bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioimmunoassay for amatoxins by use of a rapid, 125I-tracer-based system.
Authors: Andres R Y , Frei W , Gautschi K , Vonderschmitt D J 
Published: January 2020

Abstract
In this new radioimmunoassay system for determination of amatoxins in urine and plasma, a novel chemical approach is used for antigen and 125I-tracer production, based on a detoxified alpha-amanitin derivative (aldoamanitin). Total assay time, including data processing, is less than 100 min. The lowest detectable concentration is 1 microgram/L for urine, 0.1 microgram/L for plasma. In the clinically significant range, within-run CVs are less than 8%. This new 125I-based assay is a significant improvement over existing 3H technology in terms of speed, precision, and freedom from interference.
Rate of synthesis of IgG within the blood-brain barrier and the IgG index compared in the diagnosis of multiple sclerosis.
Authors: Hische E A , van der Helm H J 
Published: January 2020

Abstract
Receiver-operating characteristic curves of the IgG synthesis rate and the IgG index show that the IgG index has better discriminating properties with respect to multiple sclerosis. This, added to the fact that the precision of determining the index is much higher than that of the synthesis rate, makes the IgG index the parameter of choice in the diagnosis of multiple sclerosis.
Criteria for evaluating nonquantitative assays: application to serum choriogonadotropin.
Authors: Delfert D M , Rea M R , Kessler G , Siegfried B A , Valdes R 
Published: January 2020

Abstract
We present guidelines for assessing the performance of nonquantitative (qualitative) assay methods. Criteria to be evaluated include analytical sensitivity, imprecision near limits of detection, analytical specificity, accuracy over a wide range of analyte concentrations, potential interferents, and technical ease of performance. A protocol was developed to evaluate several nonquantitative assay kits for detection of human choriogonadotropin (hCG) in serum. These include Tandem Icon HCG (Hybritech), Quest Pregnancy Test (Quidel), Concep-7 beta hCG (Leeco), and Beta Quik V (Pacific Biotech). Quantitative measurement of beta-hCG by RIA (Immophase beta hCG, Corning Medical) was used as the reference method. Results of this evaluation are discussed. The guidelines established and utilized in this report are adaptable to the evaluation of assay kits that measure other analytes by qualitative techniques.
Electrochemical determination of hemoglobin, hematocrit, and hemolysis.
Authors: Kobos R K , Abbott S D , Levin H W , Kilkson H , Peterson D R , Dickinson J W 
Published: January 2020

Abstract
Novel electrochemical methods have been developed for determination of total hemoglobin, hematocrit, and detection of hemolysis in whole blood. Hemoglobin is measured through its peroxidase activity, a fluoride ion-selective electrode being used to monitor the rate of fluoride ion production from the oxidation of an organofluorine compound. Results agree well with those obtained with the cyanmethemoglobin method (r = 0.970). Hematocrit is determined from the ratio of the sodium ion concentrations measured with an ion-selective electrode before and after lysis of the erythrocytes. Results by this and the microhematocrit method correlated well (r = 0.987). Hemolysis in a whole-blood sample is detected by using an oxygen electrode to measure the oxygen released when hemoglobin in plasma is oxidized.
Enzyme immunoassay of free triiodothyronine in serum.
Authors: Hata N , Miyai K , Endo Y , Iijima Y , Doi Y , Amino N , Ichihara K 
Published: January 2020

Abstract
In this new solid-phase antibody enzyme immunoassay for free triiodothyronine (FT3) in serum, beta-D-galactosidase conjugated to triiodothyronine is used. Results are uninfluenced by physiological concentrations of thyroxin-binding globulin or albumin. Results correlate well with those determined by equilibrium dialysis (r = 0.95). The mean CVs within and between assays were 6.1 and 9.5%, respectively. The measurable range of FT3 in serum is 0.7 to 26 ng/L; the normal reference interval is 1.9 to 8.9 ng/L. Concentrations of FT3 in serum of patients with hyperthyroidism were high; those of patients with hypothyroidism were within normal limits or low, and those of patients with congenitally decreased or increased TBG were within the normal range. In normal pregnant women, concentrations of FT3 as determined by radioimmunoassay correlated with those of albumin, declining as pregnancy progressed, but FT3 values determined by the proposed method or equilibrium dialysis were within the normal range and did not change during pregnancy.
Improved 63Ni radiochemical assay of free fatty acids in plasma.
Authors: Barash H , Akov S 
Published: January 2020

