bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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

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

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

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.
Inhibitory effect of superoxide dismutase on fructosamine assay.
Authors: Jones A F , Winkles J W , Thornalley P J , Lunec J , Jennings P E , Barnett A H
Published: January 2020

The fructosamine assay measures the degree of nonenzymatic protein glycation by virtue of the reducing properties of such proteins in alkaline conditions. We report the marked inhibitory effect of superoxide dismutase (EC 1.15.1.1) on the reducing activity both of protein glycated in vitro and of diabetic sera, indicating superoxide intermediacy in the fructosamine reaction. The free-radical intermediates may be of analytical significance when pathological and physiological changes in serum anti-oxidant activity occur. They may also be of pathological significance in diabetic microangiopathy and protein browning.
Underestimation of monoclonal proteins by serum protein electrophoresis on cellulose acetate.
Authors: Liu F J , Fritsche H A , Trujillo J M
Published: January 2020

Our study of 95 serum samples from 37 patients with monoclonal gammopathy revealed distorted irregular monoclonal (M) protein bands after serum protein electrophoresis (SPE) on cellulose acetate membrane. In 71 (75%) of the 95 sera, the M-protein was underestimated and the albumin concentration overestimated. Dilution of the serum sample before SPE eliminated the abnormality of the M-protein bands. By SPE, the mean albumin concentration in these 71 undiluted sera was 45.8 (SD 7.4) g/L vs 37.9 (SD 5.8) g/L for the diluted sera; moreover, this was true of individual samples: measured albumin concentration in each diluted serum sample was always less than in the undiluted serum. As measured by the bromcresol green dye-binding method, the albumin concentration was 32.8 (SD 5.9) g/L. Similarly, the M-protein concentration in SPE was 49.5 (SD 12.3) g/L for the undiluted sera vs 61.8 (SD 15.1) g/L for the diluted sera, and the M-protein concentration in each diluted serum sample always exceeded that in the undiluted serum. Underestimation of M-protein limits the usefulness of M-protein measurement in evaluating the patient's response to therapy and for early detection of disease progression. SPE strips should be carefully inspected visually, and sera with M-protein band abnormalities should be diluted and re-assayed if SPE is to quantify concentrations of M-protein and albumin accurately.
Two indirect tests of exocrine pancreatic function evaluated.
Authors: Scharpé S , Iliano L
Published: January 2020

We describe and evaluate two frequently used indirect methods for assessing exocrine pancreatic function: the N-benzoyl-L-tyrosyl-p-aminobenzoic acid test (NBT-PABA) and the pancreolauryl test. In both procedures, the patient is orally administered a substrate that is metabolized into two or more products by pancreatic enzymes. At least one of the reaction products is absorbed from the gut, conjugated, and excreted in urine, where it can be measured. Both tests can be used in the diagnosis and monitoring of cystic fibrosis, chronic pancreatitis, and pancreatic carcinoma, and in monitoring pancreatic enzyme replacement therapy to determine the appropriate dose. In comparison with the NBT-PABA procedure, the pancreolauryl test seems to have better specificity and sensitivity, undergoes almost no interference from other drugs or serum compounds, requires no complex hydrolytic conditions, and is independent of renal function.
Activity of serum aspartate aminotransferase isoenzymes in patients with acute myocardial infarction.
Authors: Panteghini M , Pagani F , Cuccia C
Published: January 2020

Activities of aspartate aminotransferase (AST) isoenzymes were determined in serial serum samples from 40 cases of acute myocardial infarction, and compared with activities of creatine kinase, CK-MB isoenzyme, lactate dehydrogenase, and alpha-hydroxybutyrate dehydrogenase for temporal changes. Cytosolic (soluble) AST (s-AST) and mitochondrial AST (m-AST) respectively increased 6.6 and 9.0 h after onset of chest pain. The median time at which serum m-AST activity peaked (15.8 U/L, range 6.4-53.5 U/L) was 47.8 h after the onset of infarction, 19.8 h later than the peak s-AST activity (171 U/L, range 53-517 U/L) and m-AST also disappeared from the serum more slowly than s-AST (p less than 0.001). Serum m-AST values were above normal for at least six days after the infarct. The ratio of m-AST to total AST in serum increased after myocardial infarction, being greatest (20%, range 11-32%) on the third day after onset. For individuals, peak activities of s-AST correlated well with total CK (r = 0.91) and CK-MB (r = 0.86) peak activities, indicating that s-AST also reflects the infarct size. However, m-AST correlated poorly with the enzymes commonly used in infarct diagnosis; it apparently provides different biological information.
Time-dependent changes in bone, placental, intestinal, and hepatic alkaline phosphatase activities in serum during human pregnancy.
Authors: Valenzuela G J , Munson L A , Tarbaux N M , Farley J R
Published: January 2020

