bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flameless atomic absorption spectrophotometric determination of manganese in rat brain and other tissues.
Authors: Bonilla E 
Published: January 2020

Abstract
I describe a method for determining manganese in biological tissues by flameless atomic absorption spectrophotometry, It is simple to perform and does not require prior extraction with solvents. Small tissue samples are dried for 48 h at 110 degrees C and dissolved in concentrated nitric acid; the clear acid solution is introduced into the furnace and the sequential drying (120 degrees C, 20 s), charring (800 degrees C, 70 s), and atomization (2400 degrees C, 8 s) are automatically performed. The technique of standard additions was used ot overcome matrix effect. The detection limit is 0.86 X 10(-11) g of Mn. The CV is 4.7%. Only sodium and potassium interfere at 500-fold concentrations, and their interferences were overcome by using the Deuterium Arc Background Corrector.
Toxicology test-ordering patterns in a large urban general hospital during five years: an update.
Authors: Walberg C B , Pantlik V A , Lundberg G D 
Published: January 2020

Abstract
Analytical data from the clinical toxicology laboratory of a large urban hospital, the Los Angeles County--University of Southern California Medical Center, are reported for the year 1976 and are compared to similar data previously documented for the year 1972. Drugs assayed, number of tests requested, and number of positive results are collated. Data on 58 assays show that the overwhelming majority of the requests continue to be for those tests that were originally classified as tests with 4-h turn-around time in the patient-focused concept for a clinical toxicology service in 1972. Total workload increased by 70%. The number of patients on whom some toxicologic assay was requested doubled in spite of a decrease in the number of patients admitted to the hospital during this five-year period. The data show that assays for some socially and clinically significant drugs--ethanol diazepam, tricyclics, and phencyclidine--increased disproportionally while others remained relatively constant, or even decreased.
Comparison of double- and single-isotope enzymatic derivative methods for measuring catecholamines in human plasma.
Authors: Evans M I , Halter J B , Porte D 
Published: January 2020

Abstract
We directly compared the reliability of a single-isotope enzymatic derivative technique for measurement of plasma catecholamines with that of the well-established double-isotope method. A significant (p less than 0.001) correlation was observed between measurements (n = 52) in the two assays, both for norepinephrine (r = 0.97) and epinephrine (r = 0.80). Means and coefficients of variation for the two analytes in a pooled specimen of plasma, measured repeatedly during six months, were virtually identical by each assay method. Basal plasma catecholamine concentrations in two different groups of apparently healthy subjects were also similar by each method. Dopamine concentrations in plasma were consistently below the limits measurable by either technique. The single-isotope assay requires half the assay time and 1/200th the sample as the double-isotope method. We conclude that this assay is just as reliable as the double-isotope technique and gives virtually identical values for norepinephrine and epinephrine concentrations in the physiological range.
The "Southmead System," a simple, fully-automated, continuous-flow system for immunoassays [Appendix: application to serum thyroxine radioimmunoassay].
Authors: Ismail A A , West P M , Goldie D J 
Published: January 2020

Abstract
A simple, fully-automated, continuous-flow system suitable for radioimmunoassay, enzyme immunoassay, and fluoro-immunoassay is described. The system is versatile, inexpensive, and requires only equipment and skills that already are available in most clinical chemistry laboratories. In this system, the antibody is covalently linked to solid-phase, porous particles of agarose (Sepharose, size 40-70 micrometer in the dry form). After sampling and mixing the assay reactants, the assay "cocktail" containing the solid-phase-bound antigen and the unbound fraction is directed to the separation block. Separation is achieved by use of a highly porous membrane (pore size, about 10 micrometer) and by controlling the volume of inflow and outflow a fixed and precise amount of fluid is filtered through the membrane containing only the free (unbound fraction), which can then be quantitated. The percentage of unbound fraction misclassified is negligible (less than 1.0%). Application of these principles to the assay of serum thyroxine is described in an appendix.
Free thyroxine in serum as estimated by polyacrylamide gel filtration.
Authors: McDonald L J , Robin N I , Siegel L 
Published: January 2020