Abstract
We have modified the 63Ni radiochemical method of Ho (Anal Biochem 1970;36:105) for determination of free fatty acids (FFA) in plasma. Extracting 1 or 0.1 mL of plasma with Dole's mixture (J Biol Chem 1960;235:2595) and washing the "heptane" layer with two volumes of isopropanol/water/dilute (0.5 mol/L) H2SO4 (25/25/1, by vol) removes about 90% of the lipid phosphorus from the "heptane" layer without removing any FFA and is more convenient than treatment with silicic acid. The following modifications decrease background radioactivity and improve separation of the organic phase from the water phase containing the uncomplexed 63Ni: (a) use glassware instead of plastic test tubes; (b) evaporate the organic phase to dryness before adding the 63Ni (this removes the isopropanol, which interferes with the 63Ni assay); and (c) add anhydrous sodium sulfate before the final centrifugation step.
Potential of monoclonal antibodies to improve therapeutic monitoring of cyclosporine.
Authors: Quesniaux V , Tees R , Schreier M H , Maurer G , van Regenmortel M H 
Published: January 2020

Abstract
We show that monitoring of cyclosporine by immunoassay could be improved by using monoclonal antibodies (MAbs) of restricted specificity instead of polyclonal antisera that recognize both unmodified cyclosporine and its metabolites. MAbs with high affinity for cyclosporine have been prepared and characterized. We tested their ability to discriminate between native cyclosporine and its metabolites in indirect solid-phase enzyme immunoassay with a set of cyclosporine metabolites modified at residues 1, 4, 6, and 9 (corresponding to the six known sites of metabolism of cyclosporine). All the metabolites tested were detected by MAb1 at least 15- to 1000-fold less well than unmodified cyclosporine. A second MAb recognized unmodified cyclosporine and most of its metabolites equally well. Both MAbs retained their activity when coupled to alkaline phosphatase and could therefore be used in a direct solid-phase enzyme immunoassay.
Europium and samarium as labels in time-resolved immunofluorometric assay of follitropin.
Authors: Bador R , Déchaud H , Claustrat F , Desuzinges C 
Published: January 2020

Abstract
This time-resolved immunofluorometric assay for human follitropin involves use of europium- or samarium-labeled monoclonal antibodies, with an average incorporation ratio of 3 mol of Eu3+ or Sm3+ per mole of antibody. These lanthanide ions are bound to the antibody molecules by means of the anhydride of diethylenetriaminepentaacetic acid. The solid-phase antibody is immobilized inside polystyrene tubes in which plasma samples were assayed in a one-step procedure. After incubation, the fluorescence intensity of Eu3+ or Sm3+ label is measured by time-resolved fluorometry, with a nitrogen laser as the pulsed excitation source. The sensitivity of the assay is largely better with Eu3+ than with Sm3+ because of the difference in their intrinsic luminescence properties. Results obtained with the proposed methods correlated well with those by an immunoradiometric method.
The clinical usefulness of glycated hemoglobin in monitoring diabetes mellitus: a long-term study.
Authors: Lenzi S , Giampietro O , Giovannitti G , Sampietro T , Miccoli R , Navalesi R 
Published: January 2020

Abstract
To assess the long-term clinical usefulness of measuring glycated hemoglobin (Hb A1), we carried out a two-year longitudinal study involving 234 diabetic patients (116 males, 118 females; 139 with type I diabetes mellitus, 95 with type II). Hb A1 values correlated significantly (p less than 0.001) with a score index based on plasma glucose in a specimen collected after overnight fasting, and urinary glucose, and ketones in a 24-h specimen. However, we found that one of every three well-controlled patients (both type I and II subjects) had high values for Hb A1. Among poorly controlled patients, only those with "brittle" diabetes had good values for Hb A1.
Free and total insulin as determined after precipitation with polyethylene glycol: analytical characteristics and effects of sample handling and storage.
Authors: Arnqvist H , Olsson P O , von Schenck H 
Published: January 2020