To measure changes in bone alkaline phosphatase (EC 3.1.3.1) activity in serum as a function of duration of pregnancy, we adapted our existing alkaline phosphatase (ALP) isoenzyme assay (which has been used to measure bone, hepatic, and intestinal ALP activities in serum, in the absence of placental ALP) to allow quantification of individual ALP isoenzyme activities in the presence of placental ALP. The resulting CV for repeat measurements of bone ALP activity in artificial isoenzyme mixtures ranged from 23% for samples in which the bone isoenzyme represented 7% of total ALP activity to 11% for samples in which bone ALP accounted for 48% of total ALP activity. Values for repeat determinations of bone ALP activity in human serum samples (i.e., including samples obtained from pregnant women and from nonpregnant controls) varied by an average of 18%. We find, in initial applications of this method, that (a) the amount of bone ALP activity in serum is increased during pregnancy (P less than .001), and remains increased at six weeks postpartum, in non-lactating women (P less than .001), and (b) bone ALP activity at term was not significantly different in pregnant women with pre-eclampsia, diabetes, premature rupture of membranes, or premature labor, compared with normal pregnancies at term. Our data support the hypothesis that maternal bone formation may be increased during pregnancy.
Activity measurements of calcium, sodium, potassium, and chloride after equilibrium dialysis used to show lack of evidence for protein interference with calcium electrodes.
Authors: Thode J , Boyd J C , Ladenson J H
Published: January 2020

We measured the activity of Ca2+, Na+, K+, and Cl- with ion-selective electrodes after equilibrium dialysis of solutions with different albumin concentrations. The calculated Donnan ratio was the same for all ions in the same solution and increased with the albumin concentration, as predicted by the Donnan theory. The Donnan distribution ratio for Ca2+ was similar, as determined with instruments from three different manufacturers. For healthy subjects and patients with renal stone disease, we did not find any correlation between serum concentrations of ionized calcium and albumin. The discordance between measured ionized calcium and albumin-corrected total calcium depended on the correction algorithm we utilized. The difficulties of absolutely proving or disproving a protein error in these measurements are discussed, but our data are not consistent with protein being a source of error in measurements of ionized calcium.
Direct, simultaneous measurement of chloramphenicol and its monosuccinate ester in micro-samples of plasma by radial-compression liquid chromatography.
Authors: el-Yazigi A , Yusuf A , Al-Humaidan A
Published: January 2020

A simple method of simultaneous analysis for chloramphenicol and chloramphenicol succinate in 10-microL samples of plasma is described. We injected the plasma samples directly into a radial-compression liquid chromatograph equipped with a precolumn module and a C18 insert. A mixture of acetic acid solution (pH 3)/acetonitrile (75/25, by vol) was used as mobile phase, at a flow rate of 4 mL/min. We separated the compounds in a 10-micron (particle size) C18 cartridge with a radial compression separation system and detected them in the effluent at 280 nm. The peak height for both compounds was linearly (r greater than 0.9993) related to concentration over the range investigated, 1-50 mg/L. We also performed the analysis with use of an internal standard (methylprednisolone) and obtained equally good results (r greater than 0.9995). We observed no interference from other antibiotics or drugs in the assay, and the inter- and intra-run precision at different concentrations was good (CV, 0 to 5.6%). We analyzed microsamples of plasma from an infant treated for meningitis with chloramphenicol sodium succinate intravenously. Total analysis time for each sample was less than 8 min.
Antibodies to porcine uteroferrin used in measurement of human tartrate-resistant acid phosphatase.
Authors: Echetebu Z O , Cox T M , Moss D W
Published: January 2020