Abstract
In this new method for estimating free thyroxine concentration in serum by use of polyacrylamide gel filtration, the prolonged incubation that is characteristic of equilibrium dialysis is obviated. Although the values so obtained for the percentage of free thyroxine are severalfold higher than those obtained by dialysis, the results of the two procedures correlate well over a wide range of thyroid states. In addition, the precision of the polyacrylamide method compares well with that for equilibrium dialysis. The method is convenient for use in clinical laboratories and values for free thyroxine in serum of patients with metabolic thyroid disorders are diagnostically discriminatory.
Screening for urinary oligosaccharides: a quantitative procedure.
Authors: Purkiss P , Hughes R C , Watts R W 
Published: January 2020

Abstract
A method for screening urine for abnormalities in glycoconjugate excretion is presented. An oligosaccharide-containing fraction is isolated from urine by gel chromatography and the carbohydrate-containing components in this fraction are degraded to monosaccharides, suitable derivatives of which are analyzed by gas-liquid chromatography. A pattern which characterizes the monosaccharides originating in complex carbohydrates in urine is thus obtained. Data obtained by applying this method to normal subjects in various age groups are presented and the applicability of the method and its limitations are illustrated by the use of examples from patients with previously diagnosed disorders of glycoconjugate metabolism.
Improved technique for developing creatine kinase isoenzyme bands by using a substrate in gelatin matrix.
Authors: Mickle D A , Washington G A , Porter C J 
Published: January 2020

Abstract
We describe a simple technique for reacting CK isoenzymes with a substrate in gelatin to make them visible after they have been separated by cellulose acetate electrophoresis. The electrophoresed strip requires only 5 min of contact with the substrate in gelatin and about 12 min of drying in an oven at 55 degrees C. The developed isoenzyme bands are discrete, intense, and rectangular in shape. The technique has a sensitivity of 2 to 5 U/liter, and results for isoenzyme MB can be reported about 30 min from the time a specimen is received.
Creatine kinase isoenzyme variants in human serum.
Authors: Ljungdahl L , Gerhardt W 
Published: January 2020

Abstract
In serum from about 800 patients, total creatine kinase and its subunit B activities were determined by the recommended Scandinavian creatine kinase method in the absence and presence of a creatine kinase M subunit inhibitory antibody. Eight patients had supranormal subunit B activities, but normal or near-normal values for total creatine kinase activity. Electrophoresis of sera from these eight patients showed, in addition to the normally migrating isoenzyme MM, one or two abnormally migrating creatine kinase isoenzyme bands, located between normally migrating isoenzymes MM and MB. Experimental data suggest that these abnormal bands may be isoenzyme BB with changed electrophoretic mobility. The eight patients had no particular disorder in common.
Atomic absorption spectrophotometry of free circulating platinum species in plasma derived from cis-dichlorodiammineplatinum(II).
Authors: Bannister S J , Chang Y , Sternson L A , Repta A J 
Published: January 2020

Abstract
We describe a method of analysis for free circulating platinum species derived from cis-dichlorodiammineplatinum(II) in blood plasma. Protein-bound and free platinum species were separated from each other by centrifugal ultrafiltration. Platinum in the ultrafiltrate was converted to a cationic complex by reaction with ethylenediamine, and the product was collected on paper impregnated with cation-exchange resin, where it could be stored indefinitely without loss. The platinum was eluted from the disk with 5 mol/liter hydrochloric acid, and an aliquot of this solution was then analyzed by flameless atomic absorption spectrophotometry. The overall analytical recovery of platinum was 80 +/- 2%. The minimum quantity of cis-dichlorodiammineplatinum detectable was 35 microgram/liter of plasma at the 99% confidence level. Detector response was linearly related to drug concentration in the range from 80 microgram to 290 mg of Pt per liter of plasma. Reaction variables were made optimal, so as to yield maximum sensitivity and reproducibility (+/- 2%) consistent with minimal sample transfers and manipulations.
Increased renin concentration in plasma and amniotic fluid during storage.
Authors: Craven D J , Symonds E M 
Published: January 2020

Abstract
Renin concentration was determined in plasma and amniotic fluid samples immediately after collection, after storage at -18 degrees C for up to 48 h, and after storage at 5 degrees C for as long as 48 h. Renin concentration increased, both in plasma (p less than 0.05) and amniotic fluid (P less than 0.02), after the storage at 5 degrees C, but no significant alteration occurred on storage at -18 degrees C. Partial activation of inactive renin could explain the observed increase in renin concentration at 5 degrees C.
A totally automated system for enzyme immunoassay of theophylline in serum.
Authors: Castro A , Ibanez J , Voight W , Noto T , Malkus H 
Published: January 2020

