bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibration of Ion-Selective Electrodes for Use in Biological Fluids
Authors: Mohan M S , Bates Roger G 
Published: January 2020

Abstract
We measured electromotive force at 37 °C with pH, sodium glass, valinomycin, and the Simon calcium electrodes in synthetic electrolyte mixtures simulating serum, in cells both with and without liquid junction. Evidently these electrodes respond in a near-Nernstian manner to changes in concentration of the ion sensed. We suggest that such mixtures may serve as calibrating standards for ion-selective electrodes in clinical analysis. The effect of ionic strength on electrode response can be accounted for almost wholly by alterations in the activity coefficients. The lanthanum fluoride electrode shows promise as a reliable reference in cells without liquid junction.
Quantitation of Free, Total, and Antibody-bound Insulin in Insulin-Treated Diabetics
Authors: Gennaro William D , Van Norman John D 
Published: January 2020

Abstract
We describe a simplified method for measuring free, total, and antibody-bound insulin in insulin-treated patients in whom antibodies to insulin are present. The free, active insulin is extracted from the serum with a polyethylene glycol solution. Total insulin is extracted from the serum with a polyethylene glycol solution after dissociation of the antibody—antigen complex with dilute HCl. Aliquots of the extracts are used in the radioimmunoassay system. The figure for antibody-bound insulin is the difference between the total and free insulin values and reflects the concentration of insulin antibodies present. A commercially available ("Phadebas") radioimmunoassay for immunoreactive insulin was used to quantitate the insulin present in the two extracts. Recovery of added insulin averaged 85% for the free insulin and 87% for the total insulin.
Detection of Cardiac-Specific Creatine Kinase Isoenzyme in Sera with Normal or Slightly Increased Total Creatine Kinase Activity
Authors: Mercer Donald W , Varat Murray A 
Published: January 2020

Abstract
We describe a spectrophotometric kinetic assay for detecting creatine kinase MB isoenzyme activity in the 1 to 10 U/liter range. The MB isoenzyme was isolated [Clin. Chem. 20, 36 (1974)] and assayed (Rosalki method) with an Abbott ABA-100. Good reproducibility was demonstrated for MB isoenzyme activities near 1 U/liter (CV = 2.6%). Sera with normal or slightly increased total creatine kinase activity were evaluated. Sera of 14 patients with acute myocardial infarction contained, per liter, 84 to 236 U of total creatine kinase activity and 4.6 to 28.0 U of isoenzyme MB activity; corresponding ranges for sera from healthy lab technicians and patients with noncardiac disease were 36 to 277 and 0 to 2.6 U. MB isoenzyme activity for infarction patients rose and fell sharply within three days after the infarction. Atypical time-course patterns, MB isoenzyme activity remaining abnormally great for five days, were observed in serum from patients with prolonged atrial fibrillation and congestive heart failure or cardiomyopathy; the BB isoenzyme (1 to 5 U/liter) was also detected in sera of such patients but was absent in sera from infarction patients. Quantification of column-isolated MB by the assay described is rapid, easy, specific, and extremely sensitive for measuring MB in the 1 to 10 U/liter range.
A Versatile Temperature-Controlled Reaction Cuvet
Authors: Busby Michael G , Cottrell David B , Cembrowski George S , Toren E Clifford 
Published: January 2020

Abstract
A thermostatted reaction cuvet, operating under computerized or manual temperature control in the ultraviolet or visible region, is described and evaluated. The cell was designed for use with the automated chemistry system described earlier [Clin. Chem. 19, 1114 (1973)], but can readily be adapted for other applications. The entire 3-ml cuvet assembly warms from ambient temperature to 37 °C in less than 10 min, with ±0.15 °C stability; the long-term stability is ±0.05 °C; temperature recovery time after washing or reagent addition is less than 3 min. The optical pathlength is 10.00 mm and the carryover volume is 18 µl.
Improved Measurement of Erythrocyte Volume Distribution by Aperture-Counter Signal Analysis
Authors: Waterman Cleveland S , Atkinson Earl E , Wilkins Bert , Fischer Craig L , Kimzey Steve L 
Published: January 2020