The immunological similarity between human tartrate-resistant acid phosphatase (EC 3.1.3.2) and porcine uteroferrin previously reported for the isoenzyme from spleens of patients with leukemic reticuloendotheliosis (Ketcham et al., J Biol Chem 1985;260:5768-76) has been confirmed for partly purified acid phosphatase found in the spleen of a patient with Gaucher's disease, and for the corresponding isoenzyme in other tissues and serum. Anti-uteroferrin antibodies raised in rabbits have been used to demonstrate the feasibility of their application in an immunoassay for tartrate-resistant acid phosphatase in serum.
Optical kinetic method for calibration of spectrophotometer temperature: demonstration with the Cobas-Bio analyzer.
Authors: Armitage E K , Miller W G
Published: January 2020

The pseudo-first-order rate constant for the Jaffé reaction with creatinine varies logarithmically with temperature and was calibrated in the range 25 to 37 degrees C to measure the temperature of the liquid in the lightpath of spectrophotometric instrumentation. The reagent concentrations can be adjusted to permit rate-constant measurements in time intervals from a few seconds to several minutes. The temperature increment that can be resolved is limited only by the analytical imprecision of the instrumentation used to measure the rate constant and the calibration temperature. In this investigation, a temperature SD of 0.03 degrees C could be measured. Two Cobas-Bio centrifugal analyzers, used to demonstrate the utility of this technique, were found to have temperature errors from -1.0 to -1.7 degrees C in the 30 to 37 degrees C range and overall temperature SD of 0.19 and 0.36 degree C, respectively, at 37 degrees C. Analysis of variance gave between-rotor SD of 0.14 and 0.34 degrees C and within-rotor SD of 0.13 and 0.11 degree C, respectively. We found temperature differences of 0.3 degree C between cuvets in a rotor, and gradients of 0.3 and 0.4 degree C, respectively, from the top to bottom of an individual cuvet in the two instruments.
Role of qualitative choriogonadotropin assays in diagnosis of ectopic pregnancy.
Authors: LeMaistre A , Bracey A , Katz A , Wu A H
Published: January 2020

We compared the clinical sensitivity and cost-effectiveness of a qualitative assay for choriogonadotropin in human urine ("Icon" hCG) with a quantitative assay of serum from 142 women with pathologically-diagnosed ectopic pregnancy. Results show that although the qualitative assay had a clinical sensitivity for pregnancy of 98.6%, as compared to 100% for the quantitative assay, it was more economical to use, and had a significantly shorter turnaround time. We conclude that qualitative hCG assay of either urine or serum is a good screening method for detecting pregnancy, and can replace the stat quantitative assay in women with suspected ectopic pregnancy. We present a diagnostic algorithm to illustrate the role of qualitative and quantitative hCG assays in conjunction with ultrasonography, culdocentesis, and laparoscopy for diagnosis of ectopic pregnancy.
Immunofluorometry of choriogonadotropin by time-resolved fluorescence spectroscopy, with a new europium chelate as label.
Authors: Khosravi M J , Diamandis E P
Published: January 2020

We describe a new "sandwich"-type non-isotopic immunoassay for human choriogonadotropin (hCG) in serum. In the assay, hCG is captured by a beta-subunit-specific monoclonal antibody, which is immobilized in a white microtiter well. The sandwich is completed by adding a second biotinylated monoclonal antibody specific for the whole hCG molecule. The degree of binding of biotinylated antibody, which is proportional to the amount of hCG present in the sample, is quantified by adding streptavidin labeled with the europium chelate 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA), in the presence of excess Eu3+. The fluorescent complex formed on the solid-phase [monoclonal antibody-hCG-monoclonal antibody-biotin-streptavidin-BCPDA-Eu3+] is measured by excitation at 337.1 nm with a nitrogen laser and monitoring the emission at 615 nm in a specially designed gated fluorometer working in a time-resolved mode. A two-step procedure is proposed for routine use to avoid the "high-dose hook effect" of the simpler and faster one-step procedure. The hCG assay described has a dynamic range of 1 to 500 int. units/L, and is precise and accurate. Results agree well with those obtained with a commercially available immunoradiometric and a time-resolved immunofluorometric procedure.
Optimized atomic absorption spectrophotometry of calcium in erythrocytes.
Authors: Nomoto S , Shoji S
Published: January 2020

