bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Monoclonal Antibodies for Prostate-specific Antigen and Development of Highly Sensitive Free Prostate-specific Antigen Assays
Authors: Black Margot H , Grass C Linda , Leinonen Jari , Stenman Ulf-Håkan , Diamandis Eleftherios P 
Published: January 2020

AbstractBackground: The recent elucidation of the importance of serological free prostate-specific antigen (PSA) in the diagnosis of prostate cancer has created a demand for immunoassays specific for free PSA.Methods: We developed and characterized 11 monoclonal antibodies with high affinities for PSA (Kavalues from 1.1 × 108 to 1.8 × 1010L/mol), only 3 of which cross-react with human glandular kallikrein (hK2). Using these antibodies and PSA antibodies developed by others, in conjunction with time-resolved fluorometry, we developed ultrasensitive sandwich immunoassays specific for the free form of PSA.Results: The analytical detection limit of these immunoassays is 0.001 μg/L. To our knowledge, this is the most sensitive free PSA assay reported to date. The free PSA immunoassays exhibit &lt;1% cross-reactivity with PSA-α1-antichymotrypsin, show no cross-reactivity with hK2, and correlate well with established free PSA kits. The 11 antibodies developed by our group, in conjunction with 4 commercially available antibodies, were used to generate a putative epitope map of the PSA molecule.Conclusion: The highly sensitive free PSA immunoassays may be used for measuring PSA subfractions in female serum, an application currently impossible with other reported free PSA immunoassays.
Evaluation of a New Method for the Analysis of Free Catecholamines in Plasma Using Automated Sample Trace Enrichment with Dialysis and HPLC
Authors: Dutton John , Hodgkinson Andrew J , Hutchinson George , Roberts Norman B 
Published: January 2020

Abstract
Background: Analysis of urinary free catecholamines was automated recently, but analysis of plasma samples posed special difficulties. The present study was undertaken to evaluate a new method for the automated analysis of plasma catecholamines.
Methods: The procedure is based on an improved sample handling system that includes dialysis and sample clean-up on a strong cation trace-enrichment cartridge. The catecholamines norepinephrine, epinephrine, and dopamine are then separated by reversed-phase ion-pair chromatography and quantified by electrochemical detection.
Results: Use of a 740-μL sample is required to give the catecholamine detection limit of 0.05 nmol/L and analytical imprecision (CV) between 1.1% and 9.3%. The assay can be run unattended, although &gt;12 h of analysis time is not recommended without cooling of the autosampler rack. Comparison (n = 68) of the automated cation-exchange clean-up with the well-established manual alumina procedure gave excellent agreement (mean, 3.78 ± 2.76 and 3.8 ± 2.89 nmol/L for norepinephrine and 0.99 ± 1.72 and 1.08 ± 1.78 nmol/L for epinephrine). Hemodialysis had no clear effect on plasma norepinephrine. Epinephrine concentrations were similar (0.05 &lt; P &lt; 0.1) in chronic renal failure patients (0.24 ± 0.3 nmol/L; n = 15) and healthy controls (0.5 ± 0.24 nmol/L; n = 31). Dopamine was not quantified, being usually &lt;0.2 nmol/L.
Conclusion: The availability of such a fully automated procedure should encourage the more widespread use of plasma catecholamine estimation, e.g., after dialysis, exercise, or trauma/surgery and in the investigation of catecholamine-secreting tumors, particularly in the anuric patient.
The Future of Molecular Genetic Testing
Authors: Leonard Debra GB 
Published: January 2020

Abstract
The potential applications for genetic testing are immense, with most diseases having some aspect influenced by, if not directly caused by, changes in the genome of the patient. The translation of genetic information into medical applications will be influenced by our understanding of the human genome, technological advances, and social, ethical, and legal issues surrounding genetic testing. With time, new genetic information will be translated into clinical tests for the diagnosis of current illness and prediction of future disease risk, and will be used for the development of genetically directed therapies and preventive interventions. Most genetic testing will be highly automated, with only rare genetic disease tests performed manually. The challenge for the clinical genetic laboratory is to keep pace with this information explosion to provide state-of-the-art genetic testing and to ensure that the genetic test results are used in a morally, ethically, and socially responsible way.
Highly Sensitive Automated Chemiluminometric Assay for Measuring Free Human Glandular Kallikrein-2
Authors: Klee George G , Goodmanson Marcia K , Jacobsen Steven J , Young Charles YF , Finlay Judith A , Rittenhouse Harry G , Wolfert Robert L , Tindall Donald J 
Published: January 2020

