bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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."