bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion chromatography: a new technique for clinical chemistry.
Authors: Anderson C 
Published: January 2020

Abstract
Ion chromatography is a new analytical technique in which the ions to be analyzed are separated on a special pellicular ion-exchange column. Once separated, the effluent from the separating column passes into a second ion-exchange column, which removes the eluent or buffer ions from the moving phase without removing the sample ions, which are detected and measured by electrical conductivity on a background of low conductance. Trace quantities can be so determined. This technique has been applied to four biological fluids: blood serum, tissue extract, urine, and cerebrospinal fluid. It is shown to be a practical analytical tool, particularly for ions having no chromophores, such as sodium, ammonium, potassium, magensium, calcium, chloride, nitrite, phosphate, and sulfate.
A propagation of error analysis of the enzyme activity expression. A model for determining the total system random error of a kinetic enzyme analyzer.
Authors: Tiffany T O , Thayer P C , Coelho C M , Manning G B 
Published: January 2020

Abstract
We present a total system error evaluation of random error, based on a propagation of error analysis of the expression for the calculation of enzyme activity. A simple expression is derived that contains terms for photometric error, timing uncertainty, temperature-control error, sample and reagent volume errors, and pathlength error. This error expression was developed in general to provide a simple means of evaluating the magnitude of random error in an analytical system and in particular to provide an error evaluation protocol for the assessment of the error components in a prototype Miniature Centrifugal Analyzer system. Individual system components of error are measured. These measured error components are combined in the error expressiion to predict performance. Enzyme activity measurements are made to correlate with the projected error data. In conclusion, it is demonstrated that this is one method for permitting the clinical chemist and the instrument manufacturer to establish reasonable error limits.
Multicomponent analysis in clinical chemistry by use of rapid scanning fluorescence spectroscopy.
Authors: Warner I M , Callis J B , Davidson E R , Christian G D 
Published: January 2020

Abstract
To be useful in the clinical laboratory, multicomponent fluorescence analysis requires both the rapid measurement of the fluorescence intensity at a variety of excitation and emission wavelengths and the unambiguous reduction of the data by efficient algorithms. The Video Fluorometer, which exploits the multi-channel capability of a low-light-level television sensor to simultaneously acquire excitation and emission spectra, can meet the first requirement. For example, a complete set of emission and excitation spectra for perylene can be obtained in less than 2 s at concentrations of 10(-10) mol/liter. To meet the second need, we present two types of data-reduction strategies: (a)a least-squares fit to the data, with use of the spectra of previously determined compounds likely to be present; and (b)a determination of the eigenvalues and eigenvectors fo the fluorescence matrix, from which the number of components and the possible spectra of each can be estimated. Computer simulations of the least-squares fitting algorithms show that five strongly overlapping components can be determined in the presence of noise with an accuracy of better than 5%. Also, a fluorescent sample containing two species with very similar but unknown spectral properties can be resolved to obtain the spectrum of each.
Centrifugal system for affinity chromatography with eluate monitoring.
Authors: Shumate S E , Scott C D 
Published: January 2020

Abstract
A prototype centrifugal system has been developed that permits parallel photometric monitoring of eluate streams from a radial array of chromatographic columns. The modular rotor design consists of a discoidal center insert for eluent and sample apportionment, the chromatographic columns, and flow-through cuvetts-all mounted on an aluminum base plate. A common sample is introduced simultaneously to each column; a single eluent stream is used for all columns. The goal is to assay simultaneously for eight to 16 serum proteins separated by affinity chromatography from a single sample. The system is here exemplified by the use of immunosorbents (consisting of antibodies to human immunoglobulins covalently bound to alumina particles) to allow simultaneous determinations of IgG AND IgM from a single human serum sample in less than 16 min.
Reversed-phase liquid-chromatographic analysis of hemodialysate from uremic patients.
Authors: Senftleber F C , Halline A G , Veening H , Dayton D A 
Published: January 2020

