bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lactate dehydrogenase inhibition by immunoglobulin G in human serum.
Authors: Maekawa M , Sudo K , Iwahara K , Kanno T 
Published: January 2020

Abstract
Low lactate dehydrogenase (LD; EC 1.1.1.27) activity and an abnormal LD pattern in electrophoretograms of LD isoenzymes in the sera of two patients were caused by inhibition of LD by immunoglobulin G. One of these showed inhibitor activity in the serum upon direct analysis, while the other showed activity only after the immunoglobulin was stripped from the LD. As judged from the LD isoenzyme patterns in serum, the LD inhibitor appeared to act against M subunits. However, quantification of binding affinities to each isolated isoenzyme showed that the LD inhibitor had a stronger effect on LD isoenzymes 2 and 3 (H3M1 and H2M2, respectively).
Gas-liquid chromatographic method for determining urinary estriol, with 6 alpha-hydroxyestriol as internal standard.
Authors: Lindgren K 
Published: January 2020

Abstract
I describe a chromatographic procedure for quantification of urinary estriol in late pregnancy, with 6 alpha-hydroxyestriol used as internal standard. The hydrolyzed sample is successively passed through a Bond Elut C18 column and a DEAE-Sephadex column. The estrogens are then completely resolved as silyl ethers on a packed gas-liquid chromatographic (GLC) column in isothermal mode. Analytical recoveries of conjugated estriol ranged between 96 and 102%. Between-day precision (CV) was 4.4% at a mean concentration of 85.1 mumol/L. Specificity was assessed by comparing results obtained with a capillary GLC column.
A control system for monitoring the performance of leukocyte strip tests.
Authors: Pendergrass J H , Skjold A C , Cattell J A , Stover L R 
Published: January 2020

Abstract
The control system described here is used to monitor the performance of urinary reagent-strip tests for leukocytes. The presence of leukocyte esterase in the urine is used as a marker for leukocytes in urine. The control system is based on sonicated leukocytes, isolated from whole blood. The esterase activity of this sonicate is determined by spectrophotometry with the N-tosyl-L-alanine ester of 5-phenyl-3-hydroxypyrrole as substrate. The assay result is used to determine the amount of sonicate needed to prepare buffered esterase-containing solutions. Such control solutions mimic leukocytic urines and are stable for 6 h at room temperature. The variability of the control system was tested by preparing it five times in a day on five separate days. The overall CV for Leukostix Reagent Strips (Ames Division, Miles Laboratories, Inc.) when tested with these solutions and analyzed with a reflectance spectrophotometer was 8%; for visual readings it was 10%. The overall CV for Chemstrip LN Reagent Strips (Biodynamics, Indianapolis, IN) was 10%.
Sensitivity of isoelectric focusing, ion exchange, and affinity chromatography to labile glycated hemoglobin.
Authors: Mullins R E , Austin G E 
Published: January 2020

Abstract
We examined the effect of labile glycated hemoglobin on measurements of glycated hemoglobin by several commercial procedures. Erythrocytes from diabetic and nondiabetic patients were incubated in vitro with various concentrations of glucose, to generate labile glycated hemoglobin, and the species of glycated and nonglycated hemoglobin in each sample were identified by isoelectric focusing. Glycated hemoglobin was then assayed by the Bio-Rad A1 column method (I), the Bio-Rad A1c column method (II), and the Pierce affinity column method (III). I was sensitive to the labile (aldimine) fraction of glycated hemoglobin, and percentages of glycated hemoglobin so determined represented the sum of the labile fraction plus hemoglobin A1c and other stable glycated species. This spurious increase in glycated hemoglobin concentration by the aldimine could be obviated by any of three wash procedures, which eliminated the labile fraction from the samples: incubating the erythrocytes (a) in phosphate-buffered saline (pH 7.4) for 18 h at 22 degrees C, (b) in 100 mmol/L citrate (pH 5.0) for 30 min at 37 degrees C, or (c) in saline containing, per liter, 30 mmol of semicarbazide and 12 mmol of aniline hydrochloride (pH 5.0) for 30 min at 37 degrees C. Methods II and III did not detect the labile fraction. However, treatments a-c decreased the concentrations of stable glycated hemoglobin as determined by all three column-chromatographic methods as compared with unwashed sample. By isoelectric focusing we determined that blood with high glucose content had concentrations of aldimine roughly proportional to the blood glucose concentration. The kinetics of formation of labile glycated hemoglobin in these cells were consistent with the reported rate constants determined by using purified hemoglobin preparations in vitro.
Fluorometry of nanogram amounts of selenium in biological samples.
Authors: Tamari Y , Ohmori S , Hiraki K 
Published: January 2020