We sought to establish optimum conditions for measuring calcium in erythrocytes by atomic absorption spectrophotometry. The conditions we selected are as follows. Wash one volume of fresh heparin-treated packed cells once with 30 volumes of isotonic buffered saline (pH 7.4) at a temperature somewhat exceeding 25 degrees C. Dilute the washed packed cells 10-fold with 12 mmol/L hydrochloric acid, and analyze the supernate for calcium. Measure the hematocrit of the washed packed cells, then analyze an aliquot of them for calcium, using a computer-readout type of flame or a non-flame atomic absorption spectrophotometer equipped with a pyrocoated graphite tube. The temperature program is 1000 degrees C for ashing [corrected] and 1800 degrees C for the atomizing cycle. Intraday and day-to-day reproducibility of the assay was 6.55% and 8.19%, respectively, at the mean concentration of calcium in the erythrocytes of healthy adults, which is 4.30 mumol/L.
Isoforms of creatine kinase isoenzymes in serum in acute myocardial infarction after intracoronary thrombolysis.
Authors: Panteghini M , Pagani F
Published: January 2020

Kinetics of the catalytic activities of creatine kinase (CK;EC 2.7.3.2) for three CK-3 and two CK-2 isoforms in serum were studied in 20 patients with myocardial infarction randomly assigned to receive either intracoronary urokinase (group A) or conventional therapy (group B). The temporal characteristics of isoform changes described were (a) time at which the isoform activities are significantly greater than initial values, (b) maximal rate (Ka) at which isoforms are released into blood, (c) time lag from onset of pain until maximum activity value, (d) peak value of each serum isoform, and (e) rate (Kd) at which each isoform is cleared from serum. Thrombolytic treatment induced earlier peak times in group A: for CK-3(3), 7.4 vs 20.0 h; for CK-3(2), 11.6 vs 24.8; for CK-3(1), 18.6 vs 34.3; for CK-2(2), 9.1 vs 17.8; and for CK-2(1), 11.8 vs 26.8 (numbers given are medians; for all isoforms, P less than 0.05). Ka values were at least twofold greater and the first increase was significantly earlier in the urokinase group. Consequently, the ratio for CK-3(3) to CK-3(1) activities peaked significantly earlier in group A. Isoform peak activities and Kd were not significantly different between the two groups.
Trace-element concentrations in human autopsy tissue.
Authors: Aalbers T G , Houtman J P , Makkink B
Published: January 2020

In this report on trace-element concentrations (As, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Zn) in human heart, liver, kidney, aorta, and rib obtained from 200 autopsied patients, we give special attention to sampling procedure, analysis technique, and various sources of error (autolysis, contamination with blood, and lack of sample homogeneity). We present the concentration data (averages, standard deviations, and ranges) obtained by neutron activation analysis, and we analyze the distribution of the data. The three types of distribution we distinguished are relevant to considerations of the importance of processes of storage of certain elements in specific organs.
Preliminary clinical studies of C-reactive protein quantified by enzyme-linked immunoassay.
Authors: Martinez J A , Coll J M
Published: January 2020

We have used an enzyme-linked immunoassay technique to quantify human C-reactive protein (CRP). In this assay phosphorylethanolamine is covalently linked to polystyrene wells. Serum or plasma specimens are diluted 961-fold and assayed. After Ca2+-dependent binding of CRP to the plates, the complex is reacted with peroxidase-labeled anti-CRP antibody. The response varies linearly with CRP concentrations between 10 and 160 mg/L; the detection limit is 0.34 ng per well. The results correlate well (r greater than or equal to 0.90) with those of rate nephelometry. This new method can be automated, is not subject to interferences or cross reactivity, is highly reproducible, has low background values, and can be carried out at room temperature.
Laser immunonephelometry for routine quantification of urinary albumin excretion.
Authors: Marre M , Claudel J P , Ciret P , Luis N , Suarez L , Passa P
Published: January 2020

