bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Automated Method for the Recovery of Urinary Nitrogen in Nitrogen Balance Studies
Authors: Peaston M John T , Wilson Sandra , Pemberton Judith 
Published: January 2020

Abstract
A method previously described for the total automation of nitrogen measurements from solid biologic material has been adapted for automating nitrogen recovery from urine following micro-Kjeldahl digestion. Standard solutions gave reproducible curves which were linear between the limits of 25 and 100 mg. of N2 ped liter. Comparative studies with the Markham (1) procedure revealed mean nitrogen recoveries for the automated method of 106%. The cause of the 6% difference remains unexplained, but cannot be attributed to low recovery by the Markham method. Application of a "correction factor" of 6% to the measurements by the automated method gave recoveries for urinary nitrogen almost identical with those obtained by the Markham method.
Time studies were compared on the two methods. When the number of urine samples to be analyzed exceeded 14 per day, the automated method was time-saving, reliable, and convenient. It is suggested that the method described should replace the Markham procedure in central hospital laboratories or regional metabolic units in which more than 14 urinary nitrogen measurements are made daily.
A Simple Method for the Preparation of Agarose
Authors: Barteling S J 
Published: January 2020

Abstract
Agar was purified by adsorption of the agaropectin from a hot agar solution with an insoluble adsorbent. The best results were obtained with aluminum hydroxide gel, especially when the agar was prewashed with an EDTA solution. The product obtained has a low sulfur content and has very good electro-endosmotic properties.
Nonspecificity of Urinary Lead Measurements by Atomic Absorption Spectroscopy
Authors: Segal Robert J 
Published: January 2020

Abstract
Lead measurements by direct AAS at 217 nm on a pooled urine sample gave values of 57 µg/l by the method of standard additions. In contrast, dithizone procedures gave values of 15-20 µg/l. Studies demonstrated that various urine salts and organic compounds contributed to the absorbance at 217 nm. These native urine materials also give a similar absorbance value at 220 nm, a line not related to lead emitted by the lead hollow cathode tube. Thus, correction of the nonlead absorbance was possible by subtracting the A220 from A217. Utilizing this correction, the standard addition procedure gave values of 12 µg/l. The correction technic was also applied to the lead isolation-concentration technic of Kopito and Shwachman (3) which employs bismuth coprecipitation. The simplicity of operations, increased sensitivity and reproducibility obtained by coupling the AAS correction technic with bismuth coprecipitation recommends it as a method for serious consideration.
Serum Cholesterol Assay Using a Stable Liebermann-Burchard Reagent
Authors: Kim Edward , Goldberg Morris 
Published: January 2020

Abstract
A single stable Liebermann-Burchard reagent was prepared and studied for the rapid and accurate determination of total cholesterol in serum. The preparation, stability, and developed spectral character of the proposed reagent were assessed. Reproducibility, recovery, and interference studies on pure standard and patient sera were performed using the Abell-Kendall method as reference. The influence of water, protein, bilirubin, hemoglobin, and other serum constituents was evaluated.
A New Fluorometric Method for the Estimation or Detection of Total and Fractionated Alkaline Phosphatase
Authors: Johnson Roy B 
Published: January 2020

Abstract
A highly sensitive fluorometric method for the assay of total alkaline phosphatase and the detection of its components is described. The commercially available substrate naphthyl AS-MX phosphate, combined in 1 M 2-amino-2-methyl-1-propanol buffer, pH 9.8, is cleaved to the highly fluorescent naphthol AS-MX. Fluorometry requires filters passing 405 mµ primary and 505 mµ secondary. As little as 20 µl. of normal serum per 3 ml. of reaction mixture can be assayed. Alkaline phosphatase components, separated by vertical starch gel (or other methods of) electrophoresis, produce yellow fluorescence under ultraviolet light when incubated at 37° with the same buffer-substrate. After vertical starch gel electrophoresis, all normal serums exhibit at least one component (β-globulin region), but six distinct areas of activity have been located. These correspond to Taswell and Jeffers’ origin, beta-lipoprotein, alpha-2, alpha-beta, and beta (5). Few serums contain all of these; rather there appears to be a correlation between the ones present, their relative activity, and the disease state.
An Automated Fluorometric Procedure for the Enzymatic Determination of Ethanol in Fingertip Blood
Authors: Ellis Fred W , Hill John B 
Published: January 2020