Abstract
We evaluated results of radioimmunoassays of free and total insulin after precipitation of endogenous antibodies with polyethylene glycol (PEG), and we investigated the influence of collection time, temperature, and storage in heparin- cr EDTA-treated plasma or serum on results for free insulin. Analytical recovery of free insulin was 99.3%, of total insulin 96.4%. For free insulin, assay precision (CV) was 4.0-13.0% (intra-assay) and 7.8-10.7% (inter-assay); for total insulin, 3.6-9.5% and 6.6-11.7%, respectively. Free insulin decreased in plasma (p less than 0.05) and serum (p less than 0.01) at room temperature after 3 h and in promptly analyzed serum (p less than 0.01). Storage of samples at -20 degrees C increased the concentration of free insulin in plasma (p less than 0.025) and serum (p less than 0.005), whereas the free insulin content of supernates after PEG precipitation was stable, except for a slight decrease in serum samples (p less than 0.02). We conclude that, for radioimmunoassay of free and total insulin, plasma should be used, treated with PEG without delay; supernates then are analytically stable for as long as 26 weeks at -20 degrees C.
Human IgG subclass measurements in the clinical laboratory.
Authors: Hamilton R G 
Published: January 2020

Abstract
Complement activation, cell surface-receptor binding, blocking activity, and possibly placental transfer are among the biologically important functional differences that have been detected between the four human IgG subclasses by use of polyclonal antisera. In 1985, a IUIS/WHO panel of immunologists, using eight immunological methods, documented the specificity of select monoclonal antibodies for the IgG subclasses. Clinical assays have been developed involving these monoclonal antibodies that allow quantification of the concentration of IgG subclass protein and distribution of the IgG subclass antibodies in human immune responses. This review addresses issues of concern to investigators who are evaluating and (or) developing quantitative human IgG subclass assays in the clinical laboratory. Unique physical (structural) and biological (functional) properties of human IgG subclasses are summarized, with a focus on aspects pertinent to their clinical importance and in vitro quantification. The HP-series monoclonal antibodies with documented specificity are examined within the context of their application to several immunological methods. I describe unique technical aspects of total and antigen-specific IgG-subclass immunoassays involving these monoclonal antibodies. Finally, this report outlines clinical applications and indications for IgG-subclass measurements in the study of human health and disease.
Use of restriction fragment length polymorphism analysis for detecting carriers of "fragile X" syndrome.
Authors: Thibodeau S N 
Published: January 2020

Abstract
Recombinant DNA technology promises to play an increasingly important role in the future of medicine. Application of this technology to the study of human disease will help us to define and clarify the molecular pathology of many clinical disorders, provide new diagnostic tools and approaches, and, finally, will provide new therapeutic agents including gene-replacement therapy. We have begun to exploit these powerful new techniques to aid in the laboratory diagnosis of several genetic disorders for which reliable assays are currently not available, such as "Fragile X" syndrome.
Determination of conjugated and total bilirubin in serum of neonates, with use of bilirubin oxidase.
Authors: Mullon C J , Langer R 
Published: January 2020

Abstract
A new, simple, and rapid assay for conjugated bilirubin that does not require serum-matrix standards was developed by using the enzyme bilirubin oxidase (EC 1.3.3.5). This procedure can also be modified to measure total bilirubin. Measurements from these assays were compared with results obtained with the Sigma 605 (Jendrassik-Gróf method), Sigma 550/551 (Walters-Gerarde method), and Kodak Ektachem (BuBc) bilirubin assays. The one-year study involved serum specimens from 283 infants younger than 30 days. Linear-regression analysis of data for conjugated bilirubin collected by this assay and by the Kodak Ektachem assay yielded a slope of 0.975, an intercept of 0.088, an Syx of 1.47 mg/L, and a correlation coefficient of 0.94 for a total of 49 specimens. Correlation was also good (r = 0.95) between results for total bilirubin by this assay and both the Sigma 605 and the Kodak Ektachem methods.
Ascorbic and dehydroascorbic acids simultaneously quantified in biological fluids by liquid chromatography with fluorescence detection, and comparison with a colorimetric assay.
Authors: Lopez-Anaya A , Mayersohn M 
Published: January 2020

Abstract
We describe a "high-performance" liquid-chromatographic method for separating and quantifying ascorbic acid (AA) and dehydroascorbic acid (DHA) in plasma and urine. We used a reversed-phase C18 column with an ion-pair reagent and detected the analytes by post-column reaction with 4,5-dimethyl-o-phenylenediamine to form a fluorescent derivative (measured at excitation and emission wavelengths of 365 and 440 nm, respectively). Isoascorbic acid (IA) is the internal standard. Retention times for DHA, AA, and IA are 5.6, 15.5, and 19.9 min, respectively. Between-day CVs for AA in plasma in concentrations of 8 and 20 mg/L were 9% and 7%, respectively. The limit of detection is 10 and 4 ng for AA and DHA, respectively. Results by the present method and the methoxyaniline colorimetric method for AA are comparably accurate.
Simplified sodium dodecyl sulfate-polyacrylamide gel electrophoresis of unconcentrated urine with enhanced resolution and detection sensitivity.
Authors: Marshall T , Williams K M 
Published: January 2020