Abstract
With reversed-phase high-performance liquid chromatography we effected rapid and efficient separation of metabolites present in hemodialysate fluid from uremic patients on the artificial kidney. With an aqueous sodium acetate/methanol gradient as mobile phase, more than 50 ultraviolet-absorbing constituents were resolved in a 70-min chromatogram of a 100-mul sample of dialysate. Many of the metabolites could be detected in concentrations below 0.1 mg/liter. From results of ultraviolet spectrophotometric analysis and the gas- and liquid-chromatographic properties of standards, half the observed chromatographic peaks have been characterized or identified. The method has been shown to be more than 10-fold faster than comparable separations by ion-exchange techniques.
Comparison of estimates of long-term analytical variation derived from subject samples and control serum.
Authors: Williams G Z , Harris E K , Widdowson G M 
Published: January 2020

Abstract
Variation in the assays of uniform control serum commonly are assumed to represent day-to-day analytical variation. To test this assumption, we compared the differences between results of serum aliquots assayed immediately for 12 constituents and frozen aliquots accumulated and assayed on a single day with the results of control serum variation from the same period. One aliquot of each weekly sample was stored frozen. Eleven subjects were sampled for 12 weeks. Storage at --20 degrees C for 15 weeks had a mild destructive effect on two enzymes in serum. The control serum data revealed significant linear trends in magnesium (upwards) and alkaline phosphatase (downwards) that substantially increased the respective variances. In the other 10 constituents tested, comparison of variances indicated that long-term (weeks) variation in control serum assays is similar to the difference of variation between aliquots assayed immediately and those frozen and assayed at the same time. For these constituents, this finding justifies the use of control serum to estimate long term analytical variation.
Development and use of analytical systems based on mass spectrometry.
Authors: Horning E C , Carroll D I , Dzidic I , Haegele K D , Lin S , Oertli C U , Stillwell R N 
Published: January 2020

Abstract
Contemporary analytical systems based on mass spectrometry include as components a gas chromatograph, a mass spectrometer, and a computer. The form of operation is usually in electron impact ionization mode for identification and structural studies, and in chemical ionization mode for quantitative analyses. Important stages in the development of these systems included the design of "molecule separators" for the concentration of solutes in the gas phase, the use of mass spectrometers as specific ion detectors, the introduction of chemical ionization techniques, and the development of computer-based operation, data acquisition, and data analysis capabilities. A current line of investigation is concerned with the design and use of systems based on atmospheric pressure ionization. Samples are ionized in a small reaction chamber external to the low-pressure region of a quadrupole mass analyzer. The primary source of electrons is a 63Ni foil or a corona discharge. The ionization process leading to positive ions involves a sequence of ion molecule reactions, usually electrons leads to carrier gas ions leads to reagent ions leads to sample component ions. Negative ions may be formed by direct electron attachment, or by ion molecule reactions that include new types of elimination reactions. The source will accept a variety of gases and solvents. The sample may be introduced in the gas phase without solvents, by probe injection, or in the effluent stream from a gas chromatograph. Samples may be introduced in the liquid phase in solvents by injection after the fashion of gas chromatography or in the effluent stream from a high-performance liquid chromatograph. The novel aspects of atmospheric pressure ionization mass spectrometry lie in its versatility and high sensitivity of detection. Few clinical chemistry laboratories now use these systems. Significant future uses are likely to be in analytical work involving therapeutic drug monitoring and studies of drug metabolism, and in analyses for environmental biohazards including pesticides, herbicides, polyhalobiphenyls, dibenzodioxins, and other toxic compounds.
A list of selected reference materials in clinical chemistry.
Authors: Airall J M 
Published: January 2020

Abstract
This is a compilation of reference materials suggested for scientists considering a laboratory reference collection in clinical chemistry, or for librarians seeking to develop or add to an up-t-o-date library collection. Nine areas are represented: general clinical chemistry; analytical methods, procedures, and techniques; calculations and statistics; the clinical laboratory; drugs and metabolism; enzymology; instrumentation, interpretation of data; and ready reference.
Serum albumin: recent progress in the understanding of its structure and biosynthesis.
Authors: Peters T 
Published: January 2020

