the method, which used vitamin K1-d7 as internal standard. Recovery of vitamin K1 in external quality controls was satisfactory compared to other laboratories participating in the external quality assurance scheme. The method is currently in routine use for analysis of serum samples.

Conclusions
The method allows high-throughput reliable determination of vitamin K1 in serum in the range 0.1–50 ng/mL.
Validation of an Extensive CYP2D6 Assay Panel Based on Invader and TaqMan Copy Number Assays
Authors: Leung Edward Ki Yun , Agolini Emanuele , Pei Xun , Melis Roberta , McMillin Gwendolyn A , Friedman Paula N , Peterson Patrick , Danahey Keith , O'Donnell Peter H , Yeo Kiang-Teck J 
Published: July 2018

Abstract

Background
CYP2D6 is involved in the oxidative metabolism of approximately 20% of all clinically used medications. Genotyping cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6), is a challenge because of the high complexity of the locus.

Methods
Twenty-nine CYP2D6 sequence variants were genotyped in 50 deidentified patient samples and 29 Coriell DNAs by Invader assay, and results were compared with Infiniti assay and Sanger sequencing. To determine CYP2D6 copy number, 3 TaqMan real-time hydrolysis probes were used and results were compared with long-range PCR. Discrimination of the duplicated alleles was done on 17 DNA samples with 3 copies of CYP2D6 by long-range PCR followed by Invader genotyping and single nucleotide extension for the comparison.

Results
Complete concordance was observed for all samples between platforms except for 2 samples due to the lack of the *45 allele in the Infiniti panel. Reproducibility with the Invader assay and TaqMan copy number was 100%. Analytical sensitivity using DNA with 2 copies was determined to be 10 ng DNA for the Invader assay and 1 ng/μL DNA for the TaqMan assay, respectively. Complete concordance and reproducibility were observed for duplicated allele discrimination with the exception of 1 sample, determined to be *29/*43X2 by the Invader test and *1X2/*29 by the Infiniti method, which did not test for *43.

Conclusions
This validation study showed that Invader and TaqMan assay combined panel provides an attractive, valid, highly accurate, and reproducible approach for CYP2D6 genotyping for clinical implementation.
An Ultraperformance LC-MS/MS Method for the Quantification of the Antimalarial Atovaquone in Plasma
Authors: Chambliss Allison B , Parsons Teresa L , Marzinke Mark A 
Published: July 2018

Abstract

Background
A primary modality in the treatment and prevention of malaria is the administration of antimalarial agents. Atovaquone (ATQ) has been used in single-drug and multidrug antimalarial applications; however, studies have demonstrated high interindividual drug variability. With the scarcity of analytical methodologies available in the literature, we have developed and optimized a rapid, ultraperformance (UP) LC-MS/MS method for the quantification of ATQ in human plasma.

Methods
ATQ was extracted from 25 μL K2-EDTA human plasma via protein precipitation with acetonitrile. Sample solutions were separated on a Synergi 2.5-μm Polar-RP 100A (100 × 2 mm) column. ATQ and its internal standard were detected over 1.3 min on an API 4000 mass analyzer using an electrospray ionization source operated in negative ionization and selected reaction monitoring modes. The method was validated in accordance with the Food and Drug Administration (FDA) Guidance for Industry: Bioanalytical Method Validation recommendations.

Results
Owing to pharmacokinetic parameters associated with ATQ, 2 calibration curves were generated to quantify the drug across a dynamic concentration range. Two standard curves were established ranging from 250 to 5000 ng/mL and 5000 to 50000 ng/mL, respectively. QC levels for both lower and higher concentration ranges prepared at low (750 ng/mL, 12000 ng/mL), mid (2000 ng/mL, 22500 ng/mL), and high (4250 ng/mL, 42500 ng/mL) concentrations yielded interassay precision ≤9.1% and accuracy ≤±9.4%. Dilutional, stability, and matrix effects studies were also performed, and results were within acceptability limits.