Abstract
For fluorometry of selenium in human blood, hair, and liver and in leaves, we wet-ashed the samples with conventional nitric and perchloric acids, and then extracted piazselenol (complex of Se and 2,3-diaminonaphthalene) in cyclohexane. Selenium was back-extracted from the cyclohexane into nitric acid to remove the fluorometric interferences of trace amounts of organic compounds. This fluorometric method is rapid and suitable for routine analysis. We applied the method to human hair samples and compared it with the data for non-destructive neutron activation analysis of the hair.
Is succinyldicholine the substrate of choice for the measurement of cholinesterase activity?
Authors: Faye S , Evans R T 
Published: January 2020

Abstract
We have developed a succinyldicholine-based assay for serum cholinesterase (EC 3.1.1.8) to help establish whether patients with suspected sensitivity to drugs of this type have enzyme abnormalities that cannot be detected by conventional laboratory techniques. Although the method discriminates between cholinesterase activities of drug-sensitive and nonsensitive people as well as an assay involving propionylthiocholine does, it has not revealed cholinesterase abnormalities in patients who experienced prolonged apnea after succinyldicholine, in whom no enzyme defect could be demonstrated by other procedures. Of 50 individuals who were apneic for between 20 and 180 min, only one had a cholinesterase activity less than the mean for E1u homozygotes by more than 2.5 SD. We conclude that the number of patients who experience clinical problems due to enzyme abnormalities that at present go unrecognized is small. Consequently, although succinyldicholine might eventually become the substrate of choice for cholinesterase, its advantages over propionylthiocholine are not yet sufficient to encourage its use.
Evaluation of an enzyme immunoassay kit for estrogen receptor measurements.
Authors: Raam S , Vrabel D M 
Published: January 2020

Abstract
Using an enzyme immunoassay (EIA) procedure, we evaluated the ability of the glass beads in the ER-EIA kit of Abbott Laboratories, which were coated with monoclonal anti-estrogen receptor (ER) antibodies, to bind hormone-free and hormone-filled Type I ER in cytosols, buffer washes, and 0.4 mol/L KCI extracts of ultracentrifugal pellets of breast cancer tissue homogenates. The unmodified ER-EIA technique yields higher values than does the dextran-coated charcoal (DCC) method for Type I ER. However, the antibody-coated beads fail to bind hormone-free ER and react with only a certain proportion of ER-[3H]estradiol complexes. The antigen saturation limit of the beads could not be determined because the quantity of antigen bound by the beads was disproportionate and unrelated to the total amount of the antigen available in the cytosols. In buffer extracts of tissue pellets that were ER-negative by the DCC assay, the EIA method detected high quantities of ER. We recommend checking the ability of the monoclonal antibodies to recognize proteins other than Type I ER in the extra-nuclear and nuclear compartments of target cells before using them for immunohistochemical detection of ER.
Interlaboratory standardization of enzyme results: the Richmond project.
Authors: Miller W G , Crane P D , Cryer C 
Published: January 2020

Abstract
Three concentrations of proficiency monitoring material and two concentrations of secondary standard calibrating material were prepared and stored frozen. The materials were prepared in buffer containing amylase from human saliva, aspartate aminotransferase from human liver, creatine kinase from human muscle, human serum albumin (20 g/L), and cofactors. The proficiency monitoring material was assayed by 10 methods in nine laboratories for 15 days to establish baseline performance. Each laboratory then used the secondary standard calibrating material to calibrate their instruments' responses to that of a standardization method, and repeated the assay of the proficiency monitoring material for 15 days. For amylase before calibration, between-laboratory mean values for the three concentrations of proficiency monitoring material were 29% lower than the standardization method, and the between-laboratory CV was 28%. After calibration the mean amylase values were 4% lower and the CV was 6%. For aspartate aminotransferase, the pre-calibration between-laboratory mean values were 24% higher than the standardization method (CV 14%) but only 3% higher (CV 6%) after calibration. CK activity deteriorated at storage temperatures above -70 degrees C. This study demonstrates that, by using a common secondary standard, laboratories can improve calibration of enzyme results.
Fluorometric assay for pancreatic lipase.
Authors: Salvayre R , Nègre A , Radom J , Douste-Blazy L 
Published: January 2020

