bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Analytical Error on the Assessment of Cardiac Risk by the High-Sensitivity C-Reactive Protein and Lipid Screening Model
Authors: Middleton John 
Published: January 2020

Abstract
Background: Several prospective epidemiologic studies have demonstrated that high-sensitivity C-reactive protein (hsCRP) is an effective serum marker for cardiac risk assessment. When hsCRP is considered in conjunction with traditional lipid screening, its clinical utility is further increased. In this report, hsCRP, HDL-cholesterol (HDLC), and total cholesterol (TC) assay imprecision is evaluated in terms of the impact on the cardiac risk assessment process.
Methods: Cardiac risk assessment events were simulated using software written in Visual Basic for Applications with Microsoft Excel. Representative sets of analyte concentrations were used for true patient cardiac marker values. Monte Carlo simulations about the marker values were run using assay SD estimates based on College of American Pathologists surveys and journal articles.
Results: Risk distributions for reasonable assay imprecision showed clinically significant variation. Estimated relative risks of cardiovascular disease using the Ridker–Rifai quintile model varied by as much as 2.5-, 3.5-, and 6-fold for conditions of low, medium, and high laboratory test imprecision, respectively. The true relative risks were underestimated by &gt;25% in 3%, 6.7%, and 10.5% of cases under conditions of low, medium, and high laboratory test imprecision, respectively, and overestimated by &gt;25% in 4.4%, 8.5%, and 11.1% of cases under those conditions.
Conclusions: Use of the Monte Carlo simulation method as a tool to assess the impact of analytical variation on the clinical decision-making process is valuable. From this analysis, it is shown that multiple measurements of HDLC may reduce misclassifications that result from assay imprecision. This is most important when using HDLC assays that include sample preparation with 500 000 molecular weight dextran sulfate. For these assays the total assay method SDs are higher than for other assay methods. In addition, as demonstrated by a propagation of error analysis, HDLC has the largest component of overall error in the relative risk estimate. Under conditions of typical TC and hsCRP assay performance, replication of these assays is less important.
Effects of Temperature on Stability of Blood Homocysteine in Collection Tubes Containing 3-Deazaadenosine
Authors: Hill Diane M , Johnson Lisa J , Burns Paul J , Neale Angela M , Harmening Denise M , Kenney Andrew C 
Published: January 2020

AbstractBackground: The accuracy of homocysteine (Hcy) results is currently compromised by the requirement to separate the plasma within 1 h of sample collection. We studied the effect of temperature on the stability of plasma Hcy over a 72-h time course in blood collected into evacuated tubes containing either EDTA alone or both EDTA and 3-deazaadenosine (3DA).Methods: We recruited 100 volunteers, including both diseased and healthy individuals with a range of baseline plasma Hcy values, from two centers. Blood samples were collected into tubes containing EDTA, and EDTA plus 3DA and stored at ambient temperature (20–25 °C) or refrigerated (2–8 °C). Aliquots of blood were centrifuged at various times up to 72 h, the plasma was removed, and Hcy was measured by HPLC.Results: Plasma Hcy measurement covering the sample collection and storage conditions during the whole time course was possible on samples from 59 of those recruited. One-way ANOVA for repeated measures within subjects revealed that only samples that were collected into tubes containing EDTA plus 3DA and stored refrigerated were stable over 72 h (P = 0.2761).Conclusions: A combination of 3DA and storage at 2–8 °C will allow collection of samples for plasma Hcy measurement outside of the hospital setting and wider population screening.
Fetal DNA Clearance from Maternal Plasma Is Impaired in Preeclampsia
Authors: Lau Tai-Wah , Leung Tse N , Chan Lisa YS , Lau Tze K , Chan KC Allen , Tam Wing H , Lo YM Dennis 
Published: January 2020

