bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorometric Serum Lipase Assay: Evaluation of Monodecanoyl Fluorescein as Substrate
Authors: Klein Bernard , Standaert Fontaine 
Published: January 2020

Abstract
The elements of the mechanized fluorometric lipase (EC 3.1.1.3) assay of Fleisher and Schwartz [Clin. Chem. 17, 417 (1971)] were made optimum; a manual adaptation was also developed. Hydrolysis of the monodecanoyl fluorescein substrate by hog pancreatic lipase is a zero-order reaction. The hydrolytic activity of normal human serum, serum from hospitalized patients without pancreatitis, and serum from patients with acute pancreatitis showed considerable overlap. Bile salts, considered activators in titrimetric or turbidimetric lipase assays, inhibited hydrolysis of the substrate by human serum. We conclude that monodecanoyl fluorescein is not a specific substrate for the serum lipase measured in acute pancreatitis.
Gas Chromatographic/Thin-Layer Chromatographic Analysis of Acetylated Codeine and Morphine in Urine
Authors: Jain Naresh C , Sneath Thomas C , Budd Robert D , Leung Wai J 
Published: January 2020

Abstract
This procedure positively identifies codeine and morphine in urine. Urine samples are hydrolyzed and extracted with organic solvent, and the extracts are evaporated and acetylated. The presence of codeine and morphine is ascertained by gas chromatography (3% OV-25 and 3% Poly-A 103 columns) and confirmed by thin-layer chromatography (system: ethyl acetate/acetone/concd ammonium hydroxide, 100/10/4.5 by vol; reagent: iodoplatinate). As little as 0.5 mg each of codeine and morphine per liter, in free and conjugated forms, is detectable by this method.
Centrifugal Analyzer Determination of Ascorbate in Serum or Urine with Fe3+/Ferrozine
Authors: Butts William C , Mulvihill Harold J 
Published: January 2020

Abstract
Measurement of serum ascorbate may be useful in long-term population studies because of the possible influence of ascorbate on numerous physiological factors. We describe an automated method for determining ascorbate in serum and urine by using the reduction of ferric iron by ascorbate and the formation of a color between the resulting ferrous iron and Ferrozine [3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine]. A centrifugal analyzer is used to rapidly and simultaneously measure ascorbate in the samples and standards and minimize interference from slower reacting substances in the sample. The method is highly precise and specific. Data are also presented on the stability of ascorbate in serum, urine, and aqueous solutions.
Evaluation of an Automated Glucose-Oxidase Procedure
Authors: Rodriguez-Castellon Jose A , Robinson C Andrew , Smith Mary S , Frye Joyce H 
Published: January 2020

Abstract
We evaluated a slight modification of the automated oxidase/peroxidase method for glucose determination in blood with use of 4-aminophenazone [J. Clin. Pathol. 22, 246 (1969)]. Nonsugar reducing substances did not interfere, except for ascorbic acid in very high concentrations. Lipemic sera gave slightly lower values. Values for reproducibility, specificity, and sensitivity were closer to such values for the hexokinase method than was the case for some other commonly used methods.
Determination of Na+ and K+ in Urine with Ion-Selective Electrodes in an Automated Analyzer
Authors: Pelleg Amir , Levy Gabor B 
Published: January 2020

Abstract
We applied an automatic potentiometric electrolyte analyzer (STAT/ION) to the routine determination of Na+ and K+ in urine samples, and found a high correlation with results obtained by flame photometry. The electrodes were selective and no obvious interferences were encountered in the limited number of samples available in this study
Manual and Semi-Automated Procedures for Measurement of Triglycerides in Serum
Authors: Giegel Joseph L , Ham Anna Bell , Clema William 
Published: January 2020

Abstract
We describe manual and semi-automated procedures for serum triglyceride determinations, in which lipids are partitioned between a water/isopropanol phase and a nonane phase. More than 99% of the triglyceride is extracted into the nonane phase, as determined by recovery of 3H-labeled triolein. Studies with 14C-labeled lecithin demonstrate that less than 1.3% is extracted into the nonane phase at concentrations up to 2.5 g/liter. A novel feature of the method is that glycerol can be liberated from triglyceride by sodium hydroxide at room temperature in less than 5 min. Glycerol is oxidized by periodate in 1-2 min at 25 °C; the formaldehyde produced is reacted with 2,4-pentanedione to yield 3,5-diacetyl-1,3-dihydrolutidine. The manual procedure requires less than 20 min; the semi-automated method requires 7 min from sampling to readout. The procedure may be run at 30-40 samples/h, with stable baseline and less than 2.0% carryover. Both methods are linear to 0.50 g (5.6 mol) of triolein per liter. Analytical recoveries at several concentrations ranged from 97-101% (mean, 100%)
Measurement of Spectral Bandwidth, as Exemplified with the Beckman "Enzyme Analyzer System TR Spectrophotometer"
Authors: Passey Richard B , Gillum Ronald L , Fuller John B 
Published: January 2020

