bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multi-stage Gaussian transformation algorithm for clinical laboratory data.
Authors: Boyd J C , Lacher D A 
Published: January 2020

Abstract
We have developed a multi-stage computer algorithm to transform non-normally distributed data to a normal distribution. This transformation is of value for calculation of laboratory reference intervals and for normalization of clinical laboratory variates before applying statistical procedures in which underlying data normality is assumed. The algorithm is able to normalize most laboratory data distributions with either negative or positive coefficients of skewness or kurtosis. Stepwise, a logarithmic transform removes asymmetry (skewness), then a Z-score transform and power function transform remove residual peakedness or flatness (kurtosis). Powerful statistical tests of data normality in the procedure help the user evaluate both the necessity for and the success of the data transformation. Erroneous assessments of data normality caused by rounded laboratory test values have been minimized by introducing computer-generated random noise into the data values. Reference interval endpoints that were estimated parametrically (mean +/- 2 SD) by using successfully transformed data were found to have a smaller root-mean-squared error than those estimated by the non-parametric percentile technique.
Use of alumina, sephadex G10, and ion-exchange columns to purify samples for determination of epinephrine, norepinephrine, dopamine, homovanillic acid, and 5-hydroxyindoleacetic acid in urine.
Authors: Westerink B H , Bosker F J , O'Hanlon J F 
Published: January 2020

Abstract
We investigated the usefulness of small Sephadex columns, prepared in Pasteur pipettes, in purifying samples to be analyzed for catecholamines, homovanillic acid, and 5-hydroxyindoleacetic acid. After free catecholamines in urine samples were purified on alumina followed by Sephadex G10, a reliable and simultaneous quantification of epinephrine, norepinephrine, and dopamine was achieved by using high-performance liquid-chromatography with electrochemical detection. Purification of urine on Bio-Rad prepacked ion-exchange columns followed by Sephadex G10 resulted in a reliable, fast (200 samples processed per week) method for determination of free catecholamines in urine. Analytical recoveries of both methods were between 80 and 95%, with a CV of about 3%. Single purification on Sephadex G10 sufficed to allow simultaneous determination of homovanillic acid and 5-hydroxyindoleacetic acid in urine. Analytical recovery for this method was about 90%, with a CV of about 5%. Sephadex G10 columns, which can be re-used without regeneration for at least one year, appear to have a great potential in clinical chemistry.
Free amino acid content of lymphocytes nd granulocytes compared.
Authors: Fukuda K , Hirai Y , Yoshida H , Nakajima T , Usui T 
Published: January 2020

Abstract
For extracting free amino acids from human leukocytes, we find that disruption of the cells by ultrasonication is more reliable than freezing and thawing. The amount of free amino acids extracted by the latter method depends on the temperature and duration of thawing. We extracted free amino acids from leukocytes of healthy men by ultrasonication and compared their concentrations in lymphocytes and granulocytes. The amino acid content of granulocytes significantly (p less than 0.001) exceeded that of lymphocytes. Of the amino acids extracted from granulocytes, 76% was taurine; for lymphocytes taurine, aspartic acid, and glutamic acid were predominant, respectively composing 44%, 17%, and 26% of the total. Taurine is proposed as an index of cell disruption.
Solid-phase colorimetric determination of potassium.
Authors: Charlton S C , Fleming R L , Zipp A 
Published: January 2020

Abstract
A nonpolar organic film (plasticized polyvinyl chloride) containing the ionophore valinomycin was incubated with an aqueous solution containing potassium ion and a detectable anion (erythrosin B). The amount of erythrosin B retained by the film after washing could be measured by absorbance or reflectance, and was directly related to the potassium concentration. This dye-binding method is quantitative for potassium and is suitable for both aqueous and serum-based solutions. There was no interference by sodium in the range found in serum. Several polyvinyl chloride plasticizers and anionic dyes and some other ionophores were found to be useful. The anion binding is thought to be restricted to the surface.
An innovative technology for "random-access" sampling.
Authors: Smith J , Svenjak D , Turrell J , Vlastelica D 
Published: January 2020

