bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation of Erythrocytes of Different Ages
Authors: O'Connell Daniel J , Caruso Carmine J , Sass Martin D 
Published: January 2020

Abstract
Several methods have been evaluated for the separation of red cells of different ages on the basis of density differences. Simple sedimentation and flotation technics have been found to be unsatisfactory. Centrifugation, followed by a modified sampling procedure, has been demonstrated to provide excellent separation of erythrocyte populations of different ages. Standardization of centrifuge conditions and special precautions against redistribution of red-cell layers have contributed toward an improved and reproducible method for the separation of erythrocytes for subsequent study.
An Improved Automated Determination of Serum Total Cholesterol with a Single Color Reagent
Authors: Block Walter D , Jarrett K John , Levine Jacob B 
Published: January 2020

Abstract
An anhydrous color reagent containing ferric chloride is pumped through Tygon tubing to a glass coil in a 95° heating bath. Manually prepared serum extracts (1:20 isopropanol dilution) are presented to the stream of preheated color reagent, and the two are passed through three mixing coils, connected in series. The absorbance of the resultant color is determined at 550 mµ in a 15 mm. tubular flow-cell.
The improved N-automated procedure gave values of greater precision (5.6%) for total cholesterol determined in replicate samples from sera pools than the N-automated procedure which lacked precision (27.7%). The values found in 60 individual serums are within 6.0% of total cholesterol values determined by the Abell et al. method.
Phenolphthalein Monophosphate as a Substrate for Serum Alkaline Phosphatase
Authors: Wilkinson J H , Vodden Ann V 
Published: January 2020

Abstract
The procedure for serum alkaline phosphatase determination employing phenolphthalein monophosphate as substrate was evaluated under routine clinical laboratory conditions. A straight-line response to increasing serum concentration was observed, and the reaction was shown to be Mg++ dependent. The method proved to be extremely simple, and the results obtained correlated well with those given by a standard routine procedure involving determination of the liberated inorganic phosphate.
Concentration of Cerebrospinal Fluid Proteins and Their Fractionation by Cellulose Acetate Electrophoresis
Authors: Kaplan Alex , Johnstone Murray 
Published: January 2020

Abstract
Various technics for concentrating cerebrospinal fluid (CSF) prior to electrophoretic separation of the protein fractions were tested. Vacuum ultrafiltration through a collodion sac proved to be the most reliable and convenient method. The proteins in the concentrate were separated by cellulose acetate electrophoresis and quantitated densitometrically.
The mean values for the various protein fractions in normal CSF were the following: 4.9% pre-albumin, 61.5% albumin, 4.5% α1 globulin, 6.7% α2 globulin, 13.7% β globulin, and 8.8% γ globulin.
Specificity of the Free Fatty Acid Titration by the Method of Dole, Modified According to Trout
Authors: Parijs J , Barbier F , Elewaut A 
Published: January 2020

Abstract
The specificity of free fatty acid (FFA) titration is significantly enhanced when the modification of Trout (5) is used and the heptane extract washed with dilute sulfuric acid. Lactate, pyruvate, acetate, β-hydroxybutyrate, α-ketoglutarate, citrate, and urate, in concentrations found in normal human plasma, will not interfere with the titration. It can be expected that in some exceptional pathologic conditions, lactate, pyruvate, acetate, β-hydroxybutyrate, and urate will not be completely removed from the heptane extract. Salicylate seems to cause considerable interference. Trout's procedure substantially reduces the interference caused by phospholipids.
Automated Determination of Acid Phosphatase
Authors: Klein Bernard , Oklander Morris , Morgenstern Stanley 
Published: January 2020

Abstract
A procedure is presented for the automated determination of acid phosphatase activity in biological materials using the Robot Chemist. Although either phenylphosphate and α-naphthylphosphate may be used as substrate in this analysis, the procedure is described in detail for serum acid phosphatase using α-naphthylphosphate in 0.1 M citrate, pH 5.2, since this substrate is more selective for prostatic acid phosphatase in human serum. Enzymically generated aα- naphthol is determined by the Emerson reaction (alkaline aminoantipyrine and ferricyanide), modified for use with this automated system. Correlations are presented between the results obtained on the Robot Chemist and the identical procedure developed for the AutoAnalyzer.
Elimination of False Negative Results with the FPN Forrest Test for Phenothiazine Derivatives in Urine
Authors: Forrest Irene S , Forrest Fred M , Kanter Saul L 
Published: January 2020

Abstract
With the FPN Forrest test for urinary phenothiazine derivatives, omission of drug intake was found to be the most frequent cause of negative color reactions; accordingly, these negative reactions are true negatives. Excessive dilution of urine specimens occasionally yielded "apparent false negatives" by producing traces of drug metabolites, which cannot be detected without modification of the test. When measures to eliminate these conditions are taken, the previously specified reading time (10 sec. after mixing urine and reagent) is reliable. Unspecific color development due to reaction between endogenous urinary constituents and reagent appeared with a delay of 30 sec. or more, and hence recent recommendations of delaying reading times for the test were found to be unsuitable and productive of false positives.
The Automated Determination of Acetoacetate in Serum and Urine
Authors: Klein Bernard , Oklander Morris 
Published: January 2020