Abstract
We describe a procedure for enzyme immunoassay of theophylline (1,3-dimethylxanthine) in which all phases of the assay are totally automated in a Kinetic Analyzer (KA-150). This system permits assay of 75 10-mul samples per hour, with results available at 30-s intervals after initial sample preparation and preincubation. We compared results for 138 clinical samples by an ultraviolet method (x) and the present method (y). The slope of the comparison curve was 0.902, the y-intercept 0.402, and the correlation coefficient 0.984. The coefficient of variation for samples run in duplicate on the same day was 4.9%; it was 8.1% for samples run on different days. Specificity, sensitivity, simplicity, speed, and small reagent requirement all make this an attractive alternative to chromatographic procedures.
Enzymic determination of cholesterol in serum lipoproteins separated by electrophoresis.
Authors: Cobb S A , Sanders J L 
Published: January 2020

Abstract
We describe a reliable, straightforward procedure for measuring the cholesterol content of serum lipoproteins separated by electrophoresis on cellulose acetate. The lipoprotein fractions are made visible by use of an enzymic reagent and then quantitated by densitometry. Standard electrophoresis equipment is used and the procedure requires just over 1 h for completion. All major fractions except chylomicrons are detected readily. Accuracy and precision agree favorably with results reported for generally accepted methods. Concentration and color development are linearly related to cholesterol concentrations up to 1.5 g/liter in a given lipoprotein fraction. We recommend this method for use in assessing high-density lipoprotein cholesterol and as an aid in lipoprotein phenotyping.
Laboratory standardizatin in an international study: the Kaunas--Rotterdam intervention study (KRIS).
Authors: Boerma G J , Toleikis A , Mather A , Bartels C T , Margeviciene L , Glasunov I S , Leijnse B 
Published: January 2020

Abstract
Laboratory results obtained in different laboratories over lengthy periods of time usually are difficult to compare. In cooperative long-term studies where such results must be pooled, thorough standardization of methods is vital. We describe a program in which comparable plasma cholesterol and glucose analyses have been obtained, by simple methods. In the Netherlands and the Soviet Union in close collaboration with the Center for Disease Control, Atlanta, Ga., U.S.A. The two laboratories produced glucose values (direct o-toluidine reaction) within 2% of the target reference values and cholesterol results (direct Liebermann-Burchard reaction) with a consistent 6-8% positive bias over the reference method values. Intralaboratory precision was subject to preset acceptance limits. The use of common control materials, exchange of patient samples, and on-site comparison of all details of laboratory procedures are vital tools in standardization efforts. A laboratory protocol that included quality requirements and rejection criteria was developed and proved to be indispensable. The experience gained should be useful in standardizing inter-laboratory results in similar studies.
Analysis for glutathione in blood by high-performance liquid chromatography.
Authors: Rabenstein D L , Saetre R 
Published: January 2020

Abstract
A high-performance liquid chromatographic method is presented for determination of glutathione in whole blood. Sample preparation involves hemolysis, protein precipitation, centrifugation, and filtration. The glutathione in the filtrate is then separated from other sulfhydryl-containing molecules by liquid chromatography with Zipax SCX cation-exchanger followed by detection with a mercury-based electrochemical detector. The liquid-chromatographic analysis time is approximately 5 min. Because of the chromatographic separation and the selectivity of the detector, the detection step is free from interferences from other components of blood. The method has been checked by comparison with the colorimetric assay based on reaction with 5,5'-dithiobis(2-nitrobenzoic acid). The chromatographic results are consistently slightly lower, presumably because of the greater selectivity of this method.
Optimized method for measuring aspartate aminotransferase activity with the CentrifiChem Analyzer, with automatic preincubation of serum.
Authors: Ertingshausen G , Amsellem-Winzelberg L , Richert J F , Davids R 
Published: January 2020

