bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioassay of Serum Folate
Authors: Dunn Ralph T , Foster Lowell B 
Published: January 2020

Abstract
We describe a radioassay procedure for serum folate, in which commercially available crystalline β-lactoglobulin is used as the folate-binding agent. The folate binders present in serum are eliminated by heating serum in a boiling water bath for 15 min to denature the proteins. Radioassayable serum folate is shown to be stable under these conditions, and the results for folate compare well with those obtained by a microbiological assay.
Automated Glucose Methods: Evaluation of a Glucose Oxidase—Peroxidase Procedure
Authors: Romano Anna T 
Published: January 2020

Abstract
We have evaluated methods in which glucose oxidase is used to determine serum glucose with the "AutoAnalyzer-II" and "SMA 12/60" (Technicon). A glucose oxidase—peroxidase—dianisidine procedure with improved specificity developed during this study is described. The glucose value is unaffected by the presence of 16 mg of uric acid per deciliter, and the system is highly resistant to interference from many other reducing compounds added to serum. The method appears to give "true glucose" values for normal, hyperuricemic, and uremic subjects. Results are compared with those from the "GOD-Perid," glucose oxidase—peroxidase—MBTH—DMA, hexokinase, toluidine, ferricyanide, and SMA 12/60 neocuproine techniques, as well as with those from our index of "true glucose," a procedure based on measurement of reducing material before and after treatment with glucose oxidase. Specificity and performance of the glucose oxidase—peroxidase—dianisidine and glucose oxidase—peroxidase—MBTH—DMA procedures are similar.
Comparison of Glutethimide Concentration in the Serum and Cerebrospinal Fluid of Humans in Drug Overdose
Authors: Gold Martin , Tassoni Ernest , Etzl Michael 
Published: January 2020

Abstract
Glutethimide concentrations were measured gas chromatographically in the serum and cerebrospinal fluid (CSF) of patients in coma caused by overdose of this drug. Piperidione was used as an internal standard. In the first serum samples collected from each patient, the glutethimide concentration ranged from 0.9 to 3.1 mg/dl. No patient had a CSF glutethimide concentration of more than 0.8 mg/dl. If one excludes patients who regained consciousness in less than 7 h, the seven remaining cases may be described by the following equation: y = 16.06 x1.06 where y = duration of coma (in h) and x = maximum serum glutethimide concentration (in mg/dl). The correlation coefficient for this equation was 0.911.
Rapid Determination of Ammonia in a Perchloric Acid Supernate from Blood, by Use of an Ammonia-Specific Electrode
Authors: Proelss Henning F , Wright Billy W 
Published: January 2020

Abstract
A simple, rapid method was developed for accurate determination of ammonia in whole blood. Blood proteins were precipitated with perchloric acid (8 g/dl) and the free ammonia liberated in the supernate on alkalinization was measured directly with an ammonia-specific electrode after adjusting the sample temperature to 25 °C. Some variables affecting precision, accuracy, and electrode performance were studied. Sensitivity, specificity, and interferences are discussed. The tentative normal range is 28 ± 14 µg of ammonia nitrogen per deciliter. The coefficient of variation was 4.8% in the "normal," 3.6% in the "abnormal" range. Abnormal values were correlated with clinical status. Recoveries averaged 99.3%. Correlation with an established ion-exchange method for plasma ammonia was 0.994. Total time required for a complete assay is 15 min.
Comparison of Four Methods for Measuring Uric Acid: Copper-Chelate, Phosphotungstate, Manual Uricase, and Automated Kinetic Uricase
Authors: Lum Gifford , Gambino S Raymond 
Published: January 2020

Abstract
Glutathione, ascorbic acid and many commonly used antibiotics falsely elevate uric acid concentrations when measured with the Du Pont "aca," in which the copper-chelate method is used. L-Dopa interferes with both the copper-chelate method and the Technicon "SMA 12/60" phosphotungstate method. A new kinetic uricase method has been developed for use on the Du Pont aca. This kinetic uricase method has a coefficient of variation of 2.40% and gives values that are essentially identical to those obtained by a manual end-point uricase method.
Modified Automated Saccharogenic Determination of Serum and Urinary Amylase Activity
Authors: Matthews W S , Sterling R E , Boyd T , Flores O R 
Published: January 2020

