bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum phospholipids determined without acid digestion.
Authors: Sandhu R S 
Published: January 2020

Abstract
A method for determination of phospholipids in serum is described that involves complexing intact phospholipids with chromogenic reagent, thus eliminating the need for acid digestion, which is a mandatory step in all the current procedures for phospholipid analysis. Inorganic phosphorus and other serum components do not interfere in the determination. Excellent agreement between results of this new procedure and the conventional acid digestion method (r=0.986, y intercept=2.053, and slope=0.986) makes it an attractive alternative clinical method for determination of phospholipids in serum.
Immunofixation. III. Application to the study of monoclonal proteins.
Authors: Ritchie R F , Smith R 
Published: January 2020

Abstract
We have shown how immunofixation can be successfully used to study proteins exhibiting electrophoretic polymorphism. An analogous situation is seen in the disorders of the immune system that result in the production of variable quantitites of homogeneous immunoglobulins. Immunoelectrophroesis has been heavily used--sometimes unsuccessfully because of poor resolution--to study these materials. The appearance of a monoclonal immunoglobulin band is identical in both immunofixation and standard gel electrophoresis, a feature that allows unambiguous identification of a protein as to its heavy-chain class and light-chain type. Because antigen and antibody are placed in contact almost immediately after electrophoresis, interfering diffusion does not occur and even extremely small bands can be demonstrated and characterized.
A spot test for uroporphyrinogen I synthase, the enzyme that is deficient in intermittent acute porphyria.
Authors: Schumaker H M , Tishler P V , Knighton D J 
Published: January 2020

Abstract
We describe a spot test for detecting deficiency of uroporphyrinogen I synthase (EC 4.3.1.8), which is characteristic of intermittent acute porphyria. The specimens used for enzyme assay are 6.5-mm filter paper discs saturated with dried blood (less than 15 mul) that was collected by direct application from a fingerstick or from venipuncture, with or without anticoagulant. The enzyme in such specimens is stable for at least nine days at -20 or c degrees C or for two days at room temperature. The discs are incubated with porphobilinogen (0.11 mmol/liter) in tris(hydroxymethyl)aminomethane HCl buffer, pH 8.2, in the dark at 37 degrees C for 3.5 h. Trichloroacetic acid is added and, after centrifugation, the supernate is examined visually with a long-wavelength ultraviolet lamp. Samples from normal and porphyric subjects are readily differentiated, both by color and intensity of the resulting porphyrin fluorescence. Anemia is a potential source of falsely positive tests, but one may accurately determine the concentration of hemoglobin in the whole blood on the filter paper discs. Moreover, the fluorescence of normal but anemic samples clearly differs qualitatively from that of porphyric specimens. Another source of falsely positive tests, variation in enzyme activity creating an overlap zone of normal and porphyric results, has not been a confounding problem. The method thus seems to offer promise for screening populations for this disorder.
Energy-dispersive x-ray fluorescence spectroscopy and inductively coupled plasma emission spectrometry evaluated for multielement analysis in complex biological matrices.
Authors: Irons R D , Schenk E A , Giauque R D 
Published: January 2020

Abstract
Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.
Molar absorptivities of beta-NADH and beta-NADPH.
Authors: Ziegenhorn J , Senn M , Bücher T 
Published: January 2020

Abstract
Re-investigating the accuracy of the commonly used values for molar absorptivities (epsilon) of beta-NADH and beta-NADPH at Hg 334, Hg 365, or 340 nm, we obtained the following results: The maximum of absorbance of NADH is shifted from about 340 nm at 0 degrees C to about 338.5 nm at 38 degrees C; the corresponding maxima of NADPH are located at about 0.5-nm longer wavelengths. In addition, the absorption curves of both coenzymes broaden with increasing temperature. For these reasons, the epsilon-values of NADH and NADPH are generally different from each other, and are temperature-dependent. Only at 334 nm are they almost identical and nearly independent of temperature. Therefore this wavelength is recommended for precise measurements. The epsilon-values of these coenzymes are influenced by ionic strength and pH. To determine the absolute values of the molar absorptivities, we performed the glutamate dehydrogenase or lactate dehydrogenase assay with carefully purified 2-oxoglutaric acid or pyruvic acid in the presence of excess coenzyme. The purity of the substrates was checked through differential scanning calorimetry, moisture analysis, gas-liquid chromatography, gas chromatography in combination with mass spectrometry, and nuclear magnetic resonance spectroscopy. The epsilon-values observed under the various conditions are about 1-7% higher than those currently used.
Evaluation of two digoxin radioimmunoassay procedures in which 125I-labeled digoxin is used.
Authors: Kuczala Z J , Ahluwalia G S 
Published: January 2020

