bluuebunny/crossref_metadata_2025_split huggingface dataset:
Continuous-flow analysis for glucose in serum, with use of hexokinase and glucose-6-phosphate dehydrogenase co-immobilized in tubular form.
Authors: León L P , Chu D K , Snyder L R , Horváth C 
Published: January 2020

Abstract
Hexokinase and glucose-6-phosphate dehydrogenase, co-immobilized at the inner wall of plastic tubing, were used with continuous-flow analyzers to measure serum glucose. The performance of the enzyme-containing coils meets the hydraulic requirements of the continuous-flow instruments, and the average carryover does not exceed 2.2%. A glucose concentration change of 1 g/L yields a 0.08 change in absorbance. There is no significant deviation from linearity for glucose concentrations up to 5 g/L. The method is similar to the Reference Method proposed by the Food and Drug Administration, and results by the two methods agree and correlate well (r = 0.999). The operational stability of the enzyme tubes is sufficient to allow the analysis of at least 10 000 serum samples. We investigated in detail the effect of reagent concentrations and temperature on the performance of the enzyme coils, and the results shed light on the nature of the heterogeneous dual-enzymic reaction.
Response of ion-selective sodium and potassium electrodes in the Beckman Astra 4 and Astra 8 analyzers.
Authors: Fievet P , Truchaud A , Hersant J , Glikmanas G 
Published: January 2020

Abstract
We tested the response of ion-selective sodium and potassium electrodes that are a part of the new multi-channel chemical analyzers, Astra 8 and Astra 4 (Beckman). For this we used plain and albumin-containing aqueous solutions of known Na+ and K+ concentrations, varied inversely so we could assess how the concentration of each electrolyte would affect the response of the other electrode. The stability of the electrodes with time was good and the electrodes are indeed selective for Na+ and K+.
Rapid preparation of nucleotides from acid-soluble pools by chromatography on silica, as exemplified with acid extracts of cultured cells.
Authors: Lothrop C D , Uziel M 
Published: January 2020

Abstract
A rapid technique (5-10 min) has been developed for fractionating nucleotides from base and nucleoside contaminants in acid extracts of cells, by adsorption to silica gels. Silica gels (1-mL bed volume) were washed with 5 mL of water then with 5 mL of acetonitrile/water (90/10 by vol). After applying 3-mL samples, adjusted to 900 mL/L acetonitrile content, we washed the gel with an additional 10 mL of the acetonitrile/water solvent. More than 95% of the amounts of bases and nucleosides prsent, except for cytidine (92%), did not adsorb to silica under these conditions. Nucleotides were then quantitatively eluted with 9 mL of water. The retention volumes for positive, negative, and neutral nucleic acid components have been determined, to investigate the discriminatory properties of nucleic acid components on silica. Compounds (bases, nucleosides) that are not ionized at pH 7 do not bind to silica. However, negative, positive, and zwitterionic compounds are tightly adsorbed to the silica gels. This procedure has been used to purify nucleotides from several normal and transformed cell lines.
Concentrations of magnesium, calcium, potassium, and sodium in human heart muscle after acute myocardial infarction.
Authors: Speich M , Bousquet B , Nicolas G 
Published: January 2020

Abstract
Atomic absorption spectrometry was used to measure magnesium, calcium, and sodium, and emission spectrometry to measure potassium, in myocardium (left and right ventricles) of 26 control subjects who died of acute trauma. Results were expressed in mumol/g of proteins. Mg/Ca and K/Na ratios were also determined. The same measurements were made in 24 patients who died from acute myocardial infarction. Samples were also taken from the necrotic area. Mg/Ca and K/Na ratios were significantly higher in the left ventricle of both populations, thus providing evidence of anatomical and physiological differences between the two ventricles. As a result of cytolysis and anoxia, the Mg/Ca ratio was very significantly inverted, and the K/Na ratio very significantly smaller, for samples from the necrotic area. In these clinical conditions arrhythmias could certainly be considered likely, and there is reason to believe that magnesium depletion may be a cause of arrhythmias.
Results with six "kit" radioimmunoassays for primary bile acids in human serum intercompared.
Authors: Roda A , Roda E , Aldini R , Capelli M , Festi D , Sama C , Mazzella G , Morselli A M , Barbara L 
Published: January 2020

