bluuebunny/crossref_metadata_2025_split huggingface dataset:
Creatinine measurement proficiency testing: assignment of matrix-adjusted ID GC-MS target values
Authors: Carobene Anna , Ferrero Carlo , Ceriotti Ferruccio , Modenese Annalisa , Besozzi Marco , De Giorgi Elena , Franzin Michela , Franzini Carlo , Kienle Marzia Galli , Magni Fulvio 
Published: January 2020

Abstract
The results of an external quality-assessment experiment for serum creatinine measurement are described. Fifty-one laboratories performed quintuplicate analyses during three different analytical runs on six lyophilized sera and two frozen human serum pools. Isotope dilution gas chromatography–mass spectrometry (ID GC-MS) target values were assigned to all the materials. Intralaboratory within- and between-run imprecision results were very similar for all the materials tested (CV ≤2.20% and ≤4.70%, respectively). The overall imprecision obtained was high (CV 6.5–20.0%) because of increased interlaboratory–intermethod variability. A significant positive bias (+9.2–+43.7%) was found for all the materials at lower creatinine concentration. By using two human sera at different concentrations, we could calculate the constant and the proportional calibration bias displayed by each peer group. The majority of the lyophilized materials showed a behavior divergent from the frozen pools, indicating matrix-related problems. We propose a new algorithm for calculating matrix bias correction factor instrument–reagent specific for each material.
Errors, mistakes, blunders, outliers, or unacceptable results: how many?
Authors: Witte David L , VanNess Sue Ann , Angstadt Debbie S , Pennell Beverly J 
Published: January 2020

Abstract
We have studied 219 353 individual clinical chemistry results obtained in methods comparison studies. Each result was prospectively compared with its replicate, comparative, or repeat value to identify differences from expected values. Unacceptable results were defined as differing from the expected values by ≤7 SDs or CVs. We believe these differences represent special-cause variation and should be expressed as unacceptable rates per million results (ppm). We observed 447 ppm unacceptables: 196 ppm in control samples and 251 ppm in patients’ samples. Results judged likely to alter patient care occurred at a rate of 41 ppm. To better understand the magnitude of these rates, we compared these results with reports of error rates in HIV testing and the airline industry. The measurements reported were made for the purpose of quality improvement, not judgment or discovery. The significance of these findings for laboratorians, manufacturers, and regulators is discussed.
Immunofluorometric assay of pepsinogen C and preliminary clinical applications
Authors: Diamandis Eleftherios P , Nadkarni Sheila , Bhaumik Banani , Abdelrahman Aly , Melegos Dimitrios N , Borchert Gudrun , Black Margot H , Alonso Marta , Salas Ana , de los Toyos Juan R , Sampedro Andres , López-Otín Carlos 
Published: January 2020

AbstractWe developed mouse monoclonal antibodies (Abs) against pepsinogen C with highly purified antigen isolated from gastric mucosa. The Abs were used to construct a two-site sandwich-type assay for pepsinogen C with time-resolved fluorometry as a detection technique. The assay has a detection limit of 0.1 μg/L and is precise (within-run and day-to-day CVs &lt;11%). We used this assay to measure pepsinogen C in seminal plasma, breast cyst fluid, amniotic fluid, male and female serum, serum from patients with prostate cancer, urine, breast tumor cytosolic extracts, breast milk, and cerebrospinal fluid. Highest pepsinogen C concentrations were in seminal plasma, followed by breast cyst fluid and amniotic fluid. We found no correlation between prostate-specific antigen concentrations and concentrations of pepsinogen C in serum of prostate cancer patients, and concluded that this marker is not useful for either diagnosing or monitoring prostatic carcinoma. The availability of a highly sensitive, reliable, and convenient method for quantifying pepsinogen C will allow investigations into the possible diagnostic value of this analyte in various clinical conditions, including benign breast diseases, breast cancer, fertility, and pregnancy.
Use of filter paper for sample collection and transport in steroid pharmacology
Authors: Howe Christopher J , Handelsman David J 
Published: January 2020