Abstract
We present a comparative evaluation of two commercial kits, the "Quantitope" and "GammaCoat," for radioimmunoassay of digoxin in serum. These kits, in which iodine-125 is used as a label, proved to suitable for digoxin assay as determined by their reproducibility, sensitivity, precision, and a regression analysis. Hemolysis, lipemia, and icterus did not affect results. However, in some cases hypoalbuminemia falsely lowered the assayed digoxin concentration. Recovery of pure digoxin added to native patients' sera having low albumin concentration (24-28 g/liter) ranged from 67-105% with the Quantitope kit and 70-110% with the GammaCoat kit. Low serum albumin concentration did not always decrease the recovery of digoxin; this effect varied from serum to serum, which may indicate that there are factors other than albumin that affect the assay of digoxin.
Rapid micromethod for blood lead analysis by anodic stripping voltammetry.
Authors: Morrell G , Giridhar G 
Published: January 2020

Abstract
We describe a rapid microscale procedure for blood lead determination by anodic stripping voltammetry. Results correlate well with those obtained by atomic absorption spectroscopy. The procedure involves use of a metal-exchange reagent, which rapidly releases bound lead from its macromolecular binding sites, thus eliminating a long and cumbersome perchloric acid digestion procedure. Reproducibility and analytical recovery of added lead were both excellent. Our results show that anodic stripping voltammetry is a reliable, sensitive micromethod for routine determination of blood lead.
Measurement of diphenylhydantoin in 0.1-ml plasma samples: gas chromatography and radioimmunoassay compared.
Authors: L'Estrange Orme M , Borgå O , Cook C E , Sjöqvist F 
Published: January 2020

Abstract
Concentrations of diphenylhydantoin in 364 plasma samples have been measured both by radioimmunoassay and with a recently developed gas-chromatographic method, which requires only 0.1 ml of plasma per determination. There was an excellent correlation between values obtained by the two methods (r = 0.986), and in only 11 plasma samples did the results differ by more than 20%. Of the investigated samples, 105 were obtained from uremic patients. For these, an equally good agreement was obtained between the two methods. Within-assay variance was 3.1% for the immunoassay and 3.3% for the gas-chromatographic procedure. Without automatic pipetting equipment, the radioimmunoassay procedure took twice as long as the chromatographic assay, and the cost of chemicals was considerably higher. Nevertheless, the better sensitivity of the radioimmunoassay makes it of great value, especially in children, because plasma samples of 10 to 20 mul can be used.
Improved method for measurement of inorganic phosphate in serum with a centrifugal analyzer.
Authors: Wentz P W , Savory J , Cross R E 
Published: January 2020

Abstract
A direct mehtod [Clin. Chim. Acta 46, 113 (1973)] for determination of inorganic phosphate in serum was adapted for use with a centrifugal analyzer. Contamination is minimized and analysis rate maximized by doing the reaction in the reagent wells of the transfer disc and by utilizing the high-speed spectrophotometric and data-reduction capabilities of the centrifugal analyzer. Hemolysis, icterus, and moderate lipemia cause no interference. Grossly lipemic sera and sera from patients with plasma cell dyscrasias can be analyzed by incorporating appropriate blanking and dilution techniques. The method exhibits excellent sensitivity and precision and results correlate well with those from a continuous-flow procedure.
Direct determination of serum chloride with a semiautomated discrete analyzer.
Authors: Levinson S S 
Published: January 2020

