bluuebunny/crossref_metadata_2025_split huggingface dataset:
Commonly Used Medications that Interfere with Routine Endocrine Laboratory Procedures
Authors: Borushek Samuel , Gold Jay J 
Published: January 2020

Abstract
Ten groups of commonly utilized medications were examined both in vitro and in vivo for their ability to interfere with optical density measurement and/or color development in such routine endocrine laboratory tests as those for 17-ketosteroids and 17-hydroxycorticosteroids. Certain antihypertensives, tranquilizers, psychic energizers, monoamine oxidase inhibitors, and soporifics were found to create the most problems in interference. The importance of removing these medications from the patients' therapeutic regimes prior to obtaining specimens for such endocrine procedures is stressed.
Analysis on Heat Coagulated Blood and Serum
Authors: London Morris , Marymont Jesse H 
Published: January 2020

Abstract
A method for the determination of serum glucose employing a heat clot technic for the elimination of protein and other interfering substances is described. Serum (0.10 ml.) and absolute methyl alcohol (0.09 ml. delivered as six drops) are mixed in a shell vial and a clot is formed by immersion of the vial in a 60° water bath for 4 min. The clot is overlaid with 2.0 ml. of water and the container is placed in a 37° water bath for 45 min.; 0.50 ml. of the extract is added to 6.0 ml. of a glucose oxidase reagent and the solution placed in a 37° water bath for 30 min. Two drops of 4N HCI is added and the absorbance at 420 mµ measured. The serum glucose is calculated in the usual manner by comparing the absorbance of the unknown with that of a standard. The method is simple, reliable, and well suited for routine use in the clinical laboratory.
The Photometric Microdetermination of Tryptophan in Biologic Materials
Authors: Saifer Abraham , Gerstenfeld Shirley 
Published: January 2020

Abstract
A modification of the Fischl (6) glyoxylic acid method for tryptophan was developed which permits the reaction to occur quantitatively in aqueous solution by substitution of 70% HCIO4 (w/v) for concentrated H2S04. Spectral analysis of the chromogen formed showed a strong adsorption band at 365 mµ for pure tryptophan which was 17 times more sensitive than that at 560 mµ. Factors were studied which influence the absorbance of the tryptophan chromogen at 365 mµ and the most favorable conditions for its formation.
A new method for hydrolyzing proteins and peptides was evolved using 3.5% HCIO4 (w/v) which results in complete rupture of the peptide bond while retaining intact the indole nucleus. Application of the modified glyoxylic acid method to perchloric acid hydrolyzates of various proteins and peptides of known tryptophan content gave experimental values in close agreement with those calculated from the structural formulae. The over-all reproducibility of the procedure for separate hydrolyzates, run in duplicate, of the same protein or peptide sample was about ±3.0%.
Comparison of the tryptophan values obtained for 19 different "purified" peptides and proteins checked rather well with some of the results reported in the literature for the same materials using other procedures, except for trypsin and ovomucoid.
Simplified Estimation of Leucine Aminopeptidase (LAP) Activity
Authors: Martinek Robert G , Berger Louis , Broida Dan 
Published: January 2020

Abstract
An accepted colorimetric assay for the end product of the enzymic hydrolysis of L-leucyl-β-naphthylamide by leucine aminopeptidase in serum and urine has been modified. This modification has been shown to result in enhanced facility of handling large numbers of assays of this enzyme with considerably improved precision.
An Evaluation of Serum Protein Fractionation Using a Methyl Orange Method for Determination of Albumin
Authors: Crowley Leonard V 
Published: January 2020

Abstract
Fractionations of serum proteins using dye-binding methods have become popular because such methods are simple and can be adapted easily to automated systems of analysis, and the results of analysis performed on normal serums correlate well with results obtained by other methods. However, the good correlations do not necessarily apply when dealing with abnormal serums. Analysis of a selected group of serums revealed in 14% of cases a relatively poor correlation between fractionation by electrophoresis and a method involving dye binding. Methods of protein fractionation involving dye binding are satisfactory for routine use provided the limitations of these methods are recognized.
Determination of Cholesterol by Means of Phloroglucinol in Acid Solution
Authors: Sahagian Benjamin , Levine Victor E 
Published: January 2020

