bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of radioassay and microbiological assay for serum folate, with clinical assessment of discrepant results.
Authors: Baril L , Carmel R 
Published: January 2020

Abstract
Folate assays by use of radiolabeled folate provide obvious practical advantages over the standard microbiological assay, but remain incompletely tested. We therefore compared results for 415 sera with a kit involving 3H-labeled folate and the Lactobacillus casei microbiological method. We examined the patients' data when there were discrepancies between the two methods. Although the correlation overall was satisfactory, results were discrepant in 25% of cases. In 74% of the latter, the radioassay result appeared to be the correct one, primarily because L. casei results were suppressed by antibiotics being taken by the patient. The radioassay occasionally gave falsely high values for patients with liver disease and falsely low ones for patients who had received isotopes for scanning purposes. Several assay kits that make use of 125I- or 75Se-labeled folate were also tested. Although these results correlated with the results of 3H-labeled folate assay, various problems appeared, including the possible need for serum-supernate control tubes in one kit. Answers to these and other questions and careful clinical correlation of results are needed for any folate radioassays before their adoption for routine clinical use.
Determination of pyruvate oxidation rate and citric acid cycle activity in intact human leukocytes and fibroblasts.
Authors: Willems H L , de Kort T F , Trijbels F J , Monnens L A , Veerkamp J H 
Published: January 2020

Abstract
We measured pyruvate oxidation in intact leukocytes and fibroblasts by measuring 14C02 production. The optimal pyruvate concentration appeared to be higher than that usually applied. Activities remained constant during the incubation and were proportional to the amount of tissue protein added. Man values (+/-SD) were 2.8 +/- 0.9 nmol/h per 10(6) cells and 37 +/- 14 nmol/h per mg of protein for leukocytes and fibroblasts, respectively, for [1-14C]pyruvate oxidation; and 2.1 +/- 0.8 nmol/h per 10(6) cells and 18 +/- 7 nmol/h per mg of protein, respectively for [2-14C]pyruvate oxidation. We compared oxidation rates of pyruvate and 2-oxoglutarate by intact cells with those of isolated mitochondria. The ratio of 14CO2 production vs. activity of mitochondrial marker enzyme demonstrated that the rate of pyruvate oxidation can adequately be assayed in intact cells, but that the permeability of the cell membrane is rate-limiting in the oxidation of 2-oxoglutarate. No significant oxidation of other intermediates of the citric acid cycle was found, presumably owing to a low rate of transport of these substances across the cell membrane.
Variance components of serum constituents in healthy individuals.
Authors: Van Steirteghem A C , Robertson E A , Young D S 
Published: January 2020

Abstract
Analytical, intra-individual, and inter-individual components of variance were estimated in 10 volunteers for 34 assays encompassing 22 different constituents. Replicate blood specimens were obtained four times weekly. Nine constituents were measured with more than one instrument [Technicon AutoAnalyzer II and SMAC System, Perkin-Elmer Kinetic Enzyme Analyzer KA-150, and (or) the Abbott Bichromatic Aanalyzer ABA-100]. For those constituents that were stored for randomized batch analysis, results were examined for evidence of changes during storage and within-run analytical drift. Alkaline phosphatase, cholesterol, dopamine-beta-hydroxylase, and SMAC-measured lactate dehydrogenase had a ratio of intra-individual to interindividual variance of less than 0.10, thus exhibiting a high individuality. This ratio was greater than one for sodium, carbon dioxide, and creatine kinase. Analytical variance was more than 30% of total variance for sodium, carbon dioxide, calcium, total protein, and chloride. Analytical variance was less than 20% of intra-individual variance for bilirubin, creatine kinase, KA-150-measured lactate dehydrogenase, triglycerides, and urea nitrogen. Limits for the expected difference between measurements of the same constituent for the same individual on different days are also presented.
Hemopyrrole and kryptopyrrole are absent from the urine of schizophrenics and normal persons.
Authors: Gendler P L , Duhan H A , Rapoport H 
Published: January 2020