Abstract
The automated method of O’Neal and Gochman [Clin. Chem. 16, 985 (1970)] for determination of serum and urine amylase activity has been modified to increase its accuracy, precision, and efficiency. Sampling rate is 50 specimens per hour. The analysis depends on α-amylase hydrolyzing glycogen to maltose-like subunits, which are measured with the copper neocuproine reaction. Results obtained by this method are compared to those for a manual reference method [Clin. Chem. 6, 434 (1960)].
Critical Variables in the Radioimmunological Technique for Measuring Immunoreactive Insulin with Use of Immunosorbents
Authors: Velasco Carlos A , Oppermann Werner , Camerini-Davalos Rafael A 
Published: January 2020

Abstract
A commercial kit for determining immunoreactive insulin, the "Phadebas Insulin Test," was methodically evaluated to establish the optimal conditions for this immunoassay. Sensitivity, day-to-day and within-run precision, recovery, accuracy, and specificity are excellent. Results by this method compare favorably with those of the double-antibody technique. This rapid, simple, convenient, and reliable procedure for insulin immunoassay can be easily adapted to the facilities of a clinical laboratory as a standard diagnostic test or for clinical reseach.
Method for Determination of Cyclic AMP in Plasma
Authors: Rabinowitz Babeth , Katz Joseph 
Published: January 2020

Abstract
A simple procedure is described for measuring cyclic AMP (cAMP) in plasma, body fluids, and tissue extracts. A modification of the method of Brown et al. [Biochem. J. 121, 561 (1971)], it is based on competitive binding of cAMP by a protein in crude adrenal extracts, and precipitation of the cAMP-protein complex by ammonium sulfate. cAMP concentrations in normal human plasma ranged from 8 to 16 nmol/liter, and in the plasma of dogs from 5 to 15 nmol/liter. The range of the method is 0.5-8 pmol per assay, and up to 0.4 ml of sample can be used. A cheap and easily prepared binding-protein is used and the procedure is suitable for clinical studies of cAMP concentrations in plasma.
Evaluation of the Delves Micro System for Blood Lead Analysis
Authors: Hicks Jocelyn M , Gutierrez Aida N , Worthy Brenda E 
Published: January 2020

Abstract
Correlation between results of a conventional macroscale (5 ml of blood) atomic absorption procedure for lead determination and results of the Delves micro-scale (10 µl blood) atomic absorption method was high (0.96). Analyses of lead in capillary and intravenous blood samples also correlated well (0.93). The coefficient of variation of the Delves micro-scale method was 8% for a concentration of 46 µg of lead per milliliter. We conclude that the Delves microscale method—which is simpler, requires smaller samples than previous methods, and can be readily applied to capillary. ("finger-stick") blood—is very suitable for a pediatric practice and for the screening of large numbers of patients.
Automated Fluorometric Determination of Amphetaminein Urine
Authors: Hayes T S 
Published: January 2020

Abstract
A completely automated fluorometric determination of amphetamine in urine is described and evaluated. The dihydrolutidine derivative produced by reaction of amphetamine with formaldehyde and acetylacetone is excited at 410 nm and the resulting intensity of fluorescence measured at 476 nm. The working limit of detection of amphetamine in fresh urine (1.5-ml samples) is 0.15 mg/liter. A result is produced for the first sample in about 20 min; subsequent results are obtained at 2-min intervals. Falsely positive reactions are given by 2-phenylethylamine and tuaminoheptane.
Comparison of the Stannous Chloride and Vanadate Methods for Estimation of Serum Inorganic Phosphorus by Use of the "SMA 12/60"
Authors: Davies Janet L , Andrews G S , Miller R , Owen H G 
Published: January 2020

Abstract
We compared results of the stannous chloride and vanadate methods for estimating serum inorganic phosphorus on the "SMA 12/60" (Technicon). The technically simpler vanadate method gave better linearity and reproducibility, with virtually no carry-over or baseline drift; the reagents were stable, and it was most important to ensure that the concentration of sulfuric acid in the recipient and sample streams was identical. Instability in the stannous chloride method was due to precipitation in the stannous chloride-hydrazine working solution.
Rapid Method for Screening for Galactosemia and Galactokinase Deficiency by Measuring Galactose in Whole Blood Spotted on Paper
Authors: Grenier André , Laberge Claude 
Published: January 2020

Abstract
An inexpensive automated fluorometric technique for blood galactose determination has been modified to use dried blood spots available through phenylketonuria screening programs. The method is more efficient because of its high capacity (≃85,000 tests a year), low cost (≃$3,000 a year in reagents), and high specificity (enzymatic method).
Rapid Method for Quantitative Determination of Propoxyphene in Serum by Gas-Liquid Chromatography
Authors: Evenson M A , Koellner Susan 
Published: January 2020

