bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sandwich-type enzyme immunoassay for big endothelin-1 in plasma: concentrations in healthy human subjects unaffected by sex or posture
Authors: Aubin Philippe , Le Brun Gaelle , Moldovan Florina , Villette Jean-Marie , Créminon Christophe , Dumas Jacques , Homyrda Laurence , Soliman Hany , Azizi Michel , Fiet Jean 
Published: January 2020

Abstract
A sandwich-type enzyme immunoassay has been developed for measuring human big endothelin-1 (big ET-1) in human plasma and supernatant fluids from human cell cultures. Big ET-1 is the precursor of endothelin 1 (ET-1), the most potent vasoconstrictor known. A rabbit antibody raised against the big ET-1 COOH-terminus fragment was used as an immobilized antibody (anti-P16). The Fab′ fragment of a monoclonal antibody (1B3) raised against the ET-1 loop fragment was used as the enzyme-labeled antibody, after being coupled to acetylcholinesterase. The lowest detectable value in the assay was 1.2 pg/mL (0.12 pg/well). The assay was highly specific for big ET-1, demonstrating no cross-reactivity with ET-1, &lt;0.4% cross-reactivity with big endothelin-2 (big ET-2), and &lt;0.1% with big endothelin-3 (big ET-3). We used this assay to evaluate the effect of two different postural positions (supine and standing) on plasma big ET-1 concentrations in 11 male and 11 female healthy subjects. Data analysis revealed that neither sex nor body position influenced plasma big ET-1 concentrations. This assay should thus permit the detection of possible variations in plasma concentrations of big ET-1 in certain pathologies and, in association with ET-1 assay, make possible in vitro study of endothelin-converting enzyme activity in cell models. Such studies could clarify the physiological and clinical roles of this family of peptides.
Quantitative polymerase chain reaction for human herpesvirus diagnosis and measurement of Epstein–Barr virus burden in posttransplant lymphoproliferative disorder
Authors: Bai Xin , Hosler Gregory , Rogers Beverly Barton , Dawson D Brian , Scheuermann Richard H 
Published: January 2020

Abstract
Human herpesviruses can cause acute diseases such as chicken pox or mononucleosis, but also may reactivate during immunosuppression and result in severe or life-threatening illnesses such as shingles or lymphoproliferative disorders. We report the development and validation of a quantitative PCR method to measure viral burden for all eight human herpesviruses (HSV1, HSV2, VZV, EBV, CMV, HHV6, HHV7, and KSHV) in patients’ samples. The method uses an internal standard that is coamplified with the viral target, allowing quantification of viral genomes in absolute terms (e.g., viral targets/mL of blood) and ruling out false-negative results. We demonstrate that transplant patients with lymphoproliferative disorder carry an EBV viral burden 3 logs higher than nontransplant patients. EBV titers in transplant patients without a lymphoproliferative disorder are between these values. This quantitative PCR method may aid in differentiating clinically significant vs latent viral burden in immunosuppressed patients.
ELISA determination of soluble urokinase receptor in blood from healthy donors and cancer patients
Authors: Stephens Ross W , Pedersen Anders N , Nielsen Hans Jørgen , Hamers Maria J A G , Høyer-Hansen Gunilla , Rønne Ebbe , Dybkjær Esben , Danø Keld , Brünner Nils 
Published: January 2020

AbstractMeasurement of urokinase receptor (uPAR) in tumor extracts has prognostic value, but assay of the soluble uPAR (suPAR) in peripheral blood may offer wider applications in cancer patient management. A tumor extract uPAR ELISA was modified to eliminate nonspecific plasma protein interference, enabling specific detection of suPAR in plasma and sera with &gt;90% recovery of added calibrator. suPAR concentrations in citrate plasma correlated with sera in 93 healthy blood donors (r = 0.84, P &lt;0.0001), with a median value for both of 1.2 μg/L. The plasma median for 19 advanced breast cancer patients was 2.9 μg/L suPAR, and a similar increase was found for 10 advanced colon cancer patients, consistent with release of suPAR from tumors into blood. Repetitive monitoring of suPAR in cancer patients’ blood may have value in assessment of prognosis and tumor recurrence.
Early assessment of patients with suspected acute myocardial infarction by biochemical monitoring and neural network analysis
Authors: Ellenius Johan , Groth Torgny , Lindahl Bertil , Wallentin Lars 
Published: January 2020

