bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Manual and Automated Method for Determining Activity of Creatine Kinase Isoenzyme MB, by Use of Dithiothreitol: Clinical Applications
Authors: Rao Parinam S , Lukes James J , Ayres Stephen M , Mueller Hiltrud 
Published: January 2020

Abstract
The method is based on the selective activating capacity of dithiothreitol on creatine kinase isoenzyme MB, after isoenzyme MM is activated by glutathione. Isolated isoenzymes MM and MB of human and canine origin were assayed individually and in mixtures of known activities. When glutathione was present in the assay medium the activity of each isoenzyme could be measured individually, but glutathione did not activate isoenzyme MB if it was present in a mixture with MM. Dithiothreitol, added to the serum before assay, activated the isoenzyme MB in the mixture. Values for MB activities obtained for isolated isoenzyme MB and for the isoenzyme mixture after dithiothreitol was added averaged 110 and 111 U/liter, respectively (r = 0.998; y = 1.007x + 0.298; n = 10). In the serum of 40 patients with documented acute transmural myocardial infarction, the mean proportion of isoenzyme MB activity measured in this way was 5.5% (coefficient of variation, 7.7%). Isoenzyme MB activities measured by use of dithiothreitol compared well with those obtained by conventional electrophoresis/spectrophotometry (r = 0.998; y = 1.09x -0.65) and spectrofluorometry (r = 0.996; y = 1.10x + 0.80). The assay of MB activity by the dithiothreitol method was automated, by use of an Abbott Bichromatic Analyser and a Calbiochem Super-Stat Pack Kit. In 60 isoenzyme MB determinations the manual and automated method correlated well (r = 0.990; y = 1.0x -1.36). The simplicity of isoenzyme MB determination by use of dithiothreitol and its ease of automation allow routine monitoring of the isoenzyme activity in patients with ischemic heart disease
Patients as Their Own Controls: Use of the Computer to Identify "Laboratory Error"
Authors: Ladenson Jack H 
Published: January 2020

Abstract
I describe a system of quality control based on computer detection of changes in individual patient test results. This system, called "delta check," was used to follow all the tests performed by the clinical chemistry laboratory in a 1200-bed hospital. Analysis of 22 months’ experience indicates that specimen misidentification is a serious problem in the clinical chemistry laboratory. Over a nine-month period, errors were most frequent in the results for total thyroxine, total calcium, and total protein. Instances of laboratory error detectable by the delta check system are not detected by other currently used methods of quality control. This system therefore appears to be a valuable asset to the clinical laboratory
Factors Affecting Assay of Myoglobin by Complement Fixation or Immunodiffusion
Authors: Olerud John E , Clark Donald L 
Published: January 2020

Abstract
Quantitative micro-scale complement-fixation and semiquantitative gel immunodiffusion assays for myoglobin have been evaluated experimentally and used to measure myoglobin in the sera of more than 1500 patients. We report certain problems, observations, and methodological improvements. Serum caused enhancement of precipitin lines in the immunodiffusion assay. In the complement-fixation assay, serum interfered both by enhancing or inhibiting complement fixation. Suggested modifications in the complement-fixation assay are: (a) routine threefold or greater dilution of serum with buffer and (b) use of serum-based rather than buffer-based calibration materials in preparing standard curves. Three cycles of freeze-thaw of serum or buffer decreased detectable myoglobin by 50-100%. We conclude that certain serum-related factors and freezethaw phenomena are important causes of error in immunological assays for myoglobin
Plasma Theophylline Concentrations Measured by High-Pressure Liquid Chromatography
Authors: Sitar Daniel S , Piafsky Kenneth M , Rangno Robert E , Ogilvie Richard I 
Published: January 2020

Abstract
We present a specific, sensitive high-pressure liquidchromatographic assay for theophylline in plasma. Only 0.5 ml of plasma is required for each determination, and the lower limit of detection by this method is 0.1 mg/ liter. Other xanthines and their metabolites do not interfere. This method is suitable for use in studying the pharmacokinetics of this drug in infants and children, from whom only small volumes of blood are available.
Fluorometric Method for Measuring Serum Lipase Activity
Authors: Rietz Bernd , Guilbault George G 
Published: January 2020

