bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of High-Resolution Open Tubular Glass Capillary Columns to Separate Acidic Metabolites in Urine
Authors: Knights Brian A , Legendre Mary , Laseter John L , Storer James S 
Published: January 2020

Abstract
We used high-resolution glass capillary columns to study the trimethylsilyl derivatives of some acidic metabolites found in pooled urine specimens from control and postpartum subjects. About 30 compounds were identified by gas chromatography—mass spectrometry—computer techniques. In general, open tubular capillary columns effect better resolution of trimethylsilyl derivatives of organic acids than do conventional packed columns. GE SE-30 proved to be a good general-purpose stationary phase, whereas OV-17 offered certain advantages in resolving aromatic acid components.
Correction for Spectral Interference with Determination of Lead in Blood by Non-Flame Atomic Absorption Spectrometry
Authors: Garnys V P , Matoušek Jaroslav P 
Published: January 2020

Abstract
A non-flame atomizer incorporating a graphite tube and cup is used to determine lead in whole blood and packed erythrocytes. In a direct method, a 2-µl sample is treated in situ in the cup with 1 µl of concentrated nitric acid. The oxidized sample can then be dried, ashed, and atomized without leaving a residue. The nitric acid treatment obviates correction for nonselective absorption, something previously necessary in the determination of lead in blood by non-flame techniques. The resulting chemical conversion of the matrix compounds frees the lead atomic absorption peak from the spectral interference. Alternatively, a 50-µl sample of blood or erythrocytes is treated with 50 µl of concentrated nitric acid and a 1.5-µl aliquot is analyzed with use of the graphite tube.
Inhibitory Effect of Fluoride on Glucose Tests with Glucose Oxidase Strips
Authors: Onstad John , Hancock Daniel , Wolf Paul L 
Published: January 2020

Abstract
Sodium fluoride was inadvertently added as a preservative to the urine of an eight-year-old boy with diabetes mellitus before urinary glucose was measured. On preliminary screening of the urine, the test by glucose oxidase paper reagent strip gave a negative reading for glucose, whereas quantitative urinary glucose assay by the coupled enzyme reaction (hexokinase—glucose 6-phosphate dehydrogenase) gave a glucose concentration of 81.5 g/liter. Inadvertent use of sodium fluoride as a urine preservative may cause a falsely negative result with the glucose tests involving oxidase.
Immunological Measurement of Transferrin Compared with Chemical Measurement of Total Iron-Binding Capacity
Authors: Tsung Swei H , Rosenthal Waldemar A , Milewski Karen A 
Published: January 2020

Abstract
Because of uncertainty as to the molecular weight of transferrin, a previous comparison [Von der Heul et al., Clin. Chim. Acta 38, 347 (1972)] between transferrin content of serum and total iron-binding capacity cannot be definitive. We found a conversion factor for expressing transferrin as iron-binding capacity by measuring the maximum amount of iron bound by 1 mg of transferrin. We compared the resulting calculated value with values obtained by three other methods for measuring total iron-binding capacity. We agree with the previous observation that the latter, as measured radioisotopically, give higher results than would be judged from the transferrin content but the same as those for two chemical methods. The diffusion rate of transferrin in agar was the same irrespective of the degree of iron saturation. Serum transferrin concentrations were low in patients with anemia resulting from malignancy, chronic disorders, and cirrhosis of the liver, and high or normal in patients with iron deficiency anemia and in pregnant women or women who were taking birth-control pills. Measurement of transferrin concentration can be used to distinguish iron deficiency anemia from anemia resulting from chronic disorders, but offers no advantages over existing methods for estimating total ironbinding capacity.
Aspartate Aminotransferase and Alanine Aminotransferase Activities in Plasma: Statistical Distributions, Individual Variations, and Reference Values
Authors: Siest Gérard , Schiele Françoise , Galteau Marie-Madeleine , Panek Edwige , Steinmetz Josiane , Fagnani Francis , Gueguen René 
Published: January 2020