AbstractBackground: Increased fetal DNA in maternal plasma/serum has been reported in pregnancies complicated by preeclampsia. We hypothesized that impaired clearance of fetal DNA might contribute, at least in part, to the above-mentioned phenomenon.Methods: We studied 7 preeclamptic and 10 control pregnant women. All had male fetuses. Serial blood samples were obtained from before delivery to 6 h postpartum. Male fetal DNA in maternal plasma was measured by real-time quantitative PCR for the SRY gene on the Y chromosome.Results: The median fetal DNA concentrations before delivery were significantly higher in the preeclamptic women than in the controls (521 vs 227 genome-equivalents/mL for preeclamptic and control women, respectively; Mann–Whitney rank-sum test, P = 0.017). The median fetal DNA concentrations at 6 h after delivery were also significantly different between the two groups (208 vs 0 genome-equivalents/mL for preeclamptic and control women, respectively; Mann–Whitney rank-sum test, P = 0.002). A first-order clearance model was found to best describe the kinetics of maternal plasma fetal DNA clearance. Moreover, we observed a significant difference in the median apparent clearance half-lives of fetal DNA between the preeclamptic women (114 min) and controls (28 min; Mann–Whitney rank-sum test, P = 0.007).Conclusions: This study represents the first documentation of impaired fetal DNA clearance from maternal plasma in preeclampsia. Such an abnormality in circulating DNA clearance may also be present in other medical conditions associated with quantitative aberrations in circulating DNA concentrations.
High-Throughput Quantification of Lysophosphatidylcholine by Electrospray Ionization Tandem Mass Spectrometry
Authors: Liebisch Gerhard , Drobnik Wolfgang , Lieser Bernd , Schmitz Gerd 
Published: January 2020

AbstractBackground: Lysophosphatidylcholine (LPC) has been suggested to play a functional role in various diseases, including atherosclerosis, diabetes, and cancer mediated by LPC-specific G-protein-coupled receptors. Initial studies provided evidence for a potential use of LPC as diagnostic maker. However, existing methodologies are of limited value for a systematic evaluation of LPC species concentrations because of complicated, time-consuming procedures. We describe a methodology based on electrospray ionization tandem mass spectrometry (ESI-MS/MS) applicable for high-throughput LPC quantification.Methods: Crude lipid extracts of EDTA-plasma samples were used for direct flow injection analysis. LPC 13:0 and LPC 19:0 were added as internal standards, and the ESI-MS/MS was operated in the parent-scan mode for m/z 184. Quantification was achieved by standard addition. Data processing was highly automated by use of the mass spectrometer software and self-programmed Excel macros.Results: The calibrators LPC 16:0, LPC 18:0, and LPC 22:0 showed a linear response independent of sample dilution and plasma cholesterol concentration for both internal standards. The within-run imprecision (CV) was 3% for the major and 12% for the minor species, whereas the total imprecision was ∼12% for the major and 25% for the minor species. The detection limit was &lt;1 μmol/L.Conclusion: The developed ESI-MS/MS methodology with an analysis time of 2 min/sample, simple sample preparation, and automated data analysis allows high-throughput quantification of distinct LPC species from plasma samples, which could be a valuable tool for the evaluation of LPC as diagnostic marker.
Stability Studies of Twenty-Four Analytes in Human Plasma and Serum
Authors: Boyanton Bobby L , Blick Kenneth E 
Published: January 2020

AbstractBackground: The stability and stoichiometric changes of analytes in plasma and serum after prolonged contact with blood cells in uncentrifuged Vacutainer® tubes were studied.Methods: We simultaneously investigated the stability of 24 analytes (a) after prolonged contact of plasma and serum with blood cells and (b) after immediate separation of plasma and serum (centrifuged twice at 2000g for 5 min). We verified biochemical mechanisms of observed analyte change by concomitant measurement of pH, Pco2, and Po2. Hemolysis was qualitatively and semiquantitatively assessed. All specimens were maintained at room temperature (25 °C) and analyzed in duplicate 0.5, 4, 8, 16, 24, 32, 40, 48, and 56 h after collection. Statistically significant changes from the 0.5 h mean were determined using repeated-measures ANOVA. The significant change limit was applied to determine clinically significant changes in measured analytes.Results: Fifteen of 24 analytes in plasma and serum maintained in contact with cells showed clinically relevant changes, with the degree of change more pronounced in most plasma specimens. All analytes in plasma and serum immediately separated from cells after collection were stable.Conclusion: Storage of uncentrifuged specimens beyond 24 h caused significant changes in most analytes investigated because of (a) glucose depletion and Na+,K+-ATPase pump failure; (b) the movement of water into cells, causing hemoconcentration; and (c) leakage of intracellular constituents and metabolites. Immediate separation of plasma or serum from cells provides optimal analyte stability at room temperature. When prolonged contact of plasma or serum with cells is unavoidable, use of serum is recommended because of the higher instability of plasma analytes.
Markers of Triglyceride-rich Lipoprotein Remnant Metabolism in Visceral Obesity
Authors: Chan Dick C , Watts Gerald F , Barrett P Hugh , Mamo John CL , Redgrave Trevor G 
Published: January 2020