Abstract
We describe a method for determining lipase (triacylglycerol acyl-hydrolase, EC 3.1.1.3) activity in serum. Emulsified olive oil in tris(hydroxymethyl)aminomethane buffer is used as substrate. The course of the enzymatic reaction is followed by measuring the decrease in fluorescence with time of a fluorescent indicator, 4-methylumbelliferone, added to the substrate, caused by the change in the pH of the substrate solution resulting from the reaction. All measurements are performed at 37 °C. The reaction volume is about 2.3 ml, in a Pyrex cuvette. Change of fluorescence and of enzyme activity are linearly related in the range of 77.8 to 389.0 U/liter. An assay can be done in as little as 3 to 5 min, with excellent precision.
Screening for Drug Abuse: Use of NaCl to Increase Drug Recovery from Papers Coated with Ion-Exchange Resin
Authors: Alexander George J 
Published: January 2020

Abstract
Use of papers loaded with ion-exchange resins to adsorb drugs from urine specimens resulted in large losses during the procedure. The first step, removal of drugs from urine specimens, was 25-85% efficient. The second step, elution of drugs from paper for further processing, was approximately 40-70% complete. The efficiency of the first step was decreased and the efficiency of the second step was increased by addition of NaCl, except in the case of barbiturates. Presence of salt during elution increased the yield of dihydromorphine by 20%, of methadone by 16%, of amphetamine by 34%, and of chlorpromazine by 40%, but did not enhance the yield of pentobarbital. Overall recovery rates were: 51% for the opiates, 57% for methadone, 72% for a phenothiazine tranquillizer, but only 35% for amphetamine and 15% for a barbiturate.
Separation of Synthetic Mixtures of Sugars and of Sugars in Body Fluids with a High-Resolution Carbohydrate Analyzer
Authors: Voelter Wolfgang , Bauer Hermann 
Published: January 2020

Abstract
With use of a specially designed gradient-generating system, of anion-exchange resins of 10-20 µm particle diameter, and of an orcinol solution in concentrated sulfuric acid (1 g/liter) as detection reagent, a mixture of 16 carbohydrates can be separated in less than 4 h. The limit of detection for most sugars is in the 0.1-2.0 nanomole range. The detection reagent is stable for months and does not become colored. The reagent mixes with the column effluent in an exothermic reaction and allows use of relatively short mixing coils. The analyzer is appropriate for investigating body fluids rapidly and with high sensitivity.
Relative Efficacy of Separation of "Free" and "Bound" [3',5'-3H]Pteroylglutamate by Charcoal Coated with Various Materials
Authors: Zettner Alfred , Duly Peggy E 
Published: January 2020

Abstract
We studied the effectiveness with which various charcoal preparations separate free [3H]pteroylglutamate from that complexed with milk folate binder. We tested, in various concentrations, uncoated charcoals and charcoals coated with dextrans of various molecular weights, or with albumin, hemoglobin, or polyvinylpyrrolidone with an average molecular weight of 40 000. Although there was some distinction between the "bound" and "free" fractions with all charcoals, those treated with dextrans of average molecular weights of 43 500 or 70 000, or with polyvinylpyrrolidone gave the best separation over a greater range of charcoal concentration. Uncoated charcoal and charcoals coated with albumin, hemoglobin, or dextran T10 (average molecular weight, 10 500) were least effective.
Temporal Intrapersonal Physiological Variability of Cholinesterase Activity in Human Plasma and Erythrocytes
Authors: Sidell Frederick R , Kaminskis Andris 
Published: January 2020

Abstract
Erythrocyte and plasma cholinesterase activities were measured biweekly in one group of 22 subjects for a year and daily for three weeks in another group of nine men. The average range [i. e., (range/mean) x 100] of activity of erythrocyte cholinesterase in men during a year was 8% and during three weeks was 5%. For plasma, the corresponding values were 25% and 12%. The average ranges for erythrocyte and plasma cholinesterase activity in women during a year were 12% and 24%. Erythrocyte cholinesterase activity varies less than do hematocrit, hemoglobin, or erythrocyte count.
Comparison of Methods for Calculating Serum Osmolality from Chemical Concentrations, and the Prognostic Value of Such Calculations
Authors: Dorwart William V , Chalmers Leslie 
Published: January 2020

Abstract
Sodium, potassium, glucose, blood urea nitrogen, and osmolality were determined for 715 hospital-patient sera. The chemical concentrations were used to calculate osmolalities according to 13 different methods taken from the literature. The goodness of the comparison between calculated and measured osmolality was quite similar for several of the better methods. The agreement was unimproved when molal chemical concentrations were used instead of molar values. The difference between measured and calculated osmolality was unrelated to whether a patient was discharged from the hospital after a short or long period or ultimately died. The equation we found to yield the most accurately calculated osmolalities is
Vidicon Spectrometer Applied to Simultaneous Enzyme Determinations
Authors: Milano Michael J , Pardue Harry L 
Published: January 2020