Abstract
Rapid, accurate, and precise gas-chromatographic methods are reported for measurement of propoxyphene ("Darvon") in serum. A sample of 5 ml of serum is required for quantitation in blood after a therapeutic dose of 130-195 mg of propoxyphene; in cases of overdose of propoxyphene, only 1 ml of serum is required in a "toxic method" variation. Neither serum from healthy controls or from hospitalized patients contains interfering substances. Several commonly used analgesic and sedative drugs, added to a serum pool, also did not interfere. Day-to-day precision of the therapeutic method, as measured by the coefficient of variation (CV), is 7%; the CV for the method as applied to overdose cases is less than 3%. Propoxyphene added to serum could be about 86% accounted for analytically.
Determination of Uric Acid in Serum, with Use of Uricase and a Tribromophenol—Aminoantipyrine Chromogen
Authors: Kabasakalian Peter , Kalliney Sami , Westcott Anita 
Published: January 2020

Abstract
A manual method is described for determining the hydrogen peroxide produced from uric acid with uricase (pH 9.2) after deproteinization of 1.00 ml of serum. In the method, 2,4,6-tribromophenol is coupled with 4-aminoantipyrine (pH 7.0) by peroxidase oxidative coupling. The sensitivity of the method is such that 25 µg of uric acid from a fourth of the deproteinized serum (100 mg/liter) in a final volume of 5 ml of n-butyl acetate color extract gives a stable absorbance of 0.7 at 492 nm with a 1-cm cell. The method is reproducible, and many substances that may be encountered in serum do not interfere. Absorbances are linear for uric acid concentrations as high as 200 mg/liter.
Formaldehyde Interference in the Uric Acid—Phosphotungstic Acid Redox
Authors: Klein Bernard , Sheehan Joan 
Published: January 2020

Abstract
Formaldehyde, in quantities used to preserve uric acid standard solutions, will introduce errors in the automated analysis of serum uric acid by the Technicon N-13b phosphotungstate procedure, by retarding the dialysis rate. It will also diminish recovery of uric acid when these solutions are added to serum. The mechanism of interference is complex and may involve alteration of dialysis rates, formaldehyde— protein—uric acid interaction, and possibly a competing redox with phosphotungstic acid.
Methaqualone1 Overdose: Analytical Methodology, and the Significance of Serum Drug Concentrations
Authors: Bailey David N , Jatlow Peter I 
Published: January 2020

Abstract
Methaqualone abuse and overdose have recently become "epidemic." We determined concentrations of the drug in serum in 15 cases of overdose by gas— liquid chromatography (GLC) and ultraviolet spectraphotometry (UV). Values by GLC were consistently lower than those determined by UV after chloroform extraction, but correlated well with those obtained by UV after hexane extraction. Our studies show that at least one chloroform extractable metabolite has a spectrum very similar to that of the parent drug. This may in part explain the lower results obtained by GLC and suggests that other reported data based on UV analysis of chloroform and ether extracts may be too high. Extraction with hexane, a less polar solvent, followed by back extraction into HCl provides an accurate UV method suitable for emergency use. Concentration of unchanged methaqualone in serum after overdose ranged from 2 mg/liter to 22 mg/liter in this series; those greater than 8 mg/liter were usually associated with unconsciousness.
Evaluation of EDTA as the Chelator in the Biuret Reagent
Authors: Van Kley Harold , Claywell Carol S 
Published: January 2020

Abstract
Use of ethylenediaminetetraacetate (EDTA) as the chelating agent in the biuret reaction (in place of tartrate or citrate) was investigated. We found that this suggested modification of the reagent results in lower color yields and prolongs the time for color development. The EDTA reagent is more stable if color development is hastened by heating, but conditions are described under which the more customary reagent may be so used.
Variability of Standard Curves in Radioimmunoassay of Plasma Digoxin
Authors: Burnett George H , Conklin Robert L , Wasson Gertrude W , MacKinney Archie A 
Published: January 2020

Abstract
Evaluation of commercial kits (3H and 125I digoxin) for the radioimmunoassay of digoxin showed that different normal plasma samples yielded significantly different standard assay curves. Such differences accounted for errors of from 0.6 to 1 ng under certain conditions. The usual internal assay controls do not correct for these conditions. Because such changes may represent the differences between toxic and nontoxic digoxin concentrations, further study of the commercial test procedures appears to be indicated.
Simultaneous Competitive Protein Binding Assay for Cortisol, Cortisone, and Prednisolone in Plasma, and Its Clinical Application
Authors: Turner Adrian K , Carroll Carthage J , Pinkus Jack L , Charles David , Chattoraj Sati C 
Published: January 2020