Abstract
This paper describes simple methods for determining spectral bandwidth by measurement and by calculation. We measured the spectral bandwidth of the monochromator from the Beckman Enzyme Analyzer TR, and found it to be 3.5-4.0 nm (av 3.8) by two different methods. We visually estimated it to be 4 nm. Using the specifications for the diffraction grating, focal length, and fixed slit width, we calculated the theoretical spectral bandwidth to be 3.6 nm.
Effects of Buffers on Aspartate Aminotransferase Activity and Association of the Enzyme with Pyridoxal Phosphate
Authors: Rej Robert , Vanderlinde Raymond E 
Published: January 2020

Abstract
Using purified enzymes of human origin and patients’ sera, we examined factors influencing the in vitro association of pyridoxal phosphate with aspartate aminotransferase (EC 2.6.1.1). The rate of association was markedly retarded by phosphate buffer in comparison with tris(hydroxymethyl)aminomethane or six other buffers. Pyridoxal phosphate at an incubation concentration of 130 µmol/liter reactivated the entire apoenzyme portion of an apoenzyme/holoenzyme mixture within 5 min in tris(hydroxymethyl)aminomethane; in contrast, less than 20% was associated during 15 min in phosphate. Activity measured in tris(hydroxymethyl)aminomethane-buffer without exogenous pyridoxal phosphate was 4% greater than that in phosphate and was slightly increased by increasing the pH of the assay mixture from 7.5 to 8.0. Aspartate in the incubation medium did not retard the stimulation in tris(hydroxymethyl)aminomethane buffer. While the magnitude of stimulation varied greatly among sera, a consistent mean stimulation of 30% for groups of sera with normal activities was found when asparate at 125 mmol/liter, 2-oxoglutarate at 6.7 mmol/liter and tris(hydroxymethyl)aminomethane at 90 mmol/liter were used, an increase over the 16% with phosphate buffer [Clin. Chem. 19, 92 (1973)]. Absorbance spectra suggest pyridoxal phosphate exists as the Schiff base of tris(hydroxymethyl)aminomethane or aspartate, or both, under conditions of assay incubation (without addition of 2-oxoglutarate). Nonenzymatic catalysis of the reaction by pyridoxal phosphate alone or a formation of a protein/pyridoxal phosphate adduct was discounted with use of D-asparate substrates
Parallel Radioimmunoassay for Plasma Cortisol and 11-Deoxycortisol
Authors: Kao Michael , Voina Sandra , Nichols Albert , Horton Richard 
Published: January 2020

Abstract
We describe a direct, rapid, and specific procedure for the parallel radioimmunoassay for cortisol and 11-deoxycortisol in plasma. The plasma sample is used directly, after heat inactivation of the natural cortisol-binding protein. The radioimmunoassay utilizes antibodies generated in rabbits by steroids conjugated at their 3-oxo position to thyroglobulin. Ammonium sulfate is used to separate bound and free steroids. Our cortisol antibody and an 11-deoxycortisol antibody obtained elsewhere cross reacted negligibly with each other or with other steroids that might be present in plasma. Radioimmunoassays were therefore developed for both steroids in only 1.25 µl of plasma. The intra-and interassay coefficients of variation for both steroids were less than 10%, with a sensitivity of 4 µg/liter. Steroid values obtained by a competitive protein binding method were consistently higher than those of the present method, suggesting that the former is measuring total corticosteroids. This simple approach requires only 4 h for the specific measurement of both cortisol and 11-deoxycortisol in 20 samples of plasma
Fluorometric Determination of δ-Aminolaevulinate Dehydratase Activity in Human Erythrocytes as an Index to Lead Exposure
Authors: Chakrabarti Saroj K , Brodeur Jules , Tardif Robert 
Published: January 2020

