bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous enzyme immunoassay of two thyroid hormones.
Authors: Blake C , Al-Bassam M N , Gould B J , Marks V , Bridges J W , Riley C 
Published: January 2020

Abstract
We describe an enzyme immunoassay in which the two thyroid hormones, triiodothyronine and thyroxin, are measured simultaneously in a single tube. The method involves labeling the two with separate enzymes (beta-galactosidase and alkaline phosphatase, respectively), whose catalyzed reactions can easily be distinguished from each other by absorption spectrophotometry, with o-nitrophenyl-beta-galactoside and phenolphthalein monophosphate as substrates. Performance of this dual assay method compares well with that of conventional single-hapten enzyme-labeled assays, and results compare well with those by two single-hapten radioimmunoassays. The dual assay has certain advantages over single-hapten methods: smaller sample volume, lower reagent cost, and shorter overall assay time. As presented here, the use of enzyme labels to measure two (or more) haptens simultaneously represents a significant advance in the use of immunoassay techniques.
Plasma hormone concentrations and serum 17 beta-hydroxysteroid dehydrogenase activity in molar pregnancy.
Authors: Massart C , Le Pogamp C , Nicol M 
Published: January 2020

Abstract
Concentrations of unconjugated 17 beta-estradiol, estrone, and estriol, and of progesterone, 17 alpha-hydroxyprogesterone, testosterone, delta 4-androstenedione, dehydroepiandrosterone sulfate (DHEAS), choriogonadotropin beta-subunit, and prolactin were measured by radioimmunoassay in plasma of six patients with molar pregnancies of seven to 15 weeks of gestation. Serum 17 beta-hydroxysteroid dehydrogenase (EC 1.1.1.6.2) activity was also determined. Estriol was not detected in any of the six women. Values for DHEAS and progesterone were normal, except for one patient who had above-normal plasma progesterone. Values for the other hormones and the enzyme were within normal limits in very early intact molar pregnancies, but were above normal limits in more advanced cases. A close correlation was seen between 17 beta-hydroxysteroid dehydrogenase activity and concentrations of estradiol, estrone, testosterone, and 17 alpha-hydroxyprogesterone; the last four also correlated significantly with beta-choriogonadotropin in molar pregnancies, whether benign or invasive. Benign trophoblastic disease showed significant correlation of progesterone with beta-choriogonadotropin and with estradiol. We conclude that the estradiol, estrone, testosterone, and 17 alpha-hydroxyprogesterone were principally derived from molar tissue.
Two-cycle liquid-chromatographic quantitation of cortisol in urine.
Authors: Nakamura J , Yakata M 
Published: January 2020

Abstract
When the free cortisol in urine was analyzed by liquid chromatography after pretreatment with the usual organic extraction, interfering substances having chromatographic behavior similar to that of cortisol and the internal standard precluded accurate measurement. To remove these materials, we processed the organic extract by liquid chromatography with a normal-phase column for clean-up; the specific cortisol fraction and the internal standard collected in the effluent were then subjected to liquid chromatography with a reversed-phase column. The "two-cycle" chromatograms thus obtained were sufficiently specific for the quantitation of urinary cortisol. The method clearly detects cortisol in urine at a minimum concentration of about 5 micrograms/L when 1 mL of urine is extracted. The mean urinary free cortisol in apparently healthy individuals was 40.9 (SD 17.7) micrograms/day (n = 32) by this method.
Improved liquid-chromatographic assay of quinidine and its metabolites in biological fluids.
Authors: Rakhit A , Kunitani M , Holford N H , Riegelman S 
Published: January 2020

Abstract
We describe a simple, rapid, and specific assay for quinidine and its known metabolites in plasma, urine, and bile. Plasma proteins are precipitated by adding acetonitrile, which also contains the internal standard. The supernatant fluid is evaporated and the reconstituted residue is separated on a reversed-phase column, with fluorescence detection. The standard curve is linear and results are reproducible over the clinical concentration ranges: quinidine 0.4 to 8.0 mg/L and the three metabolites (quinidine 10,11-diol, 3-hydroxyquinidine, and quinidine-N-oxide) 0.05 to 1.5 mg/L. As little as 10 micrograms of the N-oxide metabolite per liter and 1 microgram of the other analytes per liter can be quantitated in 0.5 mL of plasma, urine, or bile. With the use of an automated chromatographic system, many samples can be analyzed in a continuous run.
Heparin interferes with the radioenzymatic and homogeneous enzyme immunoassays for aminoglycosides.
Authors: Krogstad D J , Granich G G , Murray P R , Pfaller M A , Valdes R 
Published: January 2020

