bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid-chromatographic analysis for esmolol and its major metabolite in urine.
Authors: Achari R , Drissel D , Hulse J D 
Published: January 2020

Abstract
We describe a simple, reproducible liquid-chromatographic method for determination of esmolol (a short-acting beta blocker) and its major metabolite in human urine. Esmolol is extracted from urine at a pH of 8.4 into methylene chloride; the more polar metabolite remains in the aqueous phase. We then measure esmolol with a muBondapak C18 column and measure ultraviolet absorbance at 229 nm; the metabolite is analyzed with a Spherisorb phenyl column, with absorbance measured at 280 nm. The average extraction recoveries of esmolol and the metabolite were 95 and 92%, respectively. Standard curves were linear and reproducible for esmolol from 0.025 to 5 mg/L and for the metabolite from 1 to 250 mg/L. Within-day CVs for both compounds were less than 6%.
Abbott TDx, Dade Stratus, and Du Pont aca automated digoxin immunoassays compared with a reference radioimmunoassay method.
Authors: Clark D R , Inloes R L , Kalman S M , Sussman H H 
Published: January 2020

Abstract
Automated digoxin immunoassays with the Abbott TDx, Dade Stratus, and Du Pont aca were evaluated against an RIA similar to the Centers for Disease Control Candidate Reference Method. All three automated methods correlated poorly with the reference method. Particularly disconcerting were the falsely increased values (up to 0.6 micrograms/L) obtained by the Stratus for blank specimens. We discuss the inaccuracies of the results in terms of sample matrix effects, calibrator problems, lot-to-lot reagent variation, and our laboratory requirements. We strongly support the acceptance of the CDC Candidate Reference Method for digoxin and the establishment of a standardized protocol for determining the accuracy of digoxin measurements.
Immunoradiometric assay of thyrotropin in plasma: its value in predicting response to thyroliberin stimulation and assessing thyroid function in amiodarone-treated patients.
Authors: Wiersinga W M , Endert E , Trip M D , Verhaest-de Jong N 
Published: January 2020

Abstract
We measured thyrotropin in plasma by an ultrasensitive immunoradiometric assay (TSH-IRMA, "Sucrosep," Boots-Celltech), before and after thyroliberin (TRH) stimulation, in 71 patients with suspected thyroid-function disorders. Thirty-three were taking amiodarone; none was receiving (anti)thyroid drugs. The patients were divided into four groups, according to their TSH response to TRH (as measured previously by conventional TSH-RIA) and the concentrations of thyroxin (T4) and triiodothyronine (T3) in their plasma. Observed ranges of plasma TSH-IRMA (milli-int. units/L) before and after TRH were: euthyroid (n = 20), 0.2-3.0 and 1.7-15.5; subclinically hypothyroid (n = 14), 4.3-18.5 and 20-75; hyperthyroid (n = 17), less than 0.09 and less than 0.09-0.4; and subclinically hyperthyroid (n = 20), less than 0.09-1.1 and less than 0.09-2.6. Evidently TSH-IRMA results for a single sample completely distinguish hyperthyroidism from euthyroidism. However, TSH-IRMA values may also be undetectable in subclinical hyperthyroidism. The TSH response to TRH can be predicted from basal TSH-IRMA results less than 0.09 or greater than or equal to 0.8 milli-int. unit/L, intermediate values can be associated with either a normal TSH response (euthyroidism) or a decreased TSH response (subclinical hyperthyroidism only). We advocate TSH-IRMA as the first diagnostic test of thyroid function for amiodarone-treated patients.
Statistical analysis of the stability of the standard curve for some Syva EMIT assays.
Authors: Zvaigzne G V , Brogan D A , Bernstein L H 
Published: January 2020

Abstract
Derivation of standard curves for the EMIT therapeutic drug monitoring system involves several mathematical algorithms, all of which can be rewritten in the form of a linear equation y = mx + b. We examined the stability of the standard curve in terms of slope and y-intercept for three drug assays (procainamide, gentamicin, and carbamazepine) by generating calibration curves intermittently for periods as long as 90 days. Controls at three concentrations were assayed after each calibration to validate the standard curves. On the basis of 98% confidence intervals, the slopes of standard curves for procainamide, gentamicin, and carbamazepine were stable for 89, 80, and 57 days, respectively. Control values generated from standard-curve manipulations (adjustments to the y-intercept) indicated consistent accuracy and precision throughout the entire study, as compared with control values determined after each calibration. The increased utility of the standard curve and reagents suggests that full recalibration on a regular basis is not always necessary.
Radioimmunoassay for assessing exocrine pancreatic insufficiency, based on the differential enzymatic degradation of cobalamin-binding proteins.
Authors: Marcoullis G , Gueant J L , Nicolas J P 
Published: January 2020