Abstract
We examined six radioimmunoassay procedures for measuring primary bile acids in human serum (two 3H-labeled and four 125I-labeled). A significant (p &lt; 0.01) correlation was observed between measurements in the assay both for cholic acid and chenodeoxycholic acid, at low and high concentrations of serum bile acids. All kits were acceptable with respect to accuracy, precision, stability, and analytical recovery. All six procedures gave similar results for chenodeoxycholic and cholic acid in sera of 80 healthy subjects; the agreement was also close when the two primary bile acids were compared with their sum in serum. Normal values ranged from 0.4 to 2.5 mumol/L for conjugated chenodeoxycholic acid and from 0.3 to 1.5 mumol/L for conjugated cholic acid. The 125I assays do not require liquid-scintillation equipment but 125I induces a decrease in the affinity constant of antibody. The sensitivity of the assays was still adequate for measuring bile acids in the serum of healthy fasting persons and liver-disease patients.
Simultaneous liquid chromatography of 5-fluorouracil, uridine, hypoxanthine, xanthine, uric acid, allopurinol, and oxipurinol in plasma.
Authors: Wung W E , Howell S B 
Published: January 2020

Abstract
A reversed-phase "high-pressure" liquid-chromatographic method is described for simultaneous analysis for 5-fluorouracil, uridine, hypoxanthine, xanthine, uric acid, allopurinol, and oxipurinol. Separation was optimal with phosphate buffer (50 mmol/L, pH 4.60) as eluent. A simple acid extraction procedure yielded quantitative recoveries and permitted adequate separation for interfering peaks. Compounds were identified by their retention times, absorbance ratios, co-elution with standards, and enzymatic shifts. With a computerized integrator we quantitated these compounds in widely varying concentrations with a single injection. The limit of sensitivity was 0.1 mumol/L for the compounds studied. This method was applied to determine mean values for those compounds in normal human plasma. They are (in mumol/L): uric acid 276 (SD 55), hypoxanthine 0.46 (SD 0.21), xanthine 0.40 (SD 0.27), and uridine 4.50 (SD 1.70). Erythrocytes and platelets can continue to release hypoxanthine and xanthine into plasma or serum after a blood specimen has been drawn. We believe this explains the higher values previously reported for hypoxanthine and xanthine in serum.
Binding of enzyme--IgG complexes in human serum to Protein-A Sepharose CL-4B.
Authors: Bauer K , Bayer P M , Deutsch E , Gabl F 
Published: January 2020

Abstract
We describe a simple method for detecting enzyme--immunoglobulin G (IgG) complexes in human serum. Protein-A Sepharose CL-4B binds IgG and therefore also the enzyme--IgG complexes, which can then be separated easily from the serum by centrifugation. We demonstrate this separation in two patients, one with a complex of IgG and creatine kinase (EC 2.7.3.2) BB isoenzyme, the other with an IgG--alkaline phosphatase (EC 3.1.3.1) complex. Both patients had unexplainably high activities of the respective enzymes in their serum. The method we propose should be a useful, simple, routine method of detection in cases where IgG--enzyme complexes are suspected.
Two agarose electrophoretic systems for demonstration of oligoclonal bands in cerebrospinal fluid compared.
Authors: Gerson B , Krolikowski F J , Gerson I M 
Published: January 2020

Abstract
Demonstration of oligoclonal bands by electrophoresis of cerebrospinal fluid is an important aid in establishing the diagnosis of multiple sclerosis. Electrophoretic systems vary in their effectiveness in doing so. We compared two systems in this respect. For a thin-layer agarose system, sensitivity was less (47%) than for a high-resolution agarose system (87%). Each system had good specificity (92 and 85%, respectively). Interpretation of electrophoretic patterns for cerebrospinal fluid should be available in clinical laboratories. Further, the best available system should be used for demonstration of oligoclonal bands.
Mannitol estimation in biological fluids by gas-liquid chromatography of trimethylsilyl derivatives.
Authors: Laker M F , Mount J N 
Published: January 2020