Abstract
We propose a routine method for the mechanized measurement of aspartate aminotransferase with the CentrifiChem Analyzer, which is based on the recommendations of both the International Federation of Clinical Chemistry and the Société Française de Biologie Clinique. A modification of the CentrifiChem pipettor permits simultaneous pipetting of two reagents, thus achieving automatic preincubation of the serum in the transfer disk. Owing to the fixed reagent volumes dispensed by the pipettor, preincubation conditions had to be modified, but the recommendations for the final reagent concentrations in the assay cuvet were observed. The totally automated method correlates very well with one involving manual pipetting to reproduce the detailed step-by-step recommendations of the International Federation of Clinical Chemistry. Intra-assay precision ranged from 3.4 to 4.9% and interassay precision from 1.7 to 7.5%. We assayed 135 sera and obtained a correlation coefficient of 0.996 (a = 1.025, b = 0.08).
Analysis for nickel in plasma and urine by electrothermal atomic absorption spectrometry, with sample preparation by protein precipitation.
Authors: Andersen I , Torjussen W , Zachariasen H 
Published: January 2020

Abstract
We describe and evaluate a method for determining nickel in plasma and urine by atomic absorption spectrometry. Proteins are precipitated with trichloroacetic acid and sulfuric acid; ammonium pyrrolidinedithlocarbamate is used as the chelating agent for nickel, and methyl isobutyl ketone as extraction solvent. The results were compared with results obtained by the acid-digestion technique for removing proteins and other organic substances. Analyses for both plasma and urine were better by the present procedure. The mean and standard deviation for nickel in plasma from 15 healthy individuals was 2.13 +/- 0.58 microgram/liter by this method. For nickel in urine from 15 healthy men the mean and standard deviation was 4.45 +/- 1.9 microgram/liter. The coefficient of variation for plasma was 11.9%, and for urine 12.2% in 10 analyses of the same plasma and urine with the protein-precipitation procedure, as compared with 26.0 and 38.2%, respectively, by the acid-digestion technique.
An aqueous primary standard for use with the Technicon SMA 6/60.
Authors: Balkcom R M 
Published: January 2020

Abstract
An aqueous primary standard containing sodium, potassium, chloride, carbon dioxide, glucose, and creatinine was prepared for use with the Technicon SMA 6/60 continuous-flow analyzer. This standard, compared with a protein-base primary standard, showed no significant difference in slope, gamma-intercept, and linearity for these methods. Precision with use of the aqueous primary standard was acceptable, comparable to that for a commercial reference serum. The standard was stable for at least 30 days.
Dual-column cation-exchange chromatographic method for beta-aminoisobutyric acid and beta-alanine in biological samples.
Authors: Kuo K C , Cole T F , Gehrke C W , Waalkes T P , Borek E 
Published: January 2020

Abstract
A rapid, automated chromatographic method has been developed for the quantitation of the nucleic acid catabolites beta-aminoisobutyric acid and beta-alanine in urine, serum, and other physiological fluids. The analyses were performed on a modified Beckman 121M amino acid analyzer with dual ion-exchange columns and the use of a single sodium citrate buffer (pH 4.38, 0.20 mol/liter). By carefully matching the elution pattern for the two ion-exchange columns and alternating use of these columns, analyses are completed every 40 min. The chromatography, regeneration, and equilibration of the two columns are precisely programmed, thus the detector sees only the elution of beta-aminoisobutyric acid and beta-alanine alternately from each column. Long-term precision and analytical recovery for the two metabolites in urine were 1.9 and 102%, and 3.3 and 101%, respectively. Their normal physiological values were determined in human serum and urine. Their excretion in the urine was also studied as a function of collection time, to validate a more convenient, less costly method of sampling. This study shows that randomly collected samples are acceptable when the concentration of the two metabolites are expressed in terms of creatinine excretion. In addition, the distribution of the free and conjugated forms of the two metabolites in urine and serum was studied. A preparative method was also developed for the quantitative isolation of beta-amino-isobutyric acid from urine samples. The alternating dual-column technique may be applied to any ion-exchange chromatographic method where many analyses must be performed. This method is currently used in our laboratories for measuring these beta-amino acids in urine and serum of patients with various types of cancers.
Chromatographic separation and continuously referenced, on-line monitoring of creatine kinase isoenzymes by use of an immobilized-enzyme microreactor.
Authors: Denton M S , Bostick W D , Dinsmore S R , Mrochek J E 
Published: January 2020