AbstractNeural network analysis was applied for early diagnosis/exclusion of acute myocardial infarction (AMI), prediction of infarct size, and estimation of “time from onset of infarction.” Eighty-eight patients admitted within 8 h after onset of chest pain were included. Blood samples for measurement of myoglobin, creatine kinase isoform MB, and troponin T were obtained every 30 min during the first 3 h and then after successively longer intervals. Data from 50 patients were used to train a set of neural network components of a decision support system. The performance of the system was evaluated and compared with experienced clinicians for the remaining 38 patients. The computer system detected myocardial infarction and predicted infarct size earlier than the clinicians, but did not differ significantly in terms of diagnostic sensitivity, specificity, and predictive values when disregarding time for diagnosis. With a cross-validation procedure the cumulated sensitivities of the computer system for the first five measurements were estimated to be (mean ± 2SEM, n = 100): 0.77 ± 0.03, 0.89 ± 0.02, 0.94 ± 0.02, 0.97 ± 0.01, and 0.99 ± 0.01, respectively, with corresponding cumulated specificities between 0.93 ± 0.01 and 0.91 ± 0.01. We concluded that neural network analysis of serial measurements of biochemical markers might provide useful support for the early assessment of patients with suspected AMI.
Kinetic assay of serum and urine for urea with use of urease and leucine dehydrogenase
Authors: Morishita Yoshitaka , Nakane Kiyoshi , Fukatsu Toshiaki , Nakashima Nobuo , Tsuji Katsumi , Soya Yoshihiro , Yoneda Keizo , Asano Shigeki , Kawamura Yoshihisa 
Published: January 2020

Abstract
We describe a new kinetic assay for determining urea in serum or urine with use of urease (EC 3.5.1.5) and leucine dehydrogenase (EC 1.4.1.9). The latter enzyme is suitable for the kinetic assay of NH4+ because itsKmvalue for NH4+ at pH 8.75 is large (∼500 mmol/L). Interference from endogenous NH4+ in serum or urine is obviated by subtraction of the assayed endogenous NH4+value in a sample blank. For serum, within-assay CVs (n = 10) were 0.39–0.58%; day-to-day CVs (n = 10) were 1.56–2.30%. In urine, within-assay CVs (n = 10) were 0.86–1.15%. Analytical recovery of urea (0.893–71.4 mmol/L) added to patients’ sera (urea 6.14 mmol/L) was 99.2–105.2%. The calibration curve for serum was linear through zero for urea concentrations up to 142.9 mmol/L and for urine up to 714.3 mmol/L. No influences of added ammonium ion, bilirubin, hemoglobin, ascorbic acid, or Intralipid were observed. The regression equations for this method (y) and conventional methods (x = Determiner-LUN for serum assays, Serotec UUR-R for urine) were: y = 1.016x − 0.12 mmol/L (r = 0.999, Sy|x = 0.34 mmol/L, n = 100) for sera, and y = 1.070x − 12.6 mmol/L (r = 0.998, Sy|x = 7.41 mmol/L, n = 100) for urine.
HLA-B27 phenotyping with flow cytometry: further improvement by multiple monoclonal antibodies
Authors: Hoffmann Johannes J M L , Janssen Willy C M 
Published: January 2020

Abstract
To establish the optimal flow cytometric method for HLA-B27 phenotyping, we compared several strategies, using three monoclonal anti-B27 antibodies (from the HLA-ABC-m3, GS145.2, and FD705 clones). We used a triple-color direct immunofluorescence assay, including a T-lymphocyte-specific antibody as an internal control and an anti-HLA-Bw4 antibody. Blood samples from &gt;400 subjects were tested. From ROC curve analysis none of the three antibodies appeared to be suitable for use as a single typing reagent. The efficiency of the test was affected by cross-reactions with other HLA antigens, notably the HLA-B7 antigen. Preincubation with anti-B7 serum efficiently inhibited this cross-reaction and raised the test efficiency considerably. We concluded that none of the anti-B27 antibodies investigated is suitable for use as a single typing reagent. Additional typing of Bw4 is not valuable, whereas inhibition of cross-reactions due to the B7 antigen will considerably improve the performance of the test. We recommend that two different monoclonal anti-B27 antibodies be used for accurate and reliable HLA-B27 phenotyping with flow cytometry.
Minimizing interferences in the quantitative multielement analysis of trace elements in biological fluids by inductively coupled plasma mass spectrometry
Authors: Hsiung Chiung-Sheng , Andrade Joseph D , Costa Robert , Ash K Owen 
Published: January 2020

