bluuebunny/crossref_metadata_2025_split huggingface dataset:
Urinary Excretion of Folic Acid Activity in Man
Authors: Cooperman Jack M , Pesci-Bourel A , Luhby A Leonard 
Published: January 2020

Abstract
Urinary excretion of folic acid activity was studied in healthy adults and children before and after intravenous administration of 2.5, 5, 10, 20, 40, or 80 /1g of pteroylglutamic acid per kg of body weight. Activity was measured by three improved microbiological assays that use Lactobacillus casei, Streptococcus fecalis, or Pediococcus cerevisiae. Activity excreted under normal dietary conditions was about 1% of the dietary folate intake. Excre-tion of urinary folic acid activity was appreciably increased after admin-istration of 10 big or more of pteroylglutamic acid per kg body weight. At the latter doses, there was a linear relationship between L. casei and 8. fecalis assayable folic acid activity in urine and the administered dose. Less than 1% of the activity excreted after the above doses of pteroylglu-tamic acid was detectable by P. cerevisiae assay. More than 90% of the 24-h urinary excretion occurred within 6 h after each subject received pteroyl-glutamic acid. Intercomparison of the three assays showed that the urinary folic acid activity after intravenously administered pteroylglutamic acid was due to pteroylglutamic acid or a closely related derivative. The excre-tion by children and adults was proportionately the same
A Specific Colorimetric 5′-Nucleotidase Assay Utilizing the Berthelot Reaction
Authors: Belfield Alan , Ellis Graham , Goldberg David M 
Published: January 2020

Abstract
A sensitive calorimetric assay for 5′-nucleotidase activity is described, which requires 40 µl of serum. Adenosine, formed by hydrolysis of 5′-adenylic acid, is deaminated enzymatically and the ammonia determined with the Berthelot reaction. β-Glycerophosphate is added to suppress hydrolysis of 5′-adenylic acid by alkaline phosphatase. The reaction is optimal at pH 7.9 in 0.05M Michaelis' barbital buffer containing 10 mmoles of MgCl2 per liter. In the Berthelot reaction the MgCl2 causes a precipitate, which is removed without decreasing color yield by adding EDTA. Inhibition of the Berthelot reaction by serum and constituents of the reaction mixture is predictable and can be compensated by a correction factor
A New "Bilirubinometer"1 and Its Use in Estimating Total and Conjugated Bilirubin Serum
Authors: Jackson S H , Hernandez A H 
Published: January 2020

Abstract
The prototype "Bilirubinometer" previously reported by Jackson [Clin. Chem. 11, 1051 (1965)] has been modified for commercial production. A method for the determination of conjugated (direct-reacting) bilirubin with this instrument is described.
Phenotyping of Hyperlipoproteinemias
Authors: Winkelman James , Wybenga Donald R , Ibbott Frank A 
Published: January 2020

Abstract
The stability of serum specimens collected for cellulose acetate electrophoresis of lipoproteins has been studied for each of the hyperlipoproteinemia phenotypes. In general, samples kept at room temperature for three days are still suitable for analysis. On longer standing, artifacts can cause misinterpretation of strips, or render them completely unreadable. If specimens are stored at refrigerator or freezer temperatures, deterioration is retarded but the period of stability after they are returned to room temperature is unaltered. A second freeze-thaw cycle makes specimens unsuitable for analysis. Samples can be stored at refrigerator temperatures for at least 28 days and at freezer temperatures for at least 14 days if one freeze-thaw cycle is used.
Phenotyping of Lipemias by Ultrafiltration and Nephelometry of Serum Lipoproteins
Authors: Werner Mario , Montgomery Carolyn K , Jones Albert L , Nussenbaum Siegfried 
Published: January 2020

Abstract
Nephelometry of serum before and after ultrafiltration through cellulose membranes affords a simple and rapid physical method for separately estimating pre-β-lipoproteins and chylomicrons in their native state. The method was rigorously evaluated through correlative studies with chemical analyses, electron microscopy, and electrophoresis. Together, the data indicate that this technique, combined with the determination of cholesterol as an estimate of β-lipoprotein concentration, allows the phenotyping of hyperlipemias.
Miniature Photometers for Liquid Chromatography
Authors: Thacker L H , Pitt W Wilson , Katz S , Scott Charles D 
Published: January 2020

