bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multicomponent analysis of hemoglobin derivatives with reversed-optics spectrophotometer.
Authors: Zwart A , Buursma A , van Kampen E J , Zijlstra W G 
Published: January 2020

Abstract
We describe a method for the simultaneous determination of the five clinically relevant hemoglobin derivatives (Hb, HbO2, HbCO, Hi, SHb) in a blood sample by means of a reversed-optics spectrophotometer (Hewlett-Packard HP8450 A UV/Vis). A built-in computer program is used for multicomponent analysis in an overdetermined system, i.e., a system in which the number of independent equations used exceeds the number of unknowns to be determined. First, the spectra of the five hemoglobin derivatives are measured in a series of different human blood samples. Thereafter, the multicomponent method for the simultaneous determination of the five hemoglobin derivatives is tested by comparison with conventional methods for the separate determination of oxygen saturation, HbCO, Hi, and SHb fractions. The multicomponent (multiwavelength) method is sufficiently reliable, accurate, and easy to justify its use in physiological chemical research as well as its routine application in the clinical chemical laboratory.
Brain-specific proteins: solid-phase immunobioluminescence assay for neuron-specific enolase in human plasma.
Authors: Gerbitz K D , Summer J , Thallemer J 
Published: January 2020

Abstract
We raised specific antibodies in rabbits against pure alpha alpha- or gamma gamma-isoenzymes of enolase (EC 4.2.1.11) purified from human brain. After being specifically immunoabsorbed by the respective Sepharose-coupled enolase isoenzymes, the purified antibodies are desorbed by acidification and coated onto polystyrene tubes. Each sample containing the isoenzyme activity to be determined is incubated in the respective coated tube. The coating is then washed, and the reaction of the antibody-bound enzyme is initiated by adding 2-phosphoglycerate, ADP, and pyruvate kinase. The accumulation of ATP is measured by following the increase in light emission in the firefly luciferase bioluminescence system. The assay is as specific as the antibody used for coating. Its detection limit is about 5 X 10(-9) U, corresponding to about 0.1 pg or 10(-18) mol of enzyme protein per assay. Activities of enolase isoenzymes in human plasma can be evaluated separately, rapidly, and precisely. We used the assay to measure enolase isoenzyme activities in plasma of patients suffering from different types of malignant tumors.
Rapid semiquantitative measurement of total porphyrins in urine and feces by magnetic circular dichroism.
Authors: Ivanetich K M , Movsowitz C , Moore M R 
Published: January 2020

Abstract
Magnetic circular dichroism is a suitable technique for semiquantitative determination of total porphyrins in urine and feces, being rapid, reliable, and involving little sample preparation. The sensitivity of the assay suffices to distinguish normal from above-normal concentrations of total porphyrins in urine and feces. Results for urine compare well with those obtained by thin-layer chromatography of porphyrin esters (n = 42, r = 0.92) or ion-exchange column chromatography of porphyrin acids (n = 19, r = 0.80).
A highly sensitive affinity-column-mediated immunometric assay, as exemplified by digoxin.
Authors: Freytag J W , Dickinson J C , Tseng S Y 
Published: January 2020

Abstract
We describe a highly sensitive heterogeneous enzyme-linked immunoassay in which digoxin is used as the model analyte. An excess of enzyme-labeled monovalent antibody is incubated with sample containing the analyte such that all analyte is rapidly and quantitatively bound. Excess antibody that does not acquire a antigen in its binding site is rapidly removed from the mixture by passage through a porous affinity column containing immobilized analyte (or analog), present in vast excess. Only the labeled monovalent antibody that possesses an antigen in its binding site elutes from the column in the unbound fraction. The label present in this fraction is then quantified. Such an assay is extremely sensitive and obviates the limitations imposed by antibody affinity constants on homogeneous and competitive heterogeneous immunoassays. This assay can be performed rapidly and is readily amenable to automation.
Cell membrane abnormality detected in erythrocytes from patients with multiple sclerosis by partition in two-polymer aqueous-phase systems.
Authors: Van Alstine J M , Brooks D E 
Published: January 2020