Abstract
We describe a fluorometric method for determining δ-aminolaevulinate dehydratase (EC 4.2.1.24) activity in human erythrocytes and compare it with the existing colorimetric method. Incubation conditions are identical. In the proposed method, the porphobilinogen formed during incubation is converted to a stable and highly fluorescent uroporphyrin by heating for 20 min at 93 °C in an acidic medium in the presence of air. The correlation between results by the two methods was good (r = 0.89). We found a good negative correlation between the activity of the enzyme and the concentration of circulating lead with both methods (r = -0.61 for present method and -0.59 for colorimetric method) for groups of persons subjected to various degrees of lead exposure. Our method is more sensitive and accurate, requires less sample, and the fluorescence is more stable than is the color in the colorimetric method.
Semi-Solid Surface Fluorometric Analysis of Glucose
Authors: Kiang Shiow-ling W , Kuan Jui-chang W , Guilbault George G 
Published: January 2020

Abstract
We describe an enzymatic fluorometric method for determining glucose concentrations in blood samples by analysis on a semi-solid surface (silicone-rubber pads). The method is an adaptation of existing spectrophotometric procedures based on the sequential coupling reactions with glucose-6-phosphate dehydrogenase and NADP+. The rate of appearance of NADPH fluorescence at 460 nm (excitation wavelength, 340 nm) is monitored and related to the glucose concentration in plasma or serum. The calibration curve is linear to 2.50 g/liter. The chief advantages of this method over the spectrophotometric procedure are low cost and rapid response. The results obtained correlate well with those of the o-toluidine method (correlation coefficient, 0.986).
Current Concepts of "Normal Values," "Reference Values," and "Discrimination Values" in Clinical Chemistry
Authors: Sunderman F William 
Published: January 2020

Abstract
The term "normal values" is seriously afflicted by sylleptic ambiguities and conceptual problems, and it is gradually being discarded from the lexicon of clinical chemistry. The neutral term "reference values" is preferable on semantic and scientific grounds, and its use in clinical chemistry is rapidly gaining acceptance. The term "discrimination value" has been added to the lexicon of clinical chemistry. Use of the "discrimination value" for the results of a laboratory test in a specified clinical situation provides the optimal discrimination between the "healthy" and the "diseased," or between "those who need not be investigated further" and "those who do."
Factors Influencing Evaporation from Sample Cups, and Assessment of Their Effect on Analytical Error
Authors: Burtis C A , Begovich J M , Watson J S 
Published: January 2020

Abstract
We studied sample evaporation and its effect on analytical error. Several factors influencing evaporative loss have been identified and measured: environmental, instrumental, and operational factors, and the chemical and physical properties of the sample and its container. Such losses from several different types of sample cups have been measured, either chemically or gravimetrically, and compared with those calculated by using a model that allows evaporative loss from a cup of known geometry to be predicted under various environmental conditions. We discuss some steps that may be taken to minimize evaporative loss and give an example to demonstrate that analytical error from this source can be decreased to a routine 1-2% or less by selecting a particular cup design.
Identification of Human Hemoglobins by Use of Isoelectric Focusing in Gel
Authors: Koepke John A , Thoma James F , Schmidt Robert M 
Published: January 2020

Abstract
Newly-developed gel isoelectric focusing techniques provide for rapid and correct identification of human hemoglobins. With this technique, we examined samples previously identified by the National Hemoglobinopathy Standardization Laboratory of the Center for Disease Control. A wide variety of both normal and abnormal hemoglobins was included in the 134 different specimens examined. The isoelectric points (pl's) were precisely determined; no discrepancies with results by standard techniques of identification were found. The method is accurate and precise. It is proposed as a powerful adjunct to other laboratory methods suitable for use in a hemoglobinopathy reference laboratory or specialized hematology service laboratory.
5-Decynedioic Acid, an Acetylenic Compound in Human Urine
Authors: Lindstedt Sven , Steen Göran 
Published: January 2020

Abstract
An acetylenic dicarboxylic acid, 5-decynedioic acid, has been isolated from human urine. The structure was determined by mass spectrometry of several derivatives, and by infrared spectroscopy. On osmium tetroxide oxidation, a vic-diketone was formed, the mass spectrum of which established the position of the triple bond between carbon atoms 5 and 6. Mass spectrometric evidence for the presence of a small amount of the isomeric 4-decynedioic acid was also obtained. The 24-h excretion of these acids is 0.01-0.1 mmol for healthy adults on a regular diet.
Faster Enzymatic Procedure for Serum Triglycerides
Authors: Sampson Eric J , Demers Laurence M , Krieg Arthur F 
Published: January 2020

Abstract
We describe a single-reagent, enzymatic procedure for triglycerides in serum, which may be performed in 5 min per sample with use of an Abbott ABA-100 analyzer system. This procedure is compared to the semi-automated enzymatic procedure with the ABA-100, which requires 30 min per sample.
The Double Pelican (A Cautionary Tale)
Authors: Grannis George F 
Published: January 2020