Abstract
Pancreatic proteases degrade the protein moiety of the R protein-cobalamin complex but not the intrinsic factor-cobalamin complex. Accordingly, we used these two proteins as substrates in an in vitro enzymatic assay to assess pancreatic function by incubating basal jejunal fluids with a mixture of intrinsic factor and cyano[57Co]cobalamin coupled to R-type protein and then using immunoprecipitation to determine the distribution of isotopically labeled cobalamin bound to the two proteins. With normal jejunal fluids, 91.2 (SD 6.1)% and 4.5 (SD 5.5)% of cyano[57Co]cobalamin was precipitated with antisera to intrinsic factor and anti-R protein, respectively. In the patients' jejunal fluids, the cyano[57Co]cobalamin precipitated with the respective antisera was 5.3 (SD 10.0)% and 96 (SD 6.2)%. In patients with other gastrointestinal problems, the sequestration of cobalamin was indistinguishable from that observed with the normal fluids. The clearcut discrimination this radioimmunoassay provided between abnormal and normal samples was confirmed by parallel comparative chromatographic analysis.
Evaluation of a new dynamic viscometer for measuring the viscosity of whole blood and plasma.
Authors: Chandler W L , Schmer G 
Published: January 2020

Abstract
We evaluated a new type of dynamic viscometer, the Sonoclot Coagulation Analyzer, for use in measuring the viscosity of whole-blood and plasma. Such information can be useful in monitoring patients with hyperviscosity syndromes, e.g., from multiple myeloma. A vibrating Teflon or plastic probe continuously measures dynamic viscosity. The instrument can be calibrated to measure a range of viscosities from 0.69 to 23 cP (mN X s X m-2) or more. The coefficient of variation at 0.69 cP was 3-4% for measurements with the Teflon probe, 7-9% with the plastic probe. Viscosity measured at 37 degrees C for plasma and whole-blood samples from 20 normal patients was 1.22 (SD 0.05) cP and 3.63 (SD 0.52) cP, respectively. Dynamic viscosity measured in blood samples from a single source, with contrived hematocrits ranging from 0 to 89%, increased exponentially as a function of hematocrit, confirming previous studies. Overall, we found this instrument simple and quick to operate, producing accurate, precise viscosity measurements over at least a 40-fold range of viscosity.
Liquid-chromatographic determination of progesterone in serum, with spectrophotometric detection.
Authors: Laganà A , D'Ascenzo G , Marino A , Tarola A M 
Published: January 2020

Abstract
In this precise, accurate, and specific liquid-chromatographic procedure for determining progesterone in serum, the serum is diluted 10-fold with water/methanol (65/35 by vol), and the progesterone is extracted from the sample by passage through a column of graphitized carbon black (Carbopack B, Supelco). After washing the column, we elute the progesterone with chloroform/methanol (90/10 by vol), which is then evaporated. The progesterone is separated on a reversed-phase C18 column with a mobile phase of acetonitrile/water, (46/54 by vol) at a flow rate of 1.6 mL/min. The eluted compound is detected by absorbance at 242 nm. Analytical recoveries for progesterone varied from 96.0 to 97.8%. Within-day and day-to-day precision, determined by analyzing pooled serum, ranged from 3.4 to 6.4%, and 4.1 to 7.9%, respectively. The limit of detection was about 0.2 micrograms/L. Numerous drugs and steroids tested did not interfere. Results correlated (r = 0.997) well with those by radioimmunoassay.
Rapid determination of iron in urine, in the presence of deferoxamine, by inductively coupled plasma emission spectrometry.
Authors: Leflon P , Plaquet R 
Published: January 2020

Abstract
Using a spectrometer with an argon plasma source coupled to a high-frequency magnetic field, we developed a direct method for determining iron in urine of patients being treated with deferoxamine. The detection limit for iron was 75 nmol/L; added iron was satisfactorily recovered; and we observed no interference from deferoxamine at its most commonly used concentrations. Values for between-run and within-run precision (CV) was less than 5%. Correlation of results with those obtained with a colorimetric method involving bathophenanthroline was good (r = 0.96).
Mass-spectrometric determination of serum cortisol: comparison of data from two independent laboratories.
Authors: Gaskell S J , Sieckmann L 
Published: January 2020