Abstract
A major instrumental limitation to rapid, "random-access" clinical analysis has been cross-contamination at sampling and reagent probes. Use of an immiscible, nonreactive fluid as a positive barrier between the liquid sample and reagent and the interior and exterior surfaces of their respective probes provides an inert, deformable surface that both prevents carryover and ensures accurate delivery. Being totally nonreactive under clinical chemistry conditions, the fluid does not affect the ensuing analysis. Application of this technology to the Technicon RA-1000 (trademark of Technicon Instruments Corp.) system allows transfer of a liquid sample and any of 14 liquid reagents to the reaction vessel with a carryover of less than 1/10(6) with a precision (CV) of 0.5%. Its use provides for a rapid analysis rate of 240 tests per hour, and for transfer of microliter quantities of serum, with carryover of less than 1/8000, again at an average CV of 0.5%.
On-line direct liquid introduction interface for micro-liquid chromatography/mass spectrometry: application to drug analysis.
Authors: Eckers C , Skrabalak D S , Henion J 
Published: January 2020

Abstract
We describe an integrated micro-liquid chromatograph/mass spectrometer (micro-LC/MS) system capable of performing routine determinations for 1--10 ng of drugs and their metabolites extracted from biological fluids. The micro-LC is constructed from conventional "high-performance" liquid-chromatographic instrumentation by using commercially available components. The mass spectrometer is operated in the chemical ionization mode. The direct liquid introduction micro-LC/MS interface can be constructed from commercially available materials. Chromatographic and mass spectral results demonstrate the ability of the micro-LC and micro-LC/MS system to separate and determine multiple components in standards of trace concentrations and in equine urinary extracts. The stability and sensitivity of this micro-LC/MS system are demonstrated through determinations of trichlormethiazide.
Relationship between direct-potentiometric and flame-photometric measurement of sodium in blood.
Authors: Apple F S , Koch D D , Graves S , Ladenson J H 
Published: January 2020

Abstract
The relationship between direct-potentiometric and flame-photometric measurements of sodium has been studied in human sera and other, simpler systems. When water content was varied by using an inert substance (silica), de-ionized sera, or de-ionized individual proteins, the percentage that the flame photometric values were of the direct potentiometric Na+ values was identical to the measured water content. However, in 35 patients the percentage of Na+ values was 99.1% and the water content was 92.0%, a discrepancy of 7.1%. De-ionization of sera removed this discrepancy, apparently because of the lower pH of the de-ionized sera. The percentage of flame-photometric to direct-potentiometric Na+ values varied as a function of pH in pooled sera; in lyophilized and reconstituted sera; and in de-ionized, lyophilized, and reconstituted sera. Four explanations for the discrepancy between the percentage of Na+ values and the water content are discussed: a calibration problem, a measurement artifact, Na+ binding, and water binding. At this time there are no definitive data concerning which explanation is correct. We expect that our finding of a pH dependency for the percentage of measured Na+ values can be used to develop model systems to elucidate the mechanism producing the discrepancy between the percentage of Na+ values and the water content.
Further studies on danazol interference in testosterone radioimmunoassays.
Authors: Sharp A M , Fraser I S , Caterson I D 
Published: January 2020

Abstract
Investigating the interference of danazol in testosterone radioimmunoassays, we measured serum testosterone concentrations in the serum of women receiving danazol, with three testosterone radioimmunoassay kits. All of these showed positive interference by danazol or its metabolites (or both). Values for testosterone obtained with two of the methods (Diagnostic Products Corp. and Farmos Diagnostica) depended on the volume of serum extracted per assay tube. A detailed column-chromatographic method is presented in which testosterone is resolved from danazol and its metabolites.
Multi-enzyme membrane electrodes for determination of creatinine and creatine in serum.
Authors: Tsuchida T , Yoda K 
Published: January 2020

Abstract
An enzyme electrode system for the determination of creatinine and creatine was developed by utilizing three enzymes: creatinine amidohydrolase (CA), creatine amidinohydrolase (Cl), and sarcosine oxidase (SO). These enzymes were co-immobilized onto the porous side of a cellulose acetate membrane with asymmetric structure, which has selective permeability to hydrogen peroxide. Two kinds of multi-enzyme electrodes were constructed by combining a polarographic electrode for sensing hydrogen peroxide and an immobilized CA/Cl/SO membrane or Cl/SO membrane for creatinine plus creatine or creatine, respectively. The multi-enzyme electrodes responded linearly up to 100 mg of creatinine and creatine per liter in human serum. Response time was 20 s in the rate method and the detection limit was 1 mg/L. Only 25 microL of serum sample is required. Analytical recoveries, precisions, and correlations with the Jaffé method were excellent, and the multi-enzyme electrodes were sufficiently stable to perform more than 500 assays. No loss of activity of immobilized enzymes was observed after nine months of storage at 4 degrees C in air.
Time-resolved fluoroimmunoassay of human choriogonadotropin.
Authors: Pettersson K , Siitari H , Hemmilä I , Soini E , Lövgren T , Hänninen V , Tanner P , Stenman U H 
Published: January 2020