AbstractBackground: Triglyceride-rich lipoprotein remnants are atherogenic, and this may be particularly important in visceral obesity. We investigated remnant metabolism in obese men by measuring remnant-like particle-cholesterol (RLP-C), apolipoprotein (apo) B-48, apoC-III, and the clearance of a labeled remnant-like emulsion.Methods: Fasting RLP-C, apoB-48, and apoC-III concentrations were measured in 48 viscerally obese men and 10 lean controls. RLP-C was determined by immunoseparation assay, apoB-48 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and enhanced chemiluminescence, and apoC-III by immunoturbidimetric assay. The catabolism of chylomicron remnants was measured by intravenous injection of a remnant-like emulsion containing cholesteryl [13C]oleate, with isotopic enrichment of 13CO2 in breath determined by isotope-ratio mass spectrometry and a multicompartmental model to estimate fractional catabolic rate (FCR) of the emulsion.Results: Compared with controls, obese men had significantly increased plasma concentrations of RLP-C, apoB-48, and apoC-III (P &lt;0.001 for all). Plasma total apoB-100, non-HDL-cholesterol, LDL-cholesterol, triglycerides, and insulin resistance (HOMA score) were also significantly higher in the obese group (P &lt;0.001 for all). Obese men had a significantly lower FCR of the remnant-like emulsion compared with controls (P = 0.020).Conclusions: Viscerally obese individuals have insulin resistance and increased plasma concentrations of triglyceride-rich lipoprotein remnants, which may be attributable to decreased catabolism of these particles.
Rapid Analysis of Metanephrine and Normetanephrine in Urine by Gas Chromatography-Mass Spectrometry
Authors: Crockett David K , Frank Elizabeth L , Roberts William L 
Published: January 2020

Abstract
Background: Widely used HPLC methods for quantification of metanephrine and normetanephrine in urine often have long analysis times and are frequently plagued by drug interferences. We describe a gas chromatography-mass spectrometry method designed to overcome these limitations.
Methods: Metanephrine and normetanephrine conjugates were converted to unconjugated metanephrine and normetanephrine by acid hydrolysis. To avoid the rapid decomposition of the deuterated internal standards (metanephrine-d3 and normetanephrine-d3) under hydrolysis conditions, the internal standards were added after hydrolysis. Solid-phase extraction was used to isolate the hydrolyzed metanephrines from urine. Samples were concentrated by evaporation, then derivatized simultaneously with N-methyl-N-(trimethylsilyl)trifluoroacetamide and N-methyl-bis-heptafluoro-butryamide at room temperature.
Results: The assay was linear from 25 to 7000 μg/L. The intraassay CVs were &lt;5% and the interassay CVs &lt;12%. Comparison with a routine HPLC method (n = 192) by Deming regression yielded a slope of 1.00 ± 0.02 μg/L, an intercept of −5.8 ± 7.8 μg/L, and Sy|x = 50.6 μg/L for metanephrine and a slope of 0.94 ± 0.03, intercept of 19 ± 11 μg/L, and Sy|x = 60 μg/L for normetanephrine. The correlation coefficients (r) were calculated after log transformation of the data and gave r = 0.97 for metanephrine and r = 0.97 for normetanephrine. Interference from common medications or drug metabolites was seen in &lt;1% of samples. The time between sequential injections was &lt;7 min.
Conclusions: This new gas chromatography-mass spectrometry assay for total fractionated metanephrines is rapid, compares well with a standard HPLC assay, and avoids most drug interferences that commonly affect HPLC assays for urine metanephrines.
Synthetic Peptides Identified from Phage-displayed Combinatorial Libraries as Immunodiagnostic Assay Surrogate Quality-Control Targets
Authors: Sompuram Seshi R , Kodela Vani , Ramanathan Halasya , Wescott Charles , Radcliffe Gail , Bogen Steven A 
Published: January 2020