Abstract
The determination of frequency value (percentile limits) and the classification of the different variation factors allow us to define more and more homogeneous subpopulations as we use these factors for sorting. Using as our study population those persons coming to the Centre for Preventive Medicine, we were able to: (a) Describe and measure the significance and importance of physiological variations or of variations attributed to age—the latter largely related only to excessive weight, which it seems to us is often the case. (b) Establish a classification for variation factors; the recapitulatory table should be useful to clinical chemists in helping physicians interpret a laboratory test result that falls within the zone of incertitude. (c) Suggest a preliminary group of reference values for healthy subjects, to be used in interpreting a laboratory test in this way.
Standards for Total Serum Protein Assays— A Collaborative Study
Authors: Doumas Basil T 
Published: January 2020

Abstract
We have studied the standardization of total serum protein assay with the biuret reaction. Standard solutions were prepared from lyophilized preparations of human serum albumin and bovine serum albumin, with corrections made for volatile material and ash contents. These solutions and a solution of crystalline albumin standard were analyzed with a new stable biuret reagent, to establish absorptivity values (values for the absorbance of a 1 g/liter final reaction mixture). The mean values obtained were 0.302, 0.292, and 0.290 for human serum albumin, bovine serum albumin, and the crystalline albumin, respectively. We believe that the established absorptivity value will improve the accuracy of serum protein determinations. We studied the linearity of the relation between color produced and protein concentration, with use of the solutions described above and a serum pool. The color adheres to Beer's law up to the highest concentration tested: 3 g/liter for HSA and BSA, and 2.8 g/liter for serum in the final reaction mixture. The new biuret reagent has been stable for one year at room temperature. We recommend the use of bovine serum albumin as a primary standard for serum protein assays. It is inexpensive, easily available, and exhibits the best linearity in the biuret reaction.
Standardization of Incubation Time and Temperature for Eight Radioimmunoassays
Authors: Lenz Paul H , Wien George H , Toth Janice M 
Published: January 2020

Abstract
We wanted to know if incubation time and temperature for many radioimmunoassay methods could be standardized, to decrease assay time and so improve efficiency. Percentage binding was determined for triiodothyronine, thyroxine, digoxin, digitoxin, testosterone, aldosterone, estradiol, and diphenylhydantoin when the reaction mixtures were incubated at 6-8, 22, or 37 °C for various periods of time. In all methods tested, binding of antigen to antibody was greatest when the reaction mixtures were incubated at 6-8 °C, less at 22 °C, and least at 37 °C. Maximum binding occurred within 30-60 min at each temperature for all methods tested. Hence, it is possible to standardize the incubation time and temperature for these eight radioimmunoassay methods to 60 min at 6-8 °C.
Continuous Monitoring of Radioactivity of Effluent from a High-Speed Amino Acid Analyzer, with a New System of Sample Segmentation
Authors: Bakay Bohdan 
Published: January 2020

Abstract
Radioactivity in the effluents from high-speed liquid chromatographic analyzers was continuously measured by use of a new sample segmentation system. To achieve highest counting efficiency, the column effluents were mixed with scintillation fluid carrying small segments of semisolid, resilient spacer. After passing through a mixer, the mixture was passed through a hollow-tube flow cell mounted in a liquid scintillation spectrometer. Because the added spacer acts like a continuous series of pistons, it unifies flow rate at center and walls of the conduit and so decreases sample carryover. This system was applied to measurement of radioactivity in the effluent of a high-speed amino acid analyzer, in which some amino acids emerge at 30-s intervals. The resulting profiles were as well resolved as were the ninhydrin-color profiles. Counting efficiencies for tritium and carbon-14 were comparable to those obtained by static counting in vials.
New Instrument for Rapid Determination of Activities of Lactate Dehydrogenase Isoenzymes
Authors: Everse Johannes , Reich Richard M , Kaplan Nathan O , Finn W Donald 
Published: January 2020