We describe a laser-immunonephelometric method for quantifying urinary albumin excretion (UAE) in large numbers of samples. For a 150-microL sample incubated at room temperature for 45 min with 40 microL of antiserum specific for human serum albumin, the assay range for albumin was 0.34 to 43.0 mg/L. For samples analyzed undiluted and diluted 10-fold, the range of measurable albumin was from 0.34 to 430.0 mg/L. With an automated version of this method, one can assay 240 samples per hour. Intra- and interassay CVs were less than 6% and 9%, respectively. Measurements by this method (y) correlated well with those obtained by a RIA method (x): y = 1.00x + 0.163 mg/L (n = 233; r = 0.996). The day-to-day CV for UAE was determined for three consecutive determinations done on each of 60 controls according to the time of collection and in 212 diabetics according to the amount of 24-h UAE. For controls, UAE was 8.0 +/- 8.1 mg/24 h (mean +/- SD), CV 44 +/- 23%. The CV was similar for diurnal (50 +/- 28%) and overnight (58 +/- 32%) collections from controls; and for diabetics with normal values for UAE: 35 +/- 32%, with slight albuminuria (25-300 mg/24 h):37 +/- 28%, or with macroalbuminuria (greater than 300 mg/24 h): 47 +/- 42%.
Plasma iron and transferrin iron-binding capacity evaluated by colorimetric and immunoprecipitation methods.
Authors: Huebers H A , Eng M J , Josephson B M , Ekpoom N , Rettmer R L , Labbé R F , Pootrakul P , Finch C A
Published: January 2020

We evaluated plasma iron (PI) and total iron-binding capacity (TIBC) or transferrin in normal individuals and in patients with iron imbalance. The standard colorimetric measurements of PI and TIBC and the standard isotope-dilution measurement of TIBC were compared with an immunoprecipitation method and also with immunoelectrophoresis of transferrin. PI concentrations as measured by the standard and immunoprecipitation methods agreed closely for all individuals except those with saturated transferrin, where nontransferrin iron increased the results in the standard assay. This excess iron in saturated plasma may be derived from either free iron or iron-bearing ferritin. There were also differences in TIBC between the two methods. Iron-deficient sera gave higher values for transferrin when measured by immunoelectrophoresis. Unsaturated iron-binding capacity was increased in the isotope-dilution method in some iron-saturated plasma, compounding errors when added to erroneously high PI values to compute TIBC. Perhaps some exchange of iron occurred between added iron and transferrin iron in the isotope-dilution method. These measurements confirm the accuracy of the standard colorimetric method of measuring PI and TIBC except in iron-saturated plasma. However, the greater specificity of a polyclonal immunoprecipitation method of measuring PI and TIBC makes it particularly useful in differentiating transferrin-bound iron from nontransferrin iron.
Use of alumina columns to prepare plasma samples for liquid-chromatographic determination of catecholamines.
Authors: Maycock P F , Frayn K N
Published: January 2020

We describe an improved method of sample preparation for liquid chromatographic determination of plasma catecholamines. The catecholamines are extracted from plasma by using small, cheaply-made columns of alumina, with or without prior clean-up on commercially available ion-exchange columns. Advantages of this technique over the conventional batch-extraction method of using alumina are speed, convenience, and improved sample clean-up. In particular, the one-stage method we describe allows results to be reported within 20 min of receiving the sample.
Solid-phase enzyme immunoassay of terminal deoxynucleotidyl transferase evaluated.
Authors: Fleisher M , Stankievic R , Schwartz D , Schwartz M K
Published: January 2020

We evaluated a newly developed solid-phase immunoassay (EIA) of terminal deoxynucleotidyl transferase (TdT, EC 2.7.7.3) and compared it with the enzymatic assay of TdT involving DNA polymerase. We assessed the precision, performance characteristics, and clinical efficacy of the EIA procedure, using 249 specimens of peripheral blood and bone marrow and 118 specimens of whole blood. On linear regression analysis of results for these 249 samples as measured by the two procedures, the correlation coefficient was 0.87. Distribution of TdT in mononuclear cells isolated from whole blood and bone marrow of subjects in several disease categories indicated good concordance between the two assay procedures. The EIA procedure is precise, can be performed on whole blood without first isolating mononuclear cells, is nonisotopic, and shows potential as a quantitative indicator for the differential diagnosis and monitoring of human leukemia.
Advanced technology and its impact on the clinical laboratory.
Authors: Burtis C A
Published: January 2020