Abstract
An automated fluorometric procedure, using AutoAnalyzer modules and based on the alcohol dehydrogenase reaction, has been developed for the determination of ethanol in fingertip capillary blood samples. Whole blood is measured directly from the finger prick into 0.02-ml. capacity automatic-filling disposable micropipets. The sample is quickly discharged into an AutoAnalyzer cup containing 1.0 ml. of water. This dilution can be placed on the sampler plate for immediate analysis or preserved under refrigeration for future use. The time required for sample flow from sampler to fluorometer cuvet (and recording of results) is 16 min. The coefficient of variation of replicate analyses is approximately 1%. Analyses of blood to which varying amounts of ethanol was added gave a mean recovery of 101%. As described, the method is designed to extend over the ethanol concentration range of 10-300 mg./100 ml. of whole blood. Analysis of undiluted blood or of weaker dilutions of blood samples would permit the accurate determination of as little ethanol in whole blood as 0.2 mg./100 ml. or as much as 600 mg./100 ml.
Altered Pathways of Urinary Corticosteroid Excretion in Liver Disease Studied by a Clinical Laboratory Method
Authors: Bacchus Habeeb 
Published: January 2020

Abstract
A method of sequential extraction of β-glucuronidase-hydrolyzed urine, which permits the assessment of alternative pathways of corticosteroid excretion, was employed to study urine samples from normal subjects and from patients with hepatic cirrhosis. In patients with hepatic cirrhosis there is a decrease in the excretion of methylene dichloride-soluble 17-hydroxycorticosteroids; this decrease is due to significantly lower levels of tetrahydrocortisone, with moderately low levels of tetrahydrocortisol. A significant increase was observed in the levels of 17-OH,20,21-glycols, confined mainly to cortols in the urine of patients with cirrhosis; a less marked increase in this fraction was also observed in patients with fatty metamorphosis of the liver. Urinary 17-ketosteroids were decreased in patients with hepatic cirrhosis. The intravenous infusion of adrenocorticotropin to normal subjects was followed by increased 17-hydroxycorticosteroids in all solvent fractions of the urine. In patients with hepatic cirrhosis similarly treated, there was no significant rise in the level of 17-hydroxycorticosteroids extracted with methylene dichloride, but significant increases in polar 17-hydroxycorticosteroids were found. The relative magnitudes of the alternate pathways of corticosteroid excretion were determined by calculation of the ratios of (1) total ketols to total glycols, (2) polar ketols to total glycols, and (3) less polar ketols to polar ketols; it was shown that in hepatic cirrhosis there are significant alterations in the excretory pathways of cortisol metabolites, with relative decreases in the excretion as tetrahydrocortisone and increases in the excretion as cortols. Based on these data it is clear that values of routine 17-hydroxycorticosteroid and 17-ketosteroid excretion should be evaluated carefully as to whether they represent abnormal adrenal function or alterations in the peripheral metabolism of cortisol. The method is sufficiently simple to be employed in the clinical laboratory.
The Use of the Allen Correction in the Quantitative Determination of Urinary Porphobilinogen
Authors: Loriaux L , Delena S , Brown H 
Published: January 2020

Abstract
The method of Mauzerall and Granick for the quantitative determination of urinary δ-aminolevulinic acid and porphobilinogen was found, in our hands, to give falsely elevated values for porphobilinogen. The use of the Allen correction appears to resolve this problem.
Filter Paper Blood Collection and Punching As A Means of Quantification
Authors: Hill John B , Palmer Phyllis 
Published: January 2020

Abstract
Filter paper has been tested as a medium for the collection of blood samples for the subsequent elution and analysis of phenylalanine, tyrosine, glucose, and urea nitrogen. The use of paper did not measurably alter the precision of the above methods.
The paper punch as a means of quantification has been compared with the more commonly used technic of volumetric measurement. The precision obtained with punched spots was found to be similar to that found with measured spots for the above four procedures and for weighed samples.
The hematocrit value was found to have an influence on the volume of blood contained in a punched spot. Differences in spreading through filter paper between 100 individual blood samples tested did not seem to be responsible for a variance in excess of that introduced by the analytic procedures themselves.
A Modified Orcinol Reaction for RNA Determination
Authors: Kamali Mohammad , Manhouri Hamid 
Published: January 2020