Abstract
We describe a procedure for estimating mannitol concentrations in biological fluids. Samples are mixed with internal standard solution (alpha-methylglucose), deproteinized if necessary, desalted, and dried. Specimens are then derivatized by adding pyridine/bis(trimethylsilyl)acetamide/trimethylchlorosilane and heating at 60 degrees C for 30 min. Samples are chromatographed on a 275-cm column of 10% OV-17, operated at 190 degrees C, and quantitated by peak-height measurement. The technique is linear, accurate, precise, sensitive, and free from interference. It has been used to measure mannitol in plasma, urine, and bile.
Accuracy, precision, and stability in measurement of hemoglobin A1C by "high-performance" cation-exchange chromatography.
Authors: Schifreen R S , Hickingbotham J M , Bowers G N 
Published: January 2020

Abstract
We present a "high-performance" liquid-chromatographic method for determination of HbA1c with use of a carboxylate cation-exchange column, ethanolic mobile phases, and a hemolysate-storage reagent that stabilizes a sample for up to five weeks at 4 degrees C. Temperature control and the addition of ethanol to the phosphate step-gradient increase precision by stabilizing peak shape and column activity. Lengthy equilibration of the column between samples is not necessary, because the pKa of the cation-exchange resin is decreased from 6.10 in aqueous media to 5.59 in ethanol/water (5/95 by vol) at 25 degrees C. We identified interfering heme compounds, distinct from HbA1d or HbA1e, that elute with the glycosylated hemoglobins and developed a method of correcting for their presence. The day-to-day coefficient of variation was 3.5%, and the reference interval for a mixed group of 20 healthy adults between the ages of 20 and 56 was 3.2—5.2% HbA1c.
Conditions affecting the colorimetry of orotic acid and orotidine in urine.
Authors: Harris M L , Oberholzer V G 
Published: January 2020

Abstract
We studied conditions affecting a colorimetric assay of total orotic acid (orotic acid plus orotidine) in urine. Most interfering substances can be conveniently removed on a small column of cation-exchange resin, and an improved control reaction corrects for residual background color. Analytical recovery from urine is nearly complete (greater than 95%) and the absorption spectrum for analyte eluted from the column closely resembles that for an orotic acid standard. We determined reference intervals for total orotic acid, expressed as a molar ratio to creatinine, for neonates, children, and adults, and assessed the effect of age, protein intake, and pregnancy. The method is simple enough to use as a reliable and accurate urine-screening test.
Ion effects in measurement of ionized calcium with a calcium-selective electrode.
Authors: Kaufman R A , Tietz N W 
Published: January 2020

Abstract
We examined the performance characteristics of an improved electrode for measurement of ionized calcium (Orion Research, Inc.) with respect to interferences by Na+, K+, Li+, Mg2+, and H+, as well as the effect of changes in ionic strength and osmolality. At physiologically observed concentrations, all ions except Na+ insignificantly affected ionized-calcium measurements. The decrease in ionized Ca2+ with increased Na+ concentration is caused by the increase in ionic strength and the associated decrease in Ca2+ activity. Sodium had no significant direct effect in concentrations below 250 mmol/L. A previously published (Clin. Chem. 23: 690, 1977) equation for the Na+ correction is invalid for this improved electrode. Changes in osmotic pressure negligibly affect electrode response. Significant changes in ionic strength, as would be observed in severe hypo- and hypernatremic sera, increase or decrease, respectively, values for ionized calcium by changing Ca2+ activity. With aqueous Ca2+ solutions, changes of less than or equal to 3% were observed for Na+ concentrations that deviate from 140 mmol/L by not more than 20 mmol/L. Because the calcium ion activity is considered to be the physiologically important variable, we suggest that no correlation be made for ionic strength effects.
Case report: changes in creatine kinase isoenzymes after myocardial infarction in a patient with prostatic carcinoma.
Authors: Alexander R L 
Published: January 2020

Abstract
The detection of serum proteins that can serve as tumor markers has been reported with increased frequency in patients with various localized or metastatic cancers. Many of these reports have concerned patients with prostatic carcinoma, who had normal or increased concentrations of creatine kinase (EC 2.7.3.2) in serum. In many instances the creatine kinase BB isoenzyme was increased in these patients. I describe the case of a patient with carcinoma of the prostate (stage D), who had a myocardial infarction three to four days after admission. The serum activity of the MM, MB, and BB isoenzymes changed markedly after the infarction. These changes and the possible tissue source(s) of this isoenzyme are discussed in relationship to the clinical symptoms of the patient.
On-line liquid-chromatographic analysis for drugs in serum with the Technicon "FAST-LC" system: performance data for theophylline and for four commonly used anticonvulsants and their metabolites.
Authors: Dolan J W , van der Wal S , Bannister S J , Snyder L R 
Published: January 2020

