bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated fluorometric analysis of galactose in blood.
Authors: Mason G A , Summer G K , Dutton H H , Schwaner R C 
Published: January 2020

Abstract
In galactosemia, prevention of mental retardation depends on early recognition of the disorder and institution of dietary restriction of galactose. We describe an automated fluorometric micromethod for galactose in whole blood spotted on filter paper. Galactose is oxidized by galactose oxidase to D-galacto-hexadialdose and H2O2 and measured as the highly fluorescent condensation product of homovanillic acid formed when H2O2 is acted upon by horseradish peroxidase. The procedure is 10-fold more sensitive than colorimetric procedures for galactose and is not hampered by the nonspecific fluorescence from endogenous NADPH that is encountered in methods in which galactose dehydrogenase is used. At a sampling rate of 40/h with a sample-to-wash ratio of 1/2, carryover is negligible, reproducibility is excellent, and 80% of steady state is achieved. Analytical recovery of added galactose was 95%. The method has the requisite sensitivity and accuracy for quantification of galactosemia and galactosuria in milkfed newborn infants and genetic evaluation of families of patients.
Simple procedure for measuring total protein in urine.
Authors: Meola J M , Vargas M A , Brown H H 
Published: January 2020

Abstract
We describe a procedure for measuring total protein in urine. The method is simple, sensitive, and free of interference from drugs that are known to affect other commonly used methods. The CV for a 1.1 g/liter urine control in daily, routine use is 4.6%. The procedure involves adsorbing the protein onto cellulose powder, binding of Ponceau S dye by the protein, washing away excess dye, and eluting the bound dye into dilute NaOH for colorimetry. Comparison of results by this method with those by the biuret and turbidimetric procedures showed good agreement in those cases where the specimens were suitable for assay by the comparison methods.
The beta-lipoprotein doublet in type 3 hyperlipoproteinemia.
Authors: Papadopoulos N K , Herbert P N 
Published: January 2020

Abstract
We used a previously reported agarose-gel electrophoresis system to study the lipoprotein patterns in patients with type 3 hyperlipoproteinemia. All samples from 20 subjects tested revealed the presence of two bands with beta-lipoprotein mobility, irrespective of quantitative changes in plasma lipids induced by diet or by the administration of drugs. If these observations are confirmed, the method will permit the diagnosis of type 3 hyperlipoproteinemia without resort to preparative ultracentrifugation and chemical measurement of the very-low-density lipoproteins.
Effect of analytical factors on immunochemical reference limits for complement component C3 in serum of a reference pediatric population.
Authors: Buffone G J , Lewis S A 
Published: January 2020

Abstract
We evaluated analytical factors such as antibody specificity, standard materials, and methodology for the measurement of C3. Mancini-type radial immunodiffusion and immunonephelometry were shown to give comparable data if variables other than procedural variables are eliminated. The most significant analytical factors affecting the measurement were antiserum specificity and source of standard material.
Automation of radioimmunoassays for some sex steroids with use of both iodinated and tritiated ligands.
Authors: Hammond G L , Viinikka L , Vihko R 
Published: January 2020

Abstract
We describe an automated technique for estradiol, progesterone, and testosterone, in which System Olli 3000 pipetting and incubation units are used. After extraction or chromatography, steroids are redissolved in ethanol or buffer, and duplicate aliquots are arranged for radioimmunoassay in 24-tube blocks. Addition of antibodies, tracers (125I or 3H), dextran-coated charcoal for separating free and bound ligands, and removal of a portion of the supernate for counting are all performed by the pipetting instrument. Incubations are at 37 degrees C in the incubation unit, or at 4 degrees C. After counting, steroid concentrations are computed from punch tape records by a Nova 840 computer. The management of assays in 24-tube units, and accurate simultaneous pipetting has reduced experimental error, and because there is no carryover, many different assays can be performed concurrently or in rapid sequence. Various scintillation media are compared.
Determination of "true" serum creatinine by high-performance liquid chromatography combined with a continuous-flow microanalyzer.
Authors: Brown N D , Sing H C , Neeley W E , Koetitz S E 
Published: January 2020