Abstract
We applied a simple sodium dodecyl sulfate-polyacrylamide gel electrophoresis method to urine. The method, developed for serum protein analysis (Clin Chem 1984;30:475-9), has a high sample throughput and gives excellent resolution with unconcentrated urine. It clearly distinguishes and characterizes proteinuric urine (7.5 microL) by Coomassie Blue staining and gives complex silver-stained patterns with nonproteinuric urine (2 microL). The former is recommended for routine clinical screening, the latter for research purposes.
Glycated proteins in serum: effect of their relative proportions on their alkaline reducing activity in the fructosamine test.
Authors: Zoppi F , Mosca A , Granata S , Montalbetti N 
Published: January 2020

Abstract
The fructosamine test is considered clinically useful for assessing short-term integrated control of blood glucose, but there are few published data to support this hypothesis. We fractionated glycated and nonglycated proteins by affinity chromatography on phenylboronate columns and, with specific immunochemical methods, determined in the eluted fractions the following proteins, selected according to their biological half-lives and relative concentrations in serum: albumin, IgA, IgG, IgM, apolipoprotein B, haptoglobin, transferrin, alpha 1-antitrypsin, and alpha 2-macroglobulin. We found the following correlations between fructosamine (mmol/L) and, respectively, glycated albumin, IgG, and (albumin + IgG) (each in grams per liter): r = 0.901, 0.702, 0.878. IgM had the highest percentage of glycated molecules (range 11.1-37.5%, mean 22.4%), haptoglobin and alpha 1-antitrypsin the least. This result was almost independent of the proteins' molecular masses and fractional catabolic rate. Albumin evidently contributes most to results of the fructosamine test, confirming conclusions obtained in different ways by others.
Prostate-specific antigen as a marker for prostatic cancer: a monoclonal and a polyclonal immunoassay compared.
Authors: Chan D W , Bruzek D J , Oesterling J E , Rock R C , Walsh P C 
Published: January 2020

Abstract
We evaluated the clinical utility of prostate-specific antigen (PSA) in diagnosis and management of prostatic cancer, using a monoclonal immunoradiometric assay (M-PSA) and a polyclonal radioimmunoassay (P-PSA). Assay CVs ranged from 1.3% to 4.9% (M-PSA) and from 5.1% to 8.0% (P-PSA). Detection limits were 0.1 microgram/L (M-PSA) and 0.2 microgram/L (P-PSA). Reference intervals established for healthy men were: 0-2.8 micrograms/L (M-PSA) and 0-4.2 micrograms/L (P-PSA). The regression equation for the PSA concentrations (0-100 micrograms/L) measured in normal men, men with primary prostatic cancer, and men with benign prostatic hypertrophy (BPH) was: P-PSA = 1.603 M-PSA - 0.120 microgram/L (r = 0.9923, n = 201). The P-PSA calibrators yielded one-half their assigned values when analyzed by the M-PSA assay. With either assay there were proportional increases in PSA values with advancing cancer. The proportion of PSA values exceeding the reference interval was 50% for patients with stage A prostatic cancer, 80% (stage B), 100% (stages C and D), and 65% for men with BPH. After radical prostatectomy, the follow-up PSA values for most patients were within the reference intervals for women (0-0.2 microgram/L for M-PSA, 0-0.8 microgram/L for P-PSA). Most patients with above-normal PSA values have clinically detectable disease.
Production and certification of an enzyme reference material for gamma-glutamyltransferase (CRM 319). Part 1: Preparation and characterization.
Authors: Schiele F , Muller J , Colinet E , Siest G 
Published: January 2020