Abstract
We describe a new instrument for use in assay of therpeutic drugs in serum by "high-performance" liquid chromatography, the "FAST-LC" system (Technicon). Serum samples are aspirated directly into the unit, extracted with solvent, and the evaporated and redissolved extract is injected onto a chromatographic column. We illustrate the performance of the system by assays in serum for theophylline and four anticonvulsants (primidone, phenobarbital, phenytoin, and carbamazepine) plus two of their active metabolites (phenylethylmalonamide and carbamazepine epoxide). For theophylline, final chromatograms are monitored at 270 nm, at analysis rates of 10/h. Concentration and absorbance are linearly related from 0 to 130 mg of theophylline per liter. For the anticonvulsants, chromatograms are monitored at 200 nm, at analysis rates of 7.5/h. The six individual determinations are each linear beyond the therapeutic range. For both drug panels, day-to-day CV's were 4 to 6%. Results correlate well with those by enzyme immunoassay. A total sample volume of 150 microL is required.
Mechanized amidolytic technique for determination of factor X and factor-X antigen, and its application to patients being treated with oral anticoagulants.
Authors: van Wijk E M , Kahlé L H , ten Cate J W 
Published: January 2020

Abstract
We describe a mechanized chromogenic assay for factor X, the results of which correlate well with those for the one-stage clotting assays for factor X in which it is activated either via the extrinsic pathway by thromboplastin or directly by Russell's viper venom. We purified human factor X and raised monospecific antibodies to it in rabbits. We used our chromogenic assay for factor X to develop a factor-X-inhibitor neutralization assay for determination of factor-X antigen. Patients receiving oral anticoagulant treatment had significantly different factor-X activities after activation via thromboplastin or with Russell's viper venom. The concentration of factor-X antigen, although decreased, significantly exceeded factor-X clotting activity or chromogenic activity in this group of patients. Results of the chromogenic assay for factor X correlated well with results of "Thrombotest," a clotting test introduced by Owren (Lancet ii: 754, 1959) to control anticoagulant therapy. For patients taking oral anticoagulant drugs, the therapeutic range by our assay is 180 to 300 units/L.
Continuous-flow enzymatic determination of total serum cholesterol and method standardization with CDC-calibrated pooled sera.
Authors: MacAulay M A , Jacklyn C L , Mathers J M , Storm V A 
Published: January 2020

Abstract
We compared Boehringer Mannheim's enzymatic kit for the continuous-flow (AutoAnalyzer II) determination of serum cholesterol with Technicon's N-24a extraction method. Results for patients' samples analyzed by the enzymatic method were higher than those by the comparison method. To evaluate accuracy in the cholesterol determinations, we enrolled the enzymatic method into the Center for Disease Control's (CDC) Lipid Standardization program. We calibrated the method by use of a pooled sera for which cholesterol content was assigned by CDC after analysis by their reference Abell-Kendall procedure. We discuss the difficulties with available calibration material and limitations in the application of some commercial control materials to the enzymatic cholesterol method. The continuous-flow variables, Michaelis-Menton constants, percent ester-hydrolase activity, and other factors affecting the performance of the enzyme-linked cholesterol method are evaluated. We believe pooled sera with an assigned value for cholesterol content is the best calibrator material.
A rapid electrothermal atomic absorption spectrophotometric method for cadmium and lead in human whole blood.
Authors: Subramanian K S , Meranger J C 
Published: January 2020

Abstract
A rapid graphite-furnace atomic absorption spectrophotometric procedure is described for determining cadmium and lead in heparinized human whole blood. A known aliquot of the blood sample is diluted fivefold with an aqueous solution composed of 5 g each of diammonium hydrogen phosphate and Triton X-100 per liter, the solution is vigorously agitated, and a 10-microL aliquot is injected into a pyrocoated graphite tube under optimized instrumental conditions. Values for Cd and Pb in the sample are obtained by direct comparison to linear working curves prepared from aqueous standards of the metals in the diammonium hydrogen phosphate-Triton medium; there is no need to use the method of standard addition or matrix-matched calibration curves. Also, the method is free of matrix effects. At least 30 samples can be analyzed per hour. The rapidity, simplicity, and sensitivity of the method make it attractive as a screening technique for routine environmental surveillance involving large throughput of samples.
Bilirubin binding and neonatal acidosis.
Authors: Perlman M , Kapitulnik J , Blondheim S H , Alayoff A , Russell A 
Published: January 2020