Abstract
Lactate dehydrogenase and alkaline phosphatase activities in the same medium can be determined simultaneously, at 350 and 550 nm, with a vidicon spectrometer. Substrate concentrations and pH have been made optimum for the combined analysis. These conditions result in activities for lactate dehydrogenase that are equivalent to those found by methods in common use, and activities for alkaline phosphatase that are about 31% below the maximum values that could be obtained with its substrate used at the same pH and temperature in the absence of NAD+ and lactate. However, activities measured by the simultaneous analysis were proportional to those obtained by other methods used in clinical laboratories, and the coefficients of variation were 2.3% for lactate dehydrogenase and 3% for alkaline phosphatase.
Effects on Radioimmunoassay of Digoxin of Varying Incubation Periods for Antigen—Antibody Reaction and Varying Periods of Adsorption by Dextran-Coated Charcoal
Authors: Kuno-Sakai Harumi , Sakai Hideto 
Published: January 2020

Abstract
In radioimmunoassay of digoxin by the dextran-coated charcoal method, duration of the incubation period for the antigen-antibody reaction and time allowed for dextran-coated charcoal to adsorb the free antigen are critical factors. We compared effects of prolonged periods of adsorption on results obtained with five commercial kits. In all cases, the digoxin concentrations increased linearly with adsorption time, but the increase varied among kits. Kallestad and New England Nuclear 3H-kits and the Squibb 125I-kit showed less increase (i.e., gave relatively consistent results after various periods of adsorption); the Schwarz/Mann 125I-kit and Clinical Assays 3H-kit showed greater increases. Precautionary steps are outlined for radioimmunoassays by this technique.
Statistical Evaluation of Method-Comparison Data
Authors: Wu Gaw Tzu , Twomey Stanley L , Thiers Ralph E 
Published: January 2020

Abstract
Comparison of two methods for determining a substance is a common procedure in clinical chemistry. Almost without exception, normal theory statistics are used with the tacit assumption that the data under test show gaussian distributions. Experience has led us to question this assumption for populations of differences between values obtained by two methods applied to common samples and for populations of paired values for each method as used in correlation analysis. Data are presented from our laboratory to illustrate these points, as well as an examination of data from relevant papers that appeared in this journal from 1968 through 1973. These examples indicate that incorrect interpretation of results because of insufficient attention to nongaussian distribution is a real and present danger. We present a systematic approach to the statistical aspect of comparing methods that enables one to avoid this problem.
Automated Differentiation and Measurement of Hexosaminidase Isoenzymes in Biological Fluids and Its Application to Preand Postnatal Detection of Tay—Sachs Disease
Authors: Salfer Abraham , Parkhurst George W , Amoroso June 
Published: January 2020

Abstract
Three hexosaminidase (EC 3.2.1.52) isoenzymes other than isoenzymes A and B in body fluids have been separated by chromatography on diethylaminoethyl cellulose. By inserting a microcolumn into a continuous-flow system for automated, fluorometric hexosaminidase analysis [Clin. Chem. 20, 538 (1974)], samples eluted with buffered-NaCl gradients can be continuously monitored. Isoenzyme patterns were obtained for fluids from normal individuals, pregnant women, Tay—Sachs disease carriers, pregnant carriers, and patients with the disease. These chromatograms revealed a hitherto undetected isoenzyme (I3) in serum. An increase in serum hexosaminidase isoenzyme I2(or P) during pregnancy is characteristic of a carrier pattern. Our data show that serum and urinary hexosaminidase isoenzyme patterns may be used in addition to leukocyte analysis, to distinguish a pregnant carrier from a normal pregnant woman. All fluids tested demonstrated no isoenzyme A activity and above-normal activity of isoenzymes B and (or) I2 in homozygotes. Urine is preferred fluid for postnatal and amniotic fluid for the prenatal diagnosis of the disease. Quantitative data on isoenzyme A obtained with the procedure described here agree well with those obtained by heatand pH-inactivation methods.
Determination of Orotic and Dihydroorotic Acids in Biological Fluids and Tissues
Authors: Kesner Leo , Aronson Frank L , Silverman Morris , Chan Phillip C 
Published: January 2020