Abstract
We report a new fluorometric assay in which a fluorescent triglyceride is used for determining lipase activity in serum, and we compare it with turbidimetric and radiometric methods. Because this fluorometric method is at least 50-fold more sensitive than the turbidimetric method, we have been able to develop a micromethod that requires only very small amounts of substrate reagent and serum. The use of fluorescent-labeled fatty acids allows direct determination of the product of lipase action and obviates the use of a standard for calibrating the method. Results of the fluorometric method are well correlated with those of the radiometric and turbidimetric methods, and the precision of the fluorometric assay is better than that of the turbidimetric method. Reference values for normal subjects are between 0 and 120 mU/L.
Determination of amylase activity in serum by using a wheat germ inhibitor with the Du Pont aca.
Authors: Lacher D A , Harize M B 
Published: January 2020

Abstract
A rapid procedure for determining salivary- and pancreatic-type amylase (EC 3.2.1.1) in serum by incorporating a wheat germ inhibitor (from Triticum aestivum) was developed for the Du Pont aca IV analyzer. Under optimal assay conditions, activities of salivary and pancreatic amylase were inhibited by 93% and 19%, respectively. The 95% central reference interval for the percentage of inhibition of serum amylase was 38-84%. Patients with acute pancreatitis showed less than 26% inhibition of amylase after addition of the wheat germ extract, reflecting the prevalence of pancreatic-type amylase in this disorder.
Warfarin administration increases uric acid concentrations in plasma.
Authors: Menon R K , Mikhailidis D P , Bell J L , Kernoff P B , Dandona P 
Published: January 2020

Abstract
The effect of warfarin administration on plasma uric acid was investigated. A representative sample of patients on long-term warfarin treatment had a significantly higher concentration of uric acid in plasma than did age-matched patients with comparable plasma urea concentrations who were not taking warfarin. In women, this association was observed only in patients with normal values for plasma urea, not in those with high values. In contrast, in men this association was present in both groups (normal and high plasma urea). In a longitudinal study involving patients, their plasma uric acid significantly increased after warfarin administration. There was no significant change in the renal clearance of uric acid after a single dose of warfarin in normal, healthy volunteers; this contrasts with the increase observed with other coumarin anticoagulants. Our findings suggest that the increase in plasma uric acid noted with warfarin administration is probably due to an increase in uric acid production and may predispose to gout those patients who are on long-term therapy with warfarin.
A highly sensitive immunoenzymometric assay involving "common-capture" particles and membrane filtration.
Authors: Kang J , Kaladas P , Chang C , Chen S , Dondero R , Frank A , Huhn S , Lisi P , Monchnal D , Nasser J 
Published: January 2020

Abstract
This highly sensitive immunoenzymometric method involves monoclonal antibodies, a common-capture microsphere, and a rapid, membrane-filtration separation step. The common-capture solid phase is monoclonal anti-fluorescein antibody convalently attached to 6.5 micron-diameter latex particles. In sandwich-type assays for large-molecule analytes, the capture antibody is conjugated with fluorescein isothiocyanate and the probe antibody is conjugated with beta-galactosidase (EC 3.2.1.23). In competitive assays for small analytes, the analyte-beta-galactosidase conjugate competes with the analyte in the clinical samples for the fluoresceinated capture antibody. After simultaneous incubation of the reagents for 2 h, the bound and unbound reagents are separated by filtration through the bottom of each well of a 96-well plate. Substrate (4-methylumbelliferyl-beta-D-galactopyranoside) is then added to the wells, and the rate of product formation is determined kinetically for 12 min. The rate is proportional to the concentration of analyte in the sandwich assays and inversely proportional in the competitive assays. The assay results for choriogonadotropin, thyrotropin, digoxin, and thyroxin show the assay to be sensitive, rapid, and applicable to any size analyte. With this system, several different sandwich and (or) competitive-type assays can be performed simultaneously on the same plate.
Internally referenced ImmunoConcentration assays.
Authors: Anderson R R , Lee T T , Saewert D C , Sowden K M , Valkirs G E 
Published: January 2020