Abstract
Simultaneous measurement of cortisol, cortisone, and prednisolone is described. A dichloromethane extract of plasma is separated and purified by partition thin-layer chromatography and assayed by competitive protein binding. Using 0.2 ml of plasma, we could assay about 1 µg of these three steroids per 100 ml. We measured plasma corticosteroids in men on prednisone therapy, during ACTH stimulation, and in pregnant women at the time of delivery, and also in arterial and venous blood samples collected from the umbilical cord. Plasma concentrations of prednisolone (4.46 ± 1.07 µg/100 ml) were maximal 2 h after oral administration of prednisone (10 mg). Basal concentrations of cortisol and cortisone in these subjects were 10.50 ± 1.04 and 1.88 ± 0.69 (SD) µg/100 ml, respectively. The values decreased to less than 1 µg/100 ml 4 h after administration and returned to 12.82 ± 1.92 and 2.16 ± 0.49 µg/100 ml, respectively, by 24 h. After intramuscular injection of synthetic ACTH, values for cortisol and cortisone were maximal at 30 min, declining to pre-injection concentrations within 4 h. Plasma cortisol and cortisone values for maternal venous blood at delivery were 47.0 ± 8.5 and 7.1 ± 2.2, umbilical vein blood 4.9 ± 2.6 and 19.7 ± 2.8 and in blood from the umbilical arteries 7.3 ± 4.5 and 11.6 ± 4.9 µg/ 100 ml, respectively. Cortisol was higher (P &lt; 0.05) in the umbilical arteries, cortisone (P &lt; 0.01) in the umbilical vein.
Improved Techniques for Assessment of Plasma Lipoprotein Patterns. I. Precipitation in Gels after Electrophoresis with Polyanionic Compounds
Authors: Seidel Dietrich , Wieland Heinrich , Ruppert Claudia 
Published: January 2020

Abstract
A method is described for making lipoprotein fractions visible by polyanion precipitation in situ in the gels after electrophoresis. With the new technique the pattern and its interpretation in the differential diagnosis of all primary forms of hyperlipoproteinemia is the same as for the other lipid-staining procedures. The new technique is simpler to perform, reliable, and provides the required information 60 min after electrophoresis. It also allows a very fast determination of the abnormal lipoprotein (LP-X) that characterizes cholestasis, without use of a specific antiserum.
Kinetic Colorimetric Measurement of Serum Lactate Dehydrogenase Activity
Authors: Babson Arthur L , Babson Susan R 
Published: January 2020

Abstract
A kinetic colorimetric assay procedure is described for measuring lactate dehydrogenase activity, in which the reduction of NAD is coupled to the reduction of a tetrazolium salt, 2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride (INT), with phenazine methosulfate serving as an intermediate electron carrier. The molar absorptivity of the formazan of INT was found to be 19.3 x 103 at 503 nm, which provides a threefold increase in sensitivity over the ultraviolet (340 nm) kinetic assay. The results correlate well with those obtained by 340-nm kinetic methods and the procedure does not require an ultraviolet spectrophotometer. The method is simple, rapid, and does not rely on secondary enzyme standards. It requires only two reagents, which are stable.
Computer Technique for Identification of Chromatographic Peaks
Authors: Chilcote D D 
Published: January 2020

Abstract
A computer program has been developed to identify known peaks in a chromatogram from a computer-interfaced chromatograph. The focal point of the program is a normalization technique, which refers the elution volume of each sample peak encountered to the elution volumes of two reference peaks that bracket the peak of interest, as is done in certain gas chromatographic normalization techniques. The normalized elution volume is determined by dividing the difference between the elution volumes of the sample peak and the first (early-eluting) reference peak by the difference between the elution volumes of the two reference peaks. The normalized elution volumes thus obtained are compared to normalized elution volumes of known compounds stored in bulk memory. The compounds now being used as reference peaks in the chromatograms from the UV-Analyzer are hypoxanthine, uric acid, hippuric acid, and p-cresol.
Relationship between Variables in Instrument Performance and Results of Kinetic Enzyme Assays—A System View
Authors: Maclin Ernest , Rohlfing Donald , Ansour Manoug 
Published: January 2020