AbstractThe determination of trace and ultratrace elements in biological fluids, including urine and serum, by inductively coupled plasma mass spectrometry (ICP-MS) is discussed. Nonspectral interferences and their corrections by external calibration and calibrator addition are discussed in detail. External calibration with internal calibration and dilution is mostly sufficient to correct for encountered biological matrix effects. For some elements, such as Cs and Zn, the use of calibrator addition provides more accurate results. The importance of spectral interferences and their elimination by isotope selection was also studied. Two examples, Cu and Zn, demonstrate the prime importance of selecting an isotope with minimal polyatomic interferences for analysis. By using 65Cu and 68Zn, accurate results for urine and serum can be obtained without excessive pretreatment of samples. Two reference materials, Bio-Rad Lyphochek urine and Kaulson Contox sera, were analyzed. Accuracy was evaluated by comparison with target values, and precision was estimated by the CV within 95% confidence.
7α-Biotinylated testosterone derivatives as tracers for a competitive chemiluminescence immunoassay of testosterone in serum
Authors: Luppa Peter , Brückner Christine , Schwab Ingrid , Hauck Sabine , Schmidmayr Stefan , Birkmayer Christian , Paulus Birgit , Hauptmann Hagen 
Published: January 2020

Abstract
Ring core-biotinylated testosterone tracers were synthesized with bridges of three different lengths connecting the biotin moiety to the steroid core (7α-Cn-Bio-T, n = 3, 6, or 11). Together with a position 7-specific polyclonal anti-testosterone antibody, we used the 7α-C11-Bio-T tracer to develop a novel, labeled-hapten competitive immunoassay for total testosterone in serum. (The C3 and C6 tracers proved to be not suitable for analogous immunoassays.) Enhanced chemiluminescence signal was generated by use of a second immobilized antibody and a streptavidin–horseradish peroxidase conjugate. The measuring range of the assay is 0.2–20.0 nmol/L, linearity of serial dilutions can be demonstrated, the lower detection limit is 0.125 nmol/L, and the interassay imprecisions are 13–16%. Accuracy determinations in mass spectrometry-controlled reference specimens showed a mean recovery of 95%. In addition, the assay shows low cross-reactivities, demonstrating the favorable specificity of the combination of a “nearly native” tracer with a position analog antibody. The optimized steric structure and the long spacer arm of the biotinylated testosterone tracer make this chemiluminescence assay well-suited for measuring total testosterone concentration in serum.
Age-specific distribution of plasma amino acid concentrations in a healthy pediatric population
Authors: Lepage Nathalie , McDonald Nancy , Dallaire Louis , Lambert Marie 
Published: January 2020

AbstractReference values were determined for 23 plasma free amino acids from measurements done in 148 healthy children ranging from 0 to 18 years of age. Amino acid analysis was performed by ion-exchange chromatography. We propose a graphic form of presenting the age-specific distribution of plasma amino acid concentrations where the 10th, 50th, and 90th quantiles are illustrated. Although each amino acid possesses its own pattern of distribution, we can identify five different profiles. Nine amino acids (alanine, arginine, asparagine, methionine, ornithine, phenylalanine, proline, threonine, and tyrosine) demonstrate a decrease in their concentrations during the first year of life; their concentrations then tend to increase throughout childhood and adolescence. Nine others (cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, tryptophan, and valine) show a steady increase throughout infancy, childhood, and adolescence. Five amino acids (aspartic acid, citrulline, glutamic acid, serine, and taurine) do not follow these two common profiles. For the first time, quantile curves are produced to illustrate the age-dependent variation of amino acid concentrations from infancy to adulthood. This alternative way of presenting amino acid concentrations may facilitate the follow-up of patients with inborn errors of amino acid metabolism.
Human prostate-specific glandular kallikrein is expressed as an active and an inactive protein
Authors: Herrala Annakaisa , Kurkela Riitta , Porvari Katja , Isomäki Ritva , Henttu Pirkko , Vihko Pirkko 
Published: January 2020