Abstract
Field studies of androgen pharmacology are complicated by the necessity to collect, process, and store blood samples in a central facility. We have assessed the feasibility of using capillary blood spots collected by fingerprick and dried on filter paper for pharmacokinetics and pharmacodynamic measurements with nandrolone and testosterone RIAs modified for extracts from capillary blood spots. Assays on punched spots of 7.9-mm diameter (14.9 μL of dried blood) permitted accurate quantification of testosterone down to 0.4 nmol/L from a single spot and nandrolone down to 0.9 nmol/L from two spots. Stability of the steroids in dried blood spots to adverse environmental conditions, notably increased temperatures, was investigated both in the laboratory and in field studies of dried spots sent through the postal system. Storage or postal transport under moderate conditions appeared to have no deleterious effects on apparent androgen concentrations. However, under extreme conditions of storage at 50 °C for a week or more, or transport to a very hot tropical location, a rise in the final concentration of nandrolone, and, to a lesser extent, testosterone when corrected for tracer recovery, was noticed. These effects were largely due to apparent susceptibility of tritiated tracer, but not unlabeled androgens, to thermal degradation. In a pilot pharmacological study involving intramuscular injection of 100 mg of nandrolone decanoate in 1 mL of arachis oil, nandrolone concentrations in concurrently collected plasma as well as venous and capillary blood spots showed good agreement. Testosterone concentrations in contemporaneously collected plasma and venous blood spots also showed very good agreement. We propose that these methods may allow patients and experimental subjects to self-collect samples at remote or field locations for convenient mailing to a central laboratory for androgen assay. Applications of this methodology are now under way.
Isolation and characterization of a digoxin-like immunoreactive substance from human urine by affinity chromatography
Authors: De Angelis Claudio , Riscazzi Massimiliano , Salvini Riccardo , Piccoli Alfonso , Ferri Claudio , Santucci Anna 
Published: January 2020

AbstractA series of observations has suggested that one or more digoxin-like immunoreactive substances (DLIS) in biological fluids is able to cross-react with the antidigoxin antibody. Whether this substance is the endogenous inhibitor of Na+/K+ ATPase has not been well established. The aim of this study was to identify and characterize DLIS from human urine. Treated urine from healthy men was run on an affinity chromatography column at a flow rate of 1 mL/min in which the ligand was an antibody (antiserum) to digoxin. Eluates from affinity chromatography were applied onto analytical reversed-phase HPLC. The active material was eluted with a linear gradient of acetonitrile (from 350 to 650 mL/L) and water. A second step in HPLC was carried out isocratically with 280 mL/L acetonitrile in water. We found a single peak showing cross-reactivity with antidigoxin antibody as measured by RIA. It showed the same retention time as that of a digoxin calibrator. This highly purified substance is able to displace [3H]ouabain from dog kidney-derived Na+/K+ ATPase, to inhibit Na+/K+ ATPase activity as measured by the86Rb+ uptake in red blood cells and by coupled enzyme assay. Our results are consistent with the hypothesis that DLIS, as isolated by this particular digoxin antibody, is a single substance and an inhibitor of Na+/K+ ATPase.
Amino acid determination in biological fluids by automated ion-exchange chromatography: performance of Hitachi L-8500A
Authors: Le Boucher Jacques , Charret Christelle , Coudray-Lucas Colette , Giboudeau Jacqueline , Cynober Luc 
Published: January 2020

Abstract
The Hitachi L-8500A is a newly available apparatus for amino acid (AA)analysis that allows automatic on-line mixing of the ninhydrin reagent. The within-run precision (human plasma pools at three different concentrations) showed CVs &lt;3.8% except for the lowest concentration of citrulline (4.4%), Tyr (4.5%), and α-aminobutyric acid (7.6%), and for the intermediate concentration of Asp (8.7%). Between-run precision (CV) was &lt;3.1% for 17 AAs and &lt;8.0% for 24 of 25 AAs (CV Asp = 12.0%). For retention times, within-run precision was &lt;0.4% and between-run precision &lt;1.8%. Excellent relations were found between the results from the Hitachi L-8500A and the widely used Beckman 6300 analyzer (0.929≤ r ≤0.999). The detection was still linear at 5 μmol/L except for Pro and hydroxyproline (20 μmol/L). The upper limit was at least 2500 μmol/L for 13 AAs and at least 1000 μmol/L for 27 of 29 AAs (anserine = 500, Val = 600 μmol/L). Values from 100 human plasma samples agreed with previously published data. We conclude that the results obtained with the Hitachi L-8500A are satisfactory when compared with those of other AA analyzers utilizing the same method. Furthermore, the Hitachi L-8500A displays several advantages including programming flexibility, microsample capacity, low noise plotting, ammonia filtering, and manual repacking of the analytical column.
Suitability of chemical in vitro models to investigate LDL oxidation: study with different initiating conditions in native and α-tocopherol-supplemented LDL
Authors: Seccia Milfred , Albano Emanuele , Bellomo Giorgio 
Published: January 2020