Abstract
Heparin interferes with measurement of aminoglycosides in serum by biological, radioenzymatic, and homogeneous enzyme immunoassay techniques, but not with radioimmunoassay. At concentrations greater than or equal to 10(5) and greater than or equal to 3 X 10(6) USP units/L, respectively, it interferes with the radioenzymatic assay by inhibiting the gentamicin 3-acetyltransferase (EC 2.3.1.60) and kanamycin 6'-acetyltransferase (EC 2.3.1.55) enzymes used in the assay. It interferes with the homogeneous enzyme immunoassays for gentamicin and tobramycin (at concentrations greater than or equal to 10(5) and greater than or equal to 10(4) USP units/L, respectively), but not with the commercially available homogeneous enzyme immunoassays for other drugs. Heparin interference with the homogeneous enzyme immunoassay for aminoglycosides requires both the heparin polyanion and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) bound to a cationic aminoglycoside. This interference can be reproduced with dextran sulfate (but not dextran), and does not occur with free enzyme (glucose-6-phosphate dehydrogenase) alone. We describe how heparin interferes with these two assays and demonstrate interference at heparin concentrations that may be present in intravenous infusions or in seriously underfilled blood-collection tubes.
Single-stage automated assay for heparin.
Authors: Kapke G F , Feld R D , Witte D L , Johnson G F 
Published: January 2020

Abstract
We have developed a single-stage assay for heparin, using reagents modified from the two-stage Dade Protopath heparin synthetic substrate assay. The single-stage assay involves simultaneous mixing of a plasma sample, an antithrombin III source, alpha-thrombin, and the alpha-thrombin fluorogenic substrate. The synthetic substrate, antithrombin III, and heparin-antithrombin III complex compete for the alpha-thrombin active site. The alpha-thrombin is inactivated by the heparin-antithrombin complex while substrate is being hydrolyzed, so that total product formation decreases with heparin concentration. Day-to-day CV was 9.3% at a heparin concentration of 246 USP units/L. Comparison of results of the single-stage heparin assay with those of a two-stage esterolytic assay yielded the linear regression equation: esterolytic = 0.834 (single-stage)--7 USP units/L (r = 0.94, n = 47). Bilirubin interfered with the single-stage assay, resulting in an apparent increase in sample heparin concentration. The single-stage heparin assay can be automated for centrifugal analyzers capable of double-reagent addition and fluorometric detection, substantially decreasing reagent requirements and therefore costs.
Homologous radioimmunoassay for human parathyrin (residues 53-84).
Authors: Hitzler W , Schmidt-Gayk H , Spiropoulos P , Raue F , Hüfner M 
Published: January 2020

Abstract
We describe a sequential saturation double-antibody radioimmunoassay for carboxyl-terminal fragments of human parathyrin (hPTH) in serum. Standards are prepared with synthetic hPTH (residues 53-84) in hPTH-free serum. Antisera are obtained by immunizing guinea pigs with partly purified hPTH extracted from adenomatous glands. Tracer is prepared by labeling hPTH (53-84), presumably at the histidine residue, with 125I by the Chloramine T method at pH 8.6. Dilution curves for hPTH extracted from adenomas are superimposable on dilution curves for the synthetic 53-84 fragment. Dilution of sera from hyperparathyroid patients showed linearity of response with concentration in the present assay, but non-linearity in the heterologous radioimmunoassay. In contrast to the heterologous system, which discriminated 28 of 32 patients with primary hyperparathyroidism from 32 normals (normal range: undetectable to 54 pmol/L, omitting the highest and lowest values from controls), the present assay separated these groups without overlap.
Fetal lung maturity in complicated pregnancy, as predicted from microviscosity of amniotic fluid.
Authors: Simon N V , Hohman W A , Elser R C , Levisky J S , Carp M J , Ashton S S 
Published: January 2020