Conclusions
This work describes the development and analytical evaluation of a UPLC-MS/MS method for ATQ quantification in plasma. The described method is sufficiently sensitive for ATQ quantification in plasma to support preclinical and clinical trials.
An Automated Assay for Growth Differentiation Factor 15
Authors: Wollert Kai C , Kempf Tibor , Giannitsis Evangelos , Bertsch Thomas , Braun Siegmund L , Maier Harald , Reim Manfred , Christenson Robert H 
Published: July 2018

Abstract

Background
Growth differentiation factor 15 (GDF-15) can serve as a biomarker for cardiovascular disease burden and risk. We evaluated a new, fully automated electrochemiluminescence immunoassay for measuring GDF-15.

Methods
Six laboratories independently characterized the Elecsys® GDF-15 assay (Roche Diagnostics) under routine conditions. Within-run precision (repeatability), within-laboratory precision (intermediate precision), and between-laboratory precision (reproducibility) were assessed. Plasma-serum sample correlation, reagent lot-to-lot reproducibility, and instrument comparisons were performed. The Elecsys assay was compared to a research immunoradiometric assay (IRMA) and a commercially available ELISA. GDF-15 concentrations were measured with the Elecsys assay in 739 apparently healthy individuals.

Results
CVs for within-run and within-laboratory precision ranged from 0.7% to 7.7% and 1.7% to 8.6%, respectively, for samples containing 670–16039 ng/L. CVs for between-laboratory precision ranged from 7.1% to 8.9% (766–14289 ng/L). Recovery of GDF-15 was comparable for serum, Li-heparin plasma, K2- and K3-EDTA plasma, and citrated plasma, between 2 reagent lots, and on the cobas e 411 and cobas e 601 analyzers (Roche Diagnostics). GDF-15 concentrations in the clinically relevant range (400–3000 ng/L) measured with the Elecsys assay showed a good correlation and agreement with those measured by IRMA or ELISA. GDF-15 concentrations in apparently healthy individuals increased with age but did not vary by sex.

Conclusions
The Elecsys GDF-15 assay demonstrates a robust analytic performance under routine conditions and provides an automated method for measuring GDF-15 concentrations in serum and plasma.
Creation of a Universal Sample Bank for Determining the 99th Percentile for Cardiac Troponin Assays
Authors: Wu Alan H B , Apple Fred , Love Sara A , Koch David , Myers Gary L , Christenson Robert H ,   on behalf of the AACC's Biomarkers of Acute Cardiovascular Disease Division
Published: July 2018

Abstract

Background
International guidelines authored and endorsed by professional societies of cardiology, emergency medicine, and laboratory medicine are unanimous that the cutoff concentration for establishing a diagnosis of acute myocardial infarction be set at the 99th percentile of a healthy population. The establishment of the actual 99th percentile value is assay- and sample-dependent and is influenced by the population of individuals selected for testing. We created a sample bank that will enable manufacturers of troponin assays a consistent comparison of the 99th percentile.

Methods
Participants were recruited from those attending the 2015 Annual Meeting of the AACC for the creation of a universal sample bank of apparently healthy individuals (free from uncontrolled diabetes, renal insufficiency, and heart disease). For those who met eligibility criteria and signed a written consent to participate, 60 mL blood was collected into 6 10-mL tubes each (2 serum, 3 heparin plasma, and 1 EDTA). Whole blood was tested for hemoglobin (Hb) A1c, and serum was tested for N-terminal pro–B-type natriuretic peptide (NT-proBNP) and creatinine.

Results
There were a total of 764 individuals who consented during the AACC Annual Meeting. After this initial enrollment, it was determined that there was an insufficient number of male participants recruited. Under the same protocol and consent, blood from 131 additional males was collected at the University of Maryland. Samples were centrifuged, and 240 μL aliquots of the 2 serum, 3 heparin plasma, and 1 EDTA tubes were frozen at 70 °C within 2 h of collection. The labeled samples were divided into boxes containing 1 aliquot from each individual. Sets of these samples were made available for purchase to manufacturers of cardiac troponin assays. Eighty-eight samples were excluded from the database for having a high NT-proBNP (&gt;300 ng/L), low estimated glomerular filtration rate (eGFR) (&lt;60 mL/min/1.73 m2), high Hb A1c (≥6.5%), or preanalytical sample issues and consenting/data issues. The final total was 808 individuals (402 females and 406 males; 60% Caucasian, 26% African or African American, 11% Asian or Pacific Islander, and 3% other).

Conclusions
The creation of a bank of samples from healthy individuals enables a consistent comparison of the 99th percentile results from manufacturers of cardiac troponin assays.