Abstract
In commonly used procedures for colorimetric assay of orotic acid in biological materials, certain substances interfere, positively or negatively. Some that interfere negatively are ornithine, cysteine, citrulline, tyrosine, proline, hydroxyproline, and polyamines. Protein and interfering agents are easily removed by first isolating the total organic acid fraction. The orotic acid in this fraction can then be determined by an established colorimetric procedure. A rapid liquid—liquid column-chromatographic procedure is described, if analysis of both dihydroorotic and orotic acid is required.
Comparison of Clinical Assays for Serum Corticosteroids
Authors: Jiang Nai-Siang , Machacek Dwaine , Wadel Orlando P 
Published: January 2020

Abstract
We compared results obtained by (a) chemical (spectrophotometric) and competitive protein-binding assays for serum corticosteroids, and (b) competitive proteinbinding and radioimmunoassay, with and without CCl4 extraction, for serum cortisol. The two corticosteroid methods gave identical results. Radioimmunoassay with and without a CCl4 extraction step gave identical results for cortisol. Competitive protein-binding assays for cortisol (with and without CCl4 extraction) and radioimmunoassay for cortisol gave similar results. Specimens with above-normal corticosterone or 11-deoxycortisol concentrations are an exception: only methods that included CCl4 extraction gave correct values for cortisol; methods without such an extraction step overestimated cortisol. The normal serum corticosteroid concentration (mean ± SD) was 175 ± 53 µg/liter for morning specimens, and 103 ± 40 µg/liter for specimens collected in the afternoon. For cortisol, the corresponding values were 162 ± 44 and 82 ± 29 µg/liter.
Effect of Albumin on Serum Digoxin Radioimmunoassays
Authors: Voshall David L , Hunter Lynda , Grady Harold J 
Published: January 2020

Abstract
The use of certain commercially available radioimmunoassay kits for measurement of digoxin results in errors in the determined digoxin concentration of patients when these kits are used according to manufacturers' directions. One factor that is, in part, responsible for these errors is a difference between standards and samples with respect to albumin concentration. Three of the four kits investigated showed a significant inverse relationship between the albumin concentration in the sample and the binding of radiolabeled digoxin by its antibody when the albumin concentration was varied over an extended range. It is apparent, however, that differences in albumin concentration do not completely explain the observed variations in the assay values.
Automated Method for Determination of Bound N-Acetylneuraminic Acid in Serum
Authors: Rey Elisabeth , Gerbaut Lucile , Lombart Christian 
Published: January 2020

Abstract
A modified resorcinol method for sialic acid determination has been successfully adapted to the Technicon AutoAnalyzer. The present method requires only 25 µl of serum, and 30 samples can be analyzed per hour. It may be used to measure sialic acid in concentrations ranging from 10 to 100 mg/liter.
Mechanized Enzymatic Determination of Triglycerides in Serum
Authors: Bucolo Giovanni , Yabut Juanito , Chang Ting Yen 
Published: January 2020

Abstract
A procedure for enzymatic determination of serum triglycerides [Clin. Chem. 19, 476 (1973)] has been adapted for use in continuous-flow analysis (Technicon AutoAnalyzer). A very simple manifold is used; serum is incubated at 37 °C with the lipase and α-chymotrypsin in potassium phosphate buffer (0.1 mol/liter, pH 7, containing 1.50 g of bovine serum albumin per liter). The liberated glycerol is dialyzed against the complete glycerol reagent. The change in absorbance at 340 nm resulting from oxidation of NADH is proportional to the dialyzed glycerol. The same manifold can be used to determine preformed glycerol if the hydrolyzing enzymes are omitted. The lipase used need not be extensively purified because the dialyzer removes coloring material and contaminating enzymes that would interfere with the components of the glycerol reagent in the manual procedure. The hydrolysis is complete, as shown by the use of equivalent glycerol standards. No prior treatment of the samples is necessary. Assays are run at 60 per hour in the AutoAnalyzer I, 80 per hour in the AutoAnalyzer II. Results with both instruments for 150 samples correlated well with those obtained by the same enzymatic manual method and by the AutoAnalyzer fluorometric procedure.
Binding of 63Ni(II) to Ultrafiltrable Constituents of Rabbit Serum In Vivo and In Vitro
Authors: Asato Noritake , van Soestbergen Maria , Sunderman F William 
Published: January 2020