Abstract
Cholesterol is determined by taking advantage of the fact that the digitonin moiety of cholesteryl digitonide is a glycoside containing in its molecular structure one molecule of xylose and four molecules of galactose, and therefore reacts with a sugar reagent, such as phloroglucinol in acid solution, to form a stable color complex yielding quantitative results when measured spectrophotometrically. The method agrees well with results obtained by the Schoenheimer and Sperry (8) procedure.
Determination of Phenylalanine in Blood and Urine
Authors: Woolf L I , Goodwin B L 
Published: January 2020

Abstract
A modification is described of the method of LaDu and Michael for estimating the concentration of L-phenylalanine and L-tyrosine in the blood by oxidation with L-amino acid oxidase. The proteins of serum or plasma are removed in an ultra-filtration step that greatly reduces the nonspecific absorption, increasing the sensitivity and precision of the method. The ultrafiltrate is added to a composite reagent containing all other necessary components. The method can be applied to urine after removal of pigments with basic lead acetate.
Determination of Free and Total Indole-3-acetic Acid and of the Indole Index
Authors: Fischl J , Rabiah S 
Published: January 2020

Abstract
A new method is described for measurement of the urinary excretion of free and total indole-3-acetic acid and for obtaining the chromogenic value of the total indoles. The color reaction employed is Fischl's (1) tryptophan reaction. Hydrolysis and extractions were done by Weissbach's (2) procedure. The ratio of the various fractions is expressed by a new term: "indoles index" (I.I.). By the evaluation of the data obtained under various conditions, many abnormalities of tryptophan metabolism may be detected.
A Semimicro Modification of the Karr Urea Determination Method Using the Somogyi Serum Filtrate
Authors: Ryland Margaret E 
Published: January 2020

Abstract
A semimicro adaptation of the Karr method that uses a 1:21 Somogyi filtrate is described. The method compares favorably with the Karr method and the Van Slyke and Cullen aeration method.
Optimum Clinical Application of Serum Protein Electrophoresis
Authors: Dirstine P H , MacCallum D B , Anson J H , Mohammed Anis 
Published: January 2020

Abstract
The clinical employment of serum protein electrophoresis on microporous cellulose actate support medium is described. The high precision, the freedom from error in routine use, and the speed and economy of the procedure recommend it as a replacement for the routine "salting-out" A/G ratio in most laboratories and as a five-fraction separation procedure which is a great improvement over paper electrophoresis and much easier than gel methods. Normal values, precision data, and information on time requirements are given, as are examples of potential value of the obtained information in acute conditions and in routine physical examinations.
Chemical Assay of Diethylstilbestrol
Authors: Dryer R L 
Published: January 2020

Abstract
A method for the chemical determination of diethylstilbestrol has been described which is useful for the assay of this drug and for its determination in tissue extracts. The procedure has been validated for the range of 0.005-0.125 mg., in which Beer's law is obeyed. A limited number of substances has been examined for possible interference, all of which gave negative results. Fats or lipoids do not prevent the formation of a colored complex, but the turbidity due to their presence interferes with exact color measurements.
Cholesterol in Serum and Lipoprotein Fractions
Authors: Anderson Joseph T , Keys Ancel 
Published: January 2020

Abstract
1. Methods are described for the separation, by paper electrophoresis and by cold ethanol, of α- and β-lipoproteins in 0.1 ml. of serum, with subsequent analysis of cholesterol in the separated portions.
2. It is shown that both methods of separation yield separated fractions containing substantially the same amounts of cholesterol.
3. Detailed data are given on the errors of measurement for total cholesterol and for cholesterol in the separated lipoprotein fractions.
4. Studies are reported on the stability of cholesterol in stored serum and on paper electrophoresis strips. It is shown that simple drying on filter paper causes no change in cholesterol content and yields a product that is stable for many weeks at ordinary room temperature.
5. The sources of variability in human serum cholesterol values are examined and it is shown that spontaneous intraindividual variability is a much greater source of error than the errors of measurement with these methods.
Absorption and Excretion of 17, 21-Dihydroxy-20-Ketosteroids in Dogs
Authors: Silber Robert H , Morgan Evan R 
Published: January 2020