AbstractBackground: Quantitative immunohistochemical (IHC) assays currently lack optimal reference quality-control material for cellular protein targets. To address this problem, we identified peptides that mimic the site on the native analyte to which the primary (monoclonal) antibody binds and used them as surrogate peptide controls.Methods: We identified peptide candidates from a combinatorial peptide phage-display library that mimic the epitope for the 1D5 estrogen receptor (ER) monoclonal antibody (mAb). The peptide inserts of the phage clones were sequenced. Several phage-encoded peptides were then synthesized and analyzed for affinity and specificity.Results: We identified phage clones that specifically bound to the ER 1D5 mAb. The binding was specific, in that the phage clones did not bind to two other isotype-matched mAbs. Their ability to bind the ER 1D5 mAb was related to the presence of a consensus sequence. Binding analysis revealed a Kd of 8.3 × 10−8 mol/L. The peptide was not recognized by any of 15 other mAbs commonly used for clinical IHC testing. Moreover, the peptide was able to inhibit the binding of ER 1D5 mAb to native ER, indicating that the peptide bound to ER 1D5 mAb at or close to the antigen-binding site.Conclusions: Surrogate peptide controls behave like the native analyte in terms of affinity and specificity. This technology may be especially useful when the native analyte is in short supply.
Can Measurement of Serum Apolipoprotein B Replace the Lipid Profile Monitoring of Patients with Lipoprotein Disorders?
Authors: Miremadi Saman , Sniderman Allan , Frohlich Jiri 
Published: January 2020

AbstractBackground: Current clinical guidelines require that five indices (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and the total/HDL cholesterol ratio) be measured or calculated to assess the lipid-related risk of vascular disease. All five are also targets of therapy and therefore all must be measured initially and at follow-up. Considerable evidence indicates that apolipoprotein B (apo B) is a better index of reaching or not reaching treatment targets than total or LDL cholesterol.Methods: The objective of this study was to examine whether measurement of a single marker (apo B) led to the same categorization of risk as the traditional five indices (lipid profile). If both apo B and lipid profile indicated that the patient was either within or outside their respective treatment targets, the indices were considered concordant. If not, the indices were considered discordant. Concordance/discordance was examined in 215 patients at their first and last clinic visit.Results: Concordance was high in both higher (88% at the first and 92% at the last clinic visit) and lower (76% at the first and 78% at the last clinic visit) risk groups at both the initial and final visits. Discordance was virtually restricted to the group with hypertriglyceridemia with normal concentrations of apo B, a group in which little independent evidence points to any substantially increased risk of vascular disease.Conclusions: These data raise the possibility that at least for high risk patients treated with statins, follow-up could be simplified and expenses reduced if only apo B were measured. They also raise the possibility that outcome might be improved if the therapeutic algorithm were simplified.
Validation of Liquid Chromatography–Tandem Mass Spectrometry Method for Analysis of Urinary Conjugated Metanephrine and Normetanephrine for Screening of Pheochromocytoma
Authors: Taylor Robert L , Singh Ravinder J 
Published: January 2020

Abstract
Background: Metanephrines are biochemical markers for tumors of the adrenal medulla (e.g., pheochromocytoma) and other tumors derived from neural crest cells (e.g., paragangliomas and neuroblastomas). We describe a liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the measurement of urinary conjugated metanephrines.
Methods: We added 250 ng of d3-metanephrine (d3-MN) and 500 ng of d3-normetanephrine (d3-NMN) to 1 mL of urine samples as stable isotope internal standards. The samples were then acidified, hydrolyzed for 20 min in a 100 °C water bath, neutralized, and prepared by solid-phase extraction. The methanol eluates were analyzed by LC-MS/MS in the selected-reaction-monitoring mode after separation on a reversed-phase amide C16 column.
Results: Multiple calibration curves for the analysis of urine MN and NMN exhibited consistent linearity and reproducibility in the range of 10–5000 μg/L. Interassay CVs were 5.7–8.6% at mean concentrations of 90–4854 μg/L for MN and NMN. The detection limit was 10 μg/L. Recovery of MN and NMN (144–2300 μg/L) added to urine was 91–114%. The regression equation for the LC-MS/MS (x) and colorimetric (y) methods was: y = 0.81x − 0.006 (r = 0.822; n = 110). The equation for the HPLC (x) and LC-MS/MS (y) methods was: y = 1.09x + 0.05 (r = 0.998; n = 40).
Conclusions: The sensitivity and specificity of the MS/MS method for urinary conjugated metanephrines offer advantages over colorimetric, immunoassay, HPLC, and gas chromatography–mass spectrometry methods because of elimination of drug interferences, high throughput, and short chromatographic run time.
Errors in Laboratory Medicine
Authors: Bonini Pierangelo , Plebani Mario , Ceriotti Ferruccio , Rubboli Francesca 
Published: January 2020