Abstract
Erythrocytes from multiple sclerosis patients differ significantly (p less than 0.005) from those from controls with regard to hydrophobic affinity partition in two-polymer aqueous-phase systems containing dextran, poly(ethylene glycol) and poly (ethylene glycol)-fatty acid esters. The most likely source of the abnormality is the cell membrane.
Measurement of choriogonadotropin by chemiluminescence immunoassay and immunochemiluminometric assay: 1. Use of isoluminol derivatives.
Authors: Barnard G J , Kim J B , Brockelbank J L , Collins W P , Gaier B , Kohen F 
Published: January 2020

Abstract
We have developed immunoassays, monitored by the detection of chemiluminescence, for measuring choriogonadotropin in human urine. These methods involve the use of derivatives of isoluminol and include: (a) a labeled antigen with a second antibody covalently linked to polyacrylamide beads as the solid-phase reagent (i.e., solid-phase chemiluminescence immunoassay); and (b) an excess concentration of a specific antibody passively adsorbed onto the walls of polystyrene tubes and a labeled antibody of different specificity (i.e., two-site immunochemiluminometric assay). After the respective binding reactions, the solutions are aspirated, the antigen- or antibody-bound fractions are washed twice with 500 microL of buffer, sodium hydroxide (2 mol/L; 200 microL) is added, and the mixture is incubated for 60 min at 60 degrees C. After cooling, the label is oxidized with microperoxidase/hydrogen peroxide and the resulting chemiluminescence signal is measured for 10 s. We have evaluated the methods in terms of their sensitivity, precision, and clinical utility, and we compare results with values obtained by radioimmunoassay.
Micromethod for phosphonoformate inhibition assay of hepatitis B viral DNA polymerase.
Authors: Lin H J , Wu P C , Lai C L , Chak W 
Published: January 2020

Abstract
A micromethod for the specific measurement of hepatitis B viral DNA polymerase in serum is presented, based on the phosphonoformate inhibition assay (J Med Virol 12: 61-70, 1983). In the micromethod, sample volume is reduced to 120 microL and the ultracentrifugation step is eliminated. The method allows good discrimination between serum infected with hepatitis B virus and uninfected serum. The cutoff value for rate of nucleotide incorporation, based on assays of 41 serum specimens negative for hepatitis B serological markers, was about 15 nU/L (90th percentile). Serum containing hepatitis B surface and antigens exhibited rates of phosphonoformate-inhibitive nucleotide incorporation of 150 (SD 150) nU/L, with an upper 90th percentile range of 17 to 667 nU/L (n = 41). The micromethod makes use of commercially available [32P]dCTP (specific activity about 7000 kCi/mol). 125I-labeled dCTP was found to be unsuitable for this assay. Human DNA polymerases in serum are detected by this method but are excluded from the phosphonoformate-inhibitive fraction.
Theoretical consideration of the effects of dilution on estimates of free thyroid hormones in serum.
Authors: Kamikubo K , Komaki T , Nakamura S , Sakata S , Yasuda K , Miura K 
Published: January 2020

Abstract
When concentrations of free thyroid hormones in serum are measured by equilibrium dialysis, the serum sample is diluted by dialysis buffer, resulting in a new equilibrium for distribution of these hormones that differs from that in the original serum sample. We have derived a mathematical formulation, based on an equilibrium model for multiple ligands and multiple binding sites, to determine the effect of dilution on the concentrations of free hormones in serum. Computer simulations based on the formulation indicate that both free thyroxin (T4) and free triiodothyronine (T3) are decreased by dilution of serum, free T3 being affected more than free T4. This dilution-related decrease is more prominent in hyperthyroidism than in euthyroidism, and even more striking for sera in which binding capacities for thyroid hormones are decreased (e.g., in thyroxin-binding globulin deficiency or hypoalbuminemia). These simulations can provide a basis for minimizing experimental errors in the estimates of concentrations of free thyroid hormones by equilibrium dialysis.
Glucocorticoids directly affect spectrophotometry of bilirubin in amniotic fluid.
Authors: Milwidsky A , Yagel S , Chaouat M , Mayer M 
Published: January 2020