Abstract
We measured the microviscosity of amniotic fluid between 28 and 40 weeks of gestation in 252 normal pregnancies and in 172 pregnancies complicated by factors known to influence fetal lung maturation, including chronic high blood pressure, pregnancy-induced hypertension, diabetes mellitus, and therapy with betamethasone. Comparison of the microviscosity value distributions and regression analysis indicated significantly lower microviscosity values in hypertensive disorders, in Class D and Classes F or R diabetes, and after 48 h of treatment with betamethasone. Few changes were observed in Classes A, B, or C diabetes. These observations are consistent with the accelerated maturation of surfactant observed in chronic intrauterine stress and the lower incidence of hyaline membrane disease reported after glucocorticoids.
Micromethod for lipid-chromatographic determination of cholesterol in lipemic sera.
Authors: Webb L E , Lengle E , Izzo R , Woods E 
Published: January 2020

Abstract
A micromethod involving "high-performance" lipid chromatography was developed for determining cholesterol in sera obtained from animals that has been infused with high doses of lipid emulsions. Only 50 micro L of serum is required, and there is no interference from turbidity, bilirubin, fat-soluble vitamins, and sterols. Correlation with the commonly used Abell-Kendall method was good at cholesterol concentrations as great as 10.0 g/L (r = 0.998). The assay is ideal for determinations on samples from pediatric and hyperlipidemic patients. It is particularly useful for monitoring patients on lipid-emulsion therapy and for toxicological studies with small animals.
p-Nitrophenylglycosides as substrates for measurement of amylase in serum and urine.
Authors: McCroskey R , Chang T , David H , Winn E 
Published: January 2020

Abstract
Pantrak E.K. (endpoint and kinetic) Amylase reagent (Calbiochem-Behring) is the first commercially available alpha-amylase reagent in which p-nitrophenyl-d-glycosides are used as the substrate. We describe the effect of reagent composition on reagent performance. The reagent performance compares well with that of Amylochrome reagent (Hoffmann-La Roche), Du Pont aca, and Beckman D.S. amylase reagents in assays of sera and urines. We detected no interference from increased concentrations of glucose or pyruvate in the sample. The reagent can be used in either a manual fixed-time or an automatable kinetic assay.
Functional activity of intrinsic factor measured by using solubilized receptor protein.
Authors: Marcoullis G , Rothenberg S P 
Published: January 2020

Abstract
The traditional radioimmunoassay for gastric intrinsic factor, in which this protein is measured on the basis of immunoreactivity rather than function, is of no value for identifying intrinsic factor that binds cobalamin but does not bind to the ileal receptor site, or for detecting animal intrinsic factor, which does not cross react with human intrinsic factor. Accordingly, we have applied a radioassay for the intrinsic factor receptor protein to measure the functional activity of intrinsic factor in gastric juice. The receptor protein reagent was partly purified from guniea pig ilea and its interaction with intrinsic factor--CN[57Co]-cobalamin was determined by precipitation with sodium sulfate at a final concentration of 150 g/L. Results of this assay were comparable with results obtained for intrinsic factor by radioimmunoassay. The receptor protein did not bind immunoreactive intrinsic factor that was functionally abnormal. This functional radioassay for intrinsic factor is not species specific and will be of value when specific antiserum to intrinsic factor is not available and when cobalamin malabsorption is to be evaluated in patients who are secreting normal amounts of immunoreactive intrinsic factor.
More SensitiveFlamelessAtomicAbsorptionAnalysisof Vanadiumin Tissueand Serum
Authors: Stroop Steven D , Helinek Gerard , Greene Harry L 
Published: January 2020