Abstract
Major discoveries have been made in the past few years on the structure and mode of biosynthesis of serum albumin. The complete amino acid sequence of this protein has been determined, and its covalent structure shown to be a single peptide chain grouped into a series of nine disulfide-bonded loops. These loops appear to associate into three similar domains. By study of isolated fragments of the molecule it can be demonstrated that the binding of billirubin and the primary binding of long-chain fatty acids are functions of separate domains. The biosynthesis of albumin has been found to involve a precursor form, termed "proalbumin", in which a basic hexapeptide is attached to the amino end of the chain. Similar precursor forms are now known to have a role in the formation of other secreted proteins, but in the case of albumin the purpose of the additional peptide is not clear. Clinical methodology for albumin assay has advanced but little despite--or perhaps in part because of--the increasing use of automation. Hope for improvement is foreseen in the advent of immunochemical procedures and in a better understanding of the specificity of dye-binding reactions.
Comparison of double-antibody radioimmunoassay with Farr-technique radioimmunoassay and double-antibody enzyme immunoassay for alpha-fetoprotein.
Authors: Kirkpatrick A , Wepsic H T , Nakamura R M 
Published: January 2020

Abstract
We describe double-antibody procedures for determining alpha-fetoprotein in human serum. An equilibrium procedure can be done in 24 h with a sensitivity of at least 4 mug/liter and coefficient of variation of 5.5%. There are no interferences from normal human sera or sera with certain commonly seen chemical abnormalities. We also describe and discuss sequential procedures that range in sensitivity from 250 ng to 1mug/liter and require 24-48h incubation. The precise (mid-range)portion of the dose/response curve for sequential procedures can be shifted to higher or lower values by an adjustment of the time of preliminary incubation of antibody with unlabeled antigen. With a 37 degrees C incubation, a sequential procedure can be completed in 7 h. Sensitivity is 1 mug/liter, and coefficient of variation 8.0%. The relative merits of the above assay procedures are discussed. The double-antibody redioimmunoassay is twice as sensitive as the Farr procedure [J. Infect. Dis. 103, 239 (1958)], and it is free of the large and variable nonspecific precipitation that accompanies the precipitation of bound antigen with sodium sulfate solution. Double-antibody radioimmunoassay is superior to enzyme immunoassay in both sensitivity and precision.
Gamma-Glutamyltransferase: kinetic properties and assay conditions when gamma-glutamyl-4-nitroanilide and its 3-carboxy derivative are used as donor substrates.
Authors: Shaw L M , London J W , Fetterolf D , Garfinkel D 
Published: January 2020

Abstract
The kinetics of human serum gamma-glutamyltransferase (EC 2.3.2.2) were investigated, with use of glycylglycine as a gamma-glutamyl acceptor substrate and gamma-glutamyl-4-nitroanilide and its carboxy derivative, gamma-glutamyl-3-carboxy-4-nitroanilide, as donor substrates. The simultaneous occurrence of both gamma-glutamyltransfer and autotransfer was established by descending paper chromatography. Constant-ratio double-reciprocal plots confirm that the enzyme mechanism is nonsequential (ping-pong bi-bi). Inhibition by either donor was not found, and inhibition by glycylglycine was only observed at concentrations above those of clinical interest. Kinetic constants obtained by nonlinear regression analysis of initial velocity data were used to determine reagent substrate concentrations for the assay of this enzyme. An assay with use of 4 mmol of gamma-glutamyl-3-carboxy-4-nitroanilide and 100 mmol of glycylglycine per liter yielded equivalent activities to those by assay with use of 4 mmol of gamma-glutamyl-4-nitroanilide and 40 mmol of glycylglycine per liter. These concentrations of the carboxy donor and glycylglycine are also "cost optimal" and present no procedural problems when used.
A kinetic spectrophotometric assay for rapid determination of acetoacetate in blood.
Authors: Price C P , Llyod B , Alberti G M 
Published: January 2020

