bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivariate analysis of plasma enzyme profiles in severe head injury.
Authors: Bourguignat A , Ferard G , Jung G , Klumpp T , Metais P 
Published: January 2020

Abstract
We followed the changes in the activities of four enzymes (aldolase, aspartate aminotransferase, creatine kinase, and lactate dehydrogenase) in plasma for four days after head injury. The progression of the changes differs significantly between survivors and nonsurvivors. Stepwise discriminant analysis, involving the four enzymes, allowed us to divide 81 to 92% of head-injured patients (n = 280 selected without conscious bias) correctly into the two groups as early as 72 h after trauma. Most of the patients who were misclassified according to our biochemical criteria had received phenobarbital for sedation. Valuable prognostic information in head injury evaluation may thus be obtained by daily determination of enzymatic activities of these four enzymes.
Effects of substrate concentration on results of determination of prostatic acid phosphatase with thymolphthalein monophosphate.
Authors: Kessner A , Woodard E J , Bowers G N 
Published: January 2020

Abstract
The relation between concentration of thymolphthalein monophosphate substrate and catalytic activity was investigated for the determination of prostatic acid phosphatase. This study, an extension of previously reported work (Clin. Chem. 27: 1372, 1981), shows that lot-to-lot variation in purity of thymolphthalein monophosphate preparations is reflected in substrate-velocity curves. Plateau regions in these curves at 1.5-2.5 g/L result from the combined effects of (a) substrate concentrations that are an order of magnitude below Km and (b) a further decrease in available substrate caused by formation of substrate aggregates in the presence of serum. To simplify the identification of superior lots of thymolphthalein monophosphate, we give a mixed-substrate protocol for testing different lots.
Simple, reproducible procedure for selective measurement of lipoprotein lipase and hepatic lipase.
Authors: Blache D , Bouthillier D , Davignon J 
Published: January 2020

Abstract
Existing methods for determining the release of lipoprotein lipase (EC 3.1.1.34) and hepatic lipase (EC 3.1.1.3) into plasma after heparin injection give highly variable results, primarily traceable to errors in the isolation of labeled oleate from the substrate, triolein. Methods involving anion-exchange resin to bind oleate show high variability and have a low yield. Introducing a strong base in the last step of the assay may spuriously increase the counts from oleate, whereas a detergent such as Triton X-100, used to minimize this problem, has a strong quenching effect. We report a simple and rapid method in which we eliminate rather than correct for the sources of variation. The substrate, tri[1-14C]oleoyl-glycerol, is sonicated under strictly standardized conditions with gum arabic, 50 g/L. Incubation is stopped by addition of a benzene/chloroform/methanol mixture and NaOH, 0.2 mol/L. Labeled oleic acid is extracted with hexane after acidification of the alkaline aqueous (upper) phase, so that no alkali is introduced into the scintillation liquid. For lipoprotein lipase measurement, hepatic lipase is inactivated by a specific antiserum, whereas hepatic lipase is measured after lipoprotein lipase is inactivated by NaCl, 1.0 mol/L. The method is efficient and specific, and quenching and chemiluminescence artifacts are avoided.
Urinary oxalate determination by use of immobilized oxalate oxidase in a continuous-flow system.
Authors: Potezny N , Bais R , O'Loughlin P D , Edwards J B , Rofe A M , Conyers R A 
Published: January 2020

Abstract
In this procedure, oxalate oxidase (EC 1.2.3.4) immobilized in a continuous-flow system is used to determine oxalate in urine. The hydrogen peroxide formed from oxalate is detected by use of a color reaction with peroxidase (EC 1.11.1.7), 3-methyl-2-benzothiazoline hydrazine, and N,N-dimethylalanine. However, urine contains an oxalate oxidase inhibitor, which cannot be removed by heating, ion-exchange resins, or cellulose columns. This makes it necessary to precipitate the oxalate before assay. The overall assay system is accurate (oxalate recovery, 95.9%), sensitive (less than or equal to 5 mumol/L), precise (within-batch CV less than 1.25%, between-batch CV less than 5%), and relatively rapid (60 samples per working day). The assay system has better accuracy than an established chemical method and a gas-chromatographic method, and is considerably less arduous than and correlates well (r = 0.94) with a modified chemical method. The reference interval for urinary oxalate excretion is 0.16-0.56 mmol per day (n = 97). Only nonphysiological concentrations of ascorbate interfere with the assay, by increasing the oxalate result in the overall assay, presumably by post-micturition formation of oxalate from ascorbate in the urine samples.
Effect of protein on the determination of total bile acids in serum.
Authors: Hanson N Q , Freier E F 
Published: January 2020