Abstract
We coupled a high-performance liquid chromatograph with a continuous-flow microanalyzer to produce a system for specifically determinig "true" creatinine in urine and serum specimens. A selective microbore pellicular cation-exchange column and a single eluting sodium citrate buffer are used to separate the noncreatinine but Jaffé-positive constituents from the creatinine in normal and experimental specimens. The effluent is analyzed continuously, on-line, the alkaline picrate complex being developed and measured in the microanalyzer. Physiological samples, reference standards, and internal control specimens are assayed in 6-min intervals subsequent to the initial injection. The relationship between concentration and peak are is linear for creatinine standards between 5 and 10 mg/liter. Specimen volumes ranging from 1 to 25 microliters, and containing creatinine in amounts exceeding 5 ng per injected sample, can be assayed with this system.
Concentrations of serum protein fractions in white women: effects of age, weight, smoking, tonsillectomy, and other factors;.
Authors: Wingerd J , Sponzilli E E 
Published: January 2020

Abstract
We measured the concentrations of protein in electrophoretic fractions (albumin and alpha1-, alpha2-, beta, and gamma-globulins) of serum from 9547 white women to determine their relations to age, weight, smoking and other factors. Albumin concentration decreases with age, beta globulin concentration increases. Increasing weight is associated with a decrease in albumin, but with increases in all the globulins. Cigarrete smoking is associated with highly significant differences in all the protein fractions. Surprisingly, very significantly lower concentrations of beta- and gamma-globulins were also found in women who reported a history of tonsillectomy. Height, amenorrhea, education, and alcohol and coffee consumption have some small but statistically significant effects upon the various fractions. Diurnal variation was also slight.
Determination of plasma procainamide and N-acetylprocainamide concentration by high-pressure liquid chromatography.
Authors: Dutcher J S , Strong J M 
Published: January 2020

Abstract
We describe a routine method for determining concentrations of the antiarrhythmic drug procainamide and its active metabolite, N-acetylprocainamide, in plasma. A simple extraction of 1.0 ml of plasma is followed by separation and chromatographic analysis by use of a column containing microparticulate silica. p-nitro-N-(2-diethylaminoethyl)benzamide hydrochloride was synthesized and used as the internal standard. Total chromatographic time is only 7 min. The day-to-day CV during three months of daily use was less than 4% of the mean for each compound, and we saw no deterioration in column performance during this time. Phenobarbital, phenytoin, lidocaine, primidone, methsuximide, quinidine, and their metabolites do not interfere.
Improved colorimetric determination of serum zinc.
Authors: Johnson D J , Djuh Y Y , Bruton J , Williams H L 
Published: January 2020

Abstract
We show how zinc may easily be quantified in serum by first using an optimum concentration of guanidine hydrochloride to cause release of zinc from proteins, followed by complexation of released metals with cyanide. The cyanide complex of zinc is preferentially demasked with chloral hydrate, followed by a colorimetric reaction between zinc and 4-(2-pyridylazo)resorcinol. This is a sensitive water-soluble ligand; its complex with zinc has an absorption maximum at 497 nm. Values found by this technique compare favorably with those obtained by atomic absorption spectroscopy.
Micromethod for determination of diazepam by electron-capture gas-liquid chromatography.
Authors: Rey E , Turquais J M , Olive G 
Published: January 2020

Abstract
We used 100 microliters of plasma for the determination of diazepam. After the internal standard, prazepam, is added, the serum is directly extracted with diethyl ether, the extract is evaporated, the residue is dissolved in ethanol, and the drug is measured by gas-liquid chromatography, with use of an electron capture detector. With this procedure, 2.5 ng of diazepam in the sample can be speedily measured with specificity, accuracy, and reproducibility (CV = 4.5%).
Homogeneous reactant-labeled fluorescent immunoassay for therapeutic drugs exemplified by gentamicin determination in human serum.
Authors: Burd J F , Wong R C , Feeney J E , Carrico R J , Boguslaski R C 
Published: January 2020

Abstract
We applied a homogeneous reactant-labeled fluorescent immunoassay to the measurement of therapeutic drug concentrations in human serum, exemplified here by gentamicin. A derivative of umbelliferyl-beta-galactoside was coupled covalently to the drug and this conjugate was found to be nonfluorescent under assay conditions. The drug/dye conjugate was a substrate for bacterial beta-galactosidase and yielded a fluorescent product. When the drug/dye conjugate was bound to anti-gentamicin antibody it was inactive as an enzymatic substrate. This inactivation was relieved by the presence of gentamicin in competitive binding reactions. Hence, the rate of production of fluorescence was proportional to the gentamicin concentration. The fluorescent assay yielded values which compared favorably to a radioimmunoassay for gentamicin in clinical serum samples (r=0.94, standard error of estimate=0.66 mg/liter). The fluorescent assay requires only 1 microliter of serum and offers several advantages over existing techniques: sensitivity, specificity, simplicity, and the obviation of radioisotopes.
Flow cytometric measurement of peptidases with use of 5-nitrosalicylaldehyde and 4-methoxy-beta-naphthylamine derivatives.
Authors: Dolbeare F A , Smith R E 
Published: January 2020