Abstract
We describe an automated kinetic assay for acetoacetate in blood. Acetoacetate is enzymatically reduced to D-beta-hydroxybutyrate and the reaction is monitored for 60 s with a reaction-rate analyzer. This technique allows low concentrations of acetoacetate to be measured with good precision and overcomes many of the problems associated with other automated techniques. Our studies on the stability of acetoacetate emphasize the need for care in handling specimens. The use of a reaction-rate analyzer, an item of equipment common to most laboratories, allows for rapid handling of samples in small or large batches, depending on the needs of the laboratory.
Automated kinetic determination of lactate dehydrogenase isoenzymes in serum.
Authors: Bernstein L H 
Published: January 2020

Abstract
A steady-state kinetic method has been revised for measuring lactate dehydrogenase isoenzyme activities, which relates the inhibition of heart-type isoenzyme activity to the overall isoenzyme composition of the enzyme subunits. The method depends on the pH-dependent formation of an inhibitory ternary complex by the heart-type isoenzyme with NAD+ and pyruvate (if the reaction is measured by NADH oxidation). A preincubation step in the previous method is eliminated. The isoenzymes are measured by measuring the reduction of pyruvate in two different concentrations, which favor either the total or fractional activity, depending on the concentrations of pyruvate and the percentage of heart-type subunits. The method has been adapted to a centrifugal analyzer, which has speeded automated isoenzyme determinations, with an accuracy comparable to that for electrophoretic methods.
Clinical pharmacology of anti-epileptic drugs: a summary of current information.
Authors: Leal K W , Troupin A S 
Published: January 2020

Abstract
This compendium represents what we believe to be the most current and reliable pharmacological data on anticonvulsant drugs. The information presented is derived from determinations of the drugs in plasma or serum by gas--liquid chromatography in studies of the efficacy of anti-epileptic agents. We present information on the limitations of therapeutic concentration ranges, half-lives, active and inactive metabolites, and structure/activity relationships of anticonvulsant drugs. This report provides answers to many of the questions clinicians direct to anticonvulsant-monitoring laboratories. Information on other pharmacoloical variables supplements this review in the interest of the clinical investigator.
Value of alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase, and glutamate dehydrogenase activity measurements (single and combined) in serum in diagnosis of metastasis to the liver.
Authors: Kim N K , Yasmineh W G , Freier E F , Goldman A I , Theologides A 
Published: January 2020

Abstract
We assessed, in 98 patients with cancer, the diagnostic value of measuring serum alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase, and glutamate dehydrogenase activities as an aid to detection of liver metastases. All four enzymes showed diagnostic value, but 5'-nucleotidase appeared to have the greatest. It showed the lowest false-positive results (7.4%) with the highest predictive value of a positive test (85.7%) and agreement (81.3%).. gamma-Glutamyltransferase showed the lowest proportion of false-negative results (2.8%), but was the least specific 35% false-positive results). Analysis of various test combinations showed that the best agreement (77.5%) was obtained when the patients were divided into those who had no or only one abnormal test result, and those who had two or more abnormal test results. However, this was not better than the agreement for 5' nucleotidase alone (81.3%). The agreement of 5'-nucleotidase and gamma-glutamyltransferase (i.e., both tests were positive or negative) was excellent (91.4%), but such agreement included only 67% of the patients with liver metastases.
Activity and interference effects in measurement of ionized calcium with ion-selective electrodes.
Authors: Grima J M , Brand M J 
Published: January 2020

Abstract
We assessed the magnitude of the errors in ionized-calcium measurements resulting from changes in electrolyte composition for three different ion-selective electrodes: the Orion Model 93-20, the Radiometer F2112, and the Simon neutral carrier membrane electrode. We attempted to distinguish between errors arising from changes in calcium ion activity and those due to interferences in the electrode response. Variation in sodium ion concentration over the range 100--180 mmol/liter produces changes in apparent ionized-calcium concentration that are largely attributable to activity effects for the Radiometer and Simon electrodes. The Orion electrode is subject to an additional sodium-interference effect. Apparent ionized calcium concentration measurements are independent of pH for the Radiometer electrode but not for the Orion electrode; the Simon electrode exhibits intermediate pH response, which is probably clinically negligible. Magnesium and potassium ions have little effect on ionized calcium concentration measurements, particularly when these ions are incorporated into calibration standards.
Serum creatinine assay by use of 3,5-dinitrobenzoates: a critique.
Authors: Parekh A C , Sims C 
Published: January 2020