Abstract
We describe time-resolved fluoroimmunoassay for human choriogonadotropin involving monoclonal antibodies directed against the beta- and alpha-subunits. The latter antibody was labeled with europium, which was measured by counting for 1 s after the immunoreaction was completed. In the solid-phase sandwich assay, both a one-step and two-step procedure were used; the respective measuring ranges were 0.7-135 and 0.7-350 int. units/L, the latter covering a 500-fold dynamic range. The CV within the assay range was between 4 and 8%, depending on the dose. Cross reactivity with lutropin in the one- and two-step procedures was 1.6% and 1.0%, respectively.
Measurement of glucose in plasma by a differential pH technique.
Authors: Luzzana M , Dossi G , Mosca A , Granelli A , Berger D , Rovida E , Ripamonti M , Musetti A , Rossi-Bernardi L 
Published: January 2020

Abstract
A new automatic apparatus based on the differential measurement of pH between two solutions has been developed. Two 25-microL (internal volume) glass capillary electrodes are used to measure the results of automated (under microcomputer control) chemical reactions that lead to the liberation or the uptake of hydrogen ions. The sensitivity of the differential pH measurements is better than +/- 0.0001 pH unit, and the change in H+ concentration that can be detected by such an apparatus is 1 mumol/L for plasma and 3 mumol/L for whole blood. The technique has been applied to the measurement of glucose in plasma, giving results in agreement with the specifications of the Food and Drug Administration reference method for quantitative determination of glucose (hexokinase/glucose-6-phosphate dehydrogenase method).
Simple, rapid spectrophotometry of urinary N-acetyl-beta-D-glucosaminidase, with use of a new chromogenic substrate.
Authors: Noto A , Ogawa Y , Mori S , Yoshioka M , Kitakaze T , Hori T , Nakamura M , Miyake T 
Published: January 2020

Abstract
We have developed a new spectrophotometric assay for urinary N-acetyl-beta-D-glucosaminidase (NAGase) with use of sodio m-cresolsulfonphthaleinyl N-acetyl-beta-D-glucosaminide (MCP-NAG). MCP-NAG was synthesized from acetochloro-glucosamine and m-cresolsulfonphthalein (MCP) in four steps. MCP-NAG reacts well with NAGase (Km = 0.41 mmol/L) and is highly water soluble. The absorption maximum and molar absorptivity of the aglycone MCP are 580 nm and 40 670, respectively. Spectral overlap of interfering substances at 580 nm is almost negligible, so that the urine blank can be omitted from the assay procedure. The high molar absorptivity of MCP gives sufficient analytical sensitivity at a reaction time of 15 min. The correlation between the MCP-NAG method (y) and the fluorimetric method (x) involving 4-methylumbelliferyl N-acetyl-beta-D-glucosaminide is represented by the equation y = 0.995x - 0.669 (r = 0.991). Thus, the present method provides practical advantages over conventional methods, for use in the routine laboratory.
Comparison of a logistic and a mass-action curve for radioimmunoassay data.
Authors: Raab G M 
Published: January 2020

Abstract
This paper compares a logistic curve and a mass-action curve in their ability to represent radioimmunoassay standard curves. A data base from 10 different assays is used in this comparison. Six of the 10 assays could be modeled equally well by either the logistic or the mass-action curve. In one case the mass-action curve gave a slightly better fit, though the practical distinction was negligible. In the remaining three assays the mass-action curve performed very much worse than the logistic curve. It is shown that the mass-action curve can assume only a very limited range of shapes, which explains its difficulty with these three assays. In particular, the mass-action curve cannot represent assays where the standard curve slope is less than a specified value. The paper also discusses the extension of each of these curves to more complicated equations, and their application to immunoassay data.
Kinetic enzymic method for automated determination of total cholesterol in serum.
Authors: Deeg R , Ziegenhorn J 
Published: January 2020