Abstract
Isotope dilution and mass spectrometry were used in two independent laboratories to determine cortisol in 15 plasma and serum pools used in the British and German national schemes for the external quality assessment of routine assays. For the concentration range 240-700 nmol/L, differences between the data obtained by the two laboratories were generally less than 4% but were approximately 7% in two instances. The discrepancies are nevertheless small in comparison with the bias observed for many routine assays.
Evaluation of absorption and first- and second-derivative spectra for simultaneous quantification of bilirubin and hemoglobin.
Authors: Merrick M F , Pardue H L 
Published: January 2020

Abstract
We discuss the relative merits of absorption and first- and second-derivative spectra for the simultaneous quantification of bilirubin and hemoglobin, and evaluate single-, two-, and multiwavelength methods. Although both species can be quantified from single- or two-wavelength absorption data, lipids or other absorbing or light-scattering components introduce systematic errors that can be substantially decreased by using first- or second-derivative spectra. Multi-wavelength data-processing methods with derivative spectra permit quantification of components with overlapping spectra and decrease the random error usually associated with derivative methods. A typical least-squares equation for quantifying bilirubin in the presence of hemoglobin and bovine serum albumin from multi-wavelength second-derivative data is y(computed) = 0.999x(prepared) + 0.00 mg/L.
Accuracy and comparability of long-term measurements of cholesterol.
Authors: Hainline A , Karon J M , Winn C L , Gill J B 
Published: January 2020

Abstract
Laboratories of the Lipid Research Clinics Program (LRC) maintained the accuracy of their measurements of total cholesterol by using seven pooled serum calibrators supplied by the Centers for Disease Control (CDC). Over the 11-year life of the LRC, each calibrator was prepared in succession and a target value was assigned by the CDC reference method for cholesterol. The results of a special experiment in which six of the seven calibrators were analyzed simultaneously demonstrated that the target values were accurately assigned. Deviations of the target values from the experimental means ranged from zero to 1.7% of the original target value. The experiment revealed no evidence of drift in the bias of the reference method over the life of LRC and demonstrated the accuracy, consistency, and the comparability of the values assigned to the successive calibrator pools used by the LRC laboratories during more than eight years. It demonstrated the reliability of a reference method and the suitability of frozen serum pools for maintaining an accurate measurement base for serum cholesterol.
Lactate dehydrogenase isoenzyme-1/total ratio: accurate for determining the existence of myocardial infarction.
Authors: Adan J , Bernstein L H , Babb J 
Published: January 2020

Abstract
We have gradually revised our medical protocols for measuring creatine kinase MB isoenzyme (CK-MB) and lactate dehydrogenase isoenzyme-1 (LD-1) because of identifiable problems in the use of an interpretation of CK-MB isoenzyme associated with slowly evolving or small myocardial infarct, the use of thrombolytic therapy, or burn and trauma, each of which affects the rate of appearance and composition of isoenzymes present. Despite recent evidence of the efficacy of LD-1 isoenzyme measurement in the first 12 to 24 h of myocardial infarction, this test is not widely used because of overstated assumptions about the value of CK-MB. Here we studied the adequacy of the current isoenzyme assays by determining the value of CK-MB and LD-1 at optimum serum sampling times and establishing the contribution of individual and combined predictors to diagnostic efficiency. We conclude that the LD-1/total LD activity ratio in serum is superior to measurement of CK-MB or LD-1, or both, in the diagnosis of acute myocardial infarction. Moreover, this ratio is most valuable when interpretation of the result for CK-MB isoenzyme is equivocal in patients with small or evolving myocardial infarcts.
Changes in concentrations of C-reactive protein in serum after kidney or heart transplantation.
Authors: Van Lente F , Castellani W , Abbott L B 
Published: January 2020

Abstract
C-reactive protein (CRP) concentrations were serially determined in serum after kidney or heart transplantation. The initial postsurgical CRP response in these patients was compared with that of control patients undergoing related procedures but not subjected to immunosuppressive therapy. Immunosuppression clearly depressed the postsurgical CRP response in transplant recipients. The effect is greatest with the administration of cyclosporine. In addition, we found serial CRP determinations to be a sensitive indicator of renal but not cardiac allograft rejection. The specificity of CRP as such a predictor was affected by non-rejection-based inflammation. We conclude that serial determination of CRP, interpreted by the extent by which its concentration increases between sequential samples, may be a useful adjunct to biochemical monitoring of renal transplants, but a similar approach to monitoring heart transplants is not possible.
Distribution of paraoxon hydrolytic activity in the serum of patients after myocardial infarction.
Authors: McElveen J , Mackness M I , Colley C M , Peard T , Warner S , Walker C H 
Published: January 2020