Abstract
Much effort has been expended to define individual instrumental variables and chemical requirements for kinetic assays. In this paper, these variables are grouped together to demonstrate the relationship between characteristics of the instrument system and final results for kinetic enzyme analyses. Tolerances on instrumental variables are reviewed in terms of these final results, and summarized and interpreted as they effect the results of kinetic assays. We have evaluated the effects on absorbance change as they are related to tolerances for absorbance, time, sample volume, reagent volume, temperature, and path-length. Specifications of spectrophotometric instruments in terms of linearity, accuracy, wavelength adjustability and accuracy, stray light, noise, and drift are also reviewed as to their effects on absorbance change. Generalized data are presented and are then related, as an example, to measurement of aspartate aminotransferase activity.
Design, Construction, and Two Applications for an Automated Flow—Cell Polarization Fluorometer with Digital Read Out: Enzyme-Inhibitor (Antitrypsin) Assay and Antigen—Antibody (Insulin—Insulin Antiserum) Assay
Authors: Spencer Richard D , Toledo Fernando B , Williams Ben T , Yoss Norma L 
Published: January 2020

Abstract
We have constructed and automated a flow cell polarization fluorometer and demonstrated two specific clinical applications of fluorescence polarization assay, i.e., the enzyme-inhibitor assay of antitrypsin in serum and the antigen-antibody assay of insulin and its antibody. A signal is displayed directly and is immediately available for chart recording and (or) digital data processing. Since fluorescence polarization offers a number of choices in assay parameters and the use of different fluorescent probes, its development for rapid simultaneous measurements of multiple components in body fluids should be possible.
Evaluation of Kinetic Enzyme Parameters by Use of a Small Computer Interfaced "Fast Analyzer"—An Addition to Automated Clinical Enzymology
Authors: Tiffany T O , Chilcote D D , Burtis C A 
Published: January 2020

Abstract
The evaluation of steady-state enzyme kinetic parameters such as Km, Vmax, and Ki is useful in clinical enzymology, particularly where they can be used for the detection of enzyme variants and to assess the type of isoenzymes and the extent of their abnormal activity. The multiple-cuvet parallel-analysis feature of the Fast Analyzer permits one to evaluate one or more enzymic parameters in a single rotor. Both on-line measurement of initial reaction velocities and rapid off-line reduction of statistical data can be obtained by using the small-computer interfaced Fast Analyzer. Estimates of error in determining these parameters are also obtained, for use in comparing results in future analyses. We discuss the programming approach for adapting both simple and more complex statistical nonlinear regression data-fitting routines to the Fast Analyzer’s computer. We illustrate how the analyzer may be used to determine simple kinetic parameters for placental alkaline phosphatase and glucose-6-phosphate dehydrogenase and for the more complex "stripping out" of Km’s and Vmax’s for a heterogenous mixture of placental and intestinal alkaline phosphatase.
Simplified Gas Chromatography of Trimethylsilyl Esters of C1 through C5 Fatty Acids in Serum and Urine
Authors: Mamer O A , Gibbs B F 
Published: January 2020

Abstract
All the metabolically important C1 through C5 fatty acids and lactic, pyruvic and β-hydroxybutyric acids can be gas chromatographed surprisingly well on the common 2-meter 3% methylphenylsilicone (e.g., "OV-17") column when a late-eluting silylating reagent such as trimethylsilylimidazole is used. In these circumstances, the trimethylsilyl esters elute in an interval that is free of the reagent and solvent interferences usually found when the more volatile preparations are used for silylations. Use of the method is demonstrated by its application to a serum from a case of isovaleric acidemia and a urine from a case of methylmalonic aciduria.
A Simplified Determination of Urinary Cadmium, Lead, and Thallium, with Use of Carbon Rod Atomization and Atomic Absorption Spectrophotometry
Authors: Kubasik Norman P , Volosin Michael T 
Published: January 2020

Abstract
Lead, cadmium, and thallium are determined in a single 3-ml urine sample. The three metals, simultaneously chelated with sodium diethyldithiocarbamate, are extracted (at pH 3-7) into methyl isobutyl ketone (isopropylacetone), and the carbon rod atomizer, in conjunction with atomic absorption spectrophotometry, is used to analyze the extracts. Small sample requirements (1.6 µl) permit the extraction to be carried out in small-volume disposable glassware, with use of disposable pipets. Within-run coefficients of variation were all less than 5%; recovery ranged from 96-106%. Several normal urinary constituents, added in excess, negligibly affected recoveries. Ethylenediaminetetraacetate in the urine inhibited recovery of lead; this was reversed by adding excess calcium to the urine before extraction. The method of standard additions was used to compensate for differences between standards and unknowns caused by matrix effects.