Abstract
Dexamethasone or prednisolone, added in vitro to bilirubin-containing amniotic fluid, produces a time-dependent decrease in the 450-nm absorbance of the pigment. Neither the chemical determination of bilirubin in amniotic fluid nor the lecithin/sphingomyelin ratio as determined by thin-layer chromatography is affected by these glucocorticoids. The effect probably is not a result of displacement of bilirubin from its binding sites on albumin, because the absorbance of a solution of crystalline bilirubin at 450 nm is unaffected by added bovine serum albumin. Light scattering of amniotic fluid increases slightly when dexamethasone is added, whether or not low concentrations of bilirubin (less than 1.6 mumol/L) are present. Thus the effect on absorbance evidently is not ascribable to supersaturation and formation of a colloidal sol of bilirubin particles. This direct interference of glucocorticoids with the spectrophotometry of bilirubin in amniotic fluid prompts cautious interpretation of such data as an index to the severity of hemolytic disease of the fetus, specifically in cases of Rhesus-isoimmunization that are being treated with glucocorticoids.
Cytochrome b5 reductase activity in erythrocytes and leukocytes as related to sex and age.
Authors: Panin G , Pernechele M , Giurioli R , Secchieri S , Milanesi O , Pellegrino P A , Chiandetti L 
Published: January 2020

Abstract
We measured cytochrome b5 reductase (EC 1.6.2.2) activity in erythrocytes and leukocytes from subjects of both sexes ranging in age from neonate to adulthood, all either apparently healthy or without hematologic disorders. The activities were determined spectrophotometrically (J. Lab. Clin. Med. 72: 339-344, 1968). Within-run precision (CV) of the reductase determination was 6.4% and 3.7% for erythrocytes and leukocytes, respectively. Activity in either erythrocytes or leukocytes was unrelated to sex. Activity was lowest in erythrocytes of newborns (p less than 0.001) but reached adult values within the first postnatal year. Leukocyte activity was higher (p less than 0.05) in infants one to 24 months old than in other groups, possibly because of variations in leukocyte count in the first postnatal months.
Use and significance of reference serum as a secondary standard for electroimmunoassay of apolipoprotein A-I.
Authors: Fesmire J D , McConathy W J , Alaupovic P 
Published: January 2020

Abstract
This study was designed to show the effect of different primary standards and antisera on the variability of concentrations of apolipoprotein A-I (ApoA-I) in plasma and to document the usefulness of reference sera as a secondary standard in the electroimmunoassay of this apolipoprotein. We compared the reactivities of two separate ApoA-I samples and a preparation of high-density lipoprotein (HDL3) with seven different antisera to ApoA-I. The antisera reacted differently with each of the three standards, as shown by the different slopes of their standard curves. The resulting inconsistencies in the ApoA-I values for unknown plasma samples were shown to be corrected by the use of a reference serum. When ApoA-I analyses were carried out with the reference serum as a standard, all seven antisera gave statistically indistinguishable results for concentrations of plasma ApoA-I. The use of reference sera thus represents the simplest and most convenient means of standardizing the electroimmunoassay for ApoA-I.
Liquid-chromatographic determination of penbutolol and its principal metabolites in plasma and urine.
Authors: Miner D J , Binkley D A , Bechtol L D 
Published: January 2020

Abstract
We describe a sensitive, specific liquid-chromatographic determination of penbutolol and its 4-hydroxy metabolite in plasma and urine. The method involves a simple organic extraction, evaporation of the solvent, reconstitution in methanol/water, and injection into the chromatograph. Penbutolol, its metabolites, and the internal standard, propranolol, are resolved on a CN reversed-phase column and detected fluorometrically. Conjugates of penbutolol and its 4-hydroxy metabolite may be determined after a 2-h enzymic hydrolysis. Detection limits are in the range of 3 to 12 micrograms/L of plasma. The assay is reproducible and nearly free of interferences. Representative concentrations in blood and urine of normal volunteers are reported.
Semi-automated determination of the uremic toxin "b4-2".
Authors: Faguer P , Man N K , Pierrat D , Funck-Brentano J L 
Published: January 2020

Abstract
A semi-automated two-stage chromatographic system is described for use in evaluating neurotoxin b4-2 in body fluids of uremic patients and healthy subjects. The only manual step is the injection, thus decreasing the risk of operator error inherent in the previous manual method (Clin Chem 29: 703-707, 1983) and concurrently improving CV from 9% to 6.4% as measured during a 16-month period.
Atypical alkaline phosphatase isoenzyme in serum from a patient with Hodgkin's disease.
Authors: Beilby J P , Garcia-Webb P , Bhagat C I , Prins A 
Published: January 2020