Abstract
A series of miniature photometers has been developed for use as on-stream detectors in systems for liquid chromatography. All of the detectors feature dual-beam, dual-wavelength operation without mechanical or electrical switching of either wavelength or signal. The two types of detectors originally developed—ultraviolet (254 and 280 nm) and colorimetric (any two choices of visible wavelengths)—have been integrated into a single modular instrument that can be converted from ultraviolet to use with visible wavelengths by substituting source and filter modules. Both straight-through vertical quartz tube flow cells of 3-mm i.d. and Z-cell modules with 10-mm light pathlengths are available. A single-unit power-source and rangeswitching box is used with any configuration of the detector.
Rapid Separation of the Components of Nucleic Acids and Urine by High-Resolution Liquid Chromatography
Authors: Burtis A C , Munk M N , MacDonald F R 
Published: January 2020

Abstract
The improved separations of nucleic acid components obtained with two recently developed liquid chromatography systems are presented. An ion-exchange system operating at 3000 lb/in.2, developed for use with pellicular ion-exchange resins, separates the 2',3'-ribonucleotides of the four common bases in 55 min, the 5'-deoxynucleotides in 10 min, a mixture of four dinucleotides in 30 min, and a mixture of AMP, ADP, and ATP in 3.5 min. The difficult separation of the mono-, di-, and triphosphates of the four nucleosides requires 2.5 h with the pellicular anion-exchange resin. The four bases, or their nucleosides, are separated in less than 15 min with pellicular cation-exchange resin. The system has been modified to allow separation of more than 90 uv-absorbing constituents in human urine. A versatile, nonpulsating system, operated at 5000 lb/in.2, separates the ribonucleosides in less than 5 min on small-particle, conventional cation-exchange resin. Resins from three separate sources performed comparably, but parameters such as pH, temperature, and linear velocity must be optimized for each. Both systems are designed with a minimum of dead volume and use a sensitive uv photometer. The 0.02 absorbance unit full-scale sensitivity and 1-cm pathlength of the uv photometer allow analysis of picomole quantities of nucleic acid components.
Lipids of Commercial Serum Products Offered as Controls or "Standards" for Cholesterol and Triglyceride Determinations
Authors: Witter R F , Kuchmak M , Williams J H , Whitner Virginia S , Winn Carole L 
Published: January 2020

Abstract
The cholesterol and triglyceride content of commercial control products (usually sera), purchased from six manufacturers, were measured. In addition, total fatty acid and qualitative neutral lipid composition of the total lipids were measured by gas—liquid and thin-layer chromatography, respectively. Cholesterol values we found by the Abell—Kendall method differed from the values given for six of the 12 assayed products by 6 to 37 mg/100 ml; triglyceride values, determined by a modified Carison procedure, differed from the means given for two of the four assayed products by 14 to 17 mg/100 ml. Neutral lipids present in total lipids in 13 of 15 lyophilized samples, and fatty acid composition of the latter in 12, closely resembled those of freshly drawn human serum, indicating that the lipids had not deteriorated grossly. The lipids of one lyophilized product from a bovine serum source included an appreciable amount of linolenic acid, which is not found in human serum; a second contained an unknown lipid-solvent material. Some decomposition of the lipids was noted in a filtered liquid sample. These results strongly support the use of commercial lyophilized preparations as control sera, but not as secondary serum standards.
A Discussion of the Linearity between the Measured Voltages of Ion-Selective Electrodes and the Ionic Concentrations in Whole Blood
Authors: Neff G W 
Published: January 2020

Abstract
The ion-sensitive electrodes used to measure Na+, K+, and Cl- in biological fluids have output voltages that are logarithmically related to ionic activity. This measured voltage also is linearly related to ionic concentration for the Na+ and Cl- electrodes. Furthermore, the K+ electrode, which must be corrected for its Na+ sensitivity in whole blood or plasma, exhibits a linear characteristic between measured voltage and K+ concentration in which the constants of the straight-line equation are each a linear function of the Na+ concentration. The linear relationships are discussed and fitted to data for pure electrolyte solutions, plasma, and whole blood.
Direct Potentiometric Determination of Potassium and Sodium in Blood, Plasma, and Serum
Authors: Miyada Don S , Inami Kazuko , Matsuyama George 
Published: January 2020