Abstract
We describe a method for detecting hemopyrrole and kryptopyrrole in urine, with a detection limit of 100 mug/liter (1 part in 10(7)). Urine is thoroughly extracted with methylene chloride and the extract is concentrated and examined by gas chromatography and gas chromatography-mass spectrometry. No hemopyrrole or kryptopyrrole could be detected in 52 samples, from 17 controls, 29 schizophrenics, and six persons with acute intermittent porphyria.
Automated assay of gamma-aminobutyric acid in human cerebrospinal fluid.
Authors: Böhlen P , Schechter P J , van Damme W , Coquillat G , Dosch J C , Koch-Weser J 
Published: January 2020

Abstract
We describe an automated amino acid analyzer with fluorescence detection (o-phthalaldehyde) which permits sensitive and rapid determinations of gamma aminobutyric acid in human cerebrospinal fluid. Concentrations as low as 50 nmol/liter can be accurately determined in 100 mul samples at the rate of one sample per hour. Concentrations in untreated cerebrospinal fluid increase rapidly after sampling by lumbar puncture. The concentration in immediately deproteinized samples from 38 patients with intervertebral disc disorders was 220 +/- 81 nmol/liter (mean +/- SD).
Optimal reaction conditions for assaying human lactate dehydrogenase pyruvate-to-lactate at 25, 30, and 37 degrees C.
Authors: Buhl S N , Jackson K Y , Graffunder B 
Published: January 2020

Abstract
Optimal reaction conditions for assaying human lactate dehydrogenase pyruvate-to-lactate were determined for isoenzymes 1 and 5 at 25, 30, and 37 degrees C. Three of the nine different buffers examined--imidazole, triethanolamine, and N-tris(hydroxymethyl)-methyl-2-aminoethane sulfonic acid--are satisfactory. Beta-NADH, pyruvate, and hydrogen ion concentrations were chosen to measure both isoenzymes with maximal-equal-sustainable efficiency at the lowest substrate concentrations. Approximately 95% of each isoenzyme is measured, for activities up to threefold the upper normal limit, if the measurements are made immediately after the reaction is initiated. The Arrhenius relationship for each isoenzyme is unique. Interconversion of results from one temperature to another is practical only with reservations. Results at 37 degrees C are not as reliable as those at 25 degrees C.
Determination of quinidine by high-performance liquid chromatography.
Authors: Powers J L , Sadee W 
Published: January 2020

Abstract
Quinidine in serum was measured at 330 nm, after protein precipitation, with an alkyl phenyl reversed-phase chromatographic column by peak-height determination (external standards.) Sensitivity was 0.3 mg/liter, with linear response to at least 10 mg/liter serum. Interassay precision, measured on 20 consecutive days, gave a CV of 8.2% at 2 mg/liter of serum and 5.1% at 5 mg/liter. Quinine and primaquine are not separable from quinidine under the assay conditions, and dihydroquinidine and chloridazepoxide are only partly resolved. No assay interference was encountered with a series of control serum samples obtained from patients with various diseases, who were being treated with various drugs other than quinidine, except in one serum sample with a high bilirubin concentration (300 mg/liter). If such an assay interference is present, an alkaline extraction of quinidine before analysis has to be used. Results by our assay and those by a single-extraction fluorescence method correlated poorly (r=0.87), and the fluorescence assay gave 50% +/- 7% (SEM) higher values than our method, due to chromatographic separation of a major fluorescent non-phenolic metabolite of quinidine, which can also be measured by our assay.
An enzymatic triglyceride method that is suitable for long-term population studies.
Authors: Koehler D F , Steele B W , Azar M M , Kuba K , Dempsey M E 
Published: January 2020

Abstract
An enzymatic triglyceride method has been shown to be a suitable alternative to the Lipid Research Clinics' extraction/fluorometry method in long-term population studies. Correlation of results obtained with this method by this laboratory (y-axis) and by the Minneapolis Lipid Research Clinic Laboratory (x-axis) during a nine-week standardization period produced a curve with an intercept of -72 mg/liter, a slope of 1.019, and a correlation coefficient of r=0.996 (n=47). During this standardization period certain methodological problems were observed and corrected. An increase in background in certain clinical specimens, caused by spontaneous degradation of NADH, was observed, accurately measured, and taken into account when appropriate.
Solid-phase radioimmunoassay for morphine, with use of an affinity-purified morphine antibody.
Authors: Steiner M , Spratt J L 
Published: January 2020