Abstract
Vol. 28
p 79: See response in Letter of Cornelisand Versieck, p 1709.
p 91: In the note added in proof, "131" should read "1.31."
p 241: In Table 1, "6.5" should read "65"; in the footnote to Table 2, "0.05" should read "0.5" and the next to last paragraph should read: "Finally, in a few instances we have compared the glucose values obtained by using a drop of sample according to the instructions, versus dipping the strips into the sample, and found some variance between the values obtained by the two methods."
p 344: Under "staining reagent," the correct concentration of orthophosphoric acid is 160 g/L (not 80 g/L). It is prepared by diluting 95 mL of the concentrated acid (850 g/kg, relative density 1.69 g/mL) to 1 L with distilled water.
p 418: ref. 94, cited in the first full paragraph, should read "84."
p 419: The volume number of ref. 1 should be 50, not 19.
p 502: Corrections to two equations: the term (S2y - S2x) should read (S2y - S2x)2 and in the third equation in the second column delete the repetition of the term "(wx4)," which should only appear once.
p 531: In last full paragraph in column one, the word "propionate" in the next to last line should instead read "dimethyl sulfoxide."
p 614: References 21 and 22 are missing
21: Gerhardt, W., Ljungdahl, L., Borjesson, J., et al., Creatine kinase B-subunit activity in human serum. I. Development of an iminunoinhibition method for routine determination of S-creatine kinase B-subunit activity. Clin. Chim. Acta78, 29-41 (1977).
22: Neumeier, D., Prellwitz, W., Wurzburg, U., et al., Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity: Activity kinetics and diagnostic significance in myocardial infarction. Clin. Chim. Acta73, 445-451 (1976).
p 727: With regard to this Letter, the authors later pointed out that although the first sentence states that glycosylated hemoglobins have a higher isoelectric point, glycosylation actually decreases the isoelectric point. Later (p 728) they speculated that the fast hemoglobin variant might be HbN-Baltimore (α2β295Lys→Glu), but two reference laboratories identified it as the slightly slower HbJ-Baltimore (α2β216Gly→Asp).
p 735: In the middle column, the third full paragraph, "Department of Internal Medicine" should read "Department of Laboratory Medicine."
p 736: In column one, under Awards, the citation should have stated "in recognition of his contribution in the, field of clinical chemistry."
p 1199: Table 1 folate concentrations should be "mg/L," not rg/L.
Enzyme immunoassay of the glycoprotein tropic hormones--choriogonadotropin, lutropin, thyrotropin--with solid-phase monoclonal antibody for the alpha-subunit and enzyme-coupled monoclonal antibody specific for the beta-subunit.
Authors: Wada H G , Danisch R J , Baxter S R , Federici M M , Fraser R C , Brownmiller L J , Lankford J C 
Published: January 2020

Abstract
Monoclonal antibody technology has made it possible to produce homogeneous populations of antibodies to discrete determinants on an antigen surface. We have produced monoclonal antibodies to the alpha-subunit and beta-subunits of the glycoprotein hormones choriogonadotropin, thyrotropin, and lutropin, and developed two-site simultaneous enzyme-linked immunospecific assays for these hormones. The anti-alpha-subunit monoclonal antibody was used as the solid-phase (coated tube) capture antibody for all three hormones; the anti-beta-subunit monoclonal antibodies were coupled to horseradish peroxidase (EC 1.11.1.7). Cross reactions between the closely related choriogonadotropin and lutropin were apparently greater in this method than in RIA, with use of the same antibodies. Ka of the antibodies did not appear to be as critical to sensitivity of the sandwich assay as it was for RIA. The lower limit of detection was 0.2 microgram/L after a 2-h incubation with serum sample at room temperature and a 30-min incubation with enzyme substrate at room temperature after washing away excess enzyme conjugate. Within-assay precision (CV) was very good, less than 6%.
Analysis of serum by high-field proton nuclear magnetic resonance.
Authors: Bock J L 
Published: January 2020

Abstract
Improvements in nuclear magnetic resonance (NMR) technology are generating an expanding variety of medical applications. In this investigation I have used high-field proton NMR to identify and quantity endogenous and ingested substances in human serum. After addition of a small amount of 2H2O and a reference compound to a 0.4-mL specimen, spectra were recorded for 3 min in Fourier-transform mode, with use of presaturation to suppress the extremely intense H2O peak. Compounds detected at clinically significant concentrations include glucose, alcohols, acetone, organic acids, and salicylate. Less than 1 mmol/L of some of these substances could be detected. For serum containing 20--500 mg of added methanol per liter, peak area was a linear function of concentration (r = 0.998). High-field proton NMR, despite the drawback of expensive, sophisticated instrumentation, offers some unique advantages for clinical chemistry: it permits rapid, specific, nondestructive measurement of several compounds simultaneously, including some that may be inconvenient to measure by conventional means.
Semiautomated microfluorometric instrument and reagent system for monitoring disease-related immunosuppression.
Authors: Ranney D F , Quattrone A J 
Published: January 2020