Abstract
I show how mercuric thiocyanate reagent can be used in assaying serum chloride economically, rapidly, and precisely. I used a semiautomated discrete analyzer with direct concentration read-out capability but the method can easily be applied to many mechanized instruments. Linearity between concentration and color is obtained by adding appropriate amounts of mercuric nitrate to the reagent. As many as 300 samples can be assayed per hour, and the method is excellent for emergency use.
Comparison of results for 13 clinical laboratory determinations with three automated analytical systems.
Authors: Sampson E J , Derck D D , Demers L M 
Published: January 2020

Abstract
We evaluated the Abbott Bichromatic Analyzer-100 (ABA-100) for use in the routine clinical chemistry laboratory by examining 13 different determinations that can be performed on the instrument. Results with the Du Pont "aca" and Technicon continuous-flow systems were compared to the ABA-100 in terms of upper limits of linearity, inter-run coefficient of variation, and results for samples from patients. The upper limits of linearity for the methods on the ABA-100 exceeded all of those for the continuous-flow systems, except for urea nitrogen. Precision of the ABA-100 was as good as or better than that of the aca for all determinations, except for glucose in a normal control serum and creatine kinase and creatinine in an above-normal control serum.
Statistical characterization of the random errors in the radioimmunoassay dose--response variable.
Authors: Rodbard D , Lenox R H , Wray H L , Ramseth D 
Published: January 2020

Abstract
We have developed practical methods for evaluating the magnitude of the random errors in radioimmunoassay dose--response variables, and the relationship between this error and position on the dose--response curve. This is important: to obtain appropriate weights for each point on the dose--response curve when utilizing least-squares curve-fitting methods; to evaluate whether the standards and the unknowns are subject to error of the same magnitude; for quality-control purposes; and to study the sources of errors in radioimmunoassay. Both standards and unknowns in radioimmunoassays for cAMP and cGMP were analyzed in triplicate. The same mean (Y), sample standard deviation, sy, and variance (2-y) of the response variable were calculated for each dose level. The relationship between s 2-y and y was calculated utilizing several models. Results for standards and unknowns from several assays were pooled, and a curve smoothing procedure was used to minimize random sampling errors. This pooling increased the reliability of the analysis, and confirmed the presence of the theoretically predicted nonuniformity of variance. Thus, the calculation of results from these radioimmunoassays should utilize a weighted least-squares curve-fitting program. These analyses have been computerized, and can be used as a "pre-processor" for programs for routine analysis of results of radioimmunoassay.
Evaluation of contemporary methods for serum CO2.
Authors: Lustgarten J A , Creno R J , Byrd C G , Wenk R E 
Published: January 2020

Abstract
We evaluated and inter-compared several newer methods for CO2 analysis--titrimetric (Van Slyke), automatic titrator, continuous-flow/indicator, and coupled-enzyme procedures--with respect to accuracy, precision, specificity interferences, and management criteria. All methods studied appeared to be clinically acceptable; but precision decreased (standard deviations increased) for the last two methods in above-normal ranges.
Improved method for measuring fibrinogen in plasma, with use of a plasmin inhibitor.
Authors: Steffen L W , Steffen B W 
Published: January 2020

Abstract
We describe a modified procedure for quantitating plasma fibrinogen by use of the thrombin-clottable protein technique. The method is accurate and requires a0out 30 min to complete. During its formation and isolation, the clot is protected from the degradative action of plasmin by an inhibitor, epsilon-aminocaproic acid.
Fluorometry of plasma amino nitrogen, with use of fluorescamine.
Authors: Klein B , Standaert F 
Published: January 2020

Abstract
We describe a fluorometric procedure, with use of fluorescamine, for determining plasma amino nitrogen in a 10-mul sample of deproteinized plasma. Values for apparently healthy human subjects agree well with those obtained by spectrophotometry. The simplicity and speed of the assay recommends it as a screening procedure for detecting aminoacidopathies.
High-pressure liquid-chromatographic separation of lactate dehydrogenase isoenzymes.
Authors: Kudirka P J , Schroeder R R , Hewitt T E , Toren E C 
Published: January 2020