The analytical capabilities of the clinical laboratory have continued to expand and improve as a result of technical developments and advancements made in a wide spectrum of allied disciplines. As a consequence, the clinical laboratory has evolved from the small, manual operations of yesterday to the large, central organizations of today. Technology continues to have an impact on the laboratory, especially with the advent of the fully automated analytical systems that are having such a profound effect on how the laboratory is staffed, equipped, organized, and operated. With the accelerating rate at which new developments are occurring, it is safe to assume that dramatic changes will continue to occur in this area. Consequently, it will become increasingly important for clinical laboratorians to be aware of these new developments, to understand them, and to anticipate how they will be assimilated and integrated into the overall health care system. To quote from a recent Bell Atlantic advertisement, "The genius of the future lies not in technology alone, but in the ability to manage it."
Analyses of creatine kinase isoenzymes and isoforms in serum to detect reperfusion after acute myocardial infarction.
Authors: Apple F S , Sharkey S W , Werdick M , Elsperger K J , Tilbury R T
Published: January 2020

Isoenzymes and isoforms of creatine kinase (CK, EC 2.7.3.2) were measured to assess reperfusion after acute myocardial infarction (AMI). In streptokinase-treated and in spontaneously reperfused AMI patients, total CK, CK-2 activity and concentration, and CK-3(3) isoform activity peaked significantly (p less than 0.05) earlier than conventionally treated, non-reperfused patients. The ratio for CK-3(3) to CK-3(1) activities peaked significantly (p less than 0.05) earlier in both the streptokinase-treated and spontaneously reperfused groups, and indicated a greater release of enzyme (higher ratio) than in the conventionally treated patients. The ratio of CK-3(3)/3(1) also peaked significantly (p less than 0.05) earlier in all three groups than did total CK, CK-2, and CK-3(3) activities or concentrations. The clearance rates of total CK, CK-2, and CK-3(3) were not significantly different in all three groups. Thus, the ratio CK-3(3)/3(1) was the earliest indicator of infarction in both reperfused and non-reperfused patients.
Prevalence of magnesium and potassium deficiencies in the elderly.
Authors: Touitou Y , Godard J P , Ferment O , Chastang C , Proust J , Bogdan A , Auzéby A , Touitou C
Published: January 2020

Concentrations of magnesium and potassium in erythrocytes and plasma were determined in a population of 381 unselected elderly men and women, most of them in their eighties. The effects of biological factors (age, sex, weight) and a large set of pathological conditions, malignant or not, were examined. Analyses of variance showed a relation between age and concentrations of plasma potassium and between weight and concentrations of plasma magnesium. The chi-square test showed correlations between low concentrations of plasma magnesium and diabetes, abuse of alcohol and tobacco, and also between low values for erythrocyte magnesium and hypertension. Low values for plasma potassium were correlated with hypertension whereas high values were correlated with cardiovascular disease. Although some of the differences in the mean concentrations observed were statistically significant, these differences were always small. Most interesting was the distribution of the concentrations of the cations. This study shows that assays of both of these cations in erythrocytes were better than assays in plasma to evidence a deficiency. Indeed, about 20% of the studied population had low concentrations of both erythrocyte potassium and magnesium, whereas 2 and 10% had low values for plasma potassium and magnesium, respectively. This study underlines the large prevalence of magnesium and potassium deficiencies in the elderly, an observation we could not attribute to pathology or treatment. Routine electrolyte studies therefore appear to be justified in aged human subjects.
Natural and recombinant DNA-derived human insulin-like growth factor-I compared for use in radioligand assays.
Authors: Baxter R C , De Mellow J S , Burleigh B D
Published: January 2020