Abstract
In aperture counters, particles in fluid suspension flow through a small orifice or aperture, causing a change in the electrical resistance of the aperture. This change is sensed by an external electronic circuit and translated into a voltage pulse, the signal height of which is proportional to the volume of the particle in the aperture. These signal pulses are collated into a spectrum of pulse heights by a multichannel pulse-height analyzer. The channel number (voltage increment) spectrum is proportional to the volume distribution of the particles sensed. A problem is that pulse height not only depends on cell volume, but also on the orientation and shape of the particle sensed and the current density along the path taken by the particle through the aperture. Uneven current density exists, primarily at the aperture entrance and exit, close to the wall. Orientation and shape of particles are altered near the wall by the unbalanced shear forces there. Toward the center of the aperture, the shear forces act so as not to induce continuous change in the orientation of the particles sensed. Thus introduction into the pulse-height spectrum of pulses that do not show a good proportionality to volume is primarily caused by particles that are traveling near the aperture wall. Residence time in the aperture for a particle traveling near the wall will be longer than that for a particle traveling down the center of the aperture, because of the smaller fluid velocity near the wall. Duration of the signal pulse created by a particle traveling near the wall will be correspondingly greater. We discuss an electronic filter to remove from the pulse-height spectrum those pulses that appear to result from particles traveling near the wall and the effect of the filter on the measured signal height and hence the volume distribution of erythrocytes. Use of this technique to characterize erythrocytes by volume distribution is described.
Computerized Multicuvette System for Single Substance and Group Analyses and for the Chromatographic Isolation and Quantitation of Compounds in Complex Mixtures
Authors: Vestergaard Per , Bachman Alvin 
Published: January 2020

Abstract
A new computer-interfaced system of general applicability in the clinical laboratory has been built. The system is constructed around a new type multicuvette. Quantitation is currently by spectrophotometry and is on-line, with use of a mini-computer with output going to an electrostatic printer/plotter. The system can be used for single-substance batch analyses, for group analyses, and for the estimation of profiles of compounds after preliminary high-resolution liquid chromatography tailored to interface with the multicuvette.
Comparison of four kits for enzymatic determination of ethanol in blood.
Authors: Redetzki H M , Dees W L 
Published: January 2020

Abstract
We compared results obtained with four commercially available kits for the enzymatic (alcohol dehydrogenase) determination of ethanol in blood, in a practical test in which standardized blood samples were used. Each of the kits yielded reliable results with acceptable reproducibility. A tendency to record slightly lower values in the intermediate and high alcohol range is most likely related to incomplete (inhomogeneous) deproteinization. Blood samples containing ethanol plus various concentrations of methanol and isopropanol were analyzed to evaluate the specificity of assays. Highly toxic blood concentrations of methanol (1.5 g/liter) increased apparent ethanol values only insignificantly, but even small concentrations of isopropanol (0.5 g/liter) interfered in all kits to different but substantial extents. The specific technical characteristics of the kits, their advantages and disadvantages are discussed. Costs are compared for analysis of small numbers of samples.
Normal limits of urinary excretion of eleven enzymes.
Authors: Maruhn D , Fuchs I , Mues G , Bock K D 
Published: January 2020

Abstract
Urinary excretion of lactate dehydrogenase, hydroxybutyrate dehydrogenase, gamma-glutamyltransferase, alkaline phosphatase, arylsulphatase A, alpha-glucosidase, beta-galactosidase, trehalase, N-acetyl-beta-glucosaminidase, beta-glucuronidase, and leucinearylamidase was studies in a carefully selected group of 100 healthy subjects, 50 women and 50 men. Enzyme activities were assayed in 3-h morning samples after gel filtration of the urine. Activities were related to time volume, and to urinary creatinine concentration. Several transforming functions had to be applied to enzyme output data to obtain an approximation to gaussian frequency distribution. Men showed a significantly higher excretion of gamma-glutamyltransferase, alpha-glucosidase, trehalase, N-acetyl-beta-glucosaminidase,beta-glucuronidase, and leucine arylamidase activity than did women if enzyme activity was related to urinary time volume. Women excreted more lactate dehydrogenase, hydroxybutyrate dehydrogenase, gamma-glutamyltransferase, alkaline phosphatase, alpha-glucosidase, trehalase, and N-acetyl-beta-glucosaminidase activity than did men, if urinary creatinine was used as the basis of reference. Reference intervals were calculated as 2.5 and 97.5 percentiles for both sexes.
Isolation and identification of benzodiazepine drugs and their metabolites in urine by use of Amberlite XAD-2 resin and thin-layer chromatography.
Authors: Sawada H , Hara A , Asano S , Matsumoto Y 
Published: January 2020