Abstract
The activity of paraoxonase in serum was found to be bimodally distributed, both in a control group and in a group of patients who had suffered myocardial infarction. Activity in the myocardial infarct group was significantly lower than in the control group. Low paraoxonase activity in serum may provide an indication of susceptibility to the development of coronary heart disease.
Assessment of a time-resolved fluoroimmunoassay for thyrotropin in routine clinical practice.
Authors: Lawson N , Mike N , Wilson R , Pandov H 
Published: January 2020

Abstract
We assessed the use of a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) system to measure thyrotropin (thyroid-stimulating hormone, TSH) in routine clinical practice. The assay is simple and precise, with intrabatch CV of less than 10% down to 0.1 milli-int. unit/L. When compared with free thyroxin, total thyroxin, and triiodothyronine measurements in 142 patients, the present assay most sensitively indicated hyperthyroidism and, in conjunction with free thyroxin, most sensitively indicated hypothyroidism. Free thyroxin was the most specific assay (lowest number of falsely increased or decreased results) in detecting thyroid disorders, with a specificity of 93.6% as compared with 85.1% for TSH, 81.9% for thyroxin, and 77.6% for triiodothyronine.
Concentration of free thyroxin in serum of a patient with euthyroid hyperthyroxinemia secondary to increased thyroxin-binding prealbumin: results by various methods compared.
Authors: Skiest D , Braverman L E , Emerson C H 
Published: January 2020

Abstract
We used various kits to measure free thyroxin (T4) in serum from a patient with the very rare syndrome of euthyroid hyperthyroxinemia secondary to increased thyroxin-binding prealbumin in serum. This patient's free T4 by equilibrium dialysis was 13 ng/L (normal 9-21), whereas the free-T4 index was 18.6 (normal 5.5-11.5). Using six different commercial methods, the last three listed being T4-analog methods, we measured the serum free T4 in this patient. The mean +/- SD (and normal range) free-T4 concentrations (ng/L) measured were: GammaCoat, Two-Step, 19.2 +/- 4.5 (6.9-26.9); Liquisol, 17.8 +/- 3.0 (12.4-20.8); Immo Phase, Two-Step 26.8 +/- 0.3 (12.4-21.2); GammaCoat, Single-Step, 19.7 +/- 5.7 (10.3-21.0); Immo Phase, Single-Step, 27.7 +/- 0.9 (8.6-25.0); and Amerlex, 14.1 +/- 0.6 (5.3-14.1). In four patients with familial dysalbuminemic hyperthyroidism, in whom the serum T4 by equilibrium dialysis was normal, all three T4-analog methods gave results far exceeding normal (greater than 50 ng/L).
Creatine kinase variant type I in children with anoxic insult.
Authors: Ludvigsen C W , Muus C , Meyer I , Haven M 
Published: January 2020

Abstract
We evaluated 31 consecutive patients, including 11 children, with creatine kinase variants (CKV) in our laboratory during a year. All had a clinical history of central hypotonia with myocardial damage resulting in severe central hypoxia. Seven of the 11 were neonates and had Apgar scores of 2.8 (SD 2.3) at 1 min and 4.8 (SD 2.4) at 5 min, which reflected their severe birth hypoxia. For the seven neonates, the mean value for total serum creatine kinase (EC 2.7.3.2; CK) was 773 (SD 553) U/L. The mean percentage CKV was 20.7% (SD 12.5%). The other four children were being evaluated for failure to thrive; all had birth asphyxia with residual cerebral palsy and seizure activity. These older children had a lower percentage of CKV (7.3%, SD 1.01%) than did the neonates, but the total CK (725, SD 1335 U/L) was not significantly different. In four neonates there was a three- to 20-day delay in the appearance of CK variant, which followed a marked increase in total CK activity. Tissue necrosis is apparently an important factor in the pathogenesis of Type I CK variant.
Four monoclonal immunoglobulins in a patient with chronic lymphocytic leukemia.
Authors: Tienhaara A , Irjala K , Rajamäki A , Pulkki K 
Published: January 2020

Abstract
We report here the case of a 73-year-old woman with chronic lymphocytic leukemia. Two years after the diagnosis, electrophoresis of her serum showed two monoclonal fractions, but our modified immunofixation procedure revealed four monoclonal immunoglobulins in five fractions: two IgG lambda fractions, one IgG kappa fraction, one IgA kappa fraction, and one IgG kappa fraction. This is an exceptionally high number of monoclonal immunoglobulins in a single patient. In the course of her disease the patient did not show any clinical, radiological, or laboratory signs of multiple myeloma or macroglobulinemia. The different monoclonal immunoglobulins were considered to be one expression of her B-lymphocytic malignancy.
Luminometric assays of seven acute-phase proteins in minimal volumes of serum, plasma, sputum, and bronchioalveolar lavage.
Authors: Braun J , Schultek T , Tegtmeier K F , Florenz A , Rohde C , Wood W G 
Published: January 2020