Abstract
Gather Dew in the Month of May, when the Sun is in Aries and the Moon is in Taurus, with a clean white Linen Cloth spread upon the Grass [Figure 1]. Filter the Dew into a clean white Porcelain Pan, and deliver it into the Great Egg. Combine this Dew with Virgin's Milk and Infant's Blood, digest for fourteen Days in Horse Dung, and distill to one quarter its Bulk four times running. This Procedure will yield a potent Spirit of Dew which, if you are truly an Artist, may be used to prepare an Elixir of Wonderful Virtue that will Transmute all Metals, and will cause Old Men to rejoice in their restored Youth and Vigor.
Drug Screening by Enzymatic Immunoassay with the Centrifugal Analyzer
Authors: Broughton Alan , Ross Doris L 
Published: January 2020

Abstract
We describe a method for determination of barbiturates, amphetamines, opiates, and methadone by the "enzyme multiplied immunoassay technique" (EMIT) applied to the centrifugal analyzer. This method gives results that agree well (92% for barbiturates, 97% for opiates, 94% for methadone, and 96% for amphetamines) with those obtained by the same technique with the SyvaGilford EMIT instrumentation. Its advantages include use of half as much of the expensive reagents; capability of batch operation, which removes the need for continual attention; and more nearly complete automation. For individual samples it is as fast as the manual method; for large numbers of specimens it is faster.
Immunochemical Determination of Serum Albumin with a Centrifugal Analyzer
Authors: Blom Mogens , Hjørne Niels 
Published: January 2020

Abstract
The turbidity resulting from the reaction between albumin and specific anti-human serum was measured with a good precision by using a GEMSAEC centrifugal analyzer. The reaction was enhanced by polyethylene glycol to shorten the reaction time (5 min) and to displace the point of equivalence between antigen and antibody to an albumin concentration unlikely to occur in human sera (about 100 g/liter). An additional program for the computer was necessary to fit the absorbance readings of individual sera to the nonlinear standard curve. Serum albumin values obtained by the described method correlated well with values obtained by the electroimmuno-technique. About 100 samples could be analyzed per hour, 500 µl of 100-fold diluted antiserum being used per specimen.
Routine Radioimmunoassay of Plasma Testosterone, and Results for Various Endocrine Disorders
Authors: Wong Pui-Yuen , Wood Donald E , Johnson Thomas 
Published: January 2020

Abstract
We describe a modification of published methods for radioimmunoassay of plasma testosterone. This simpler method involves no chromatographic steps, and the necessary reagents, including tritiated testosterone and testosterone anti-serum, are commercially available. A digital computer is used for the calculation. Without difficulty, a technician can complete 100 assays in three working days. Mean testosterone concentrations (± 2 SD) in the plasmas of 21 normal men and 26 women with a normal menstrual cycle were 684 ± 300 and 45 ± 2O ng/dl, respectively. Within- and between-assay precision (coefficient of variation) were 5.2% (n = 29) and 6.7% (n = 26), respectively. We have assayed more than 1000 samples during the past year. We give data on the concentrations of testosterone in plasma of patients with various endocrine disorders.
Serum and Erythrocyte Argininosuccinate Lyase Assay by NADH Fluorescence Generated from Formed Fumarate
Authors: Sherwin John E , Natelson Samuel 
Published: January 2020

Abstract
Measurement of argininosuccinase (I; EC 4.3.2.1) activity is useful in following the course of disease in hepatitis and in screening for the genetic defect, argininosuccinic aciduria. Methodology is proposed for a novel procedure for the determination of I in serum and erythrocytes. In the procedure, fumarate, generated in the reaction, is assayed by conversion to malate with fumarase, determining the malate enzymatically with malate dehydrogenase, and estimating the NADH formed spectrofluorometrically. By this procedure, the enzyme activity in serum from normal individuals is less than 11 µmol/liter of serum/per hour. The normal range for this enzyme's activity in erythrocytes is 1120 to 2420 µmol/liter of erythrocytes/per hour. The correlation coefficient between results by this method and by the colorimetric method, which measures the arginine generated in the reaction, is +0.97 for serum and +0.98 for erythrocytes. The proposed procedure has a relatively low initial blank, requires less serum, and is completed faster.
Evidence Supporting a Proposed Mechanism Explaining the Inverse Relationship between Guanidinoacetate and Guanidinosuccinate in Human Urine
Authors: Koller Anthony , Comess Jay D , Natelson Samuel 
Published: January 2020