Abstract
Enzyme activity can be measured in single cells or in cell suspensions by either static or flow microfluorometry when a fluorogenic substrate is used. We have used amino acid derivatives of arylamines as fluorogenic substrates for tagging cellular proteinases. The liberated aromatic amine, which can diffuse from the cell, is trapped as a fluorescent insoluble Schiff-base product with 5-nitrosalicylaldehyde, with the peak of fluorescence emission shifted from lambdaem 425 nm to lambdaem 530 and 595 nm. Although the reaction is faster at pH 4 than at higher pH's, the equilibrium during the assay of certain peptidase activities is such that the liberated aromatic amine is trapped in the cell at pH values as high as 7.5. 5-Nitrosalicylaldehyde causes almost no inhibition of substrate hydrolysis at 1 mmol/liter, a concentration exceeding that required for complete trapping of reaction product. The kinetics of enzymatic reactions with four synthetic substrates are demonstrated in intact Balb 3T3 cells and sonicated preparations in the presence of 5-nitrosalicylaldehyde. Hydrolytic rates for the substrate, CBZ-ala-arg-arg-4-methoxy-beta-naphthylamine, are given for single 3T3 cells by microfluorophotometry and for suspensions of 3T3 cells by flow cytometry. The clinical value of the method is demonstrated for differentiating mixed populations of leukocytes.
Some observations on the kinetics of the Jaffé reaction for creatinine.
Authors: Shoucri R M , Pouliot M 
Published: January 2020

Abstract
The Jaffé reaction for creatinine assay appears to follow pseudo-first-order kinetics; first-order rate constants are different for different samples. Rate constants for 10 different serum samples varied from a low value of 0.0040 +/- 0.0003 s-1 to 0.0084 +/- 0.0008 s-1. We describe an approach for determining first-order rate constants from kinetic data and discuss the effects of the above observations on the mathematical formulations required for reliable kinetic determinations of creatinine.
Temperature dependence of the absorbance of alkaline solutions of 4-nitrophenyl phosphate--a potential source of error in the measurement of alkaline phosphatase activity.
Authors: Burtis C A , Seibert L E , Baird M A , Sampson E J 
Published: January 2020

Abstract
The absorbance of an alkaline solution of 4-nitrophenyl phosphate is a function of temperature. Quantitative evaluation of this phenomenon indicates that it (a) depends on the concentration of the compound and is independent of source, buffer concentration, and pH above 9.0; (b) is reversible; (c) is not a result of alkaline hydrolysis or 4-nitrophenol contamination; and (d) correlates with a temperature-induced shift of its absorbance spectrum. The phenomenon may represent a potential analytical problem in methods for alkaline phosphatase in which this compound is the substrate. If thermal equilibrium is not reached and maintained during an alkaline phosphatase assay, the thermochromic response will be included in the measured rate. The magnitude of this error depends on the thermal response and control characteristics of each particular instrument and the reaction conditions under which such an analysis is performed.
Radioimmunoassay of human homologous prolactin in serum with commercially available reagents.
Authors: Kao P C , Jiang N S , Abboud C F 
Published: January 2020

Abstract
A clincally useful and reproducible radioimmunoassay for human homologous prolactin, established with commercially available reagents, was studied and validated. We present detailed conditions for iodination and purification of labeled prolactin and the optimal conditions for the assay. By the method, we found values (microgram/liter) as follows for serum prolactin: normal men. 8.9 +/- 5.2 (mean +/- SD); normal women, 11.8 +/- 5.5; normal women taking contraceptive pills, 9.2 +/- 5.0; pregnant women in the third trimester, 188 +/- 69.5; patients with various diseases other than of the hypothalamic-pituitary axis, 9.3 +/- 6.3; in some patients with amenorrhea and galactorrhea of diverse origin, 78.2 +/- 87.4; and in some patients with surgically proven pituitary tumor, 1414 +/- 1980. Results under provocative testing are also presented for a patient with normal hypothalamic-pituitary function.
Creatine kinase: re-examination of optimum reaction conditions.
Authors: Morin L G 
Published: January 2020