Abstract
We measured total serum bile acids on a fluorescence-light-scattering micro centrifugal analyzer by the direct enzymatic method with 3 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.50) and with resazurin as a fluorogenic electron acceptor. We found that serum protein has an inhibitory effect on the measurement of bile acids, but this effect was eliminated by adding bovine serum albumin to the reaction mixture in a final protein concentration (12.2 g/L) that was high compared with that contributed by a normal serum specimen. The assay is a sensitive method that reaches equilibrium in 5 min. The method is microscale (5 microL of sample, 150 microL of working reagent), is easy to perform, and is accurate (analytical recovery = 104.1%) and precise (CV = 11.1 and 5.7% on specimens with bile acid concentrations of 7.6 and 35.4 mumol/L, respectively). Normal values are 1-12 and less than 9 mumol/L on nonfasting and fasting individuals, respectively. Pure 3 alpha-hydroxysteroid dehydrogenase must be used: we found several enzyme preparations that gave falsely high values for bile acid.
Simplified liquid-chromotographic analysis for cyclosporin A, and comparison with radioimmunoassay.
Authors: Carruthers S G , Freeman D J , Koegler J C , Howson W , Keown P A , Laupacis A , Stiller C R 
Published: January 2020

Abstract
We describe a simplified isocratic "high-performance" liquid-chromatographic method for measuring a new immunosuppressive drug, cyclosporin A, in biological fluids with use of its analogs cyclosporin C and cyclosporin D as internal standards. The method is reproducible and accurate and appears to be specific for cyclosporin A; the detection limit is 31 micrograms/L. The chromatographic measurements of the concentration of cyclosporin A in serum of patients receiving the drug were invariably lower than those by radioimmunoassay and the difference became more pronounced the greater the period of time after dosing. Because measurements of cyclosporin A in serum standards were almost identical with both techniques, the differences between the two sets of results for patients' samples suggests that the radioimmunoassay is nonspecific and measures metabolites of cyclosporin A.
Assessment of the fundamental accuracy of the Jendrassik-Gróf total and direct bilirubin assays.
Authors: Lo D H , Wu T W 
Published: January 2020

Abstract
Using unconjugated bilirubin (Bu) and authentic human disconjugated bilirubin (dBc) supplemented in low-bilirubin serum pools, we have directly verified for the first time that the Jendrassik-Gróf total bilirubin assay modified after Doumas et al. (Clin. Chem. 19: 984-993, 1973) detects Bu and dBc quantitatively, in Bu-equivalent concentrations relative to gravimetric concentration assignment reinforced with quantification by nuclear magnetic resonance (Wu et al., Clin. Chem. 26: 1323-1335, 1980). By contrast, the Jendrassik-Gróf direct bilirubin assay (also modified after Doumas) quantifies only 70 +/- 5% of the gravimetrically determined dBc as Bu equivalents. By using Bu and dBc (instead of Bu only, as is routinely done) to calibrate the responses of the total and direct bilirubin assays, the analyses of Bu and dBc become much more quantitative. We mathematically explored the meanings of the conventional terms total, direct, and indirect bilirubins. The clinical and diagnostic implications of our observations are discussed.
Evolutionary changes in acute-phase proteins in alcoholic hepatocellular diseases.
Authors: Perier C , Chamson A , Engler R , Frey J 
Published: January 2020

Abstract
We studied the pattern of acute-phase proteins (orosomucoid, C-reactive protein, and haptoglobin) in hepatocellular deficiency due to chronic alcohol consumption, characterized by a decrease in serum transferrin concentration. We found that their patterns could vary independently of hepatocellular deficiency, but depend on the progression of hepatic disease. The most useful protein for discriminating the stage of inflammatory reaction is orosomucoid. In moderate hepatocellular deficiency, acute-phase proteins are increased independently of the decrease in transferrin, whereas in severe hepatocellular deficiency the acute-phase proteins are also decreased. Thus, it is possible to distinguish the two stages of hepatocellular deficiency by following changes in the concentration of orosomucoid.
Soluble forms of gamma-glutamyltransferase in human adult liver, fetal liver, and primary hepatoma compared.
Authors: Selvaraj P , Balasubramanian K A 
Published: January 2020