Abstract
The Schneider orcinol technic for pentose estimation was modified by replacing ferric chloride with cupric acetate in glacial acetic acid as catalyst, to make the test more sensitive and less DNA-reactive. In addition, data were obtained showing that human plasma contains no detectable nucleic acid by the spectrophotometric determinations applied.
Quantitative Comparative Immunohistology
Authors: Semar Martin , Treser Gerhard , Lange Kurt 
Published: January 2020

Abstract
A quantitative assay for the determination of fluorescence of tissue sections stained with fluorescein-labeled antibodies using a fluorometer is described. Sequential microtome sections were stained with labeled antiserums, washed repeatedly with buffered saline, and digested with 20% (w/v) NaOH at 60° for 12 hr. The fluorescence of the resultant solution is then read in a fluorometer. There is similarity between sequential sections of the same biopsy specimen. Specific blocking procedures reduce the readings of the fluorescence markedly. By comparison with values obtained simultaneously from standard curves of the labeled antiserums used, the amount of bound antibody or specific proteins can be determined quantitatively.
Measurement of Lead in Blood and Urine by Atomic Absorption Spectrophotometry
Authors: Farrelly R O , Pybus J 
Published: January 2020

Abstract
An extraction method for the estimation of lead in red cells is given. The method avoids both acid digestion and/or protein precipitation. It is extremely simple and reliable, and can easily be performed by technicians. A technical error of 4.5 v.g lead per 100 ml of red cells has been obtained. The use of red cells instead of whole blood provides a more accurate measure of exposure to lead as the lead is concen¬trated within the red cells. Normal and toxic ranges are given. As it is frequently required to monitor the lead excretion of patients receiving chelates for therapy, a method for the analysis of urine specimens from patients on this therapy is given.
Glucose Oxidase Method for Continuous Automated Blood Glucose Determination
Authors: Rosevear John W , Pfaff Kenneth J , Service Frederick J , Molnar George D , Ackerman Eugene 
Published: January 2020

Abstract
A glucose oxidase-peroxidase method for continuous automated monitoring of blood glucose has been developed. The response is linear over the range 0-800 mg/100 ml. Sensitivity can be maintained for 24 hr or longer and can be restored by rinsing the analytic system with sulfuric acid to permit studies of longer than 48 hr in duration. A precision of ± 1% can be maintained between rinses for samples containing 100-600 mg of glucose per 100 ml. This method is satisfactorily specific for glucose: The response with other sugars is less than 1% of the response obtained with the same concentration of glucose. Ascorbic acid causes no significant inhibition of the response to glucose. The inhibition by uric acid has been reduced fifty-fold compared to that in other methods. Transit through the sampling catheter and analytic system requires 15 min. Timed from the first detectable response to a change in concentration, 25% of total response is achieved in 30 sec and 90% in 80 sec. Fifty percent of an oscillation with a half-period of 45 sec can be detected; no oscillations this short were observed in records of human blood glucose. Applicability and feasibility of this method have been demonstrated in over 2000 hr of repeated blood glucose recordings in 12 diabetic and 6 normal subjects.
A Method for Measurement of Sodium and Potassium in Erythrocytes and Whole Blood
Authors: Bugyi Helen I , Magnier Eugene , Joseph William , Frank Gordon 
Published: January 2020

Abstract
The analysis of concentration of cations in erythrocytes and plasma, in theory, offers a means of identifying disease states in peripheral blood. Technical difficulties associated with cation analysis in erythrocytes and whole blood have resulted in a lack of precision and accuracy. This lack has increased the difficulties of using the analysis of blood in the diagnosis of disease. It is felt that the technic discussed in this paper with its increased precision, in combination with previously mentioned research in the diagnosis of disease, will increase the clinical significance of the analysis of red cells and whole blood for the diagnosis of disease states.
Measurement of Cholesterol in Tissues with Phospho-6-tungstic-12-molybdic Acid
Authors: Negrin A 
Published: January 2020