Abstract
We have developed a method for incorporating an internal reference zone in addition to the test zone in a single immunoConcentration device. We have illustrated the method by constructing an internally referenced assay for human choriogonadotropin (HCG) in serum. The internally referenced assay, which can be performed in about 5 min, provides a measured overall precision (CV) of approximately 15% at a concentration, in serum, of approximately 50 int. units/L. The test zone consists of an anti-HCG antibody adsorbed onto latex microspheres and entrapped within a porous support. The reference zone contains antibody against alkaline phosphatase (EC 3.1.3.1), which has also been adsorbed onto latex microspheres and trapped within the support. The use of an internal reference moderates the effects of variations in assay conditions on the interpretation of assay results.
Correct and incorrect estimation of within-day and between-day variation.
Authors: Bookbinder M J , Panosian K J 
Published: January 2020

Abstract
Between-day variance is an ambiguous term representing either total variance or pure between-day variance. In either case, it is often incorrectly calculated even though analysis of variance (ANOVA) and other excellent methods of estimation are available. We used statistical theory to predict the magnitude of error expected from using several intuitive approaches to estimation of variance components. We also evaluated the impact of estimating the total population variance instead of pure between-day variance and the impact of using biased estimators. We found that estimates of variance components could be systematically biased by several hundred percent. On the basis of these results, we make recommendations to remove these biases and to standardize precision estimates.
Reference intervals for vitamins B1, B2, E, D, retinol, beta-carotene, and folate in blood: usefulness of dietary selection criteria.
Authors: Herbeth B , Zittoun J , Miravet L , Bourgeay-Causse M , Carre-Guery G , Delacoux E , Le Devehat C , Lemoine A , Mareschi J P , Martin J 
Published: January 2020

Abstract
Reference intervals for normal concentrations in blood of vitamins B1, B2, E, D, retinol, beta-carotene, and folic acid were determined from a selected sample of people attending a Health Examination Center or being examined in occupational health services in France. This reference sample consisted of 362 men and women, ages 18 to 44 years, selected according to the main variation factors known for the vitamins studied: consumption of tobacco and alcohol, ponderal index (relating height and weight), use of drugs and oral contraceptives, and past history of surgical or medical treatment. Reference intervals were determined for each sex. Vitamin B1 (erythrocyte transketolase activity), plasma retinol, and folic acid values in whole blood are significantly higher in men than in women (p less than 0.001), but vitamin B2 (activation of erythrocyte glutathione reductase) and plasma beta-carotene values are significantly higher in women (p less than 0.001 and less than 0.01 respectively). Dietary intake of vitamins produced no significant displacement of the reference values. For each vitamin we discuss the other major sources of variation factors and the usual values reported in the literature.
Immunological and colorimetric determination of prostatic acid phosphatase--technical and clinical reappraisal in symptomatic patients.
Authors: Gibb I , Wilson L A , Powell P H , Tarbit I , Pratt D , Hall R R 
Published: January 2020

Abstract
We compared a selection of quantitative immunological methods for prostatic acid phosphatase (PAP) with routine colorimetric assays for total and tartrate-labile acid phosphatase and evaluated their relative clinical merits in the differential diagnosis of prostatic carcinoma. We also assessed a wide range of commercial control materials for suitability of use with these methods. Patients studied included 111 cases of prostatic carcinoma, 42 cases of benign prostatic hyperplasia, and 33 controls. The principles of the methods used included determination of enzymatic activity using p-nitrophenyl phosphate, RIA, immunoradiometric, and enzymoimmunometric assays. Performance characteristics for the immunological methods were inferior to manufacturers' precision and specificity claims. We identified control materials that were unsuitable for routine use. Poor discrimination between clinical groups was observed for all methods. Analysis by use of a receiver operator characteristic plot failed to improve this. We conclude that the immunological methods we studied offer no advantages over colorimetric methods in the differential diagnosis of prostatic cancer in symptomatic patients.
Solid-phase immunoassay of digoxin by measuring time-resolved fluorescence.
Authors: Helsingius P , Hemmilä I , Lövgren T 
Published: January 2020