Abstract
Plasma of neonates with severe metabolic acidosis secondary to fetal hypoxia bound less bilirubin than that of neonates without acidosis, as determined by Sephadex gel filtration. There was a significant correlation between the amount of bilirubin adsorbed by Sephadex and the base deficit. The method used ruled out any influence of plasma pH per se on binding. Our results suggest that organic anions that accumulate in the plasma of asphyxiated acidotic neonates may compete with bilirubin for binding sites on albumin.
Enzyme immunoassay of disopyramide in serum.
Authors: Pape B E 
Published: January 2020

Abstract
Disopyramide, an antiarrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than or equal to 5% and a between-assay coefficient of variation of less than or equal to 7%. Regression analysis of 105 serum samples analyzed by this technique (y) and by gas chromatography (x) gave the equation y = 0.99x + 0.04 (r = 0.97). Clinical evaluation of the results indicates the enzyme immunoassay technique to be highly specific and sensitive for disopyramide. The selectivity of the assay vs other drugs has been determined.
Liquid-chromatographic assay for urinary homovanillic acid, with fluorescent detection.
Authors: Rosano T G , Brown H H , Meola J M 
Published: January 2020

Abstract
We describe a procedure for measuring urinary homovanillic acid by "high-performance" liquid chromatography. The pH of urine samples is adjusted, and they are chromatographed directly on an octyl silica column. The effluent is reacted with a ferricyanide reagent, to convert homovanillic acid to a product that is fluorescent at 420 nm on excitation at 320 nm. The standard curve is linear up to a homovanillic acid concentration of 20 mg/L; the detection limit is 0.3 mg/L. The method is evaluated for precision, recovery, potential interference, and reference values, and compared (r = 0.99) with a published spectrophotometric method. The proposed method is suitable for the routine analysis for homovanillic acid in urine.
gamma-Glutamyltransferase in human serum: an analysis of kinetic models.
Authors: Solberg H E , Theodorsen L , Strømme J H 
Published: January 2020

Abstract
The purpose of the study was to elucidate details of the kinetic model for gamma-glutamyltransferase when assayed with gamma-glutamyl-3-carboxy-4-nitroanilide and glycylglycine as substrates. Data from several sets of initial velocity measurements were fitted by nonlinear regression to a set of different kinetic models. gamma-Glutamyltransferase acts by a "ping-pong bi-bi" mechanism. A model encompassing transfer and autotransfer, competitive inhibition by the acceptor substrate, and no inhibition by the donor substrate gives the best fit to the experimental data. Effects of spectrophotometric nonlinearity may simulate noncompetitive inhibition by the donor substrate. The nonlinearity is dependent on the absorption of the incubation mixture and therefore is related to the concentration of the donor substrate and the wavelength (405-412 nm) used to monitor the reaction. With decreasing pH the autotransfer fraction decreases and the binding of the donor substrate to the acceptor site increases, simulating an increased competitive inhibition by the donor substrate. These results are of importance when elaborating optimum assay conditions for gamma-glutamyltransferase in serum.
Spectrophotofluorometry of serotonin in blood platelets.
Authors: Vatassery G T , Sheridan M A , Krezowski A M 
Published: January 2020

Abstract
A rapid sensitive, and reproducible assay for determination of platelet serotonin is reported. Serotonin in extracted into an ascorbic acid solution by freezing and thawing and sonication. Ascorbic acid stabilizes the serotonin in the extract, and added ethanol enhances the final fluorescence of serotonin, which is measured in a concentrated hydrochloric acid medium (activation at 295 nm and emission at 540 nm). The method has an average coefficient of variation of 4.1%; 95% of added standards is accounted for. The average serotonin content of platelets from 15 men, ages 30-65 years, was 0.67 (SE 0.03) microgram/10(9) platelets, which compares favorably with previously reported values. 5-Hydroxyindole compounds such as 5-hydroxyindole-3-acetic acid and 5-hydroxytryptophan interfere with the assay, but there is relatively little of these compounds in platelets.