AbstractIsolated human LDL, used in the native form or supplemented with α-tocopherol (αT), were oxidized with Cu2+, 2,2′-azobis-(2-amidino propane) hydrochloride (AAPH), and H2O2 plus horseradish peroxidase (HRP). The oxidation kinetics were measured spectrophotometrically at 234 nm to follow the formation of conjugated dienes and evaluated as resistance to oxidation (lag phase, LP) and maximal oxidation rate (propagation rate, PR). The duration of LP in nonsupplemented LDL was different with the three prooxidant stimuli (LP, in min: 96 ± 19 for Cu2+, 28.7 ± 6.7 for HRP, and 67.1 ± 11.2 for AAPH). No correlation was found between the values obtained with Cu2+ and AAPH or HRP, but a significant correlation was found with AAPH and HRP (r = 0.798, P &lt;0.002). In vitro αT supplementation prolonged the LP and decreased the PR with all the stimuli. The extent of increase in LP was highly correlated (r = 0.872, P &lt;0.001 for Cu2+ and HRP; r = 0.603, P &lt;0.03 for Cu2+ and AAPH; r = 0.749, P &lt;0.005 for AAPH and HRP). Although the evaluation of ex vivo LDL oxidation is dependent on the prooxidant stimulus, the three prooxidant conditions used detect equally well the efficiency of αT supplementation in preventing LDL oxidation.
Hepatitis B: diagnosis, prevention, and treatment
Authors: Gitlin Norman 
Published: January 2020

AbstractHepatitis B virus (HBV) infection occurs worldwide and is an important cause of acute and chronic viral hepatitis in the US. In this review, I describe the virus, risk factors for infection, clinical features of infection, results of laboratory tests during infection, and standard and emerging treatment for chronic infection. Although 95% of adult patients recover completely from HBV infection, 90% of children ≤4 years of age develop chronic infection. Active vaccination is highly efficacious.
Comparison of analytical performance and biological variability of three bone resorption assays
Authors: Ju Hsin-Shan J , Leung Sunny , Brown Bradley , Stringer Matthew A , Leigh Scott , Scherrer Christy , Shepard Karen , Jenkins Dean , Knudsen Jane , Cannon Robert 
Published: January 2020

AbstractWe have compared the analytical performance and biological variability of three commercially available bone resorption assays: Pyrilinks®-D, Osteomark®, and CrossLaps™, for the measurement of urinary free deoxypyridinoline (Dpd), cross-linked N-telopeptides of type I collagen (NTx), and linear C-telopeptides of type I collagen (CTx), respectively. The intraassay and interassay CVs for precision of the Dpd and NTx assays were &lt;10% for analyte concentrations greater than the second calibrator (i.e., 3 nmol/L Dpd or 30 nmol bone collagen equivalents/L NTx). The CTx assay demonstrated poor precision for analyte concentration lower than the third calibrator (i.e., 200 μg/L). The NTx assay exhibited nonlinear recovery for sample dilutions prepared in buffer; however, this nonlinear recovery could be corrected for sample dilutions made in urine at a low analyte concentration. Supplement recoveries of each of the three assays were within 100% ± 10% on average. All three analytes showed stability through five freeze–thaw cycles. The mean day-to-day variations were 16% for Dpd, and 23% for both NTx and CTx. Similar diurnal rhythm was observed for all three assays on average, with the peak in the early morning and the nadir in the afternoon. Mean amplitude of the diurnal variation was 37% for Dpd and NTx, and 57% for CTx. Variations within the reference intervals for a healthy premenopausal population were 28% for Dpd, 57% for NTx, and 56% for CTx. Pyrilinks-D has demonstrated analytical precision and accuracy equal or superior to Osteomark and CrossLaps in all areas. Dpd exhibits the least biological variability day-to-day, within individuals across the diurnal cycle, and within a healthy premenopausal population.
Analytical performance of Bayer Immuno 1™ estradiol and progesterone assays
Authors: Lévesque Ann , Letellier Marc , Dillon Paul W , Grant Andrew 
Published: January 2020