Abstract
Morphine antibody purified by affinity chromatography was used to develop a solid-phase radioimmunoassay for morphine in polystyrene tubes. The tubes are coated with an appropriate concentration of the purified antibody, rinsed three times with buffered saline, and stored at -15 degrees C. Using tritiated dihydromorphine, we determined competitive morphine binding by difference when the radioactivity in the assay supernates was measured after incubation (1 h, 37 degrees C). Five standard curves, with use of serum equivalents of morphine ranging from 0 to 6 mug/liter, were linear and had a mean correlation coefficient of 0.98. Uncer conditions of the assay, levorphanol was comparable to morphine in its inhibitory effect on binding of labeled dihydromorphine, whereas dextrorphan was essentially inactive. Morphine-3-glucuronide, a major metabolite, is 55-fold less inhibitory in terms of its capacity to displace the radiolabel. We believe that the sensitivity of the technique, coupled with the simplicity of nonseparatory sampling, renders the system suitable for rapid determination of morphine and related compounds in biological fluids.
Automated measurement of serum thyroxine with the "ARIA II," as compared with competitive protein binding and radioimmunoassay.
Authors: Reese M G , Johnson L R 
Published: January 2020

Abstract
Two conventional serum thyroxine assays, run in separate laboratories, one by competitive protein binding and one by radioimmunoassay, were used to evaluate the automated ARIA II (Becton Dickinson Immunodiagnostics) serum thyroxine assay. Competitive protein binding as compared to ARIA II with 111 clinical serum samples gave a slope of 1.04 and a correlation coefficient of 0.94. The radioimmunoassay comparison to ARIA II with 53 clinical serum samples gave a slope of 1.05 and a correlation coefficient of 0.92. The ARIA II inter-assay coefficient of variation for 10 replicates of low, medium, and high thyroxine serum samples was 6.2, 6.0, and 2.9%, respectively, with an inter-assay coefficient of variation among 15 different assays of 15.5, 10.1, and 7.9%. The automated ARIA II, with a 2.2-min cycle per sample, gives results that compare well with those by manual methodology.
High-speed automated atomic absorption spectrophotometry.
Authors: McMurray C H , Blanchflower W J 
Published: January 2020

Abstract
We describe an integrated automated system for the atomic absorption spectrophotometer. The system makes use of a light-dependent resistor to detect the presence of a marker ion which is present along with the sample ion in the flame. An electronic circuit has been developed which enables the marker ion to trigger the read signal of the spectrophotometer. The system has been tested by determining magnesium and calcium in serum. Alternative modes of operation and different potential applications are discussed.
Improved ultraviolet spectrophotometry of serum theophylline.
Authors: Carter P , Wallace J E , Blum K 
Published: January 2020

Abstract
We present an improved method for ultraviolet spectrophotometry of theophylline in serum. We studied various extraction techniques aimed at eliminating interferences from co-extractable serum constituents. In the resulting modified procedure, 1 ml of serum is required and a salt-solvent pair of ammonium sulfate and chloroform/hexane is used for extraction. The solvent forms the top phase after extraction, the lower phase after back-extraction, thereby permitting easy removal of the appropriate phase from culture tubes. The use of ammonium sulfate coupled with the added specificity of the extraction solvent results in an extract with low background absorption and a well-defined spectrum for the extracted theophylline.
Spectrophotometry of theophylline-7-acetic acid and theophylline.
Authors: Owen J A , Nakatsu K 
Published: January 2020

Abstract
A spectrophotometric assay procedure is described for individually measuring theophylline-7-acetic acid and theophylline in 2.0 ml of serum. Absorbance is a linear function of concentration over a range of 0.5-40 mg/liter for theophylline-7-acetic acid and 0.5-40 mg/liter for theophylline. No endogenous or exogenous compounds were found that interfere with theophylline-7-acetic acid determinations. As with other spectrophotometric theophylline assays, theobromine and, to a slight extent, phenobarbital interfere with theophylline determinations.
An enzymatic assay for determining free and total cholesterol in tissue.
Authors: De Hoff J L , Davidson L M , Kritchevsky D 
Published: January 2020