AbstractBackground: Human glandular kallikrein (hK2) is a serine protease that has 79% amino acid identity with prostate-specific antigen (PSA). Both free hK2 and hK2 complexed to α1-antichymotrypsin (ACT) are present in the blood in low concentrations. We wished to measure hK2 in serum with limited contribution from hK2-ACT for the results.Methods: We developed an automated assay for hK2 with use of a select pair of monoclonal antibodies. The prototype assay was implemented on a Beckman Coulter ACCESS® analyzer.Results: The detection limit of the assay was 1.5 ng/L, the “functional sensitivity” (day-to-day CV &lt;15%) was &lt;4 ng/L, cross-reactivity with PSA and PSA-ACT was negligible, and cross-reactivity with hK2-ACT was 2%. After surgical removal of prostate glands, serum hK2 was &lt;7 ng/L and was &lt;15 ng/L in most healthy women. The median serum concentration of hK2 in healthy men without prostate cancer was 26 ng/L. The median concentration of hK2 was 72 ng/L for men having prostate cancer with lower Gleason scores compared with 116 ng/L for men with more advanced cancer. The concentration of hK2 correlated weakly with PSA, with the mean hK2 concentrations generally 30- to 80-fold lower than PSA concentrations.Conclusion: The availability of a robust, high sensitivity automated assay for hK2 should facilitate further investigations of the role of hK2 measurements in the management of patients with prostate disease.
Lipoprotein(a)-Cholesterol and Coronary Heart Disease in the Framingham Heart Study
Authors: Seman Leo J , DeLuca Carl , Jenner Jennifer L , Cupples L Adrienne , McNamara Judith R , Wilson Peter WF , Castelli William P , Ordovas Jose M , Schaefer Ernst J 
Published: January 2020

AbstractBackground: Increased plasma lipoprotein(a) [Lp(a)] concentrations have been reported to be an independent risk factor for coronary heart disease (CHD) in some prospective studies, but not in others. These inconsistencies may relate to a lack of standardization and the failure of some immunoassays to measure all apolipoprotein(a) isoforms equally.Methods: We measured plasma Lp(a)-cholesterol [Lp(a)-C] in a Caucasian population of offspring and spouses of the Framingham Heart Study participants, using a lectin-based assay (LipoproTM). We compared the prevalence of increased Lp(a)-C to the presence of sinking pre-β-lipoprotein (SPB). We also related Lp(a)-C concentrations to the prevalence of CHD risk in the entire population.Results: The mean (± SD) Lp(a)-C concentration in the Framingham population (n = 3121) was 0.186 ± 0.160 mmol/L, with no significant gender or age differences. The mean Lp(a)-C concentrations in the absence or presence of SPB were 0.158 ± 0.132 mmol/L and 0.453 ± 0.220 mmol/L, respectively (P &lt;0.0001). The mean Lp(a)-C concentration in men with CHD (n = 156) was 0.241 ± 0.204 mmol/L, which was significantly (P &lt;0.001) higher, by 34%, than in controls. The odds ratio for CHD risk in men with Lp(a)-C ≥0.259 mmol/L (≥10 mg/dL), after adjusting for age, HDL-cholesterol, LDL-cholesterol, smoking, diabetes, blood pressure, and body mass index, was 2.293 (confidence interval, 1.55–3.94; P &lt;0.0005). Lp(a)-C values correlated highly with a Lp(a)-mass immunoassay [ApotekTM Lp(a); r = 0.832; P &lt;0.0001; n = 1000].Conclusions: An increased Lp(a)-C value ≥0.259 mmol/L (≥10 mg/dL) is an independent CHD risk factor in men with a relative risk of more than 2, but was inconclusive in women. Lp(a)-C measurements offer an alternative to Lp(a)-mass immunoassays and can be performed on automated analyzers.
Broad Spectrum Drug Identification Directly from Urine, Using Liquid Chromatography-Tandem Mass Spectrometry
Authors: Fitzgerald Robert L , Rivera Jeffrey D , Herold David A 
Published: January 2020