AbstractA polymorphism in the human prostate-specific glandular kallikrein (hKLK2) gene was described by direct sequencing (by PCR) of genomic DNAs isolated from prostatic cancer tissue, benign prostatic hyperplasia tissue, and blood leukocyte specimens. Results showed two forms of human prostate-specific glandular kallikrein protein (hK2), a consequence of a change from C to T at base 792 in the hK2 coding region. Producing the two forms as recombinant proteins in insect cells demonstrated that Arg226-hK2 (CC genotype) is an active protein and Trp226-hK2 (TT genotype) is inactive. Polymorphism studies of 36 patients with prostatic diseases identified only 1 with the TT genotype. The same kind of polymorphism was not detected in the human prostate-specific antigen (hKLK3) gene. Arg226-hK2 possessed only trypsin-like enzyme activity, whereas recombinant human prostate-specific antigen (hPSA) had only chymotrypsin-like activity. Monoclonal and polyclonal antibodies raised against hPSA purified from seminal plasma detected both active and inactive hK2. Thus, because inactive as well as stable hK2 protein may be present, a lack of trypsin-like activity in hPSA standards is not enough to confirm that the materials are free of hK2 contamination.
Clinical evaluation of serial blood processing at point of care
Authors: Estey Christopher A , Felder Robin A 
Published: January 2020

Abstract
The Axial Separation Module (ASM™), which separates whole-blood specimens serially in Axial Process Containers (APC™), was evaluated for clinical performance at the University of Virginia Health Sciences Center (UVA HSC) in a community-based outpatient laboratory (North Ridge Clinic). We hypothesized that moving the task of blood separation to point of care would reduce specimen turnaround time within the main laboratory. Blood drawn into an APC was separated in the ASM at point of care at the North Ridge Clinic. Blood drawn into a Vacutainer Tube™was separated in a conventional centrifuge at the main laboratory. Turnaround time was calculated for the “chem 17” test from files stored in our laboratory information system. Blood serially separated at point of care yielded turnaround time savings for specimens originating from the North Ridge Clinic. Average turnaround time decreased by 24%. Phlebotomists found no appreciable workload increase from incorporating the ASM as a point-of-care blood separation device. Phlebotomists also found that they could immediately detect hemolysis. We concluded that serial separation at point of care reduces specimen turnaround time at the main laboratory. The ASM/APC was found to be better suited for point-of-care blood separation than a conventional centrifuge. We speculate that immediate blood separation has the potential to improve the quality of analytical results.
HPLC method for monitoring SDZ PSC 833 in whole blood
Authors: Scott Mitchell G , Hock Karl G , Crimmins Daniel L , Fracasso Paula M 
Published: January 2020

Abstract
P-glycoprotein (Pgp) is a 170-kDa membrane transporter that mediates drug efflux and is an effector of multidrug resistance. SDZ PSC 833 (PSC), a nonimmunosuppressive cyclosporine that potently modulates Pgp, is currently under clinical evaluation in patients with cancer. We have developed a reversed-phase HPLC assay for determining PSC blood concentrations that utilizes a step gradient with linear segments to resolve PSC into two distinct peaks (likely to be keto and enol isomers). To clinically validate the assay, PSC concentrations were obtained by HPLC from nine patients receiving oral doses of 5 mg/kg every 6 h. Values ranged from 0.91 to 5.4 mg/L during the dosing period, comparable with concentrations of PSC that modulate Pgp in vitro. In addition, we investigated the immunoreactivity of the Abbott TDx cyclosporin A (CsA) monoclonal whole-blood assay for PSC. The TDx CsA assay cross-reacts ∼17% with PSC as determined by adding known amounts of PSC to whole blood. When PSC concentrations obtained by the TDx CsA assay were divided by 0.17, we found agreement between the TDx CsA assay and the HPLC PSC assay for samples from nine patients.
Comparative evaluation of three assay systems for automated determination of hemoglobin A1c
Authors: Halwachs-Baumann Gabriele , Katzensteiner Susanne , Schnedl Wolfgang , Pürstner Peter , Pieber Thomas , Wilders-Truschnig Martie 
Published: January 2020

Abstract
We evaluated three newly introduced systems for automated determinations of hemoglobin (Hb) A1c, which allow the processing of large amounts of samples in a routine clinical laboratory. We compared these methods—the Variant HPLC, the Hi-Auto A1c analyzer system, and the Roche immunoassay—with the Diamat HPLC system. All showed good precision and good concordance with the Diamat HPLC. The reference range for Hb A1c has to be determined by the laboratory for each assay system. Interference study showed no statistically significant influence of anemia, polycythemia, rheumatoid factor, or chronic hemodialysis, although individual Hb A1c values can be influenced by polycythemia (when measured with the Hi-Auto A1c analyzer) and by chronic hemodialysis (when measured with the Variant HPLC). HPLC was not suitable for measuring Hb A1c in the examined cases of hemoglobin variants; assaying fructosamine seems to be better for monitoring these patients.
Analysis of a polyadenine tract of the transforming growth factor-β type II receptor gene in colorectal cancers by non-gel-sieving capillary electrophoresis
Authors: Oto Michiei , Koguchi Akira , Yuasa Yasuhito 
Published: January 2020