Abstract
A potentiometric analyzer, developed to directly measure potassium and sodium concentrations, was evaluated on aqueous solutions, whole blood, serum, and plasma. The analyzer consists of three electrodes—sodium, potassium, and reference—mounted in a flow-cell configuration, and a modified digital pH meter, which displays the ion concentrations directly. Volume of the cell is about 100 µl. The electrodes equilibrate to each new sample in less than a minute. Calibrated with aqueous standard solution, the system yields essentially the same values for whole blood and the corresponding plasma, and results agree with those obtained for the same samples of plasma by flame photometry.
The In Vitro Sensitivity of Erythrocyte Aggregation to Quinine: Assessment by a Serial Blood Sedimentation Procedure
Authors: Robbins R C , Harbin James E 
Published: January 2020

Abstract
A serial erythrocyte sedimentation procedure is based on maintaining blood in vitro in thermal (body temperature) and flow equilibrium, as changes in sedimentation rate are evaluated at 20-min intervals. Each measurement was made 1 h after the determination was begun. We thus confirmed in vitro the clinically observed effects of quinine on blood cell aggregation. A delayed effect of quinine on aggregation corresponded to in vivo observations that aggregation is first affected 3 to 12 h after the drug is administered. Quinine’s greatest effect (p &lt; 0.01) on erythrocyte sedimentation in vitro was at 200 min with 2 mg of quinine per 100 ml of blood, 220 min with 1 mg/100 ml, and 240 min with 0.5 mg/l00 ml.
Evaluation of the Microzone System for Simultaneous Electrophoresis of 16 Sera
Authors: Fingerhut Benjamin , Ortiz Antonia 
Published: January 2020

Abstract
We investigated the feasibility of using the "Microzone" electrophoresis system to produce 16 instead of eight electrophorograms on a single cellulose—acetate membrane by placing eight specimens at the left of center, rotating the cellulose—acetate membrane and supporting bridge 180° horizontally, and again applying eight samples to the left of center. The membrane, now with eight samples each on anodic and cathodic sides, is electrophoresed according to the usual recommended procedure. There was a statistically demonstrated association between sample application position and results (for 96 samples). This technique is nevertheless useful for determining albumin/globulin ratios and for screening large numbers of samples. Sera with borderline or abnormal results should be rerun by the usual technique.
Isolation of Urinary 17-Ketosteroid Conjugates by Ammonium Sulfate Precipitation
Authors: Pinkus Geraldine S , Pinkus Jack L 
Published: January 2020

Abstract
Ammonium sulfate precipitation of urinary 17-ketosteroid conjugates is a rapid, effective method for isolating and purifying them. Negligible quantities of pigment are produced during acid hydrolysis of solutions of the precipitated conjugates. Despite elimination of nonspecific chromogenic material, colorimetric determinations of Zimmerman chromogens with use of the Allen correction of absorbances [J. Clin. Endocrinol 10, 71 (1950)] gave comparable 17-ketosteroid values for solutions of the precipitate and for urines. Recoveries of urinary 17-hydroxysteroid conjugates were variable when the ammonium sulfate procedure was used.
Improved Method for Measurement of delta-Aminolevulinic Acid Dehydratase Activity of Human Erythrocytes
Authors: Burch Helen B , Siegel Abraham L 
Published: January 2020

Abstract
We have evaluated and modified a current method for estimating δ-aminolevulinic acid dehydratase (5-aminolaevulinate hydro-lyase, EC 4.2.1.24) activity in blood, so as to adequately control the pH of the enzyme-substrate solution at the optimum throughout the incubation period. This has improved the sensitivity and reliability of the assay. Also, N-ethylmaleimide has been substituted for a potentially hazardous mercury salt, used to remove sulfhydryl groups before color development with a modified Ehrlich’s reagent.
Hepatitis-Associated Antigen (HAA). II. A Survey of Antisera from Different Sources and Species
Authors: Boenisch Thomas , Katz Gerson 
Published: January 2020

Abstract
Thirty-two antisera against the hepatitis-associated antigen (HAA) were studied for titer and specificity. Titers were expressed in milligrams of the antigen precipitated by one milliliter of the antiserum. Specificity was investigated by Ouchterlony double diffusion against 40 HAA-positive sera and a serum pool consisting of about 200 HAA-positive specimens. Antiserum titers ranged from 0.04 mg/ml to 4.52 mg/ml. With some antisera, titers of 0.11 mg/ml or lower gave questionable or falsely negative results for specimens with high antigen concentrations, with use of counter-electrophoresis. By the classic criterion of spur formation in Ouchterlony double diffusion, antibody specificities were not different among the antisera studied. A relatively high number of falsely negative reactions was obtained with some antisera in double diffusion, which could not be explained by excess of either antigen or antibody. Several of our observations and those of others are cited to offer tentative explanations.
Rapid Solubility Test for Detection of Hemoglobin S
Authors: Matusik Jean E , Powell James B , Gregory David M 
Published: January 2020