We compared two preparations of human insulin-like growth factor (IGF)-I, one isolated from human plasma and the other prepared by recombinant DNA technology, for use in three radioimmunoassays and a radioreceptor assay for IGF-I, two radioreceptor assays for IGF-II, and a protein-binding assay for both IGFs. In the IGF-I assays, iodinated natural IGF-I consistently showed higher binding than did iodinated biosynthetic IGF-I, whether or not the iodopeptides were purified before use by hydrophobic interaction chromatography. Comparing the potency of the unlabeled peptides in the eight assay systems, we found the natural and the biosynthetic IGF-I to be equipotent in every case except for a radioimmunoassay involving a monoclonal IGF-I antibody (the synthetic peptide had 2.4 times greater activity), and an IGF-II radioreceptor assay involving ovine placental membrane receptors (the natural peptide had 10-fold greater activity). We conclude that recombinant DNA-derived IGF-I is suitable for use, both as a standard and as a radioligand, in a wide variety of IGF assays.
Comparison of Coomassie Brilliant Blue protein dye-binding assays for determination of urinary protein concentration.
Authors: Marshall T , Williams K M
Published: January 2020

We investigated the influence of assay protocol upon results of Coomassie Brilliant Blue protein dye-binding assays for urinary protein. Sensitivity and working range for, and linearity of response (including dilution dependence) of, three standard assays and four micro assays to bovine albumin, gamma-globulin, and urine are compared. The Read and Northcote standard assay (Anal Biochem 1981; 116:53-64) appears to be the method of choice.
Activity of phospholipase A compared in serum of patients with pancreatic and nonpancreatic diseases.
Authors: Schmidt D , Hoffmann G E
Published: January 2020

Phospholipase A (PLA) activity was measured with a semi-automated photometric test system that is based on liberation of fatty acids from phosphatidylcholine by phospholipases A1 (EC 3.1.1.32) and A2 (EC 3.1.1.4). We studied 528 serum samples from 86 patients whose lipase activities were increased owing to pancreatitis, pancreatic carcinoma, and extrapancreatic diseases. PLA activity showed no correlation with lipase or amylase activities or with the primary cause of the disease, but was clearly related to prognosis. Noncomplicated acute pancreatitis was characterized by "normal" PLA activities (0-10 U/L), whereas the values (50-137 U/L) were highest in necrotizing pancreatitis and septicemia with a lethal outcome. Changes in lipase and phospholipase A activities exhibited completely different time courses in the various diagnostic groups.
Immunoglobulin A (lambda chains) conjugated with lactate dehydrogenase in serum.
Authors: Burlina A , Secchiero S , Bertorelle R , Plebani M , Zaninotto M
Published: January 2020

An atypical pattern for lactate dehydrogenase (EC 1.1.1.27) isoenzymes in a patient with sclerosis of the bladder neck was ascribable to complexing between lactate dehydrogenase and IgA. This complex formation was also replicable "in vitro." We determined that the IgA bound to lactate dehydrogenase was of the lambda type, a very unusual occurrence.
Laboratory performance and regulatory requirements.
Authors: Kenney M L
Published: January 2020

We compared performance levels of four clinical laboratory groups defined by federal regulatory characteristics, to assess the appropriateness of selected regulations: laboratories in JCAH-accredited hospitals; non-doctoral-directed independent laboratories; state-regulated but federally exempt group-practice laboratories; and unregulated laboratories in physicians' offices (POLs). Federal regulations evaluated were those dealing with the doctoral directorship requirement and exemption of POLs from regulation. Quantitative analytes were compared by using linear regression on log-normal transformations of mean absolute-z scores of proficiency test results. The scope of services offered by laboratories was statistically related to performance in quantitative analytes. Confounding effects of scope-of-service levels were statistically controlled. Proportions of errors in qualitative analytes were compared. No pattern of statistically discernible differences in performance was found between hospital laboratories and non-doctoral-directed laboratories. Both regulated non-doctoral-directed laboratories and state-regulated but federally exempt group-practice laboratories demonstrated higher levels of performance than unregulated POLs.
Concentrations of morphine and codeine in serum and urine after ingestion of poppy seeds.
Authors: Hayes L W , Krasselt W G , Mueggler P A
Published: January 2020