Abstract
An alkaline phosphatase isoenzyme that did not move from the origin in agarose gel electrophoresis was detected in serum from a 51-year-old woman with Hodgkin's disease. Inhibitor and heat-inactivation studies of the patient's serum alkaline phosphatase showed properties resembling those of both liver and bone isoenzymes. No immunoglobulin or high-molecular-mass complexes with the alkaline phosphatase isoenzyme were detected. The relative molecular mass (Mr) of the atypical alkaline phosphatase isoenzyme was 182 000, that of the liver alkaline phosphatase isoenzyme control 170 000. Treatment of both of these isoenzymes with neuraminidase gave a product with an Mr of 140 000. We propose that a post-translational modification increased the carbohydrate content of the liver alkaline phosphatase isoenzyme, thus changing the charge characteristics of the enzyme and decreasing its electrophoretic mobility. We believe this to be the first report of a post-translational modification in a heat-sensitive isoenzyme of alkaline phosphatase.
High-density-lipoprotein cholesterol in heparin-MnCl2 supernates determined with the Dow enzymic method after precipitation of Mn2+ with HCO3-.
Authors: Bachorik P S , Walker R E , Virgil D G 
Published: January 2020

Abstract
Manganese interferes with enzymic cholesterol methods. In this study, we enzymically measured high-density-lipoprotein (HDL) cholesterol in heparin-Mn2+ supernates that had been treated with NaHCO3 (91 mmol/L) to precipitate Mn2+, and compared results with those by an automated Liebermann- Burchard method. For untreated supernates of 96 fresh plasma samples, the enzymic values were 10.4% higher than comparison-method values, a bias that declined to +2.3% for treated supernates. For 72 sera promptly frozen and stored after collection, the enzymic values for untreated and treated supernates were, respectively, 6.0% and 0.5% higher than comparison-method values. In all cases, the magnitude of the bias was independent of the concentrations of cholesterol, triglyceride, and HDL-cholesterol. Enzymic HDL-cholesterol measurements in NaHCO3-treated heparin-Mn2+ supernates prepared from four pooled serum controls agreed within 21 mg/L with values established for these pools by the Centers for Disease Control. We conclude that the accuracy of enzymic HDL cholesterol measurements in heparin-Mn2+ supernates in considerably increased by treatment with NaHCO3.
High-resolution densitometry: analysis of stained albumin bands as a model for electrophoresis of serum proteins.
Authors: Epstein D J , Neeley W E 
Published: January 2020

Abstract
In discussing the principles of quantitative analysis in thin-layer media, we show that requirements for quantitative analysis are not satisfied when stained protein electrophoretic bands are scanned with a conventional rectangular-slit densitometer. We investigated a high-resolution densitometer based on a linear photodiode array as an alternative analytical tool, using stained electrophoretic bands of radio-labeled human serum albumin as a simplified model for results of serum protein electrophoresis. Identical protein bands scanned with both the high-resolution densitometer and a conventional densitometer were quantified with improved accuracy and precision by the new instrument. We also used the high-resolution densitometer to develop a computer model for performance characteristics of a rectangular-slit densitometer.
Liquid-chromatographic measurement of amino acids in biological samples after formation of phenylthiohydantoin derivatives.
Authors: Biggs H G , Gentilcore L J 
Published: January 2020

Abstract
In this method for measuring amino acids in urine, serum, and tissue, the amino acids to be assayed and the internal standard, L-norleucine, are converted to phenylthiohydantoins , isolated by organic solvent extraction, separated by reversed-phase "high-pressure" liquid chromatography, and detected by ultraviolet absorbance. The analytes are identified by retention times and quantified by comparing peak heights with that of the internal standard. The peak-height ratios vary linearly with concentrations of 50 to 500 mg/L, corresponding to the concentration range usually found in biological samples. Detection limits are 5 to 20 mg/L. Inter- and intra-assay precision (CV) varies between 1 and 26%. Average analytical recoveries range between 67 and 100%.
Suitability of various control sera for use in testing the accuracy of cholesterol determination with enzymic kits.
Authors: Demacker P N , Boerma G J , Jansen A P 
Published: January 2020