Abstract
We describe a method for determining free and total cholesterol in extracts of rat-liver lipids by use of a cholesterol esterase/cholesterol oxidase enzymatic kit (Boehringer Mannheim Corp). The lipids are solubilized (as micelles) directly into the aqueous reagent mixture. Results of the enzymatic method correlate well with those obtained by an acid/ferric chloride assay of digitonin precipitates of the extracts. The enzymatic assay of free and total cholesterol in tissue offers advantages of simplicity over previously used methods.
Quantitative toxicology: interlaboratory and intermethod evaluation in New York State.
Authors: Buhl S N , Kowalski P , Vanderlinde R E 
Published: January 2020

Abstract
The New York State Department of Health has conducted a proficiency evaluation program in quantitative toxicology since 1974. Serum samples containing a barbiturate and phenytoin, together with either glutethimide, procainamide, or theophylline, are sent to participating laboratories quarterly. Within the first two years of the program the percentage of laboratories able to quantitate 75% of the test samples to within 25% of the gravimetric values increased from 25 (1974-1975) to 40% (1975-1976). This improvement was partly due to licensure requirements, improved technology for sample preparation and analysis, and the availability of better quality-control practice. An obstacle to obtaining uniform accuracy is the lack of adequate calibration or testing materials. To overcome these obstacles, pure drugs are weighed into a bovine serum matrix, and the weights are confirmed by reference laboratories and used as the target values in the testing program. Comparison of the methods used by participants in this program for barbiturate and phenytoin yielded equations different from those found in other method evaluations.
Amperometric nonenzymatic determination of serum glucose by means of a nickel-catalyst electrode.
Authors: Schick K G , Magearu V G , Huber C O 
Published: January 2020

Abstract
We describe a new, nonenzymatic method for determining serum glucose. This method is based upon the direct electrochemical oxidation of glucose by means of stable nickel-catalyst that is electrodeposited onto a lead dioxide electrode surface. Linear calibration plots are obtained for glucose in the 0.1 to 4500 mg/liter range. Values for 23 sera with glucose concentrations ranging from 300 to 4300 mg/liter showed a linear correlation coefficient of 0.996 when compared with values reported by a hospital laboratory using the hexokinase method. Typically a 25-microliter sample is used, but samples as small as 5 microliter have been successfully analyzed. The sample is added to 25.00 ml of pH 13 electrolyte containing 1 mmol of NiSO4 per liter; the amount of increase in anodic current comproses the analytical signal. For 20 repetitive analyses of a serum specimen, the CV was less than 4%. Ascorbic acid is rapidly decomposed in the electrolyte used and thus does not interfere. Uric acid is inactive at the concentrations present in serum samples. The sensitivity and simplicity of the new method suggest it as an alternative to currently available procedures.
Some factors affecting the utility of bovine blood as a control material in lead-screening programs.
Authors: Penton Z , Bissell G 
Published: January 2020

Abstract
Bovine blood is used frequently as control material in interlaboratory comparisons for blood-lead analysis, but an erythrocyte protoporphyrin control material is needed. We present data on the rate of changes in blood lead and erythrocyte protoporphyrin in steers fed lead acetate. We also show, by comparison of fluorescence spectra with those of known compounds, that most of the porphyrin in lead-burdened steers probably exists as free protoporphyrin IX along with some zinc-complexed protoporphyrin IX. Bovine blood is suitable as an erythrocyte protoporphyrin control material for laboratories using acid extraction procedures, but not for the proficiency testing of laboratories using hematofluorometers.
Method-specific variations in the calibration of a new immunoglobulin standard suitable for use in nephelometric techniques.
Authors: Whicher J T , Hunt J , Perry D E , Hobbs J R , Fifield R , Keyser J , Kohn J , Riches P , Smith A M , Thompson R A , Ward A M , White P 
Published: January 2020