Abstract
We describe a rapid, kinetic, fixed-time method for determining serum total cholesterol by use of cholesterol esterase, cholesterol oxidase, and the indicator reaction with peroxidase, 4-aminophenazone, and phenol. On addition of the competitive inhibitor 3,4-dichlorophenol the Michaelis constant of cholesterol oxidase is apparently increased, which extends the linear relation between absorbance change and cholesterol concentration to 20.7 to 25.9 mmol/L, depending on the analyzer being used. For calibration, a single standard is used. Total analysis time is in the range of 80 to 210 s. Incubation temperature is 25 degrees C or 37 degrees C. The single-reagent procedure has been adapted to three different centrifugal analyzers and to the Eppendorf ACP 5040 analyzer. It yields precise and accurate results and is insensitive to potential interferences.
Kinetic enzymic assay for D(-)-lactate, with use of a centrifugal analyzer.
Authors: Ludvigsen C W , Thurn J R , Pierpont G L , Eckfeldt J H 
Published: January 2020

Abstract
The D(-) isomer of lactic acid appears to cause a form of metabolic encephalopathy experienced by patients who have had jejunoileal bypass for morbid obesity. However, analysis for D(-)-lactate is not routinely available in clinical or reference laboratories. We describe an enzymic centrifugal-analyzer assay for D(-)-lactate in plasma or serum, with use of D(-)-lactate dehydrogenase. The method involves two-point kinetic calibration and preincubation of specimen and NAD+, thus eliminating the need for specimen-blanking or protein-precipitating pretreatment. This rapid, accurate, and precise assay should be helpful in evaluating patients with "short-bowel syndrome" who display confusion, lethargy, ataxia, or other central nervous-system disturbances that may be ascribable to D(-)-lactic acidosis.
Evaluation of a radioimmunoassay for estradiol in unextracted serum.
Authors: Mertens R , Liedtke R J , Batjer J D 
Published: January 2020

Abstract
We describe the performance of a commercial (Steranti/EIR) RIA reagent kit for measuring 17 beta-estradiol directly in serum. Day-to-day precision data for control sera were as follows: mean = 102.8 ng/L, CV = 6.8%, n = 20; mean = 231.1 ng/L, CV = 5.3%, n = 21; mean = 747.7 ng/L, CV = 9.4%, n = 21. Analytical recovery of added estradiol from seven different serum pools from men, to which three different concentrations of estradiol had been added, was (mean +/- SD): 98.6 +/- 7.0% at 107.5 ng/L added; 98.8 +/- 4.7% at 322.5 ng/L added; 108.2 +/- 4.8% at 645 ng/L added. Overall recovery of estradiol in these experiments (mean +/- SD for 21 determinations) averaged 101.9 +/- 7.0%. Assay of 32 serum specimens from women by both the direct (y) and an extraction method (x) gave the following linear regression statistics: y = 1.12x - 1.3, r = 0.998, Sy/x = 30.2 ng/L, mean y = 438.2 ng/L, mean x = 391.4 ng/L. Hemoglobin, bilirubin, and moderate lipemia do not interfere. Sensitivity of the direct assay was 2.6 ng/L. Compared with the extraction assay, the direct estradiol assay has advantages of speed and simplicity.
The chemical basis and specificity of the nitrosonaphthol reaction.
Authors: Knight J A , Robertson G , Wu J T 
Published: January 2020

Abstract
1-Nitroso-2-naphthol reacts with various 5-hydroxyindoles as well as para-substituted phenols and guaiacols. Consequently, this reaction has long been used to measure tyrosine in tyrosinosis and tyrosinemia, homovanillic acid in neuroblastoma, and 5-hydroxy-3-indoleacetic acid in the carcinoid tumor. We report here on the specificity of this reaction, as well as our early observations with respect to the chemical basis of the reaction.
Seven different digoxin immunoassay kits compared with respect to interference by a digoxin-like immunoreactive substance in serum from premature and full-term infants.
Authors: Pudek M R , Seccombe D W , Jacobson B E , Whitfield M F 
Published: January 2020