Abstract
We used the method described here to detect and identify seven benzodiazepine derivatives--diazepam, chlorodiazepoxide, nitrazepam, cloxazolam, oxazolam, oxazepam, and medazepam--and their metabolites in the urine of rabbits given the seven drugs orally. We column-chromatographed 25-ml samples of urine on Amberlite XAD-2. The drugs and their metabolites in the urine were adsorbed by the resin, irrespective of urinary pH, and upon successive elution with methanol and ethyl acetate/methanol/acetic acid (90/10/0.1 by vol) they could be separated and extracted from the normal components of urine with satisfactory analytical recovery. The conjugated metabolites were then enzymatically hydrolyzed and the hydrolysate was extracted into ethyl acetate and the extract thin-layer chromatographed to detect and identify each drug and each of its metabolites. In an experiment in which the urine of human subjects given 5 mg of nitrazepam orally was analyzed by this method, the metabolites of nitrazepam in the 24-h urine could be identified satisfactorily.
Automated method for determination of mercury in urine.
Authors: Richardson R A 
Published: January 2020

Abstract
I describe a sensitive, specific, automated method for determination of mercury in urine by the "flameless atomic absorption" technique. One can analyze 20 samples per hour, with less than 0.5-ml samples of urine. The detection limit is 0.01 mumol/liter (2mug/liter) and the mean coefficient of variation 12%. The procedure is being used to monitor mercury excretion by workers exposed to mercury.
Clinical usefulness of measuring prothrombin time as a routine admission test.
Authors: Eisenberg J M , Goldfarb S 
Published: January 2020

Abstract
A questionnaire indicating the presence of a history or physical findings consistent with liver desease or bleeding disorders was completed by house officers on 301 admissions to a Veterans Administration medical service. Each patient had prothrombin time determined on admission. Only two of 107 patients for whom the prothrombin time was measured as a screening test had an abnormal results and one of these was normal when repeated. Of 73 patients with a history of alcoholism but no other pertient case history or physical examination results, only one had an abnormal prothrombin time. Of the remaining 121 patients, who had a pertinent history or physical examination, 41 had an abnormal admission prothrombin time. We conclude that measurement of prothrombin time adds little additional information to that obtained by history and physical examination in screening for liver disease and coagulation defects unless the patient has specific clinical evidence of liver disease, anticoagulation, or other conditions predisposing to bleeding disorders.
High-pressure liquid-chromatographic determination of 5-(4-hydroxyphenyl)-5-phenylhydantoin in humanurine.
Authors: Kabra P M , Marton L J 
Published: January 2020

Abstract
We describe a sensitive and precise high-pressure liquid-chromatographic method for measurement of total 5-(4-hydroxyphenyl)-5-phenylhydantoin, a metabolite of phenytoin, in urine. An aliquot of urine, containing 5-(4-methylphenyl)-5-phenylhydantoin as an internal standard, is processed and chromatographed. The metabolite and internal standard are identified from their retention times and quantitated from their relative response factors. The metabolite is separated from normal urine constituents and internal standard in less than 8 min. The sensitivity of the method is such that after the usual dose it can be measured in 0.5 ml of urine; the lower limit of detection is 300 ng.
Proficiency testing for blood-gas quality control.
Authors: Delaney C J , Leary E T , Raisys V A , Kenny M A 
Published: January 2020

Abstract
We have conducted a voluntary, community blood-gas proficiency testing program, with use of tonometered human blood, for 32 analyzers located in 16 laboratories. Instruments initially showed inaccuracies as large as -30.8 to +17.3% for po(2), and -14.0 to +42.9% for pco(2), but inaccuracy and imprecision decreased in most laboratories during the program. For a typical 15-week period, mean group precision (CV) was 4.3 To 5.1% for po(2) from 6.92 to 33.3 Pa (52 to 250 mmHg), and 4.0 to 6.9% for pco(2) from 2.0 to 6.8 Pa (15 to 51 mmHg). This program can detect increasing imprecision or inaccuracy caused by analyzer deterioration, and can identify interlaboratory or interinstrument bias and problems not detected by participant quality-control programs. Participants have used the proficiency information in discussing data quality with clinicians, promoting internal control and maintenance programs, and justifying instrument purchases. We believe that proficiency-testing documentation of variability in blood-gas analysis may help to establish realistic patient-care protocols.
Enzymatic, fluorometric assay of alpha-amylase in serum.
Authors: Guilbault G G , Rietz E B 
Published: January 2020