Abstract
The putative International Federation of Clinical Chemistry immunoglobulin standard, IFCC 74/1, was calibrated against the World Health Organization (WHO) immunoglobulin standard 67/99 by three different methods: automated immunoprecipitation, Laurell rocket immunoelectrophoresis, and radial immunodiffusion. The same antisera were used in all the assays, which were performed in five expert laboratories. With the aid of linearizing transformations for the dilution curves of both materials and use of a carefully weighted statistical evaluation, values in International Units for IgG, IgA, and IgM were ascribed to IFCC 74/1. The values achieved by the three different methods were not statistically different, except in the case of IgA. IgM assays by automated immunoprecipitation were excluded owing to a high degree of imprecision.
Serum chromium and angiographically determined coronary artery disease.
Authors: Newman H A , Leighton R F , Lanese R R , Freedland N A 
Published: January 2020

Abstract
Human aortas sampled from populations where there is little advanced atheromatous plaque formation contain higher concentrations of chromium than do aortas from populations in which atheromatosis is prevalent. In the present study serum cholesterol, triacylglycerols, and chromium (Cr3+) concentrations were measured in 32 subjects in whom coronary artery disease was assessed by cineangiography. The distribution of subjects with diseased and normal arteries overlapped below 5.50 microgram of chromium per liter. Only subjects free of coronary artery disease had chromium concentrations greater than or equal to 5.50 microgram/liter. The role of chromium was assessed in the context of the selected risk factors: cholesterol, triacylglycerols, and systolic and diastolic blood pressure. The group with coronary artery disease had significantly lower serum chromium concentrations than did the group with normally patent arteries.
Computer-controlled instrument system for sequential chemical testing III. Application to liver assessment.
Authors: Cembrowski G S , Larson F C , Huntington R W , Selliken J H , Toren E C 
Published: January 2020

Abstract
We used the previously described [Clin. Chem. 19, 1114 (1973)] and evaluated [Clin. Chem. 19, 1122 (1973)] computer-controlled instrument system for sequential chemical testing to select and perform tests of hepatic status, to aid the clinician in the diagnosis of liver disease. Results for total bilirubin, aspartate aminotransferase, and alkaline phosphatase obtained from the continuous-flow analysis (SMA 12/60) admission screen were used by the instrument system to determine selectively the values for gamma-glutamyltransferase, alanine aminotransferase, creatine kinase, and total and direct bilirubin. Kit methods for the latter four tests were evaluated on the system; results were similar to manual procedures. A software, enzymatic ratemeter was found to be better than the previously described hardware ratemeter. The follow-up tests of serum prescribed by the system are compared to clinician-prescribed follow-up tests and discharge diagnoses. In 10 of 19 cases, the system and clinician ordered similar follow-up tests; in three cases follow-up differed, and in six cases, the system ordered follow-up tests and the clinician ordered none.
Characteristics of statistical parameters used to interpret least-squares results.
Authors: Davis R B , Thompson J E , Pardue H L 
Published: January 2020

Abstract
This paper discusses properties of several statistical parameters that are useful in judging the quality of least-squares fits of experimental data and in interpreting least-squares results. The presentation includes simplified equations that emphasize similarities and dissimilarities among the standard error of estimate, the standard deviations of slopes and intercepts, the correlation coefficient, and the degree of correlation between the least-squares slope and intercept. The equations are used to illustrate dependencies of these parameters upon experimentally controlled variables such as the number of data points and the range and average value of the independent variable. Results are interpreted in terms of which parameters are most useful for different kinds of applications. The paper also includes a discussion of joint confidence intervals that should be used when slopes and intercepts are highly correlated and presents equations that can be used to judge the degree of correlation between these coefficients and to compute the elliptical joint confidence intervals. The parabolic confidence intervals for calibration cures are also discussed briefly.
Analysis for potassium in human erythrocytes by use of a standard-additions method and an ion-selective electrode.
Authors: Mangubat E A , Hinds T R , Vincenzi F F 
Published: January 2020

Abstract
A method based on standard additions to the sample was used to measure potassium (K+) in human erythocytes with an ion-selective electrode. A computer program was developed for rapid analysis of data obtained with the electrode. The analysis takes into account factors such as temperature that may affect electrode behavior. Results obtained by the method agree with those obtained by flame-emission spectroscopy. The coefficient of correlation between the two methods is 0.96. Our method is simple and rapid. The computer program is applicable to other analyses with ion-selective electrodes.