Abstract
Several common metabolites and drugs in the serum in of patients with inflammatory, infectious, autoimmune, immunodeficient, neoplastic, and toxicant-induced diseases can produce artifactual suppression of the [methyl-3H]-thymidine assay, which is widely used to evaluate lymphocyte responsiveness. We have developed a sensitive, semiautomated, fluorescence-enhancement assay in which true immunosuppressors are measured in the presence of absence of such interfering substances. Peripheral blood lymphocytes are activated with mitogens in standard microtiter culture trays. Changes in lymphocyte DNA content are quantified with a reagent formulation containing mithramycin, the fluorescence of which is enhanced on binding to DNA in the presence of MgCl2. We solubilize cells within the intact microtiter tray by using an automated, inverted "Array Sonicator," and measure fluorescence with an automated, photon-counting fluorometer. With this system, immune response modulation can be accurately assessed in the presence of patients' sera and other complex test substances (e.g., supernates from hybridomas, fermentation vats, viral preparations, and macrophage cultures.
Establishing the direct-potentiometric "normal" range for Na/K: residual liquid junction potential and activity coefficient effects.
Authors: Czaban J D , Cormier A D , Legg K D 
Published: January 2020

Abstract
The observed reference ranges for sodium and potassium as determined by direct potentiometry vary from instrument to instrument, depending on the composition of the calibration standards. To resolve the existing confusion as to which reference intervals are most appropriately considered "normal," we propose a straightforward convention (based on plasma-water concentration units) in which the difference between direct (undiluted sample) and indirect (diluted sample) methodologies is accounted for by the volume displacement effect of proteins, lipids, and other dissolved substances in a typical plasma sample. Thus, the proposed reference intervals for sodium and potassium are approximately 7% greater by direct potentiometry than by procedures involving dilution. Data consistent with this convention can be obtained with a variety of aqueous-based calibrants, provided care is taken to minimize the errors resulting from activity coefficient and liquid junction potential effects. Additional experimental results are presented to show that these effects also account for the apparent suppression of the sodium ion concentration observed in the presence of bicarbonate ion.
Electrochemical investigation of hapten-antibody interactions by differential pulse polarography.
Authors: Wehmeyer K R , Halsall H B , Heineman W R 
Published: January 2020

Abstract
The binding of electroactively labeled estriol with estrogen-specific antibody and its subsequent displacement by unlabeled estriol have been monitored by differential pulse polarography. Estriol was found to be electro-inactive in the potential range -200 mV to -1000 mV vs a silver/silver chloride electrode. Estriol labeled in the 2 and 4 position with nitro groups was electroactive, giving two reduction waves at -422 mV and -481 mV vs a silver/silver chloride electrode. The peak current was linear with concentration over the range 60 micrograms/L to 3.7 mg/L. The addition of aliquots of estrogen-specific antibody reduced the peak current proportionately, indicating the binding of ligand to specific antibody. Subsequent addition of unlabeled estriol produced incremental increases in peak reduction current, indicating competitive and reversible binding of the two ligands for the antibody. Separation of bound from free labeled hapten was not necessary because reduction of the antibody-bound labeled estriol is attenuated at the electrode.
Separation of alkaline phosphatase isoenzymes from human kidney and comparison with alkaline phosphatases from other human tissues, urine, and Escherichia coli.
Authors: Hodson A W 
Published: January 2020

Abstract
Human kidney isoenzymes of alkaline phosphatase (EC 3.1.3.1) after extraction with butan-1-ol were separated by ammonium sulfate precipitation, gel filtration, and chromatofocusing fractionation methods. The separation at each fractionation step was monitored by starch gel and equilibrium-gradient-pore electrophoresis, the latter technique also being used to determine molecular mass. The determined molecular mass (daltons) of alkaline phosphatase from human placenta was 132 000, from urine 95 000, and three isoenzymes from kidney were 195 000, 140 000, and 95 000, respectively. The mass of Escherichia coli alkaline phosphatase was 80 000 daltons, and that of human liver alkaline phosphatase was assumed to be 160 000 daltons. The urinary isoenzyme and the electrophoretically fastest migrating kidney isoenzyme were similar with regard to pH optima, charge, and molecular mass as well as response to L-phenylalanine, L-homoarginine, heat, and urea. Bacterial alkaline phosphatase could be distinguished from the alkaline phosphatases in human tissues and urine by differences in the response to changes in pH and several other physicochemical properties.