Abstract
Lactate dehydrogenase isoenzymes can be distinguished kinetically by the fact that isoenzyme H is strongly inhibited a few seconds after the reaction is started if high concentrations of pyruvate are present, in contrast to the M isoenzyme. A new instrument that exploits this fact can measure both the total activity and the proportion of H isoenzyme in serum or plasma in 8 to 10 s. The instrument consists of a simplified stoppedflow apparatus in which the plasma is assayed for lactate dehydrogenase activity, and an electronic device that measures the rate of the reaction at two pre-set time intervals. The first rate is taken between 0.2 and 0.4 s after the reaction is started, a time at which both isoenzymes are fully active, and at which the rate obtained thus reflects total lactate dehydrogenase activity in the plasma sample. The second rate is measured 4 to 6 s after the start of the reaction, at which time the H isoenzyme has become inhibited and the observed rate compared to the initial rate is therefore proportional to the percentage of H isoenzyme activity in the serum. These two rates are electronically displayed on two three-digit voltmeters, the first display being the total activity, the second a number proportional to the inhibited slope. The percentage of M isoenzyme can then be calculated from the initial and final rate. A total of five to six repeat assays may be done within a minute on 1 ml of plasma or serum. This instrument may be of significant value in following the progress of myocardial infarctions and other diseases.
Clinical Applications of Gas Chromatograph/Mass Spectrometer/Computer Systems
Authors: Horning Marjorie G , Nowlin Jean , Butler Carla M , Lertratanangkoon Khing , Sommer Kathleen , Hill Reba M 
Published: January 2020

Abstract
Gas chromatograph/mass spectrometer/computer systems can be used to quantify a wide variety of compounds of clinical interest. A quadrupole instrument operated in the chemical ionization (Cl) mode was used in these studies. Because of the sensitivity and specificity of selective ion detection, it is possible to make measurements routinely in the nanogram to picogram range, with 0.1-1.0 ml samples of plasma and 1-5 ml samples of urine. Internal standards, preferably stable-isotopelabeled compounds, were added to the biological samples before isolation was begun. We describe clinical applications of these procedures to problems in toxicology, pharmacokinetics, and perinatal pharmacology.
Gas-Chromatographic and Mass-Spectrometric Detection of Low-Molecular-Weight Aliphatic Alcohols in Urine of Normal Individuals and Patients with Diabetes Mellitus
Authors: Liebich Hartmut M , Al-Babbili Ossama , Zlatkis Albert , Kim Kyoung 
Published: January 2020

Abstract
We studied the aliphatic alcohols in 100 urines from 25 patients with diabetes mellitus under treatment with insulin, oral antidiabetic medication, or special diet. The procedure involves adsorption of the low-molecular-weight urinary metabolites on a porous polymer of 2,6-diphenyl-p-phenylene oxide (Tenax GC), gas-chromatographic separation, mass spectrometric identification, and mass fragmentographic representation of the primary alcohols by a computer. The concentrations of ethanol, n-propanol, isobutanol, n-butanol, and isopentanol are increased as compared with urine from normal persons.
Effects of storage in the cold on activity of gamma-glutamyltransferase in serum.
Authors: Rhone D P , White F M 
Published: January 2020

Abstract
Sera from patients with hepatobiliary disorders were selected to represent a wide range of activity of gamma-glutamyltransferase (EC 2.3.2.2). Samples were stored at 4 degrees C and periodically tested for as long as nine weeks, others at -6 degrees C for as long as 40 weeks. The frozen-stored samples were thawed and then frozen again after each testing. The activity of the enzyme was essentially unchanged under both conditions of storage. These results are consistent with comments in the literature on the enzyme's stability.
Recently discovered hypothalamic-pituitary hormones.
Authors: Malarkey W B 
Published: January 2020

Abstract
In recent years a variety of peptide hormones have been isolated from the mammalian hypothalamus and pituitary. Several hypothalamic hormones, including thyroliberin (thyrotropin-releasing factory), luliberin (luteinizing hormone-releasing factor), and somatostatin (somatotropin release-inhibiting factor), have been characterized and synthesized. The subsequent development of radioimmunoassays for these hormones has made possible the study of their physiology. The measurement of prolactin in serum and the release of pituitary hormones after the administration of the hypothalamic hormones has proved to be useful in clinical diagnosis. The use of hypothalamic hormones in treating various clinical disorders and the isolation and characterization of new releasing and inhibiting hormones in the hypothalamus are actively being investigated.
Improved microscale assay for purine phosphoribosyltransferase activities.
Authors: Schmidt R , Forêt M , Reichert U 
Published: January 2020