Abstract
We describe a new concept in continuously referenced monitoring of the isoenzyme activities of creatine kinase (EC 2.7.3.2) after liquid-chromatographic separation. After separation on a diethylaminoethyl-Sephacel column, the three isoenzymes of creatine kinase undergo a series of coupled enzyme reactions, ultimately resulting in the formation of ultraviolet-detectable NADPH. A major advantage of this detection system is the immobilized-enzyme microreactor (2 X 17 mm), which may be removed and stored refrigerated when not in use. A split-stream configuation allows self-blanking of endogenous ultraviolet-absorbing constituents in authentic sera samples, which would otherwise make definitive diagnosis and quantitation difficult or impossible. This system is applicable to the automated analysis of creatine kinase isoenzymes in the clinical laboratory.
Radioimmunoassay for urinary albumin.
Authors: Woo J , Floyd M , Cannon D C , Kahan B 
Published: January 2020

Abstract
We describe a rapid, sensitive, and precise radioimmunoassay for urinary albumin (Ualb). Aliquots of diluted urine were incubated at room temperature for 1 h with 125I-labeled albumin and a rabbit antiserum monospecific for human albumin. Phase separation was effected by the double-antibody technique. The dose-response curve as linear in the range of 15.6-10000 ng, equivalent to 4 to 3000 mg/liter of urine. The limit of sensitivity was 16 ng of albumin. The coefficient of assay variation was 4.8%, both at 44 mg/liter and at 1304 mg/liter. A displacement curve obtained with a serially diluted urine sample of high albumin concentration was completely superimposable with the curve for which human albumin was used as a standard. In 26 normal individuals the range for Ualb was 2.2--12.6 mg/24h, and for albumin clearance (Calb, 1.8 x 10(-5)-19.6 x 10(-5) ml/min. After renal homografts in 25 patients, Ualb ranged from 16.9 to 9928 mg/24 h, and Calb from 2.7 x 10(-4) to 1.7 x 10(-1) ml/min. Both increased Ualb and Calb correlated well with the severity of renal homograft rejection.
Simple radioimmunoassay of cortisol in diluted samples of human plasma.
Authors: Connolly T M , Vecsei P 
Published: January 2020

Abstract
We describe a simple radioimmunoassay of plasma cortisol, which can be performed in 3 h and which requires no purification, heating, or refrigeration steps. The plasma proteins are inhibited through direct competition between them and the antiserum at room temperature, at which the antiserum's affinity exceeds that of the binding proteins. Plasma, diluted with water, is incubated for 3 h at room temperature with [3H]cortisol and the antiserum. We compared results with those by the usual extraction method. The correlation between methods on evaluating normal samples with one antiserum. We compared results with those by the usual extraction method. The correlation between methods on evaluating normal samples with one antiserum was r = 0.954 (P less than 0.001), and the slope was 0.661. With three other antisera it was r = 0.922 (P less than 0.001) and slope 0.644. Plasmas with abnormal protein concentrations (i.e., from preganant women, and after corticotropin administration), tested to examine the validity of the method for routine use, and to define the role of the protein carriers, showed r = 0.859 (P less than 0.001) and slope 0.726 for the four antisera used. Additional samples, assayed with diluted standards plus stripped plasma, showed a correlation with the usual extraction method of r = 0.945 (P less than 0.001) and slope 1.026.
Measurement of free calcium ion in capillary blood and serum.
Authors: Fogh-Andersen N , Christiansen T F , Komarmy L , Siggaard-Andersen O 
Published: January 2020

Abstract
We describe a new calcium ion-selective electrode for measurement of the substance concentration of free calcium ion [Ca2+] in the plasma phase of whole blood and in serum at 37 degrees C. A sample volume of 50 microliter suffices to obtain simultaneous values of pH and [Ca2+]. We found the within-series analytical standard deviation for serum to be 0.013 mmol/litre (CV, 1.1%) and day-to-day precision to be 0.022 mmol/litre (CV, 1.7%). The reference interval for [Ca2+] (at pH 7.40) in serum was found to be 1.184 +/- 0.054 mmol/litre (2 SD) from measurements on sera from 121 healthy blood donors. Measurements on capillary blood from 29 healthy volunteers gave a mean (+/- 2 SD) value for [Ca2+] (at pH 7.40) of 1.22 +/- 0.072 mmol/litre.