Abstract
I have re-examined optimum reaction conditions for measurement of creatine kinase (EC 2.7.3.2). The optimum pH is 6.45, and 2,2-bis(hydroxymethyl)-2,2',2''-nitrotriethanol acetate, 200 mmol/liter, is the buffer of choice. Thioglycerol, 20 mmol/liter, is superior for both in-assay reactivation and for storage stability of sera. Fluoride, 25 mmol/liter, a broad inactivator of adenylate kinase (EC 2.7.4.3), has little effect on creatine kinase and is superior to AMP for adenylate kinase inhibition in the assay of creatine kinase. Magnesium ion, ADP, and buffer concentrations are interdependent and their optima must be determined together. The hexokinase/glucose-6-phosphate dehydrogenase activity ratio should not exceed 1.6. The range of linearity is limited by the glucose-6-phosphate dehydrogenase and NAD+ concentrations. Glucose-6-phosphate dehydrogenase, ADP, and NAD+ are the constituents most likely to result in unacceptable blanks. Creatine kinase is inhibited noncompetitively by anions: acetate and fluoride inhibit slightly, but sulfates, nitrates, and excessive chlorides should be avoided.
Formation and properties of lactate dehydrogenase inhibitors in NADH.
Authors: Loshon C A , McComb R B , Bond L W , Bowers G N , Coleman W H , Gwynn R H 
Published: January 2020

Abstract
We describe some characteristics of the mode of formation of inhibitors of lactate dehydrogenase from commercial NADH. Inhibitor formation is time- and concentration-dependent and also varies with the commercial source of NADH. At least two inhibitory components can form in concentrated NADH solutions. One of these can be separated from NADH by chromatography on either diethylaminoethyl-celluose or diethylaminoethyl-Sephadex; the second cannot. The NADH-associated inhibitor appeared to be present in each of the three commercial NADH preparations studied. The 260 nm/340 nm absorbance ratio was of no help in locating this inhibitor during chromatography.
Detection of heterozygotes for phenylketonuria. Total body phenylalanine clearance and concentrations of phenylalanine and tyrosine in the plasms of fasting subjects compared.
Authors: Jagenburg R , Regårdh C G , Rödjer S 
Published: January 2020

Abstract
Two tests have been compared for detection of heterozygotes for phenylketonuria, one based on determination of plasma phenylalanine and tyrosine concentrations in fasting individuals and the other on kinetic evaluation of the plasma elimination curve after intravenous loading with L-phenylalanine. The plasma elimination curve was biexponential and the kinetics were evaluated according to the two-compartment model. The constant, beta, expressing the rate of elimination from plasma at pseudo-equilibrium, the rate constant for the elimination from the central compartment, and the total body clearance were determined. Of these three, total body clearance, which on the average was reduced by 32% in the phenylketonuric heterozygotes, showed the best discriminatory ability, but was not better than the information on concentrations of phenylalanine and tyrosine in detecting heterozygotes for phenylketonuria.
High-pressure liquid chromatography and enzyme immunoassay compared with gas chromatography for determing phenytoin.
Authors: Chamberlain R T , Stafford D T , Maijub A G , McNatt B C 
Published: January 2020

Abstract
We compared a gas-chromatographic method for determination of phenytoin with a high-pressure liquid chromatographic technique and with enzyme immunoassay by three instrumental procedures. More than 100 sera from patients being treated with this drug were assayed by all these techniques. The coefficient of variation was the lowest (4.0%) with liquid chromatography, but all methods gave a CV of less than 10%. The correlation coefficients for all methods exceeded 0.97 when compared to gas chromatography. Operation costs varied with the number of tests per batch, reagent costs, and operator labor costs. All assays gave comparable values for the therapeutic range, so it would be plausible to use more than one method in a situation where (e.g.) satellite laboratories handle different quantities of assays. In any of these techniques, interferences from carbamazepine, mephenytoin, phenobarbital, and primidone were negligible.
Determination of some L-3,4-dihydroxyphenylalanine and dopamine metabolites in urine by means of mass fragmentography.
Authors: Muskiet F A , Fremouw-Ottevangers D C , van der Meulen J , Wolthers B G , de Vries J A 
Published: January 2020