Abstract
We isolated the soluble forms of gamma-glutamyltransferase (EC 2.3.2.2; gamma-GT) from adult and fetal human liver and primary hepatoma and compared their properties. The Km value for L-gamma-glutamyl-p-nitroanilide and glycylglycine, the Ki for anthglutin, and the pH optimum were identical for the enzyme from all three sources. Nor were significant differences observed among the three in their heat stability, inhibition by serine and borate, or ability to transfer the gamma-glutamyl moiety to various amino acids and dipeptides. Unlike membrane-bound gamma-GT, the soluble form from all three sources entered polyacrylamide gel and showed identical electrophoretic mobilities. Treatment with neuraminidase decreased the electrophoretic mobilities to a similar extent. The relative molecular mass of the enzyme from each of the three sources is about 84 000. Immunoinhibition and immunoprecipitation of gamma-GT from the three sources by antibody to fetal liver gamma-GT followed an identical pattern. Gamma-GT from fetal liver and hepatoma differed significantly from that of adult liver in affinity for wheat-germ agglutinin and Ricinus communis agglutinin (RCA-120). In many of the properties studied, soluble gamma-GT resembles the papain-digested form of membrane-bound gamma-GT.
Assay of urinary N-acetyl-beta-glucosaminidase in a centrifugal analyzer.
Authors: Powell S C , Scaro J , Wilson E , Shihabi Z K 
Published: January 2020

Abstract
We describe a kinetic, fluorometric assay for urinary N-acetyl-beta-glucosaminidase (EC 3.2.1.30) by measurement of the release of 4-methylumbelliferone (7-hydroxy-4-methylcoumarin). The method is simple, involving only a single reagent, and is applicable to the assay of other enzymes that hydrolyze similar fluorescent-labeled substrates. The enzyme distribution in human tissues and fluids is described. The enzyme is present in high concentrations in human kidney, liver, and lung. Its concentration in urine is shown to be a sensitive indicator of early renal damage, which precedes changes in serum creatinine and urinary protein. Assay of the enzyme is quite useful in monitoring renal damage due to myoglobinuria.
Cathodal bands in electrophoretograms of creatine kinase isoenzymes in serum collected after cardiac surgery: a poor prognostic sign.
Authors: Keshgegian A A , Marchant B L 
Published: January 2020

Abstract
Of 708 patients who had undergone cardiac surgery, the serum of 23 showed one or two enzyme bands cathodal to CK-MM in creatine kinase (CK) isoenzyme electrophoretograms. Postoperative mortality rate during hospitalization was: no bands, 8.8%; one band, 13%, two bands, 63% (p less than 0.001). Patients whose sera showed cathodal bands were slightly older than those without, and their postoperative serum lactate dehydrogenase (LD) activity was greater, with very high proportions of LD 5. The two cathodal bands in patients who died differed in cathodal electrophoretic mobility from the two bands in survivors, implying that different enzyme forms were involved. All cathodal bands were inhibited by reagent containing diadenosine pentaphosphate, as was adenylate kinase from erythrocytes and liver cytoplasm. Mitochondrial CK from liver and presumed mitochondrial CK in serum from a patient with malignancy were not inhibited. We conclude that the appearance of two enzyme bands cathodal to CK-MM, probably representing adenylate kinase and possibly originating from various tissues, is associated with a poor prognosis in patients after cardiac surgery.
A "column-batch" method for separating MB and LD1 in a single fraction.
Authors: Morin L G , Barton E G 
Published: January 2020

Abstract
In this "column-batch" method for separating the MB and BB isoenzymes of creatine kinase and the LD1 isoenzyme of lactate dehydrogenase, one can, alternatively, separate MB from BB or obtain a combined fraction containing MB, BB, and LD1. The principal advantage is that the resulting fractions are twofold as concentrated as was the applied sample. Thus, activity can be measured by conventional automated methods, with no need for the modifications to compensate for diluted fractions that are required by other ion-exchange methods. Another advantage is the total absence of interference by the MM isoenzyme. A strong anion exchanger (AG-MP1, Bio-Rad) is used in the acetate form at pH 6.3. There is no retention of MM; retained MB, BB, and LD1 are eluted with a solution of magnesium acetate. Results are compared with those obtained for subunit B and LD1 by immunoinhibition. Results with patients are considered consistent with myocardial infarction if MB exceeds 20 U/L and 3% of the total CK and LD1 exceeds 130 U/L or 28% of the total LD activity.
Purification and characterization of human pancreatic phospholipase A2.
Authors: Eskola J U , Nevalainen T J , Aho H J 
Published: January 2020