Abstract
We describe an improved and rapid filter-type assay for purine phosphoribosyltransferase activities. 14C-labeled purine bases are used as substrates, and the equipment includes a sampling manifold and glass-fiber filters coated with polyethyleneimine-cellulose. The method is especially suited for assay of a large number of samples, and may be useful for other enzyme activity measurements.
Evaluation of a reagent-strip method for glucose in whole blood, as compared with a hexokinase method.
Authors: Stewart T C 
Published: January 2020

Abstract
The hexokinase method (I) for glucose in biological fluids, proposed by the FDA as a potential national standard method, is compared with the Eyetone/Dextrostix/Control method (II) for measurement of glucose in whole blood. I used a new, two-step calibration procedure based on a 1.30 g/liter standard for the II system. The correlation coefficient for results by the two methods was 0.99 for 142 assays in duplicate. Recovery values were near 100% (I, range 100.0 to 106.2%; II, range 100.8 to 105.1%), and the coefficients of variation were respectively +/- 4.1% and +/- 4.5%. Considering the close correlation between the two methods, together with the simplicity, speed, and convenience of II, I conclude that it has great clinical utility, particularly in emergency situations. The precision and accuracy of II depends greatly on proper calibration and control procedures and on adequate training of the operator.
Automated method for L-carnitine determination.
Authors: Seccombe D W , Dodek P , Frohlich J , Hahn P , Skala J P , Campbell D J 
Published: January 2020

Abstract
Because of renewed interest in a possible connection between carnitine, lipid disorders, and myopathy, an automated method of analysis is desirable. Deproteinization of serum by use of membrane filter cones and automated assay with a bichromatic analyzer (the ABA-100) substantially increases efficiency without sacrificing the specificity and accuracy of the original manual enzymatic method. The described procedure allows for analysis of 80 speciments a day and is thus suitable for screening of selected populations. Normal values found in blood sera of adults were in the range of 25.0-73.8 mu mol/liter and the method has sufficient sensitivity to accurately measure concentrations as small as 10 mu mol/liter.
Comparison of procedures for extracting free amino acids from polymorphonuclear lekocytes.
Authors: Houpert Y , Tarallo P , Siest G 
Published: January 2020

Abstract
We studies five methods for extracting amino acids from human polymorphonuclear leukocytes. Both the use of cell lysis and of a deproteinizing agent interfere with quantitative determination of the amino acids, basic amino acids being the most sensitive to the extraction procedure. Among the methods used, disruption of the cells by freezing-thawing is the best method for extracting all the amino acids. Taurine is the only amino acid extracted in the same amount by all the methods studied, and it represents half of the intracellular pool.
Serum alkaline phosphatase measured by using thymol blue monophosphate and a bichromatic analyzer.
Authors: Elser R C 
Published: January 2020

Abstract
Thymol blue monophosphate is evaluated as a substrate for use in kinetic bichromatic analysis of serum alkaline phosphatase activity. The effect of abnormally high concentrations of hemoglobin, bilirubin, or chylomicrons is negligible. The expected range for ambulatory adults established by assaying sera from 206 blood donors, was 12-44 U/lliter at 37 degrees C. Comparison of the method with a commonly used p-nitrophenyl phosphate method yielded a correlation coefficient, r, of 0.9949. Advantages of the method are the reduced cost per test and the exceptionally stable substrate.
Toward absolute methods in clinical chemistry: application of mass fragmentography to high-accuracy analyses.
Authors: Björkhem I , Blomstrand R , Lantto O , Svensson L , Ohman G 
Published: January 2020

Abstract
We review recently developed reference methods based on mass fragmentography (specific ion monitoring) with use of isotope-labeled internal standard, for determination of cholesterol, triglycerides, urea, glucose, cortisol, progesterone, and testosterone. With an optimal ratio between standard and material to be determined, the relative standard deviation of these methods, based on duplicate determinations, is between 1.3 and 2.7%. The very high specificity of the methods, in combination with the fact that the ratio between labeled and unlabeled molecules is determined with a high degree of accuracy, makes it likely that the most significant errors in the methods are related to errors in pipetting. The possibility is discussed that these methods might be developed into "absolute" or "definitive" methods by subjecting each individual step in the determination to a detailed analysis with respect to possible error. We also discuss some of the consequences of the different reference methods on the choice of routine methods.
Metabolic response of humans to ingestion of nicotinic acid and nicotinamide.
Authors: Mrochek J E , Jolley R L , Young D S , Turner W J 
Published: January 2020