Abstract
A proposed mechanism [Clin. Chem. 19, 668 (1973)] for the inverse relationship between guanidinoacetate (I) and guanidinosuccinate (II) in human urine is explored. The mechanism proposes that canavaninosuccinate (III) may be reduced to form homoserine and II or, alternatively, that the III may be acted upon by a lyase to form canavanine and fumarate. The canavanine would then proceed to transamidinate to glycine to form I. This study demontrates for the first time that lyase activity for converting III to canavanine and fumarate exists in human liver and kidney extracts. Transamidination from canavanine to glycine to form I is also readily accomplished with human tissue. Reductive cleavage of III to II and homoserine has been demonstrated before [Clin. Chem. 15, 397 (1969)]. The optimum pH for the lyase reaction is 6.5, for the reductive cleavage it is 8.7. In following the course of the lyase reaction, we developed a technique whereby the fumarate formed was hydrated with fumarase (EC 4.2.1.2) and then dehydrogenated with malate dehydrogenase (EC 1.1.1.37). The changes in absorbance of NADH formed in the reaction were then measured and used to determine the amount of fumarate formed, as a measure of lyase activity. Canavanino-succinate lyase activity follows pseudo-first-order reaction kinetics. The Michaelis constant of this lyase was 6.16 x 10-4 mol/liter, for argininosuccinate lyase 9.74 x 10-4 mol/liter. These data suggest that the binding affinity for III to the enzyme is greater than that for argininosuccinate. Glycine added to the reaction acts as an activator, probably because it removes the canavanine from the reaction mixture. On the other hand, arginine acts as an inhibitor of Ill-lyase. Other substances tested, such as canavanine, fumarate, and argininosuccinate had no effect on the reaction kinetics.
pH Measurement Problems Affecting Assay of Carcinoembryonic Antigen
Authors: Ladenson Jack H , Bell C Elliott 
Published: January 2020

Abstract
Measurement with combination pH electrodes of the pH of the dilute buffers used in a commercial kit (CEA-Roche) for assay of carcinoembryonic antigen resulted in pH values 0.1 to 0.3 unit lower than pH values measured on an electrode system with a capillary junction. If the pH values of these buffers were adjusted, based on such measurements, an error in the assay of 0.2 to 0.6 ng/ml in the 1.5-3.0 ng/ml range would result. We recommend that the pH of dialyzed samples and of the working ethylenediaminetetraacetate and ammonium acetate-acetic acid buffers be monitored with pH electrodes that have a capillary junction between sample and saturated KCl, as is true of most blood-pH instruments. We also recommend use of a 1 mol/liter rather than 2.5 mol/liter stock ammonium acetate-acetic acid buffer, because of the closer similarity of the pH of buffers at this molarity to those at 0.01 mol/liter.
Lipoprotein Electrophoresis Should Be Discontinued as a Routine Procedure
Authors: Iammarino R M 
Published: January 2020

Abstract
Reviewing our five-year experience with more than 1000 lipid profiles (assays for cholesterol and triglycerides In plasma of fasting patients and lipoprotein electrophoresis of their plasma lipoproteins), I conclude that lipoprotein electrophoresis is superfluous for routine clinical laboratory use, being generally redundant to the other parts of the profile. This conclusion is also prompted in part by recent information that changes our conceptions of lipoprotein metabolism and the clinical expressions of genetic hyperlipoproteinemia. A different approach to lipid profiling is suggested.
Interlaboratory Comparison of Enzymatic Methods for Serum Glucose Determination
Authors: Gochman Nathan , Ryan William T , Sterling Rex E , Widdowson Graham M 
Published: January 2020

Abstract
This report describes an interlaboratory comparison of enzymatic serum glucose methods as currently applied in several instrumental adaptations. Four spectrophotometric, hexokinase-based methods used with the Du Pont "aca," the Abbott "Bichromatic Analyzer," the Aminco "Rotochem," and the Technicon "AutoAnalyzer II" were compared with glucose oxidase-based methods as used with the Beckman "Glucose Analyzer" and the "AutoAnalyzer II." We analyzed both normal samples and samples that contained potential interfering substances or were otherwise abnormal. Although all methods were satisfactorily precise, methodological bias was noted in several cases, particularly with abnormal specimens. The hexokinase-based methods were generally more variable. The most consistent data were obtained from the two glucose oxidase methods and the Du Pont aca. Results of this study comprises part of the background information required for development of an accurate glucose reference method under the auspices of the AACC Standards Committee.