Abstract
We have devised a rapid screening test for use in detecting sickling hemoglobins. This test depends on the insolubility of sickling hemoglobins in 2.24 molar phosphate buffer. Sickling hemoglobins form a turbid suspension in this test, in which positive and negative results, respectively, appear very much like those for the "Sickledex" test.
Evaluation of Pneumatic-Tube System for Delivery of Blood Specimens
Authors: Steige Harold , Jones James D 
Published: January 2020

Abstract
Blood specimens from normal individuals and patients (with and without blood dyscrasias) were sent through a 1,423-m pneumatic-tube system that included two monitoring devices, three switches, and 67 bends (62 with a 152-cm radius and 5 with a 76-cm radius), and then returned to the central laboratory. Each specimen was thus subjected to twice the trauma it usually would receive during transit. After transit, these specimens and duplicates kept in the laboratory were analyzed in the same manner for serum or plasma Na, K, Cl, CO2, Ca, Pi, LDH, urea, uric acid, glucose, creatinine, total protein, fibrinogen, hemoglobin, and bilirubin. Filling the tubes completely with blood and using a foam-rubber-Iined vinyl insert to hold the specimen tubes in the carrier decreased the differences attributable to transportation. Allowing the blood to clot before transport did not alter the results. Increases attributable to transport occurred only in hemoglobin, LDH, and K. Values were altered considerably less when the transported aliquot made only one leg of the trip via pneumatic tube. The alterations observed for the remaining analyses were within laboratory error. The pH of whole blood and the mean for PCO2 were not significantly altered, while the mean value for PO2, was increased 1.7 (0.5 to 4.5) mm Hg on transport.
Modified Manual or Automated o-Toluidine System for Determining Glucose in Serum, with an Improved Aqueous Reagent
Authors: Yee Hugh Y , Jenest Edward S , Bowles Fred R 
Published: January 2020

Abstract
A manual and automated method has been developed in which a new "aqueous" o-toluidine reagent is used that is compatible with standard tubing throughout the system. Citric acid, boric acid, and thiourea are incorporated, to increase absorbance readings. The sampling rate is 50/h, and the sample volume is 0.12 ml. Measurements may be made at either 630 or 385 nm.
Differentiation of Urinary N-Acetyl-p-Aminophenol from Endogenous Phenolic Compounds
Authors: Imashuku Shinsaku , LaBrosse Elwood H 
Published: January 2020

Abstract
An unknown spot, observed on two-dimensional paper chromatograms of extracts of human urine, was identified as N-acetyl-p-aminophenol (APAP), a drug metabolite. This finding suggests that APAP is clearly separable from other endogenous phenolic compounds in urine by a two-dimensional paper chromatographic method. This simple technique is feasible for the specific routine analysis of APAP in urine.
An Assay and Screening Procedure for Serum Glutamic Oxaloacetic Transaminase
Authors: Itoh Hajime , Srere Paul A 
Published: January 2020

Abstract
A clinical method for measuring serum GOT activity and its application as a screening test for GOT are described. Results for sera, compared by two popular methods, correlated well. This method may be suitable for routine use as a screening test in the blood bank.
Molecular Heterogeneity of Human Serum Cholinesterase
Authors: LaMotta Rudolph V , Woronick Charles L 
Published: January 2020

Abstract
The evidence is described that serum cholinesterases are a group of discrete isoenzymes, differing primarily in molecular size but also kinetically. A number of genetically determined variants have been described which probably differ by virtue of structural modifications. The clinical importance of the measurement of serum cholinesterase activity is discussed.
Simplified Measurement of Monoglycerides, Diglycerides, Triglycerides, and Free Fatty Acids in Biological Samples
Authors: Marzo A , Ghirardi P , Sardini D , Meroni G 
Published: January 2020

Abstract
A sensitive (5 to 100 µg) and reproducible (±3.54% SD) method is described for determining monoglycerides, diglycerides, triglycerides, and free fatty acids. After these lipid classes are separated from extracts of plasma or tissues by a single thin-layer chromatographic development, they are eluted into concentrated H2SO4 at 200°C. The resulting color is stable for more than six days.
Effects of Treatment on Tyrosine Tolerance in Thyroid Disease
Authors: Williams Trevor , Besser Gordon M 
Published: January 2020