Abstract
We used 20 different commercial enzymic kits to measure cholesterol in 19 commercial control sera and in a pooled specimen of human serum and compared the relative biases, with the Abell -Kendall procedure as reference. Our purpose was to select those sera in various enzymic kits showing behavior similar to that of human serum and which thus can be used to measure the accuracy of these kits. The overall mean relative biases obtained with each of the 20 kits for the pooled human serum on the one hand and for a given control serum on the other generally correlated significantly. On the basis of the correlation coefficients and regression equations, we could select the control sera best suited for measurement of accuracy. They were all human-serum based, with cholesterol concentrations greater than 5 mmol/L. Animal sera with above-normal lipid values produced by feeding special diets appeared to be less reliable control sera in this respect.
Evaluation of the EMIT reagent system for measurement of caffeine with the EMIT Lab 5000 System and a centrifugal analyzer.
Authors: Ou C N , Frawley V L , Ellis J M 
Published: January 2020

Abstract
Using a Syva EMIT Lab 5000 System, we evaluated a newly developed EMIT assay for measurement of caffeine in serum of neonates. The method is rapid, and coefficients of variation for within-run and day-to-day precision were less than 5%. The accuracy of the method, as evaluated from analytical recovery and a calibrator-crossover study, is excellent. Comparison of the results analyzed by the EMIT caffeine assay (y) and the liquid-chromatographic comparison method (x) yielded the linear regression equation y = 1. 052x + 0.293 (n = 110, r = 0.987, and Sy . x = 0.625). The method was also adapted to a COBAS-BIO centrifugal analyzer (y) and optimized to minimize sample and reagent consumption. Linear regression analysis yielded the equation y = 1. 031x + 0.227 (n = 61, r = 0.992, and Sy . x = 0.488). As many as 400 assays per EMIT kit can be performed with the analyzer method, with excellent precision and accuracy. The kit assay and this centrifugal analyzer are well suited for rapid batch testing: 28 analyses (including six calibrators) in 10 min.
Semiautomated analysis for mercury in whole blood, urine, and hair by on-stream generation of cold vapor.
Authors: Peter F , Strunc G 
Published: January 2020

Abstract
In this method for quantitative determination of mercury in blood, urine, and hair, the specimen is first digested in a mixture of solid potassium permanganate and concentrated sulfuric acid. Excess oxidizing agent is reduced by hydroxylamine hydrochloride. The mercury liberated with stannous chloride is quantified by measuring its absorbance at 254 nm. This method shortens digestion time considerably and ensures accurate and reproducible results. Reagents must be free of mercury contamination; every new lot must be checked before use. This system can reliably accommodate as many as 30 specimens per hour and is suitable for use in laboratories that analyze a large number of biological specimens for total mercury.
Free thyroxin index and direct measurements of free thyroxin compared for evaluating postpartum autoimmune thyroid dysfunction.
Authors: Jansson R , Forberg R , Levin K 
Published: January 2020

Abstract
Measurement of free thyroxin (FT4) by a recently introduced commercial assay (Amerlex Free T4 RIA) was compared with the calculated free thyroxin index (FT4I) for serum from 104 postpartum women. Of these, 63 had transient thyroid dysfunction due to autoimmune thyroiditis, six had transient Graves' thyrotoxicosis, and 35 were euthyroid with no signs of autoimmune thyroid disease. The correlation between results for FT4 and the calculated FTI for 95 serum samples from women with no signs of autoimmune thyroiditis (r = 0.941; p = 0.0001) was almost identical to that for 270 serum samples from women with thyroid microsomal autoantibodies characteristic of autoimmune thyroiditis (r = 0.937; p = 0.0001). Furthermore, we observed no difference when the autoimmune group was subdivided according to low or high titers of thyroid microsomal antibodies. In no case did autoantibodies to thyroxin interfere with the FT4 assay. However, one woman had a spuriously low value for FT4I owing to interference by autoantibodies to triiodothyronine with the triiodothyronine resin uptake test. We conclude that the FT4 RIA assay provided diagnostic information in this group of postpartum women equivalent to that of the more elaborate procedure of determining FT4I.
Simultaneous determination of penicillin and cephalosporin antibiotics in serum by gradient liquid chromatography.
Authors: Annesley T , Wilkerson K , Matz K , Giacherio D 
Published: January 2020

Abstract
We describe a "high-performance" liquid-chromatographic method for simultaneously measuring various penicillin and cephalosporin antibiotics. After extraction from serum, which in general is quantitative, the drugs are separated by use of a "Bondapak phenyl" column and a gradient mobile phase. For these drugs retention times depend on the pH of the mobile phase; we present retention times under selected pH conditions.