Abstract
We developed a method to analyze a polyadenine tract, the (A)10 repeat, within the cysteine-rich domain of the transforming growth factor-β (TGF-β) type II receptor gene using a non-gel-sieving capillary electrophoresis technique and applied it to the DNA diagnosis of colorectal cancers. This method consists of single-strand DNA amplification of the (A)10 repeat by an asymmetric PCR technique and capillary electrophoresis. A higher concentration of dATP in the PCR reaction mixture led to more specific amplification of the (A)10 repeat. Under the optimal electrophoretic conditions, one nucleotide difference could be determined in 8 to 32 nucleotides. One or two base deletions of the (A)10 repeat in colorectal cancers could be detected under these conditions within 30 min, and the results coincided with those obtained on DNA sequencing analyses. According to a sensitivity study, we could detect the deleted sequence if it was present in 12.5% or more of the wild-type allele. The reproducibility of this technique was satisfactory because the intraassay imprecision (CV) (n = 10) was 1.4%. These results indicate that capillary electrophoretic analysis of small repeated sequences results in easier handling and more feasible automation, compared with conventional gel electrophoretic analysis.
How many mistakes, how to find them
Authors: Blase Amy B 
Published: January 2020

Abstract
The topic of quality control often evokes prolific discussion among those whose business is its administration. Reliable methods for identifying mistakes must be developed in both the manufacture and use of test devices. Unit test devices are uncomplicated to run and provide quick results in a world where speed and simplicity are paramount, yet their very nature as individual assay units introduces questions about the relevance of conventional quality control procedures. Hybritech’s ICON® QSR® CKMB assay is a unit test device that requires daily monitoring according to CLIA’88 regulations. The challenge is to ensure that quality- control testing is value-added, assuring clinicians valid patient sample results although controls are run in a separate “assay.” We find that conventional quality- control procedures are indeed valid; however, the fundamental difference of unit test devices must be recognized and accounted for by understanding the capability of the assay in each laboratory.
Assessment of a portable clinical blood analyzer during space flight
Authors: Smith Scott M , Davis-Street Janis E , Fontenot Tina B , Lane Helen W 
Published: January 2020

Abstract
This study was designed to validate the utility of a commercial portable clinical blood analyzer (PCBA) in ground-based studies and on the space shuttle. Ionized calcium, pH, electrolytes, glucose, and hematocrit were determined. Results agreed well with those from traditional laboratory methods, and the PCBA demonstrated good between-day precision for all analytes. In-flight analysis of control samples revealed differences in one analyte (sodium). There were few changes in crew members’ results during flight, and these were expected. Potassium increased in flight compared with before flight, and potassium, pH, and hematocrit decreased after flight. Ionized calcium was decreased in flight and on landing day. Changes during flight were likely related to sample collection technique. Postflight changes likely reflected the fluid redistribution that occurs after exposure to weightlessness. These data confirm that the PCBA is a reliable instrument for most analytes, and can provide important medical data in remote locations, such as orbiting spacecraft.
Diagnostic strategies and test algorithms in liver disease
Authors: Black Edgar R 
Published: January 2020

Abstract
As clinicians evaluate patients, they first develop problem lists based on the history, physical examination, and basic laboratory studies. Synthesis and analysis result in a differential diagnosis with associated disease probabilities. Experienced clinicians then selectively use diagnostic tests to rule in or rule out these possibilities. For example, in a patient presenting with jaundice, anorexia, fever, and abdominal pain, the relative increases of the serum aminotransferase activity and the serum alkaline phosphatase will help to guide the subsequent evaluation. If the aminotransferase activity is markedly increased, then the subsequent evaluation will be targeted toward identifying an etiology for hepatocellular injury. In contrast, if the alkaline phosphatase is markedly increased, then the evaluation would be targeted toward identifying an etiology for obstructive jaundice. This paper reviews clinical decision making, discusses characteristics of diagnostic tests, and presents examples of how basic clinical information can guide the use of the laboratory in evaluating patients with suspected liver disease.