Abstract
Seven different digoxin immunoassay kits showed cross reactivity with an endogenous digoxin-like immunoreactive substance consistently present in serum of neonates, whether premature or full-term. The degree of interference, in decreasing order was: NML greater than New England Nuclear greater than Bio-Rad greater than Clinical Assays greater than Becton Dickinson greater than Serono greater than Syva (EMIT). More recently purchased NML kits showed less sensitivity to the substance, evidently reflecting lot-to-lot differences in antibody. A single baseline determination of the substance before digoxin is administered inadequately compensates for this interference, because the interferent concentrations can differ from day to day, with evidence that it may be most concentrated on the fourth to sixth postnatal day. Its concentration in the serum of neonates is unrelated to the concentration of dehydroepiandrostenedione sulfate, an indicator of fetal adrenal-cortical activity.
Determination of ultrafiltrable zinc in plasma by flameless atomic absorption spectrophotometry.
Authors: Whitehouse R C , Prasad A S , Cossack Z T 
Published: January 2020

Abstract
Ultrafiltrable zinc can be determined in small volumes of plasma by using Amicon ultrafiltration membrane cones and either flameless atomic absorption spectrophotometry or 65Zn. The ultrafiltration membrane cone is made sufficiently zinc-free by acid washing, followed by rinsing with de-ionized water. Within-run CVs were 12 and 10%, respectively, for the two methods. Matrix effects are compensated for by using standards in solutions with an inorganic matrix that simulates the sample matrix. Results for ultrafiltrable zinc by the two techniques agreed, and agreed with previously published data obtained by different ultrafiltration techniques. The mean (and SD) percentage of plasma zinc that was ultrafiltrable in 12 control subjects was 1.0 (0.5) by AAS and 0.7 (0.3) by 65Zn.
Use of immunoaffinity chromatography for purification of 125I-labeled human prolactin.
Authors: Stuart M C , Boscato L M , Underwood P A 
Published: January 2020

Abstract
We assessed a simple method for purifying 125I-labeled human prolactin, taking advantage of the abundant supplies of monoclonal antibodies available. 125I-Labeled human prolactin purified by immunoaffinity chromatography is compared with that purified by gel filtration on Sephadex G-100. We used monoclonal antibodies to prolactin to prepare the affinity chromatography columns. Prolactin was radiolabeled by the Chloramine T method, purified by each of the above procedures, and the binding and displacement characteristics were studied in radioimmunoassays in which either monoclonal antibodies or a rabbit anti-prolactin serum was the first antibody. A nonimmune fraction of 125I-labeled prolactin that co-eluted with the immunoreactive hormone from Sephadex G-100 was removed by affinity chromatography, which increased the antibody binding of 125I-labeled prolactin in the radioimmunoassay in the absence of unlabeled antigen (B/T0, in percent) twofold or more, increased the assay sensitivity, and increased the slope of antigen displacement measured by the 50% intercept. Several advantages make this the purification method of choice.
A direct radioimmunoassay for aldosterone in plasma.
Authors: Lun S , Espiner E A , Nicholls M G , Yandle T G 
Published: January 2020

Abstract
This rapid radioimmunoassay for aldosterone is performed directly on 100 microL of unprocessed plasma, with 125I-labeled aldosterone as the labeled antigen. Our use of steroid-free plasma in preparing the standard curve resulted in an overestimate of aldosterone; this problem was overcome by adding to such plasma a mixture of other steroids to provide a constant steroid/aldosterone ratio. Over a wide range of aldosterone concentrations, results agreed well between the present assay and a routine method involving solvent extraction and paper chromatography (r = 0.85), and sensitivity (20 ng/L) and inter- (10.4%) and intra- (3.9%) assay CVs were better with the present assay. Our assay is especially useful for multiple samples and (or) when only small-volume samples are available.
Determination of the antidepressants maprotiline and amoxapine, and their metabolites, in plasma by liquid chromatography.
Authors: Wong S H , Waugh S W 
Published: January 2020

Abstract
Maprotiline, amoxapine, and their metabolites were determined in plasma by three separate procedures, each of which involves a three-step extraction followed by reversed-phase separations. Amoxapine, maprotiline, and N-desmethylmaprotiline can be measured with use of a conventional C-18 column with 10% carbon load, but analyses for 7- and 8-hydroxyamoxapines require a small (5-microns) particle size, high carbon load, 20% C-18 column with 0.2 mol/L phosphate as mobile phase. Within-run and day-to-day CVs were 5% and 8%, respectively. Peak-height ratios were linearly correlated with concentrations between 0 and 400 micrograms/L. Detection limits ranged from 1 to 3 ng. Interference studies indicated that nortriptyline co-elutes with maprotiline. Assays of patients' plasma showed substantial amounts of these drugs and most of their metabolites, but only trace amounts of 7-hydroxyamoxapine.