Abstract
The plasma concentrations of free 17,21-dihydroxy-20-ketosteroids and urinary excretion of both free and glucuronide forms have been determined after oral, intramuscular, and intravenous administration of cortisone, hydrocortisone, their δ1 forms, and 9α-fluorohydrocortisone to dogs.
Excretion of the glucuronide forms of those steroids with a double bond at the 1-2 position or with a fluorine at position 9 was depressed, and the plasma half-life of each of these steroids was longer than that of the parent compound.
Serum Iron Determination
Authors: Kingsley George R , Getchell Gloria 
Published: January 2020

Abstract
1. A sensitive, reproducible method for serum iron determination has been developed employing extraction of serum acid hydrolysate with isoamyl alcohol and development of a highly colored ferrous complex of 4,7-diphenyl-1, 1O-phenanthroline for quantitative photometric measurement of iron.
2. The method gives good recoveries and also good agreement with the dry-ashing procedure.
3. A normal range of 120-200 µg./100 ml. (average 160) for the female and 125-238 µg./100 ml. (average 182) for the male for serum iron was obtained by the method.
Simplified Rapid Technic for the Extraction and Determination of Serum Cholesterol without Saponification
Authors: Carr Julius J , Drekter I J 
Published: January 2020

Abstract
An accurate yet simple procedure for the determination of total cholesterol, based upon the application of a Liebermann-Burchard color reaction directly in the solvent employed for extraction of cholesterol from serum, has been described. Extraction of cholesterol and removal of protein are accomplished by means of acetic acid and acetic anhydride. Serum water is removed by the acid-catalyzed hydrolysis of acetic anhydride. The Liebermann-Burchard color is then developed with a stable, modified reagent consisting of equal volumes of H2SO4 and acetic acid.
Excellent agreement with the technic of Schoenheimer and Sperry is obtained. Equal intensities of color are produced by equivalent concentrations of free and esterified cholesterol. Preliminary saponification of cholesterol esters is therefore not required. Color development may proceed in ordinary room lighting without loss of accuracy.
Plasma Tributyrinase in the Neonatal Period
Authors: Friedman Max M , Shriro Robert L 
Published: January 2020

Abstract
A method is described for the microestimation of tributyrinase activity in plasma that requires only 0.1 ml. of sample. This is an electrometric procedure adapted from a titrimetric method.
A comparison curve is established which relates titration units to electrometric units.
Data are presented for the plasma tributyrinase levels in the first 6 days of neonatal period. No significant daily variations could be detected.
Nitrofurantoin Estimation in Urine with the Aid of Chromatography
Authors: Bender Raymond C , Nohle Esther G , Paul Mary F 
Published: January 2020

Abstract
A method for the determination of Furadantin in urine has been described. Furadantin is separated from interfering urinary pigments by a chromatographic adsorption technic. Furadantin concentration may then be determined spectrophotometrically from the absorbance (375 mµ) of the eluate, or the eluate may be further treated to form the phenylhydrazone of nitrofuraldehyde from Furadantin and the determination carried out colorimetrically.
Determination of Serum Urate by Direct Acid Fe3+ Reduction or by Absorbance Change (at 293 nm) on Oxidation of Urate with Alkaline Ferricyanide
Authors: Morin Leo G 
Published: January 2020

Abstract
An acid ferric reduction procedure is described for determining serum urate with 2,4,6-tripyridyl-s-triazine at 593 nm, whereby each mole of urate reduces 4 moles of ferric ion. The procedure requires no deproteinization and as little as 20 µl of serum is needed. It gives results that are linearly related to concentration to about 30 mg/dl, and it is precise (CV, 2.6%), accurate, and sensitive (a = 538). An ultraviolet spectrophotometric procedure is also described, in which urate is determined from the difference in absorbance at 293 nm with and without alkaline ferricyanide oxidation of urate. This procedure also is linear to at least 15 mg/dl, precise (CV, 1.2%), and accurate. Results by both procedures agree and correlate well with a reference uricase method. More than 99% of urate added to serum can be accounted for analytically.
Design and Operation of a Signal Comparator to Increase Efficiency of Continuous-Flow Analyzers
Authors: Neeley W E , Wardlaw S , Swinnen M E T 
Published: January 2020