Abstract
A new spectrophotometric method for the determination of minute amounts of cholesterol in tissues is described. This method is a modification of the Yoshimatsu reaction which is based on the reduction of the yellow aqueous solution of phospho-6-tungstic-12-molybdic acid by a solution of cholesterol in concentrated sulfuric acid. The color of the resulting hydrosol of "molybdenum/tungsten blue" is particularly intense. The conditions for saponification confer virtual specificity for cholesterol. The proposed method is verified by comparison with estimates obtained by Abell’s procedure (9) as well as by the automated methodology of Block et al (8).
Practical Spectrophotometric Standards
Authors: Rand Royden N 
Published: January 2020

Abstract
The Subcommittee on Spectrophotometry of the Standards Committee of the American Association of Clinical Chemists presents a discussion of spectrophotometric standards for use in the routine clinical chemistry laboratory. Numerous surveys have demonstrated the need for regular checks to assure that instruments meet specifications, and that proper technics are employed. Methods for evaluation of linearity, sensitivity, wavelength calibration, stray light, and photometric accuracy are discussed, and the details for testing are given in the Appendix. Criteria of performance for wide-band-width colorimeters and spectrophotometers as well as the more elaborate spectrophotometers are presented.
A Rapid and Simple Thin-Layer Chromatographic Method for Amino Acids in Blood
Authors: Culley William J 
Published: January 2020

Abstract
Simple and rapid thin-layer chromatographic methods, using heel or finger-tip blood, are described that are suitable for screening for inborn errors of amino acid metabolism. Serum is chromatographed without deproteinizing. A variation of this method utilizes blood impregnated on paper discs for chromatography. These methods are much faster, more sensitive, and provide better resolution of amino acids than paper chromatography. Because untreated serum- or blood-impregnated discs are placed directly on thin-layer chromatograms, these methods require considerably less working time than other thin-layer chromatographic methods.
Micromethod for Total Serum Cholesterol that Eliminates Interference by High Bilirubin Concentrations
Authors: Jordan William J , Knoblock Edward C 
Published: January 2020

Abstract
The analysis of pediatric serum for total cholesterol in the presence of high amounts of bilirubin presents special problems. The serum specimens are so small that a direct micro- or ultramicromethod has to be used, and consequently the error owing to bilirubin is impressive. In the proposed method, cholesterol is precipitated, along with other serum lipids, from only 20 µliters of serum as a dextran sulfate—lipoprotein complex. The precipitate is dissolved in molar NaCl, treated with glacial acetic acid, and incubated for 5 min at 70°C. A ferric chloride—sulfuric acid reagent is then added and, after 20 min at room temperature, the color is read at 560 nm. Total cholesterol values obtained by the proposed method are not statistically different from those obtained by the direct method of Pearson et al. Bilirubin added to sera does not affect the results. Agreement was obtained with the stated cholesterol values for Versatol-A and Moni-trol II reference sera to which known amounts of cholesterol and bilirubin had been added by the manufacturer.
Silicic Acid Chromatography of Organic Acids in Blood Cells and Biological Fluids
Authors: Barness Lewis A , Morrow Grant , Nocho Robert E , Maresca Rita A 
Published: January 2020

Abstract
The separation of organic acids and their elution from silicic acid columns and their quantitative measurement by color change of buffered indicator, a technique mechanized by Kesner and Muntwyler, are applicable to the study of biological materials. As little as 25 µg of acid can be measured. Elution times and color yield in terms of peak areas obtained with the commercial apparatus are given for 25 organic acids. Blood, plasma, red cells, and spinal fluid have been analyzed; specimens were either untreated or extracted with ether. The most abundant acids detected were propionic, lactic, hippuric, and acetic. Methylmalonate was measured in body fluids and blood cells of patients with methylmalonic acidemia and pernicious anemia. Concentrations of organic acids in blood and spinal fluid are given.
Blood Volume Changes during Three-Week Residence at High Altitude
Authors: Myhre L G , Dill D B , Hall F G , Brown D K 
Published: January 2020

Abstract
Circulating red blood cell volumes were determined by the carbon monoxide method, and plasma volumes were calculated in four men 20, 29, 71, and 75 years old, and two women 29 years of age before, during, and after exposure to an altitude of 3800 m. In the four youngest subjects there were early increases in hemoglobin concentration during the first days at the stated altitude attributed to decreases in plasma volume. At the same time, hemoglobin concentration decreased and plasma volume increased in the oldest subject. Red cell volumes were slow to change, and it was concluded that 3 weeks or more of exposure to this altitude are required to affect significantly the red cell volume in man.
Use of a Computer Program to Correct for Sample Interaction: A Significant Adjunct to Continuous-Flow Analysis
Authors: Thiers Ralph E , Meyn Jute , Wildermann Robert F 
Published: January 2020