AbstractBackground: The problem of medical errors has recently received a great deal of attention, which will probably increase. In this minireview, we focus on this issue in the fields of laboratory medicine and blood transfusion.Methods: We conducted several MEDLINE queries and searched the literature by hand. Searches were limited to the last 8 years to identify results that were not biased by obsolete technology. In addition, data on the frequency and type of preanalytical errors in our institution were collected.Results: Our search revealed large heterogeneity in study designs and quality on this topic as well as relatively few available data and the lack of a shared definition of “laboratory error” (also referred to as “blunder”, “mistake”, “problem”, or “defect”). Despite these limitations, there was considerable concordance on the distribution of errors throughout the laboratory working process: most occurred in the pre- or postanalytical phases, whereas a minority (13–32% according to the studies) occurred in the analytical portion. The reported frequency of errors was related to how they were identified: when a careful process analysis was performed, substantially more errors were discovered than when studies relied on complaints or report of near accidents.Conclusions: The large heterogeneity of literature on laboratory errors together with the prevalence of evidence that most errors occur in the preanalytical phase suggest the implementation of a more rigorous methodology for error detection and classification and the adoption of proper technologies for error reduction. Clinical audits should be used as a tool to detect errors caused by organizational problems outside the laboratory.
β-Trace Protein, Cystatin C, β2-Microglobulin, and Creatinine Compared for Detecting Impaired Glomerular Filtration Rates in Children
Authors: Filler Guido , Priem Friedrich , Lepage Nathalie , Sinha Pranav , Vollmer Ilka , Clark Heather , Keely Erin , Matzinger Mary , Akbari Ayub , Althaus Harald , Jung Klaus 
Published: January 2020

AbstractBackground: Because of the limitations of serum creatinine as a marker of glomerular filtration rate (GFR) in children, we assessed the diagnostic accuracy of the novel marker β-trace protein (BTP) in comparison with cystatin C (Cys-C), β2-microglobulin (β2-MG), and creatinine as conventional indicators of reduced GFR.Methods: We obtained serum samples from 225 children (age range, 0.2–18 years) with various renal pathologies who were referred for nuclear medicine clearance investigations (technetium-diethylenetriamine pentaacetic acid or chromium-EDTA). We measured Cys-C, BTP (nephelometric tests; Dade Behring), β2-MG (Tinaquant; Roche), and creatinine (enzymatic assay; Creatinine-PAP; Roche).Results: Seventy-five children had reduced GFR (&lt;90 mL · min−1 · 1.73 m−2). One hundred fifty children (independent of gender and age) with values &gt;90 mL · min−1 · 1.73 m−2 comprised the control group with gaussian distributions of BTP and Cys-C concentrations. The upper reference limits (97.5 percentile) were 1.01 mg/L for BTP and 1.20 mg/L for Cys-C. The correlations of nuclear medicine clearance with the reciprocals of BTP, Cys-C, and the Schwartz GFR estimate were significantly higher (r = 0.653, 0.765, and 0.706, respectively; P &lt;0.05) than with the reciprocal of creatinine or β2-MG (r = 0.500 and 0.557, respectively). ROC analysis showed a significantly higher diagnostic accuracy of BTP, Cys-C, and the GFR estimate for the detection of impaired GFR than serum creatinine (P &lt;0.05). Compared to creatinine, BTP increased the diagnostic sensitivity by ∼30%, but it was not more sensitive than Cys-C or the Schwartz GFR estimate.Conclusions: BTP is superior to serum creatinine and an alternative for Cys-C to detect mildly reduced GFR in children, but it is not better than the Schwartz GFR estimate.