Abstract
We evaluated the analytical performance of new estradiol and progesterone assays performed on the Bayer Immuno 1™system. Within-run and between-day CVs for estradiol at concentrations of 116.8–6645.8 pmol/L were ≤6.4% and for 5.54–103.95 nmol/L progesterone were ≤7.7%, thus meeting published analytical goals. The detection limits (2 SDs from mean of zero calibrator) were 27.1 pmol/L for estradiol (n = 72 over 20 days) and 0.51 nmol/L for progesterone (n = 47 over 20 days). The assays were linear to 9766 pmol/L and 113.0 nmol/L, respectively. Estradiol results agreed well with the Diagnostic Products Corporation (DPC) assays, except for serum samples from patients receiving estrogen replacement therapy; results for these samples agreed closely with the DPC estradiol-6 assay. The progesterone assay agreed closely with the DPC assay, except for samples from uremic patients. Reference values were estimated by the study of 29 women throughout the menstrual cycle with 15 samples per subject. We concluded that both assays demonstrate suitable precision, linearity, and intermethod agreement to allow their use in the clinical laboratory.
Multicenter study of Abbott AxSYM® Digoxin II assay and comparison with 6 methods for susceptibility to digoxin-like immunoreactive factors
Authors: Azzazy Hassan M E , Duh Show-Hong , Maturen Andrew , Schaller Elisabeth , Shaw Leslie , Grimaldi Robert , Shock Gloria , Christenson Robert H 
Published: January 2020

Abstract
Performance characteristics of the Abbott nonpretreatment AxSYM® Digoxin II assay were evaluated for quantification of digoxin at four independent sites. Correlation of digoxin measurements with the Abbott pretreatment AxSYM®, Baxter Stratus® II, Abbott TDx/TDxFLx II®, Abbott IMx®, Emit® 2000, and Beckman Synchron CX® digoxin assays showed acceptable agreement, as indicated by: slope values &gt;0.84, r &gt;0.90, y-intercepts for all comparisons at or below the assay detection limit, and Sy|x ranging between 7.5% and 15.4% of the average digoxin value. Susceptibility to interference from digoxin-like immunoreactive factors (DLIFs) was examined in 233 samples from renal patients, liver disease patients, cord blood, and third-trimester pregnancies; the AxSYM Digoxin II assay demonstrated the least DLIFs interference. DLIF susceptibility for four of the methods was significantly greater (P &lt;0.05) than in the AxSYM Digoxin II assay; susceptibilities of the Stratus II and Emit 2000 methods were similar to the AxSYM Digoxin II assay.
Evaluation of new immunoenzymometric assay for measuring soluble transferrin receptor to detect iron deficiency in anemic patients
Authors: Suominen Pauli , Punnonen Kari , Rajamäki Allan , Irjala Kerttu 
Published: January 2020

AbstractDuring the last few years the measurement of serum-soluble transferrin receptor (sTfR) has been introduced as a tool to detect iron deficiency and as an analyte to differentiate between anemia caused by iron deficiency (IDA) and that caused by chronic disease (ACD). Commercially available methods have emerged to make diagnostics by sTfR more readily accessible. We documented the analytical performance of a newly introduced IDeATM sTfR immunoenzymometric assay (IEMA) by Orion Diagnostica. We also evaluated its clinical performance in 98 consecutive anemic patients, with information derived from bone marrow aspirate samples as the reference for iron status. The clinical usefulness of two other commercially available sTfR assays was assessed for comparison. The analytical performance and clinical applicability of the IDeA were sufficient to support reliable clinical work. We conclude that IDA and iron deficiency in the presence of inflammatory states can be differentiated efficiently from ACD with this new commercial test to measure sTfR.
Detection of hepatitis B surface antigen in whole blood by coupled particle light scattering (Copalis™)
Authors: Benecky Michael J , Post Diane R , Schmitt Susan M , Kochar Manish S 
Published: January 2020