Abstract
We purified human pancreatic phospholipase A2 from postmortem pancreatic tissue by elution of the semi-purified enzyme on CM-Sephadex C-25 with a linear NaCl gradient at pH 6.0. The enzyme appeared as a single polypeptide chain with an isoelectric point of 9.2 +/- 0.1. The relative molecular mass of the enzyme was estimated to be 15 800 +/- 1000 by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The enzyme is resistant to heating and to a 25 g/L concentration of sodium dodecyl sulfate. It is inhibited by Ca2+ ions in the presence of ovolecithin and deoxycholate. By immunohistochemical methods we showed the enzyme to be localized in the apical zymogen granule portion of pancreatic acinar cells.
Five recent urinary tests for early pregnancy evaluated.
Authors: Ryder K W , Munsick R A , Oei T O , Young P C , Blackford H F 
Published: January 2020

Abstract
We evaluate five tests developed for the earlier detection of pregnancy, either in the clinical laboratory or by the patient in her home. These tests offer no advantage over other urinary pregnancy tests, and the results are distinctly inferior to those reported (Clin. Chem. 29: 561-563, 1983) for some serum tests for pregnancy.
Quantification of urinary oxalate with oxalate oxidase from beet stems.
Authors: Obzansky D M , Richardson K E 
Published: January 2020

Abstract
We describe an automated (ABA-100) enzymic method for determination of urinary oxalate by use of oxalate oxidase (EC 1.2.3.4) isolated from beet stems. The H2O2 produced by the oxidation of oxalate by oxalate oxidase is measured by coupling with oxidation and conjugation of 3-methyl-3-benzothiazolinone hydrazone with N,N-dimethylaniline with catalysis by horseradish peroxidase. The resulting indamine dye is measured spectrophotometrically by the difference in absorption at 500 and 600 nm. Interfering substances are removed by oxidation with acidic ferric chloride and by cation-exchange chromatography. The assay is sensitive to 5 mg of urinary oxalate per liter, the standard curve is linear to 70 mg/L, and the procedure requires less than 3 h for completion. The within-run CV was less than 1.6%, the between-day CV less than 5.6%. The oxalate oxidase method results in a mean and reference interval for oxalate excretion that are comparable with those by isotope dilution, gas-chromatographic, colorimetric, and other enzymic procedures.
Salivary urea nitrogen as an index to renal function: a test-strip method.
Authors: Akai T , Naka K , Yoshikawa C , Okuda K , Okamoto T , Yamagami S , Inoue T , Yamao Y , Yamada S 
Published: January 2020

Abstract
To investigate the feasibility of using salivary urea nitrogen as an index of renal glomerular filtration rate, we developed and applied a new analytical system consisting of a urease-containing test strip and an automatic reflectance spectrometer. The concentrations of urea nitrogen so determined correlate well (r = 0.93) with concentrations in serum. These preliminary data suggest that our method can be used routinely as a simple and reliable means of detecting abnormalities of renal function.
An enzyme-linked immunosorbent assay for lactose synthase (galactosyltransferase) in serum and its application as a tumor marker in ovarian carcinoma.
Authors: Verdon B , Berger E G , Salchli S , Goldhirsch A , Gerber A 
Published: January 2020

Abstract
This assay for lactose synthase (galactosyltransferase, EC 2.4.1.22) in serum involves two sequential incubations: serially diluted standard or sample antigen is reacted with a fixed amount of antibody; unbound antibody is then adsorbed to wells of antigen-coated microtiter plates and determined by a second antibody directed against the first antibody and coupled to phosphatase. The standard curve is linear for galactosyltransferase concentrations of 10 to 600 micrograms/L. The within-assay CV of a serum sample was 9.3% (SD 4.1%), the between-assay was 3.8% (SD 2.4%). Serum galactosyltransferase concentrations computed from three different dilutions yielded CVs of 6.5% (SD 5.7%, n = 14). We evaluated the method's accuracy by recovery analysis and by comparing enzyme activity in serum with that of purified galactosyltransferase from human milk. The normal reference interval, as estimated from data on 27 healthy blood donors, was 60-436 micrograms/L (mean 224, SD 101 micrograms/L). We applied the assay to samples of serum from ovarian carcinoma patients grouped according to tumor burden. We also determined galactosyltransferase in ascites fluid and found these values useful for diagnosis, whereas determinations in serum may serve mainly for patient monitoring.
Spectrophotometric method for selective assay of the five isoenzymes of human lactate dehydrogenase, based on their different stabilities at alkaline pH.
Authors: Takizawa N , Yamauti J , Marui Y , Hayashi C , Yamashita J , Horio T 
Published: January 2020