AbstractBackground: Currently the rate-limiting step for mass spectrometric analysis of drugs in biological samples is sample preparation. Many gas chromatography/mass spectrometry (GC/MS) methods are specific for a certain class of compounds, requiring extraction and/or derivatization before analysis. The purpose of this study was to develop a broad spectrum liquid chromatography/mass spectrometry (LC/MS) procedure that allowed for direct analysis of urine specimens with potential for quantitative analysis.Methods: We modified a commercially available column-switching instrument, the REMEDi HS from Bio-Rad Diagnostics, to make it compatible with atmospheric pressure ionization. The system we developed was based on electrospray ionization and used three LC columns to extract, purify, and separate drugs directly from urine specimens. Drugs and metabolites were tentatively identified on the basis of retention times and (M+H)+ ions. Tandem mass spectrometry (MS/MS) was used to confirm the qualitative identification of suspected drugs, using data-dependent acquisition. For quantitative analysis, the cocaine metabolite benzoylecgonine was analyzed using isotope dilution and selected reaction monitoring.Results: Seventeen basic drugs from a variety of classes of compounds were identified directly from urine without the need for prior sample extraction, using LC and MS/MS. Quantitative analysis was demonstrated for benzoylecgonine. When benzoylecgonine-d3 was used as the internal standard, the method was linear from 30 to 10 000 μg/L (range tested). At these concentrations, the within-run accuracy was ± 10% of the target concentration, with CVs &lt;10%. Analytical results by LC/MS/MS compared favorably with GC/MS values for 50 benzoylecgonine-containing specimens and for 25 negative specimens.Conclusions: The ability to directly analyze urine for a wide variety of drug classes, combined with the sensitivity and specificity of LC/MS/MS makes this technique attractive for many clinical, forensic, and biotechnology applications.
Determination of the Sum of Bilirubin Sugar Conjugates in Plasma by Bilirubin Oxidase
Authors: Doumas Basil T , Yein Fred , Perry Billy , Jendrzejczak Bernadine , Kessner Arthur 
Published: January 2020

Abstract
Background: A reliable indicator of cholestasis is the presence of abnormal concentrations of bilirubin mono- and diglucuronide [conjugated bilirubin (CB)] in blood. A routine assay of CB is available only to those who possess a certain type of clinical analyzer. We describe a two-point manual method for CB that could be adapted as a rate assay to automated clinical analyzers.
Methods: The measurement of CB is based on its oxidation to biliverdin by bilirubin oxidase. The resulting decrease in absorbance at 460 nm is proportional to the CB concentration. The assay is calibrated with solutions of ditaurobilirubin in human serum.
Results: Under the conditions of the assay (0.1 mol/L glycine buffer, pH 10.0; reaction time, 2 min), only 5% of unconjugated bilirubin is oxidized and δ-bilirubin is not oxidized at all. Results obtained with the bilirubin oxidase method agreed well with those obtained by HPLC. The long-term CVs at CB concentrations of 6 and 63.4 mg/L were 20% and 2.6%, respectively. The reference values, established by analyzing 51 plasma specimens from healthy adults, were 0.0–1.2 mg/L, with a mean value of 0.2 mg/L.
Conclusions: The proposed method for CB has good analytical specificity and obviates the requirement for HPLC or a dry chemistry analyzer. The measurement of CB in blood is superior to the measurement of direct bilirubin because an abnormal concentration of direct bilirubin does not necessarily indicate the presence of cholestasis.
Comparison of Plasma Total Homocysteine Measurements in 14 Laboratories: An International Study
Authors: Pfeiffer Christine M , Huff Dan L , Smith S Jay , Miller Dayton T , Gunter Elaine W 
Published: January 2020

Abstract
Background: Information on interlaboratory variation and especially on methodological differences for plasma total homocysteine is lacking.
Methods: We studied 14 laboratories that used eight different method types: HPLC with electrochemical detection (HPLC-ED); HPLC with fluorescence detection (HPLC-FD) further subdivided by type of reducing/derivatizing agent; gas chromatography/mass spectrometry (GC/MS); enzyme immunoassay (EIA); and fluorescence polarization immunoassay (FPIA). Three of these laboratories used two methods. The laboratories participated in a 2-day analysis of 46 plasma samples, 4 additional plasma samples with added homocystine, and 3 plasma quality-control (QC) pools. Results were analyzed for imprecision, recovery, and methodological differences.
Results: The mean among-laboratory and among-run within-laboratory imprecision (CV) was 9.3% and 5.6% for plasma samples, 8.8% and 4.9% for samples with added homocystine, and 7.6% and 4.2% for the QC pools, respectively. Difference plots showed values systematically higher than GC/MS for HPLC-ED, HPLC-FD using sodium borohydride/monobromobimane (however, for only one laboratory), and EIA, and lower values for HPLC-FD using trialkylphosphine/4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. The two HPLC-FD methods using tris(2-carboxyethyl) phosphine/ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F) or tributyl phosphine/SBD-F, and the FPIA method showed no detectable systematic difference from GC/MS.
Conclusions: Among-laboratory variations within one method can exceed among-method variations. Some of the methods tested could be used interchangeably, but there is an urgent need to improve analytical imprecision and to decrease differences among methods.
Maximizing Efficacy of Endocrine Tests: Importance of Decision-focused Testing Strategies and Appropriate Patient Preparation
Authors: Klee George G 
Published: January 2020