Abstract
Design features and operation of a signal comparator are described. The efficiency of continuous-flow analyzers is improved by allowing the bubbled stream to remain intact as it passes through the colorimeter flow cell. The signal comparator eliminates the bubble artifact from the photodetector signal while allowing the signal produced from the fluid segment to remain intact. The instrument is reliable, easy to use, and does not require any adjustments by a technician.
Rocket Immunoselection for Detection of Heavy-Chain Diseases
Authors: Gale D S J , Versey J M B , Hobbs John R 
Published: January 2020

Abstract
A method is described that allows heavy-chain disease proteins to be simply detected. The sample is electrophoresed in an agarose plate containing kappa and lambda antisera in the lower section, and the relevant heavy-chain antisera in the upper section. Light chains and immunoglobulins containing light chains are precipitated in the lower region. Free "heavy chains" migrate into the upper region, where they are precipitated as a separate rocket. The method is quick, sensitive, and requires little antiserum.
New Evidence for a Binding Principle Specific for Folates as a Normal Constituent of Human Serum
Authors: Zettner Alfred , Duly Peggy E 
Published: January 2020

Abstract
The binding of folate by human serum was investigated by incubating serum with [3H]pteroylglutamic acid followed by charcoal separation of free and bound fractions. Sera from all of 99 normal volunteers and 9 16 patients exhibited some degree of folate binding, ranging from less than 0.1 to greater than 8 ng/ml. This binding phenomenon was found, by competitive inhibition, to be specific for folate derivatives when we used pooled serum as well as 10 individual sera representative of the entire range of folate binding as encountered in the total of 1015 sera. Studies of the association and dissociation reactions of folate and serum indicated that the binding reaction is of the reversible type. Hence, a mass-action equilibrium must also exist in vivo between bound and free folate fractions. The binding principle appears to be protein in nature. The implications of the interference of this binder in competitive binding assays of serum folates are discussed.
Comparison of Electroimmunodiffusion and Radial Immunodiffusion for Measurement of IgG in the Laboratory Diagnosis of Multiple Sclerosis
Authors: Perry J Joseph , Bray Patrick F , Hackett Theodore N 
Published: January 2020

Abstract
The detection of a supranormal quantity of immunoglobulin G (IgG) in cerebrospinal fluid is valuable in diagnosis of multiple sclerosis. In a previously published study of over 300 patients, including 46 patients with a clinical diagnosis of multiple sclerosis, 74% of the patients were found to have an abnormally high IgG value, expressed as a ratio of IgG/albumin, by the reliable method of electroimmunodiffusion. In the present study the recently introduced method of radial immunodiffusion was compared with established electroimmunodiffusion technique in divided samples of cerebrospinal fluid from 49 patients with a wide range of IgG/albumin values. The correlation of the results obtained by these two methods was very good (r = 0.945), but the variance with radial immunodiffusion (±20%) is greater than with electroimmunodiffusion (±15%). Two samples that exhibited increased values by the electroimmunodiffusion method were normal with the other technique. We conclude that electroimmunodiffusion remains a slightly more accurate and sensitive technique, although radial immunodiffusion is simpler and requires less technician time.
Simplified Colorimetry of α-Amino Nitrogen in Plasma, Serum, or Urine
Authors: Lorentz Klaus , Flatter Barbara 
Published: January 2020

Abstract
We describe a simple procedure for estimating amino acids, based on the formation of charge-transfer complexes with p-benzoquinone. The reaction is insensitive to ammonia, urea, purines, creatinine, and other nitrogenous compounds present in serum or urine, except amines, peptides, and proteins. The reagent is cheap, stable, and does not require prior treatment of urine before determination. Specifity, precision, and normal values of this method are reported and compared with those obtained by a colorimetric ninhydrin technique.
Simultaneous Determination of Copper and Iron in a Single Aliquot of Serum
Authors: Yee Hugh Y , Goodwin Jesse F 
Published: January 2020