Abstract
We describe a time-resolved fluoroimmunoassay for the cardiac glycoside digoxin. The assay depends on the competitive distribution of Eu3+-labeled anti-digoxin antibodies between solid-phase-bound digoxin and the digoxin in the sample or standard. After this immunoreaction, the bound fraction of the Eu3+-label is dissociated from the solid phase, converted into a highly fluorescent beta-diketone chelate, and measured in a fluorometer with time-resolution (1230 Arcus, LKB-Wallac). Sample volume is 20 microL, the incubation lasts 30 min, and the concentration range of the assay for digoxin is from 0.25 to 4.0 ng/mL (0.32-5.1 nmol of digoxin per liter). Correlation with an in-house RIA was good (r = 0.97, n = 43). The sensitivity was equivalent to that of most RIAs: 0.2 ng/mL (0.25 nmol/L).
The lability of estrogen receptor: correlation of estrogen binding and immunoreactivity.
Authors: Clayton F , Wu J 
Published: January 2020

Abstract
We compared the Abbott enzyme immunoassay method for estrogen receptor with a standard dextran-coated charcoal method, and studied the effects of treatments causing denaturation. Estrogen receptor values were slightly higher by the Abbott method, but the methods agreed with regard to receptors being present or absent in 94-98% of 50 cases. Heat lability of immunoreactivity by the Abbott enzyme immunoassay is comparable to the lability of estrogen binding by the estrogen receptor. Estrogen and molybdate substantially stabilized estrogen receptor during the assay, but improper handling of tissue before the assay may cause similar, substantial decreases in estrogen receptor by either method. The Abbott method is easier to use than the dextrancoated charcoal method, requires less tissue, and measures receptor with or without endogenously bound estrogen, but reagent cost is high.
High-affinity monoclonal antibodies specific for human prostatic acid phosphatase.
Authors: Höyhtyä M , Vihko P , Vuolas L , Tryggvason K , Vihko R 
Published: January 2020

Abstract
We produced two monoclonal hybridoma cell lines that secrete IgG immunoglobulins with high affinities (Kd = 7.3 to 8.0 X 10(-11) mol/L, Ka = 1.25 to 1.37 X 10(10) L/mol) for 125I-labeled human prostatic acid phosphatase (PAP), and that specifically bind this enzyme from human serum. The antibodies were produced in high titers in murine ascitic fluid (700 mg/L) and in cell-culture media (30 mg/L) and were further purified to homogeneity by affinity chromatography on PAP- and Protein A-Sepharose CL-4B. After purification they were shown to be homogeneous by liquid chromatography. Both of these monoclonal antibodies exhibit strict specificity for PAP as determined by radioimmunoassay and by immunofluorescence studies of human pancreas, kidney, prostate, and leukocytes. The antibodies react only with the native form of the enzyme, as shown by the slot-immunoblotting method.
Protocols for use of ultrafiltration in determination of free ligand concentration and of complexity of ligand/protein interactions.
Authors: Wolfer G K , Rippon W B 
Published: January 2020

Abstract
Analysis of a simple ligand/binding-protein association model predicts a decrease in the percentage of free hormone during ultrafiltration. Re-analysis of the original data validating ultrafiltration in free-ligand determinations (Sophianopoulos et al., Arch Biochem Biophys 1978;187:132-7) confirms this prediction. Binding data indicating a constant percentage of free hormone (Hammond et al., J Biol Chem 1980;255;5023-6) require a more complex ligand-protein interaction model. Application of these procedures to any new ligand system requires measurement of the percentage free, or of free-ligand concentration, as a function of filtration time or volume. The protocol becomes important if values for percentage free are to be accurate.
Influence of ambient temperature on the Ektachem DT60 results for total bilirubin and total protein.
Authors: Dujardin B C , Hafkenscheid J C , Roijers A F , Schoorl M , van der Ven-Jongekrijg J 
Published: January 2020

Abstract
We evaluated the Kodak Ektachem DT60 analyzer with the DTE module in a two-month clinical trial before its introduction in the Netherlands. At ambient temperatures that differed from that at which the DT60 was calibrated, aberrant behavior for total bilirubin and total protein assays was observed. At subnormal temperatures the former gave higher results than expected, and the latter, lower results. We found a similar effect for total protein determined by the manual biuret reaction at different temperatures, when results were calculated from calibration at a fixed temperature. Total bilirubin assayed by the manual diazobilirubin method showed no such effect. Although the DT60 analyzer is equipped with a temperature-regulated incubator, we conclude that the manufactures's recommended room temperature range for these assays should be narrowed and the three-month calibration period adjusted according to external circumstances.