Abstract
We have produced a batch of lyophilized gamma-glutamyltransferase as enzyme reference material. The "light" enzyme form was purified from pig kidney to a relatively high specific activity (120 kU/g) and was essentially free of contaminating enzymes. The partly purified gamma-glutamyltransferase, lyophilized in a matrix containing bovine serum albumin (Fraction V, 60 g/L), yielded a batch of 4000 ampules and was stored at -20 degrees C. The vial-to-vial variability with respect to the catalytic concentration of the final product (CV 0.6%) and its stability (predicted loss of activity at -20 degrees C was less than 0.01% per year) were considered sufficient to allow the use of this preparation for a certification procedure. The behavior of the reference material in comparison with human serum samples was evaluated three ways: (a) by kinetic characteristics, (b) by the ratio of activities for duplicate determinations by different methods, and (c) by use of the reference material to convert values obtained by various methodologies to those by the IFCC proposed method. The material appeared to be commutable for the two methods studied. The difference in the ratios obtained for patients' samples and reference material was less than +/- 5%, and the recalculated values for patients' samples as determined with the reference material differed from values determined by the IFCC method by no more than 4.8%.
Production and certification of an enzyme reference material for gamma-glutamyltransferase (CRM 319). Part 2: Certification campaign.
Authors: Schiele F , Muller J , Colinet E , Siest G 
Published: January 2020

Abstract
We describe the process of certification for a gamma-glutamyltransferase reference material (CRM no. 319). Fifteen laboratories participated to this interlaboratory evaluation. All steps of the measurements were controlled in an effort to locate potential sources of variations. In particular, the exclusion of some data was strictly documented or justified by the non-observance of the IFCC method and (or) discrepancies in instrumentation, reconstitution of the lyophilized samples, or measurement technique. Inaccuracy in the reconstitution of the lyophilized material was +/- 0.68%, and the molar absorptivity of the 5-amino-2-nitrobenzoate reported by each laboratory was within +/- 2% limits of the value reported by the IFCC. Calculated from the sets of accepted results, the total CV among samples was 2.6% and the overall CV was 3.2%. Within-day and between-day CVs were 1.1% and 1.4%, respectively. The greatest variation for a single component was the between-laboratory variability (CV 3.1%); the within-laboratory CV, including the day effect, was 1.8%. Finally, the certified value for the catalytic concentration of this enzyme in the reconstituted lyophilized reference material was 86.8 U/L with an uncertainty of +/- 2.1 U/L (0.95 confidence interval). The uncertainty appeared to be compatible with the end-use of this reference material.
Biotin radioligand assay with an 125I-labeled biotin derivative, avidin, and avidin double-antibody reagents.
Authors: Livaniou E , Evangelatos G P , Ithakissios D S 
Published: January 2020

Abstract
We describe a new radioligand assay for determining biotin in biological fluids by using a mixture of N-[beta-(4-OH-3-125I-phenyl)ethyl]- and N-[beta-(4-OH-3,5-di-125I-phenyl)ethyl]biotinamides as radiotracer, avidin as a binding protein, and an avidin double-antibody as a separation reagent. The radiotracer is synthesized by coupling (at pH 8.5, 20-22 degrees C, 90 min) N-hydroxysuccinimidobiotin to radioiodinated tyramine. The assay curve is linear and the assay itself is sensitive (less than 10 ng/L), reproducible (intra- and interassay CVs 4.1% and 7.0%, respectively), and allows the simultaneous handling of more than 100 samples in less than 4 h. Serum samples from apparently normal subjects contained 100-840 ng of biotin per liter (mean 340 ng/L). Pregnant women had low concentrations of biotin (100-300 ng/L) in their serum. Patients undergoing chronic hemodialysis treatment showed high concentrations (0.5-3.0 micrograms/L), which may be ascribable to the inability of avidin, which was used as the assay binding protein, to distinguish biotin from biotinyl derivatives with an intact ureido ring.
An examination of heart proteins by two-dimensional electrophoresis.
Authors: Gianazza E , Osio L , Grazioli G , Astrua-Testori S , Righetti P G , Accinni R , Renoldi I , Repossini A 
Published: January 2020

Abstract
We examined specimens from explanted human hearts by two-dimensional electrophoresis. The protocol selected includes: (a) solubilization of the sample in a urea-detergent mix; (b) charge fractionation in the presence of urea and nonionic detergent on a pH 4-10 immobilized pH gradient; (c) size fractionation on a polyacrylamide concentration gradient in the presence of sodium dodecyl sulfate; and (d) staining with silver nitrate. The method is sensitive enough for analysis of biopsies in the 1-3 mg range (wet tissue). We saw, for explanted hearts, variations in the protein pattern with the site of sample dissection. Results are presented for 11 explanted human hearts: one control organ and 10 pathological samples. The recorded pathologies included dilatative cardiomyopathy (six cases), valvulopathy (one case), ischemic cardiopathy (two cases), and graft rejection (one case). The patterns for whole extracts as well as for cytoplasmic proteins and myofibril components are compared. Extensive individual variability was observed both between control and pathological cases and among the abnormal samples.