AbstractThe efficacy of endocrine tests depends on the choice of tests, the preparation of the patients, the integrity of the specimens, the quality of the measurements, and the validity of the reference data. Close dialogue among the clinicians, the laboratory, and the patients is a key factor for optimal patient care. The characteristics of urine and plasma samples and the advantages and limitations of paired test measurements are presented. The importance of test sequence strategies, provocative or inhibitory procedures, and elimination of drug interferences is illustrated with four cases involving Cushing syndrome, pheochromocytoma, primary aldosteronism, and hypercalcemia. For each of these scenarios, key clinical issues are highlighted, along with discussions of the best test strategies, including which medications are likely to interfere. The importance of targeting laboratory tests to answer well-focused clinical decisions is emphasized. The roles of some time-honored provocative procedures are questioned in light of more sensitive and specific analytic methods. The importance of decision-focused analytical tolerance limits is emphasized by demonstrating the impact of analytic bias on downstream medical resource utilization. User-friendly support systems to facilitate the implementation of test strategies and postanalytic tracking of patient outcomes are presented as essential requirements for quality medical practice.
Development of a Chemiluminescence Competitive PCR for the Detection and Quantification of Parvovirus B19 DNA Using a Microplate Luminometer
Authors: Fini Fabiana , Gallinella Giorgio , Girotti Stefano , Zerbini Marialuisa , Musiani Monica 
Published: January 2020

Abstract
Background: Quantitative PCR of viral nucleic acids can be useful clinically in diagnosis, risk assessment, and monitoring of antiviral therapy. We wished to develop a chemiluminescence competitive PCR (cPCR) for parvovirus B19.
Methods: Parvovirus DNA target sequences and competitor sequences were coamplified and directly labeled. Amplified products were then separately hybridized by specific biotin-labeled probes, captured onto streptavidin-coated ELISA microplates, and detected immunoenzymatically using chemiluminescent substrates of peroxidase. Chemiluminescent signals were quantitatively analyzed by a microplate luminometer and were correlated to the amounts of amplified products.
Results: Luminol-based systems displayed constant emission but had a higher detection limit (100–1000 genome copies) than the acridan-based system (20 genome copies). The detection limit of chemiluminescent substrates was lower (20 genome copies) than colorimetric substrates (50 genome copies). In chemiluminescence cPCR, the titration curves showed linear correlation above 100 target genome copies. Chemiluminescence cPCR was positive in six serum samples from patients with parvovirus infections and negative in six control sera.
Conclusions: The chemiluminescence cPCR appears to be a sensitive and specific method for the quantitative detection of viral DNAs.
Increased Ability of LDL from Normolipidemic Type 2 Diabetic Women to Generate Peroxides
Authors: Guerci Bruno , Antebi Helena , Meyer Laurent , Durlach Vincent , Ziegler Olivier , Nicolas Jean-Pierre , Alcindor Louis-Gerald , Drouin Pierre 
Published: January 2020

AbstractBackground: We assessed the ability of LDL from 30 type 1 diabetic patients (18 men, 12 women), 65 type 2 diabetic patients (35 men, 30 women), and 35 controls (19 men, 16 women) to generate peroxides. The men and women in the diabetic groups were studied separately and matched for age, body mass index, duration of diabetes, glycohemoglobin, and conventional lipid characteristics according to the presence or absence of hyperlipidemia.Methods: The ability of LDL to form peroxides was assessed by measuring the thiobarbituric acid-reactive substances corrected for LDL-cholesterol [ratio of malondialdehyde (MDA) to LDL-cholesterol]. LDL particle size was expressed as the ratio of LDL-cholesterol to apolipoprotein B (LDL-cholesterol/apoB).Results: The MDA/LDL-cholesterol ratio was higher in type 1 and type 2 diabetic patients with hyperlipidemia than in controls. The MDA/LDL-cholesterol ratio was also higher in type 2 normolipidemic women than in controls (P &lt;0.01). The LDL-cholesterol/apoB ratio was lower in type 2 diabetic women than in type 2 diabetic men (P &lt;0.05). The MDA/LDL-cholesterol ratio was negatively correlated with the LDL-cholesterol/apoB ratio (r = −0.78, P &lt;0.001) in hyperlipidemic type 1 (not type 2) diabetic patients. In normolipidemic type 2 diabetic patients, the MDA/LDL-cholesterol ratio was also negatively correlated with the LDL-cholesterol/apoB ratio (r = −0.75, P &lt;0.001) because of the highly significant negative correlation in type 2 diabetic women (r = −0.89, P &lt;0.01).Conclusions: LDL from well-controlled type 2 diabetic women is smaller and more prone to form peroxides. This could explain why diabetic women are at greater risk of cardiovascular disease.
Measurement of Urea in Human Serum by Isotope Dilution Mass Spectrometry: A Reference Procedure
Authors: Kessler Anja , Siekmann Lothar 
Published: January 2020