Abstract
Methyl-3,5-dinitrobenzoate and 3,5-dinitrobenzoyl chloride are demonstrated to react with creatinine through their conversion to 3,5-dinitrobenzoate. Analytical recovery of creatinine added to serum is improved by an "acid-supernate" modification, which is also much less susceptible to a combination of known interfering agents than is the picrate procedure. The "neutral-supernate" procedure shows negligible interference by cephalothin as compared to commonly used picrate procedures. Replacement of tetramethylammonium hydroxide by sodium hydroxide was also tested. The interrelationships between dimethyl sulfoxide concentration, recoveries of creatinine, and slopes of correlations (r greater than .992) of various dinitrobenzoate and picrate methods are critically assessed. Because of its precision, greater specificity, and other criteria, we recommend the methyl-3,5-dinitrobenzoate (or 3,5-dinitrobenzoic acid) neutral-supernate method for routine applications.
Detection of endotoxins in human blood and plasma. An improved in-vitro pyrogen test.
Authors: Nandan R , Nakashima C Y , Brown D R 
Published: January 2020

Abstract
We describe an improved in-vitro procedure for detection of endotoxin in human blood and plasma by use of Limulus amoebocyte lysate. Increasing concentrations of Escherichia coli endotoxin added to a constant amount of the lysate cause a proportional increase in protein precipitated by the endotoxin. By measuring the amount of protein precipitated, it was possible to determine the equivalent E. coli endotoxin concentration in unknown samples, when samples were run with E. coli endotoxin standards and negative controls. The E. coli endotoxin, present in human whole blood and platelet-rich plasma, failed to react with the lysate. However, the concentration of endotoxin in whole blood and platelet-rich plasma could be measured with this Limulus test after lysing the platelets to release the endotoxin and subsequently removing the inhibitory proteins by chloroform precipitation. With this procedure it was possible accurately and repeatedly to determine E. coli equivalent endotoxin concentrations as low as 195 ng per liter of whole blood or 49 ng per liter of platelet-rich plasma.
New method for determining thrombin-clottable fibrinogen.
Authors: Frigola A , Angeloni S , Cerqueti A R 
Published: January 2020

Abstract
We describe a new method for determination of thrombin-clottable fibrinogen, which eliminates the systematic error caused by occlusion of other serum proteins in the fibrin clot and reduces the sensitivity to high concentrations of fibrin degradation products. Essentially, the method consists of densitometric quantitation of the fibrin band after a standard electrophoresis run of plasma, thrombin fixation of the fibrinogen, and removal of the non-clotted proteins by washing in saline. The procedure shows good precision and gives results that are accurate, significantly correlate with results for the classical thrombin clotting method (r = 0.92, P less than .001), and are not affected by fibrin degradation product concentrations up to 900 mg/liter. These characteristics make the method especially valuable in establishing fibrogen concentration in patients who are undergoing thrombolytic therapy.
Development, validation, and application of a single-tube radioimmunoassay for cholic and chenodeoxycholic conjugated bile acids in human serum.
Authors: Roda A , Roda E , Aldini R , Festi D , Mazzella G , Sama C , Barbara L 
Published: January 2020

Abstract
A single-tube radioimmunoassay for both cholic acid and chenodeoxycholic acid conjugates in serum is based on the use of [1-(14)C]glycocholic acid and [H-3H]glycochenodeoxycholic acid as tracers. The assay was shown to be specific, sensitive, accurate, and precise (CV = 13% at low concentrations, 5.5% at higher concentrations) when used for serum samples from subjects and patients with increased bile acid in the serum because of liver disease, and results correlate well with those by gas chromatography (r = .99).