Abstract
We describe immunoluminometric assays for seven acute-phase proteins, which can be determined in minimal volumes of plasma, serum, sputum, and bronchioalveolar lavage. The theoretical volume of serum or plasma required to measure all seven analytes in duplicate is 130 nL, although in practice the smallest volume of sample was enough to fill a hematocrit tube (about 25 microL of blood), collected from neonates by the heel-prick method. The assays could be performed with 10 microL of sputum or with 100 microL of bronchioalveolar lavage. We measured alpha 1-antitrypsin, alpha 2-macroglobulin, alpha 1-acid glycoprotein, thyroxin-binding prealbumin, C-reactive protein, and total and secretory immunoglobulin A. The assays are rapid enough for all results to be returned to the ward on the same day and are suitable for monitoring neonatal sepsis. All coefficients of variation, derived from compound precision profiles, were less than 7% for clinically relevant analyte concentrations. Correlation with commercially available nephelometric assays was good.
Colorimetric determination of carboxypeptidase A activity in serum.
Authors: Saruta H , Ashihara Y , Sugiyama M , Roth M , Miyagawa E , Kido Y , Kasahara Y 
Published: January 2020

Abstract
This simple, reproducible colorimetric method for determining the activity of carboxypeptidase A (EC 3.4.17.1) is based on measuring the absorbance at 505 nm of a quinoneimine dye produced from the action of this enzyme on the new substrate p-hydroxybenzoyl-glycyl-L-phenylalanine. The enzyme acts on the substrate to produce p-hydroxybenzoyl-glycine and L-phenylalanine. The former is then hydrolyzed by hippuricase (EC 3.5.1.14) to produce p-hydroxybenzoic acid and glycine. Finally, oxidative coupling of p-hydroxybenzoic acid with 4-aminoantipyrine by sodium periodate forms a quinoneimine dye. The Km for the reaction with this substrate is 3.6 mmol/L; the optimum pH is 7.8. Our within-run and between-run CVs are 4.3% and 6.6%, respectively. The activity of carboxypeptidase A in serum correlates well with that of lipase (r = 0.96) and immunoreactive elastase-1 (r = 0.76).
Turbidimetric assay of IgG with use of single monoclonal antibodies.
Authors: Maynard Y , Scott M G , Nahm M H , Ladenson J H 
Published: January 2020

Abstract
We describe a turbidimetric assay for quantifying total immunoglobulin G (IgG) in serum with use of a single monoclonal antibody. The reaction, monitored by a centrifugal analyzer, is technically simple, rapid, and precise. Buffer of low ionic strength and polyethylene glycol are required for formation of detectable antibody-antigen complexes. We measured IgG concentrations in 49 polyclonal sera (Group 1) and 84 sera containing monoclonal IgG (Group 2) in assays in which we used either of two anti-IgG monoclonal antibodies (HG6 or HG8). Results compared well with those obtained with a nephelometric assay involving polyclonal antiserum, except for sera from four persons of Group 2 whose immunoglobulins were not detected by antibody HG6. HG6 bound IgG from these four sera in a solid-phase binding assay. HG6 and HG8 recognize epitopes on the Fab and Fc regions of IgG, respectively, and they do not compete for binding to the whole molecule. However, use of the two monoclonal antibodies combined failed to improve the sensitivity or range of the assay. We conclude that light-scattering assays of IgG can be validly performed with a single monoclonal antibody.
Radioimmunoassay of laminin in serum and its application to cancer patients.
Authors: Brocks D G , Strecker H , Neubauer H P , Timpl R 
Published: January 2020

Abstract
In this sensitive radioimmunoassay for laminin fragment P1 (purified from pepsin extracts of human placenta), monovalent antibody fragments obtained from rabbit antisera against the laminin component are used. The inhibition assay showed a low intra- and interassay variability, and the inhibition curves for various serum samples had parallel slopes. Molecular-sieve chromatography demonstrated heterogeneity of the laminin antigen in serum. For quantification we defined arbitrary units based on the amount of antigenic material present in normal human serum. Sera from 361 tumor patients showed increased values in about half of the cases. Correlation with increased concentration of carcinoembryonic antigen was poor (r = 0.259). The assay may be useful for diseases involving basement-membrane metabolism.