Abstract
We describe a mass-fragmentographic method for determination in urine of the following metabolites of L-3,4-dihydroxyphenylalanine and dopamine: vanillactic acid, 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylethanol, and 3,4-dihydroxyphenylethanol. Deuterated analogs were used as internal standards. The method is fast, reproducible, sensitive, and selective, and does not require the use of time-consuming clean-up procedures. Normal excretion values in terms of creatinine, expressed as a function of age, as well as values obtained for patients with neurogenic tumors, a patient during therapy with L-3,4-dihydroxyphenylalanine, and a patient receiving dopamine are presented and discussed.
Results for serum and plasma compared in 15 selected radioassays.
Authors: Kubasik N P , Sine H E 
Published: January 2020

Abstract
We evaluated the results for serum vs. plasma samples for 15 selected radioassay procedures, using 19 manufacturers' kits. Blood samples were collected with heparin, oxalate-fluoride, or ethylenediaminetetraacetate anticoagulants and compared with serum samples. Differences were demonstrated between serum and plasma which may be of sufficient magnitude to alter clinical interpretation of the results. Assays also demonstrated significant differences based on the kit manufacturer and procedure used.
The peak monitor of the Technicon SMAC system.
Authors: Percy-Robb I W , Simpson D , Taylor R H , Whitby L G 
Published: January 2020

Abstract
The peak-monitor software of the Technicon SMAC system has been investigated by experiments designed to test its ability to detect abnormally shaped peaks, deliberately produced by presenting serum samples of inadequate volume for analysis. The software provided by the manufacturer is shown to detect faulty peaks inefficiently, and a set of modified parameters has been identified which greatly improves the performance of the peak-monitor software.
Simple determination of high urinary excretion of 5-hydroxyindole-3-acetic acid with ferric chloride.
Authors: Yamaguchi Y , Hayashi C 
Published: January 2020

Abstract
We describe a method for determination of urinary 5-hydroxyindole-3-acetic acid, a metabolite of serotonin and tryptophan and a useful indicator of metastasizing carcinoid tumor. The analysis is based on the color development with ferric chloride added to the residue obtained on evaporating a diethyl ether extract of the sample that has been acidified with sulfuric acid and saturated with sodium chloride. The color is measured by 510 nm. The reaction was made highly specific by the acidification so that nonspecific reactions with catecholamines and with other phenolic compounds such as salicylic acid could be eliminated.
Analysis for 1,3-bis(2-chloroethyl)-1-nitrosourea by chemical ionization mass spectrometry.
Authors: Weinkam R J , Wen J H , Furst D E , Levin V A 
Published: January 2020

Abstract
We used chemical ionization mass spectrometry to quantify the cancer chemotherapeutic agent 1,3-bis(2-chloroethyl)-1-nitrosourea in biological fluids. A stable isotope-labeled internal standard was added to the fluid being analyzed. Protonated molecular ion intensity ratios were determined by selected ion monitoring of sample extracts inserted directly into the chemical ionization source. Peak ratios were calculated for chlorine isotope ratios in their natural abundance, to verify the integrity of the data acquired, and to compute the drug concentration. The assay was applied to measure the compound in rat blood and plasma and in human plasma, and to monitor in vitro metabolism in rat-liver microsomal preparations. For the analyses we used a quadrupole mass spectrometer interfaced to a commercial computer system. Data-system characteristics are described.
Homogeneous enzyme immunoassay for cannabinoids in urine.
Authors: Rodgers R , Crowl C P , Eimstad W M , Hu M W , Kam J K , Ronald R C , Rowley G L , Ullman E F 
Published: January 2020

Abstract
We describe a homogeneous enzyme immunoassay for measurement of cannabinoid metabolites, as well as delta9-tetrahydrocannabinol (I) in urine. Malate dehydrogenase from pig heart mitochondria was labeled with a derivative of I. The compound used to calibrate the assay was the I metabolite, 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (II). With 15 microgram of II per liter of urine as the cutoff concentration, the assay can detect 25 microgram of II per liter with greater than 95% confidence. A positive response was obtained for urine specimens assayed within 30 min after exposure to cannabinoids. However, the persistence of metabolites of I in urine indicates that assay of this fluid is useful as an indicator of cannabinoid use but not as an indicator of intoxication.