Abstract
A computer program has been developed to correct errors resulting from interaction in continuous-flow analysis. The correction applies to both the unknown samples and the standards of the calibration curve. A reiterative calculation is necessary that is practical only on a computer, but which accurately measures the interaction from the standards of the calibration curve, even though they are themselves rendered inaccurate by interaction. One extra standard is added to the conventional calibration curve. After correction, the calibration curve is independent of the order in which the standards were run. Because interaction is a principal factor limiting the speed of continuous-flow analysis, this program can be used to increase the rate of routine analysis. It has been added to the LABCOM system for use on the LINC-8 computer and has proved effective and valuable in practice
Comparison of Serum Lithium Determinations by Flame Photometry and Atomic Absorption Spectrophotometry
Authors: Levy Arthur L , Katz Eve M 
Published: January 2020

Abstract
Lithium determinations by flame photometry and atomic absorption spec-trophotometry are compared with respect to precision, sensitivity, and the effects of the presence of various concentrations of proteins and cations. Flame photometry gave results closely similar to those obtained by atomic absorption; under the conditions we used, it is more sensitive, slightly less precise, but easier to use. Varying the protein, Na, and K concentrations produces small but demonstrable effects, insignificant for clinical applica-tions. No protein effect was found with flame photometry, in contrast to atomic absorption spectrophotometry, for which protein standards are recommended. Sera from 65 patients receiving lithium therapy were an-alyzed on both instruments; no significant differences were found.
Urinary Excretion of Hydroxyproline after Fractures
Authors: Herzberg Mala , Oberman Z , Khermosh O , Weissman S L 
Published: January 2020

Abstract
Urinary excretion of hydroxyproline was measured in 12 cases of multiple fractures as an index of bone collagen metabolism. Measurements were made for 10 consecutive days after injury; 10 patients with low back pain served as the control group. With three exceptions, the mean daily excretion of hydroxyproline and the day-to-day variations were within the same range in the group with multiple fractures as in the control group.
Progesterone in Nonpregnancy Plasma: An Assay Method for the Clinical Chemistry Laboratory
Authors: Lurie Aron O , Patterson Richard J 
Published: January 2020

Abstract
A simple method for the assay of progesterone in nonpregnancy plasma was designed specifically for the clinical chemistry laboratory. One technician can readily perform 22 assays in less than one work day. Although no chromatographic step was used, the method was highly specific. Repro-ducibility studies indicated that the assay had a coefficient of variation of 7.5% for pregnancy plasma, 11.5% for nonpregnancy plasma. Clinical application of the method to specimens obtained from subjects during the normal menstrual cycle yielded values very similar to those obtained by more laborious and costly assay techniques.
Rapid Assay for Glycogen-Cycle Enzymes in Small Samples of Muscle
Authors: Russell J C , Tougas Diane , Taylor A W 
Published: January 2020

Abstract
A rapid assay is described for the glycogen-cycle enzymes glycogen synthetase and α-glucan phosphorylase (UDP glucose:glycogen α-4-glucosyltransferase, EC 2.4.1.11 and α-1,4-glucan: orthophosphate glucosyltransferase, EC 2.4.1.1) in muscle tissue. UDP glucose-14C and G-1-P-14C are used as substrates for reaction with muscle homogenates, and the rate of incorporation of labeled glucose into primer glycogen is measured. Muscle samples weighing 25 to 75 mg are suitable for assay. We found activities in rat gastrocnemius muscle of 0.37 ± 0.02 µmol of glucose per minute per gram of tissue for synthetase I, 2.84 ± 0.29 µmol per minute per gram of tissue for synthetase D, and 34.5 ± 2.8 µmol per minute per gram of tissue for phosphorylase b. Corresponding values for human muscle tissue for phosphorylase a and b were 12.6 and 10.6 µmol per minute per gram of tissue, and synthetase activity of 0.011 and 0.399 µmol per minute per gram of tissue.