Abstract
The isoenzymes of lactate dehydrogenase (EC 1.1.1.27) were separated with excellent resolution in less than 1 h by high-pressure anion-exchange chromatography. These isoenzymes were determined in some tissue extracts and high-activity serum samples by this technique.
Performance studies on the Technicon "SMAC" analyzer: Precision and comparison of values with methods in routine laboratory service.
Authors: Westgard J O , Carey R N , Feldbruegge D H , Jenkins L M 
Published: January 2020

Abstract
We present performance studies on the Technicon "SMAC" analyzer. Precision was estimated from control data during routine operation and from blind duplicates of sera from patients. Patients' specimens were analyzed with the SMAC and the SMA 12/60 during initial evaluation studies. Comparisons were also made with the Du Pont aca and other methods during routine service. Performance is judged relative to medical usefulness requirements, by using previously developed criteria and recommendations for decision levels and allowable errors.
Serum iron determination in patients receiving therapy with iron dextran ("Imferon").
Authors: McIntosh M E , Lynn J K , Meyerriecks N , Contant I 
Published: January 2020

Abstract
Imferon (Lakeside Labs., Inc.), an iron dextran complex, is widely used for parenteral therapy with iron. Colorimetry and atomic absorption spectroscopy give different values for serum iron concentration in patients receiving such therapy. Values determined by atomic absorption spectroscopy were usually much higher than those obtained by either a manual or an automated colorimetric procedure, and also were higher than the total serum iron-binding capacity of the same sera. This difference is attributed to circulating iron being present both as iron dextran as as transferrin-bound iron. We conclude that atomic absorption spectroscopy should be used to determine serum iron in patients receiving Imferon.
Radioimmunoassay of bile acids in serum.
Authors: Demers L M , Hepner G 
Published: January 2020

Abstract
We developed four radioimmunoassay procedures for the determination of glycine-conjugated bile acids in serum. Antibodies to two primary bile acids, cholylgycine and chenodeoxycholylglycine, and to two secondary bile acids, sulfolithocholylglycine and deoxycholylglycine, were raised in rabbits after the acids were covalently linked to albumin by use of the carbodiimide reaction. Assay sensitivity for each of these bile acids is in the picomole range with the standard curve extending from 10-80 pmol. The concentration of bile acids in serum increased in various states of liver disease and its measurement appears to be an extremely sensitive indicator of liver function.
Method for measuring the concentration of urinary proteins according to their molecular size category.
Authors: Pesce A J , Hsu A , Kornhauser C , Sethi K , Ooi B S , Pollak V E 
Published: January 2020

Abstract
We combined the use of a concentrating device (Minicon) and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate to semi-quantitate the concentration of (a) the collective low-molecular-weight proteins and (b) of albumin excreted in the urine of patients after renal transplantation. Analytical recovery of many serum proteins from samples concentrated 100-fold in the Minicon apparatus was about 70%. It was possible to examine many urine samples by polyacrylamide gel electrophoresis after concentration with this device. The reproducibility (CV) of the technique was on the order of 20% when albumin and low-molecular-weight protein were in about equal concentration. The method was adequate to differntiate glomerular and tubular proteinuria, because in glomerular proteinuria the ratio of albumin to low-molecular-weight proteins is about 20/1, whereas in tubular proteinuria the ratio is about 1/1.
Specificity and reproducibility of acetone precipitation in identifying surface-active phosphatidylcholine in amniotic fluid.
Authors: Penney L L , Hagerman D D , Sei C A 
Published: January 2020