Abstract
A widely used assay technique for plasma tyrosine determination has been found to give rise to large errors. It was modified to improve accuracy, and the relationship between the values derived by the modified and unmodified procedures was studied. The plasma tyrosine concentrations in thyrotoxic and hypothyroid patients during oral tyrosine loading are reported. Tyrosine tolerance in thyrotoxicosis reverts to normal after successful treatment. In hypothyroidism, most patients had normal tyrosine tolerance before and after treatment.
Normal Clinical Chemical Values for Pregnant Women at Term
Authors: Elliott Joseph R , O’Kell Richard T 
Published: January 2020

Abstract
Results for clinical chemical determinations on serum of 20 to 39-year-old pregnant women at term were compared (SMA 12/60) with those for nonpregnant women in the same age group. Sera from the pregnant group had higher mean uric acid and cholesterol concentrations; higher mean alkaline phosphatase, lactic dehydrogenase, and glutamic oxaloacetic transaminase activities; and lower mean glucose, urea nitrogen, protein, and albumin concentrations. All differences are significant (P &lt;0.001). Phosphorus and bilirubin concentrations did not differ significantly for the two groups. The increase in alkaline phosphatase activity in the pregnant group is evidently due to a heat-stable fraction, which does not correlate (at term) with number of weeks gestation, infant sex, infant weight, or placental weight. Forty women who had high concentrations of serum uric acid showed no signs of toxemia of pregnancy and delivered normal infants.
A Simplified Alkaline Phosphotungstate Assay for Uric Acid in Serum
Authors: Carroll James J , Coburn Holly , Douglass Roberta , Babson Arthur L 
Published: January 2020

Abstract
An alkaline phosphotungstate procedure was developed in which the phosphotungstic acid reagent is used both as protein-precipitating and oxidizing reagent. The procedure requires only a 0.2-ml sample and fewer reagents and manipulations than similar procedures, but yields results equivalent to those obtained by Henry’s alkaline phosphotungstate procedure. Recovery, precision, and linearity were good over a wide range of uric acid concentrations. Standardization was easy with use of aqueous albumin standards or of commercial calibration reference sera.
Comparison of Laboratory Test Results for Assessing Thyroid Function in Normal Subjects and Treated and Untreated Hyper- and Hypothyroid Patients
Authors: Lee Norman D , Catz Boris , Margolese M S , Pileggi Vincent J 
Published: January 2020

Abstract
Various indexes of thyroid status were measured in sera from normal men and women, normal women who were using oral contraceptives, hyper- and hypothyroid patients, and hypothyroid patients being successfully managed with various forms of replacement therapy. Total circulating thyroxine concentrations were measured by three methods as well as the thyroxine-binding capacity of the serum inter-alpha globulin, "free" thyroxine, and "free" thyroxine index. Our purpose was to compare the various measurements, and to assess their diagnostic usefulness. The most significant finding was that, of 197 hypothyroid patients, all of whom possessed total circulating thyroxine concentrations within normal limits, 28% showed subnormal "free" thyroxine concentrations.
Design of an Analog Converter for Use in Colorimetry
Authors: Lapidus Berton M , Tetrud James W , Karmen Arthur 
Published: January 2020

Abstract
A simple analog circuit, incorporating commercially available components, has been used to convert the output of a colorimeter photocell into units directly related to concentration. The converter is useful for analyses that obey Beer’s law approximately, with continuous-flow automatic analyzers or other colorimetric systems. The results obtained by analog conversion agree within 1% with the photocell output read out in the usual manner.
Determination of Serum and Urine Amylase with Use of Procion Brilliant Red M-2BS Amylopectin
Authors: Sax Sylvan M , Bridgwater Anna B , Moore John J 
Published: January 2020

Abstract
We describe a sensitive, precise assay of serum or urine amylase activity, with use of a new substrate, Procion Brilliant Red M-2BS—Amylopectin. After 0.2 ml of serum or urine is incubated with substrate for 10 min at 37°C, ethylene glycol monomethyl ether is added to precipitate proteins and larger substrate particles. Clarity and chromogenicity of the final solution are not sensitive to small changes in temperature or concentrations of the various reagents. No interferences necessitating preparation of specimen blanks have been encountered. Human salivary amylase, assayed by a reference saccharogenic method, is used for calibration. When read against the resulting curve, normal sera and urines give activities comparable to those obtained with the reference method. Human pancreatic extract, sera and urines from pancreatitis patients, and macroamylasemia serum show higher activities by the proposed method.