Abstract
The identification of nicotinamide-N1-oxide as a metabolite in the urine of a schizophrenic patient prompted a study of the relative metabolism of nicotinic acid and nicotinamide in mental patients and healthy volunteers. Metabolites quantified included N1-methyl-2-pyridone-5-carboxamide, N1-methyl-4-pyridone-3-carboxamide, N1-methylnicotinamide, nicotinuric acid, and nicotinamide-N1-oxide. More of most of these metabolites evidently was excreted after nicotinamide ingestion than after nicotinic acid. At the highest doses (3000 mg/day), the relative proportions of these metabolites in the urine were changed. There were only slight difference between healthy individuals and mental patients in the quantities of metabolites excreted, and no statistically significant trends were noted.
Evaluation of three commercially available menual "kit" methods for triglycerides in serum.
Authors: Kykstra S L , Lawrence J D 
Published: January 2020

Abstract
We compared three commercially available kits for use in determining triglycerides (triacylglycerols) in serum, by different methods, for accuracy and precision, with use of pooled sera of low, normal, and high triglyceride concentrations. Accuracy varied from -17% to +16% of the independently determined value, depending on the method and triglyceride concentration. In general, the Calbiochem method was the most nearly accurate, and only it met Center for Disease Control criteria for precision at all three triglyceride concentrations. The relationships of mean values to the suggested normal range for each method varied, some significant differences being found. Our data demonstrate the importance of a correlation between the independently determined value and the normal range for the method used and stresses the need for normal-range values to accompany all patients' reports.
Evaluation of enzyme-multiplied immunoassay technique (EMIT) for determination of serum digoxin.
Authors: Rosenthal A F , Vargas M G , Klass C S 
Published: January 2020

Abstract
Sixty-seven digoxin-containing sera were analyzed by both radioimmunoassay and EMIT. After some important modifications of the EMIT method, agreement between the two methods was very good. Reproducibility of the EMIT assay was excellent; daily variations in values found for control sera were quite small, and recovery of added digoxin was good. Slight hemolysis hadnegligible effects, but highly hemolyzed specimens gave low recoveries of digoxin.
More sensitive high-pressure liquid-chromatographic determiantion of theophylline in serum.
Authors: Adams R F , Vandemark F L , Schmidt G J 
Published: January 2020

Abstract
We present procedures for determining theophylline in 50 mul of serum. The drug is extracted into a small volume of solvent that contains an internal standard, 8-chlorotheophylline. The extract is Analyzed by isocratic reversedphase chromatography, with measurement of eluted theophylline at 273 nm. Day-to-day reproducibility within 5% is attainable for the concentration range 5--20 mg/liter. Other xanthines and related metabolites do not interfere. Sensitivity is 1 mg/liter. The correlation coefficient, when results by a spectrophotometric procedure were compared, was 0.989. Amobarbital, secobarbital, phenobarbital, and diphenylhydantoin do not interfere. Total analysis time for a single sample is 15 min.
Separation and quantitation of serum constituents associated with calcium by gel filtration.
Authors: Toffaletti J , Gitelman H J , Savory J 
Published: January 2020

Abstract
Gel filtration of serum by use of polyacrylamide beads (Biogel P-2) separates total colcium into four distinct peaks: an initial peak, corresponding to protein-bound calcium; a second peak containing the calcium complexes of citrate, phosphate, lactate, and sulfate; a third peak containing calcium bicarbonate; and a fourth peak or trough corresponding to the serum ionic calcium. An eluent containing (per liter) 140 mmol of sodium, 1.1o mmol of calcium, 0.50 mmol of magnesium, and 10 mmol of 2-([tris(hydroxymethyl)methyl]amino)ethanesulfonic acid(pH 7.40 at 37 degrees C) provides physiological conditions that determine the equilibria between these calcium components. Association constants determined under these conditions permit calculation of the expected concentration of the calcium complexes in each tube of eluent, and these concentrations closely correspond to the amount of bound calcium measured experimentally. The mean distribution of calcium in healthy individuals, as determined by this method, is (per liter): calcium protein, 1.00 mmol; calcium complexes, 0.31 mmol; and ionic calcium, 1.07 mmol.