Abstract
Coupled particlelight scattering (Copalis™) is a homogeneous immunoassay technology that permits simultaneous determination of multiple analytes in serum, plasma, or whole blood. Copalis differentiates monomeric latex microparticles from latex aggregates and cells on the basis of their unique light scatter properties. Copalis readily discriminates small (∼0.1 μm) differences in latex microparticle size. Therefore, multiple simultaneous assays are configured by the use of mixtures of different-size latex microparticles. The Copalis research immunoassay for hepatitis B surface antigen (HBsAg) is configured in a sandwich format where the extent of light scatter histogram broadening due to HBsAg-mediated binding of colloidal gold to latex provides the basis for antigen quantification. Simultaneous Copalis forward- and wide-angle light scatter measurements allow discrimination of latex microparticles from the cell components of whole blood. Consequently, direct detection of HBsAg in unprocessed whole-blood samples by Copalis is feasible.
Ethylene glycol poisoning: toxicokinetic and analytical factors affecting laboratory diagnosis
Authors: Eder Anne F , McGrath Cindy M , Dowdy Yvonne G , Tomaszewski John E , Rosenberg Frances M , Wilson Robert B , Wolf Bryan A , Shaw Leslie M 
Published: January 2020

AbstractEthylene glycol poisoning is an important toxicological problem in medical practice because early diagnosis and treatment can prevent considerable morbidity and mortality. When ingested in the form of antifreeze or other automotive products, ethylene glycol results in central nervous system depression, cardiopulmonary compromise, and renal insufficiency. Metabolism of ethylene glycol to organic acids is required for metabolic derangement and organ damage. Laboratory features of ethylene glycol poisoning include increased anion gap metabolic acidosis, increased osmolal gap, calcium oxalate crystalluria, and detectable ethylene glycol in serum. This Case Conference integrates discussion of the toxicokinetic and analytical variables that affect the laboratory diagnosis of ethylene glycol intoxication.
Clinical utility of the soluble transferrin receptor and comparison with serum ferritin in several populations
Authors: Mast Alan E , Blinder Morey A , Gronowski Ann M , Chumley Cara , Scott Mitchell G 
Published: January 2020

AbstractSoluble transferrin receptor (sTfR) and ferritin concentrations were measured in a variety of clinical settings to compare the ability of these two tests to identify iron deficiency. Among 62 anemic patients who either had a bone marrow aspirate performed or had a documented response to iron therapy, the diagnostic sensitivity and specificity of sTfR (at a diagnostic cutoff of &gt;2.8 mg/L) were 92% and 84%, respectively, with a positive predictive value of 42% in this population. Ferritin (≤12 μg/L) had a sensitivity of 25% and a specificity of 98%. However, the sensitivity and specificity of ferritin could be improved to 92% and 98%, respectively, by using a diagnostic cutoff value of ≤30 μg/L, resulting in a positive predictive value of 92%. Ferritin and sTfR were also measured in 267 outpatient samples and 112 medical students. In the outpatient group, the two tests agreed in 73% of the samples; however, 25% of the samples had ferritin values &gt;12 μg/L and increased sTfR. Among the medical students, there was 91% agreement between the two tests, but 7% of the samples had ferritin ≤12 μg/L and normal sTfR. Together, these data suggest that measurement of sTfR does not provide sufficient additional information to ferritin to warrant routine use. However, sTfR may be useful as an adjunct in the evaluation of anemic patients, whose ferritin values may be increased as the result of an acute-phase reaction.
X-Chromosome inactivation in healthy females: incidence of excessive lyonization with age and comparison of assays involving DNA methylation and transcript polymorphisms
Authors: El Kassar Nahed , Hetet Gilles , Brière Jean , Grandchamp Bernard 
Published: January 2020

Abstract
Skewed lyonization in healthy females represents the major disadvantage of X-chromosome-based clonality assays. Because most techniques are based on the difference in DNA methylation between active and inactive X-chromosomes, incomplete DNA digestion may occur, giving an unreliable clonality result. Here, we compare two different techniques carried out in healthy females belonging to three age groups and in a group of patients with essential thrombocythemia. The first technique involved the human androgen receptor gene, the second the transcript analysis of the iduronate-2-sulfatase, P55, and glucose-6-phospate dehydrogenase genes. Results between both techniques were concordant in most cases except in neonates, and the same pattern was observed in all fractions in healthy females. We conclude that: (a) clonality assays involving DNA and RNA polymorphisms are usually concordant except in neonates; (b) appropriate control tissue embryologically related to the sample must be chosen to eliminate excessive lyonization; (c) acquired skewing increases with age, whereas nonrandom lyonization is a rare phenomenon.