Abstract
An enzymatic, fluorometric method for kinetic assay of serum alpha-amylase (1,4alpha-D-glucan 4-glucanohydrolase, EC 3.2.1.1) is described. A soluble starch is used as substrate, in tris(hydroxymethyl)methylamine buffer. All measurements are made in Pyrex cuvettes at 37 degrees C, with a reaction volume of 1.16 ml. The assay is based on the following reaction sequence: (see article) The rate of appearance of fluorescence of NADH (lambdaex = 365 nm, lambdaem = 460 nm), developed in the indicator reaction (4), is measured and equated to the activity of alpha-amylase in serum. A calibration plot of the change of fluorescence per min vs. enzyme concentration shows a good proportionality in the range of 0.50-5.0 kU/liter.
Spectrophotometric and electrochemical determinations of L(+)-lactate in blood by use of lactate dehydrogenase from yeast.
Authors: Durliat H , Comtat M , Baudras A 
Published: January 2020

Abstract
Lactate can be determined rapidly in blood by spectrophotometric and amperometric (enzyme electrode) procedures based on its oxidation by ferricyanide, the reaction being catalyzed with yeast L(+)-lactate dehydrogenase (cytochrome b2) (EC 1.1.2.3). In the photometric method lactate can be measured in a few minutes, but blood samples must first be deproteinized. In the amperometric procedure no treatment of blood is needed except ferricyanide addition. The enzyme electrode we used has a response time shorter than 1 min when its critical variables are optimized. Preliminary standardization is reduced to minimum operation, because electrode response is proportional to lactate concentration over a wide range (0.1 to 8.0 mol/liter) and many determinations can be done with little cost in enzyme. A simple electrical device ("two-electrode device") is described that is well suited for furture micro-cell construction. Lactate determinations on a series of normal blood samples show no deviation between results by these new methods and the usual ultraviolet spectrophotometric lactate tests.
Creatine kinase in serum: 2. Interference of adenylate kinase with the assay.
Authors: Szasz G , Gerhardt W , Gruber W , Bernt E 
Published: January 2020

Abstract
Interference of adenylate kinase with Oliver's method [Biochem. J. 61, 116 (1955)] for creatine kinase is usually suppressed by including an adenylate kinase inhibitor, AMP. We studied the kinetics and compared the inhibition capacities of AMP and diadenosine pentaphosphate. Both are competitive inhibitors, AMP being markedly weaker, with a Ki of about 300 mumol/liter for adenylate kinase from erythrocyte, muscle, and liver. AMP also weakly inhibitis creatine kinase. Diadenosine pentaphosphate inhibits erythrocyte and muscle adenylate kinase strongly (Ki about 0.03 mumol/liter), the liver isoenzyme less strongly (Ki about 3 mumol/liter), and has no effect on creatine kinase up to 100 mumol/liter. All three adenylate kinases may be present in a patinet's serum, causing sample blanks to be high in a creatine kinase assay that lacks inhibitors. In acute hepatic damage, liver adenylate kinase activity in serum can be grossly increased. Use of sufficient diadenosine pentaphosphate alone for complete inhibition is relatively expensive. Consequently, we recommend a combination of both inhibitors. Diadenosine pentaphosphate, 10 mumol, combined with 5 mmol of AMP per liter inhibits adenylate kinase from erythrocytes and muscle by 97% and from liver by 95%.
An 125I-labeled cortisol radioimmunoassay in which serum binding protein are enzymatically denatured.
Authors: Hasler M J , Painter K , Niswender G D 
Published: January 2020