Abstract
After preincubation of human lactate dehydrogenase (EC 1.1.1.27) isoenzymes 1 through 5 with lactate at pH 9.4, 9.8, 10.25, and 10.6 at 30 degrees C for 10 min, the reduction of NAD+ was measured at the same pH values and temperature during the interval 1-2 min after adding the coenzyme. Relative to the reference activities measured at pH 8.7 by the method of Buhl et al. (Clin Chem 23: 1289-1295, 1977), the respective activities of isoenzymes 1 through 5 thus measured were 111, 104, 96, 68, and 0% at pH 9.4; 123, 108, 88, 0, and 0% at pH 9.8; 140, 100, 0, 0, and 0% at pH 10.25; and 138, 0, 0, 0, and 0% at pH 10.6. These relations allow selective assay of the respective isoenzymes in samples containing mixtures of them. Optimal conditions for such selective assay at 37 degrees C are reported.
(3-sn-Phosphatidyl)cholines (lecithins) in amniotic fluid.
Authors: Touchstone J C , Levin S S , Dobbins M F , Matthews L , Beers P C , Gabbe S G 
Published: January 2020

Abstract
Many currently used thin-layer chromatographic methods for phospholipid assay rely on charring the developed plate in the presence of cupric acetate. Saturated acyl phospholipids do not react. We find that substitution of cupric sulfate results in detection of both saturated and unsaturated phospholipids. By exploiting the difference with the two reagents, one can separately estimate the amounts of saturated phospholipid. The method described here is reproducible, and we illustrate its use in determinations of (3-sn-phosphatidyl)cholines (lecithins) in amniotic fluid from problem pregnancies.
Time-course of cigarette smoke contamination of clinical hydrogen breath-analysis tests.
Authors: Rosenthal A , Solomons N W 
Published: January 2020

Abstract
The time-course of the contamination of exogenous hydrogen from cigarette smoke on postprandial breath hydrogen concentration was evaluated in 10 subjects, six regular smokers and four occasional smokers. Breath hydrogen values were determined by gas chromatography 10 min, 5 min, and immediately prior to smoking a filter cigarette; during smoking from a sample of exhaled air containing smoke; and 5, 10, and 15 min after extinguishing the cigarette. A three- to 137-fold increase above basal hydrogen concentrations was produced by exhaled cigarette smoke, but most subjects had re-equilibrated to baseline values within 10 to 15 min after the cigarette. If subjects undergoing clinical hydrogen breath tests cannot refrain from smoking during the duration of the test, one should allow an interval of at least 15 min from the end of smoking to the collection of a breath sample.
Enzyme immunoassay for carcinoembryonic antigen.
Authors: Smith A M , Macdonald D J 
Published: January 2020

Abstract
In this rapid, simple enzyme immunoassay for carcinoembryonic antigen (CEA) in serum the "sandwich" system is used. The CEA is first extracted from the serum into acetate buffer by heating at 70 degrees C, then incubated in a polyvinyl microtitration plate previously coated with anti-CEA. The bound CEA is then reacted with anti-CEA conjugated to horseradish peroxidase and the activity of the peroxidase bound to the wells of the plate is quantified by adding the enzyme substrate. The assay is sensitive to 3.1 micrograms/L (which can be improved to 0.39 microgram/L by prolonging the incubation times to 120 min), precise (between-assay CV 8.0%), and shows adequate analytical recoveries. Results compared favorably with those by a radioimmunoassay kit (Abbott Diagnostics), r = 0.99. The reference interval for serum CEA in normal adults is shown. This assay is appropriate for use in monitoring patients with colorectal tumors after surgery.
Absorbance nephelometry of immune complexes by reaction with anti-IgG after treatment with polyethylene glycol.
Authors: Levinson S S , Goldman J 
Published: January 2020

Abstract
We describe absorbance nephelometry of immunoglobulin G (IgG) in immune complexes (IC) with use of anti-IgG after precipitating the IgG from serum by three treatments with polyethylene glycol, 25 g/L final concentration. The three-step procedure removed all of the monomeric IgG, eliminating interference with the IC assay. Analytical recovery of IC was nearly 100%. Both the standard curve and results for control sera showed good day-to-day reproducibility, with CVs of less than 8%. Eighteen of 20 patients with diseases involving IC showed distinctly increased concentrations of IC; no increases were seen in 15 normal persons. Measurement of IC in 44 samples by this assay and a C1q assay gave a Spearman rank correlation coefficient of 0.76. The assay appears suited to routine use with manual double-beam spectrophotometers and stable nephelometers. The procedure is inexpensive, straightforward, and easy to perform.