Abstract
Background: A reference measurement procedure is needed to demonstrate the traceability of results of urea measurements in human serum. We developed a measurement procedure using the principle of isotope dilution gas chromatography/mass spectrometry.
Methods: [13C,15N2]Urea as internal standard was added to a serum sample and equilibrated with endogenous nonlabeled urea. For the preparation of calibrators, the same amount of labeled urea was mixed with known amounts of nonlabeled urea. The serum samples were treated with ethanol to remove proteins by precipitation. The labeled and nonlabeled urea of the samples was converted into a trimethylsilyl derivative of 2-hydroxypyrimidine. The gas chromatography/mass spectrometry system was adjusted to monitor m/z 153 and 168 for the nonlabeled urea derivative and m/z 156 and 171 for the isotopically labeled analogs. The results of the determination were calculated from peak ratios by a hyperbolic calculation function based on the theory of isotope dilution analysis.
Results: The procedure was applied to control samples and patient samples and evaluated with respect to its trueness and precision. The standard uncertainty of the results was 0.47–1.72%.
Conclusions:This reference measurement procedure allows values to be assigned to controls and calibrators that are traceable to the primary urea reference material of NIST and, therefore, to the Système International unit “mole” with a low degree of uncertainty. This procedure provides a tool for the highly accurate determination of urea in control materials as well as in patient sera.
Standardized Comparison of Processing Capacity and Efficiency of Five New-Generation Immunoassay Analyzers
Authors: Hendriks Henriëtte Alice , Kortlandt Wouter , Verweij Willem Marius 
Published: January 2020

AbstractBackground: With the trend toward laboratory and workstation consolidation, more studies are necessary to evaluate instrumentation, solutions for coping with workflow and test diversity, and opportunities for increasing the overall efficiency of laboratory testing. We assessed the processing capacity and efficiency of new-generation immunoassay analyzers by determining productivity parameters of five commercially available systems.Methods: A workload protocol was developed and used to assess processing capacity and efficiency parameters of five immunoassay analyzers under standardized conditions in a real-life routine situation. We studied the ACS:Centaur® (analyzer A), ArchitectTMi2000 (analyzer B), Elecsys® 2010 tandem (analyzer C), Immulite® 2000 (analyzer D), and Vitros ECi (analyzer E) on the basis of a standardized workload protocol that reflected a routine laboratory situation. This workload encompassed reflex and STAT testing, dilutions, and in-run calibration of a new reagent lot number. The analyzers were compared for hands-on labor time, unattended time (UT), throughput, and differentiated relative productivity indexes [RPI(UT); number of reportable results/(processing time − sum of unattended time)]. The RPI data for analyzers linked to an automated (aut) sample-handling system [RPI(aut)] were also calculated.Results: The evaluation produced a set of parameters for the productivity of the instruments. An overview of the most important parameters revealed the following: the throughput was 193, 123, 97, 109, and 46 tests/hour for instruments A, B, C, D and E, respectively; the RPI(10) was 425, 238, 161, 445, and 151 tests/operator-hour; the RPI(30) was 229, 136, 118, 264, and 86 tests/operator-hour; the RPI(10,aut) was 1701, 637, 235, 964, and 223 tests/operator-hour; and the RPI(30,aut) was 298, 150, 174, 400, and 114 tests/operator-hour.Conclusions: The combination of a standardized workload protocol and determination of parameters for productivity and labor efficiency, especially the differentiated RPIs, made it possible to make an objective comparison of the organizational consequences of the use of these instruments. The described parameters allow for a scientifically based choice, given a certain workflow and a particular laboratory organization.