We measured morphine and codeine in commercially available poppy seeds and in serum and urine samples from healthy adults who had ingested these poppy seeds. Four brands of black poppy seeds, examined by gas chromatography-mass spectroscopy (GC-MS) with deuterated internal standards, contained from 17 to 294 micrograms of morphine and 3 to 14 micrograms of codeine per gram of seeds. Morphine was detected by GC-MS in hydrolysates of serum as late as 24 h after ingestion, with a maximum mean concentration of 100 ng/mL (range 82-131) measured 2 h after the subjects ingested 25 g of seeds. Opiates were detectable (greater than 300 micrograms/L) in urine by enzyme-multiplied immunoassay (EMIT; Syva Co.) and by radioimmunoassay screening procedures for as long as 48 h after ingestion. The identity and quantities of morphine and codeine in poppy seed extracts and in hydrolysates of serum and urine were confirmed by GC-MS. Therefore a positive finding of morphine or codeine in blood and urine may sometimes be due to ingestion of poppy seeds.
Changes in cerebrospinal fluid IgG and apolipoprotein E indices in patients with multiple sclerosis during demyelination and remyelination.
Authors: Rifai N , Christenson R H , Gelman B B , Silverman L M
Published: January 2020

Approximately 85% of patients with multiple sclerosis (MS) can be diagnosed by using magnetic resonance imaging and laboratory tests such as determination of the cerebrospinal fluid (CSF) IgG Index and electrophoresis to detect oligoclonal banding. However, these tests results are abnormal in MS patients whether they are in clinical remission or acute exacerbation. Because apolipoprotein E (apo E) is synthesized in the central and peripheral nervous system, particularly during remyelination, we propose that apo E might be a reliable marker of the remyelination that accompanies clinical remission in MS patients. We studied 33 patients with MS, 22 in remission and 11 in exacerbation, and 26 controls of comparable ages. The apo E Index, calculated from the concentrations of apo E and albumin in CSF and serum, allowed us to discriminate between MS patients in remission and MS patients in exacerbation (P less than 0.001); the IgG Index failed to show similar differences. However, combining the apo E and IgG indices gave maximum discrimination between controls, MS patients in remission, and those in exacerbation. This study suggests that apo E measurements should be included in the laboratory evaluation of MS patients.
Critical evaluation of a commercial enzyme kit (Sigma) for determining oxalate concentrations in urine.
Authors: Parkinson I S , Sheldon W L , Laker M F , Smith P A
Published: January 2020

The Sigma reagent kit for urinary oxalate determination is reportedly simple, rapid, and specific for oxalate. We evaluated the kit and identified a number of shortcomings. Our investigations suggest that the recommended time for chromophore development is too short and should be doubled. Oxalate recovery during the extraction procedure depends strongly on urine pH. For complete extraction, urine should be acidified to pH 1.8-2.4. We also observed positive interference from ascorbate in urine. This interference was substantial, absorbances produced from ascorbate standards being approximately 80% of those obtained from oxalate standards of similar concentration. Our investigations also indicate the presence of a substance on the Sigma adsorbent that is eluted during the extraction procedure and interferes in the color reaction. These interferences represent potentially major sources of imprecision in the assay.
Clinical significance of a low concentration of thyrotropin: five immunometric "kit" assays compared.
Authors: Piketty M L , Talbot J N , Askienazy S , Milhaud G
Published: January 2020

We compared results of five sensitive immunometric assays of serum thyrotropin (TSH) in controls and in different groups of patients with hyperthyroidism, untreated or treated; secondary hypothyroidism; nonthyroidal illness (NTI); or depression; or who were being treated with amiodarone. With most kits, measured TSH concentrations did not overlap between controls and hyperthyroid patients. In untreated secondary hypothyroidism TSH was not always undetectable. Patients with NTI and depression showed many low TSH values, and among these categories of patients, we observed large discrepancies among the kits. This lack of specificity at low concentration means that one cannot assess hyperthyroidism by TSH measurement alone, but it can be used as the first screening test. Similarly, TSH determination cannot be used alone in monitoring therapy (e.g., with carbimazole, thyroxin, amiodarone) to assess the presence of hyperthyroidism. Nonetheless, this assay plays a well-established role in hypothyroidism detection. Four of the five kits were found useful for clinical evaluation, the fifth less so.