Abstract
Binding of 63Ni(Il) to ultrafiltrable constituents of rabbit serum was studied (a) after in vitro incubation (2 h, 37 °C) of rabbit serum with 63NiCl2 (10-100 µmol/liter), and (b) at intervals (0.25-2 h) after in vivo administration of 63NiCl2 (40-160 µmol/kg body wt, i.v.). Serum ultrafiltrates were fractionated by thin-layer chromatography, and the separated compounds made visible by autoradiography and by ninhydrin staining. Several (≃5) ultrafiltrable 63Ni-complexes were demonstrable as distinct radiodense 63Ni-bands with chromatographic mobilities corresponding to those of ninhydrin-positive bands. Unbound 63Ni(II) was not detected in serum ultrafiltrates in either the in vitro or in vivo experiments. In sera (n = 10) incubated in vitro with 63Ni(II) (10 µmol/ liter), the mean percentage of ultrafiltrable 63Ni was 36% (range = 33-38) of total serum 63Ni. In contrast, in sera (n = 10) obtained 2 h after i.v. injection of 63Ni(II) (40 µmol/kg), the mean concentration of total serum 63Ni was 10.8 µmol/liter (range = 6-14), and the mean percentage of ultrafiltrable 63Ni was 15% (range = 9-21) of total serum 63Ni. The disparity between the percentages of ultrafiltrable 63Ni obtained in vitro and in vivo was obviated when the in vivo experiments were performed in rabbits bilaterally nephrectomized, with ligated common bile ducts. This investigation confirms the existence of several nickel receptors in serum ultrafiltrates and substantiates the role of ultrafiltrable complexes in the excretion of nickel.
Intercomparison Program of Lead, Mercury, and Cadmium Analysis in Blood, Urine, and Aqueous Solutions
Authors: Lauwerys Robert , Buchet Jean-Pierre , Roels Harry , Berlin Alexander , Smeets Jan 
Published: January 2020

Abstract
Sixty-six European laboratories participated in an intercomparison program of lead, mercury, and cadmium analysis in blood, urine, and aqueous solutions. The experimental protocol was designed in such a way that the effect of precision, experience, and analytical method could be evaluated. For all the analyses, the scatter of the reported results is important. The major factor influencing the variability of the results is the intralaboratory variation. Analytical methods and degree of experience do not seem to have a significant influence. However, with the exception of mercury determination in urine, a satisfactory intralaboratory precision is not sufficient to make the interlaboratory variation acceptable. It appears that systematic errors are responsible for the high interlaboratory variation observed between "precise" laboratories.
Micromethod for Lead Determination in Whole Blood by Atomic Absorption, with Use of the Graphite Furnace
Authors: Fernandez Frank J 
Published: January 2020

Abstract
I describe a micro-scale method for determining lead in whole blood by utilizing a graphite furnace. Sample pretreatment consists of fivefold dilution with a dilute surfactant. The method is directly calibrated with lead standards prepared in dilute HNO3. To eliminate a small, nonspecific absorption signal from the blood matrix, simultaneous background correction is used. Interlaboratory comparison with a flame atomic absorption technique that requires extraction yielded high correlation (r = 0.98). Within-run precision (coefficient of variation) ranged from 2 to 4%. Lead in blood can be accurately measured in as little as 20 µl of blood, hence the method is suitable for routine laboratory use and for pediatric screening.
Microanalytical System for Determination of Picogram Quantities of Metals in Metalloenzymes, as Illustrated with Zinc-containing Enzymes
Authors: Kawaguchi Hiroshi , Auld David S 
Published: January 2020

Abstract
Microwave-induced emission spectrometry combined with gel-exclusion chromatography provides a microanalytical system capable of precisely measuring 10-10 to 10-13 g of metal in microgram amounts of enzyme. Such sensitivity greatly exceeds that of other, more conventional methods. Metal quenching agents and low-molecular-weight protein contaminants were removed from the enzyme by Sephadex G-100 chromatography in microbore columns (0.3 x 25 cm). Droplet fractions were analyzed for zinc by the present method, for enzyme activity, and for protein content. With this analytical system we could demonstrate that stoichiometric amounts of zinc are present in the RNA-dependent DNA polymerase, the reverse transcriptase, from woolly monkey type C RNA tumor virus. The precision of the method for zinc was demonstrated by the coefficient of variation of 4.4% for 10 µg of zinc per liter. Validity and accuracy of the method were established by determining zinc in a series of zinc metalloenzymes of known metal content and stoichiometry.