Abstract
We report an iodine-125 radioimmunoassay for cortisol in biological fluids, in which interfering binding proteins are enzymatically denatured. An antiserum to cortisol-3-carboxymethyloxime-bovine serum albumin, extremely low cross-reacting with other corticosteroids, was raised in rabbits. A cortisol-3-carboxymethyloxime tyrosine methyl ester derivative was synthesized and labeled with iodine-125 by standard radioiodination techniques. To eliminate the need for extraction and recovery procedures, we digested interfering binding witha proteolytic enzyme, which then was heat-inactivated before adding the labeled derivative and the premixed, preincubated antiserum complex. There was quantitative analytical recovery of esogenous cortisol added to sera from a normal man, a normal woman, and a pregnant woman. Values for the same samples agreed after extraction and chromatographic purification and agreed well with values obtained by other techniques by independent reference laboratories. The five-step assay can be done in 6 h or less.
Low apparent creatine kinase activity and prolonged lag phases in serum of patients with metastatic disease: elimination by treatment of sera with sulfhydryl agents.
Authors: Bruns D E , Morgan W S , Davis J E , Ladenson J H 
Published: January 2020

Abstract
We find lag phases exceeding 20 min in measuring creatine kinase activity, by using the kinetic creatin phosphate leads to creatine assay, in sera of some patients with carcinoma metastatic to the liver. Such long lag phases are accompanied by a decreased apparent enzyme activity. These problems are eliminated by adding sulfhydryl agents to the serum before assay, but not by adding more of such agents to the assay reagent. beta-Mercaptoethanol is supperior to Cleland's reagents, glutathione, and cysteine. The long lag phases could not be explained by inadequate activity of the coupling enzymes, interference with the coupling steps, high proportions of cardiacisoenzymes activity, simple oxidation of the enzyme, low concentrations of albumin, or increased concentrations of glutathione reductase, lactate dehydrogenase, or uric acid. We conclude that the prolonged lag phases reflect inadequate reactivation of the enzyme by sulfhydryl agents under the usual assay conditions. Reactivation before assay can prevent potentially serious negative errors in the assay of creatine kinase.
Error introduced by specimen handling before determination of inorganic phosphate concentrations in plasma and serum.
Authors: Carothers J E , Kurtz N M , Lemann J 
Published: January 2020

Abstract
Values for serum inorganic phosphate (Pi) concentrations in groups of healthy adults vary widely, the coefficient of variation ranging from 10 to 15%. We undertook to determine in 23 healthy adults whether part of this variation could be accounted for by (a) drawing blood in syringes vs. evacuated tubes (b) the time between blood sampling and separation of serum or plasma, and (c) the prevention of clotting. Values were unaffected by a, decreased significantly with time at room temperature between blood sampling and separation of cells in both serum and plasma, and were significantly lower in plasma than in serum. The group coefficient of variation for Pi averaged 13% and was uninfluenced by the blood-processing technique.
Erythrocyte porphyrin analysis in the detection of lead poisoning in children: evaluation of four micromethods.
Authors: Hanna T L , Dietzler D N , Smith C H , Gupta S , Zarkowsky H S 
Published: January 2020

Abstract
We evaluated four procedures for determination of erythrocyte porphyrin: double extraction with ethyl acetate/acetic acid-HCl, single extraction with ethanol, single extraction with acetone, and direct solubilization with detergent-buffer. The ethyl acetate procedure, when used with two portions of HCl, apparently gives complete recovery of porphyrin and is suitable for reference as a comparison method. The ethanol procedure gives a high and consistent recovery and is technically simpler. The acetone procedure gives low and variable recovery of porphyrin, and the detergent-buffer method is subject to serious hemoglobin interference; neither of these two procedures offers any technical advantage. Stability of samples and methods for standardization were explored. A procedure for expressing results in terms of erythrocyte Zn-protoporphyrin content is given. Because of its stability, coproporphyrin is useful as a daily working standard. The ethyl acetate and ethanol methods are about equally efficient for detecting lead intoxication. Because of its simplicity, the ethanol method seems to be the best for use in screening.
High-performance colorimeter with an electronic bubble gate for use in miniaturized continuous-flow analyzers.
Authors: Neeley W E , Wardlaw S C , Yates T , Hollingsworth W G , Swinnen M E 
Published: January 2020

Abstract
We describe a high-performance colorimeter with an electronic bubble gate for use with miniaturized continuous-flow analyzers. The colorimeter has a flow-through cuvette with optically flat quartz windows that allows a bubbled stream to pass freely without any breakup or retention of bubbles. The fluid volume in the light path is only 1.8 mul. The electronic bubble gate selectively removes that portion of the photodector signal produced by the air bubbles passing through the flow cell and allows that portion of the signal attributable to the fluid segment to pass to the recorder. The colorimeter is easy to use, rugged, inexpensive, and requires minimal adjustments.