Abstract
Copper and iron may be sequentially measured in a single aliquot of a protein-free filtrate by use of bis (1 -piperidylthiocarbonyl) disulfide and disodium 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (also known as ferrozine). Recovery studies showed excellent results for both metals in various concentrations. Copper interference has been obviated by use of thiourea in mercaptoacetic acid. Simultaneous equations are not needed in calculating results and high-reading blanks are eliminated. Comparative results are given with methods in which each metal was measured singly.
Determination of Sulfonylureas and Metabolites by Pyrolysis Gas Chromatography
Authors: Aggarwal Vijay , Sunshine Irving 
Published: January 2020

Abstract
We describe a simple, rapid method for determination of sulfonylureas that is not susceptible to significant interference from metabolites. An acidified plasma is extracted with toluene, followed by a back extraction from the toluene to methanolic trimethylanilinium hydroxide. The resulting compounds are measured by gas chromatography.
Identification of Free and Conjugated Metabolites of Methaqualone by Gas Chromatography—Mass Spectrometry
Authors: Bonnichsen R , Mårde V , Ryhage R 
Published: January 2020

Abstract
Gas chromatography—mass spectrometry was used to identify and measure methaqualone metabolites. All samples were silylated before analysis. Free and conjugated metabolites of methaqualone in urine, liver, and blood were studied in three suicide cases. Both free and conjugated metabolites were found in blood and urine, only free metabolites in liver. The conjugated metabolites were hydrolyzed with hydrochloric acid. A comparison hydrolysis with β-glucuronidase showed that much of the sample was destroyed by hydrolysis with hydrochloric acid. Mass chromatography is presented as a computer-based gas chromatographic—mass spectrometric method.
Chromogenic-Substrate Method for Demonstrating Multiple Forms of Alpha-Amylase after Electrophoresis
Authors: Spiekerman A M , Perry P , Hightower N C , Hall F F 
Published: January 2020

Abstract
A chromogenic-substrate method is described for demonstrating multiple forms of alpha-amylase (isoamylases) after they have been electrophoretically separated in a continuous-buffer, slab-type, polyacrylamide-gel system. After electrophoresis, the various isoamylases are detected by layering the gel slabs onto thin-film plates of agar impregnated with Remazolbrilliant Blue starch. Isoamylases appear on the substrate plates as clear hydrolytic zones on a blue background of undigested substrate. After dehydration, the substrate plates can be stored indefinitely, and the polyacrylamide slabs are available for protein staining or elution of the isoamylase bands, if desired. This method has significant advantages: it is simple, substrate plates are easy to prepare, the plates can be permanently stored, optimum time required for isoamylase detection can be judged visually, and the method can be adapted for special two-dimensional electrophoretic studies.
Enzymatic Method for Determination of Inorganic Phosphate in Serum and Urine with a Centrifugal Analyzer
Authors: Pesce Michael A , Bodourian Selma H , Nicholson John F 
Published: January 2020

Abstract
We describe an enzymatic method for determining inorganic phosphate in serum and urine, with use of the "CentrifiChem." The sample is mixed with a combined enzyme—substrate system consisting of the enzymes phosphorylase a, phosphoglucomutase, and glucose-6-phosphate dehydrogenase, the coenzyme NADP, the substrate glycogen, and adenosine 5'-monophosphate as the activator for phosphorylase. The increase in absorbance at 340 nm as NADPH is formed is linearly proportional to the concentration of inorganic phosphate to 15 mg P/dl. This method circumvents deproteinization and requires only 10 µl of sample. Results obtained with the automated enzymatic method show good correlation with manual and automated molybdenum blue methods.
Single-Antibody Technique for Radioimmunoassay of Cortisol in Unextracted Serum or Plasma
Authors: Foster Lowell B , Dunn Ralph T 
Published: January 2020

Abstract
A radioimmunoassay procedure for cortisol is described that requires only 5 µl of serum or plasma. Native cortisol-binding proteins are denatured by heating 5 µl of sample in 0.2 ml of glutamate buffer in a boiling water bath for 15 min. After a 2-h incubation of heat-treated serum or plasma with [H3]cortisol and cortisol antibody, "free" and "bound" cortisol are separated by use of hemoglobin-coated charcoal. The method is easy and sensitive, and results compare favorably with those of a well-accepted acid-fluorescence method. In addition, we show that serum and heparinized plasma yield the same results by this method, and therefore either can be assayed by this procedure.