Abstract
We show the thoretical and actual variability in the amount of surface-active lecithin precipitated in the acetone-precipitation step of determining lecithin/sphingomyelin (L/S) ratios in the clinical laboratory. Lecithins precipitated may range from 60 to 90% of the total surface-active lecithins present. The range is sufficient to account for the occasional "immature" L/S ratios (less than 2/1) found in amniotic fluid from women bearing mature fetuses.
Detection of drugs of abuse by radioimmunoassay: a summary of published data and some new information.
Authors: Cleeland R , Christenson J , Usategui-Gomez M , Heveran J , Davis R , Grunberg E 
Published: January 2020

Abstract
We review the status of radioimmunoassays for detection of abused drugs. Individual assays with use of 125I-labeled antigens are all performed in an identical manner and can be completed in 30 min to 1 h. Combined assays for simultaneous detection of two or more such drugs or assays in which a tritium-labeled antigen is used require 1-2 h for completion. All tests can be performed with 0.1 ml or less of specimen. The assays involving 125I reliably detect urinary concentrations of, per liter, 40-100 mug of morphine, 100 mug of barbiturates, methadone, methaqualone, or benzoylecgonine, and 1000 mug of amphetamine. The assay for morphine involving 3H detects 60 mug/liter. Each assay is capable of providing a qualitative and quantitative estimate of the drugs sought. The 125I-labeled antigens have a usable shelf life of at least two to four months after the antigen is iodinated; the tritium assay is stable for six months. The assays can be performed with use of paper discs that have been suspended in urine and then dried, in place of the liquid specimen. The assays appear to be equally applicable to detection of drugs in urine, blood, saliva, and tissues. All of them are done at ambient temperature and can be used equally well for emergency (stat) tests or mass screening. Except for the benzoylecgonine assay, the clinical reliability of these tests has been demonstrated.
Gas-chromatographic analysis for therapeutic concentrations of amitriptyline and nortriptyline in plasma, with use of a nitrogen detector.
Authors: Bailey D N , Jatlow P I 
Published: January 2020

Abstract
We describe a gas-chromatographic procedure for the simultaneous determination of amitriptyline and its active metabolite, nortriptyline, in therapeutic concentrations in human plasma, with use of a nitrogen detector. Both drugs are extracted at pH 10.5 into hexane/isoamyl alcohol, back-extracted into dilute HCl, and re-extracted into hexane/isoamyl alcohol after alkalinization of the HCl. The solvent is evaporated and the residue gas-chromatographed. Protriptyline is used as the internal standard. As little as 5 mug of amitriptyline or nortriptyline can be detected per liter of plasma. The coefficients of variation, for a concentration of 200 mug/liter, are 4.6% and 4.3% within-day and 8.6% and 3.4% day-to-day for amitriptyline and nortriptyline, respectively. The procedure was applied to patients receiving therapeutic doses of both drugs and also to patients who had taken overdoses of amitriptyline.
Enzymatic assay for methotrexate in serum and cerebrospinal fluid.
Authors: Falk L C , Clark D R , Kalman S M , Long T F 
Published: January 2020

Abstract
We describe an assay for methotrexate in biological fluids. The assay is based on inhibition by methotrexate of dihydrofolate reductase from Lactobacillus casei. The lower limit of sensitivity in serum is 2 X 10(-8) mol (about 10 mug) of methotrexate per liter. Within-run precision is +/- 5% (coefficient of variation) and day-to-day variation is 18%. Advantages of the assay are ease of manipulation, high sensitivity, and specificity.
Rapid gas-chromatographic measurement of anticonvulsant drugs in serum.
Authors: Dorrity F , Linnoila M 
Published: January 2020

Abstract
We describe a rapid method for precisely measuring concentrations of anticonvulsant drugs in serum. The simple procedure, adaptable to the clinical laboratory, can be used for the routine simultaneous measurement in sera of phenobarbital, primidone, dephenylhydantoin, and (or) ethosuximide. The extraction procedure requires no solvent evaporation and gives a good yield for primidone and quantitative extraction for the other drugs. The relatively small amount of "early phenobarbital" formed during on-column methylation permits a precise analysis of phenobarbital based on a single peak. Results can be made available directly, without manual measurements or calculations.