Abstract
A procedure based on the Rothera reaction is presented for the automated determination of acetoacetate in serum and urine. The mean serum acetoacetate concentration determined by this procedure for normal human subjects is 0.20 mM; S.D. is 0.059 mM. Recovery experiments demonstrate excellent reliability. The interferences are identified and their effects evaluated.
Comparison of Serum Magnesium Values by Photometric, Fluorometric, Atomic Absorption, and Flame Emission Methods
Authors: Pruden Elizabeth L , Meier Rebecca , Plaut David 
Published: January 2020

Abstract
Magnesium was determined on aliquots of the same serum by atomic absorption and flame emission spectrophotometry, by Titan Yellow and Magon photometry, and by 8-hydroxy-quinoline and 8-hydroxy-quinoline-sulfonate fluorometry. Comparison is presented of reproducibility of results by the various methods and of the normal values obtained.
Determination of Copper and Zinc in Biological Material
Authors: Parker Mary M , Humoller Fred L , Mahler Delmar J 
Published: January 2020

Abstract
Copper and zinc are readily determined in biological material by atomic absorption spectrophotometry. Two procedures are presented for the quantitative estimation of these metals in serum. One of these involves simple dilution and aspiration into the burner of the instrument. Suitably prepared standards must be used. The other method involves trichloroacetic acid preparation of the proteins prior to aspiration. With both methods satisfactory results in precision and recovery of added metals are obtained. Urinary copper determinations require chelation of the metal with ammonium pyrrolidino dithiocarbamate or some similar sequestering agent and concentration by extraction of the chelate into a suitable organic solvent. A similar procedure must be used in analyzing cow's milk for copper. Tissue analysis requires heating with boiling nitric acid and removal of the acid under reduced pressure prior to aspiration into the burner. It has been shown that procedural errors in such determinations are very much smaller than biological variation.
A Modified Copper Method for the Estimation of α-Amino Nitrogen in Urine
Authors: Clayton C C , Steele Betty F 
Published: January 2020

Abstract
The copper method of Pope and Stevens (1) for estimation of α-amino N has been modified by a change in buffer and the use of tetraethylenepentamine as a color intensifier, giving a good colorimetric assay. α-Amino N was measured successfully in concentrations of 0.2-2.8 mg./10 ml. Interference due to ammonia has been minimized, and interference due to certain other materials has been determined with suggestions for its elimination. The modified procedure offers the advantages of simplicity and speed in obtaining an approximate determination of α-amino N in urine.
Hemiglobin Sodium Nitrite vs. Hemiglobin Potassium Ferricyanide
Authors: Theil George B , Auer James E 
Published: January 2020

Abstract
A number of different spectrophotometric patterns have been described for methemoglobin (hemiglobin). These appear to be a function of the oxidizing agent employed. Only the 630-nm peak is common to hemiglobin formed by the addition of sodium nitrite or potassium ferricyanide to oxyhemoglobin.
Microestimation of Fibrinogen with a Semimicro Modification Applicable to Icteric Plasma
Authors: Goodwin Jesse F 
Published: January 2020

Abstract
The sulfite precipitation technic for fibrinogen has been modified to assay micro-volumes of plasma and eliminate interference from bilirubin. The precipitated fibrinogen is dissolved in urea and reacted with a modified biuret reagent. The resulting biuret complex may be read at 320 or 540 mµ. Bilirubin interference is eliminated by an oxidation step employing NaOCl and citric acid. The values obtained by the modified technics compare favorably with each other and with the macroprocedure.
Spectrophotometric Measurements of Serum Nickel
Authors: Sunderman F William 
Published: January 2020

Abstract
An ultraviolet spectrophotometric procedure has been developed for the measurement of serum nickel. Samples of serum are lyophilized and the dry residues are subjected to acid digestion. Nickel is separated from interfering elements by chloroform extraction of nickel dimethylglyoximate at alkaline pH. Nickel is converted to the diethyldithiocarbamate complex and is extracted with isoamyl alcohol. The absorbance of nickel bisdiethyldithiocarbamate is measured as the difference between the absorbance maximum (325 mµ) and the absorbances at 2 background wave lengths (295 and 355 mµ). The concentrations and volumes of the reagents have been adjusted in order to achieve a sensitivity of 0.002 ppm (2 µg/L.). The recovery of 2.5 µg. of nickel added to 8 samples of serum averaged 104% (S.D. ± 8), with a range from 91 to 115%. The mean concentration of nickel in serum from 23 normal subjects was 2.2 µg/100 ml. (S.D. ± 1.8), with a range from 0.1 to 7.7 µg/100 ml. The median concentration of serum nickel was 1.7 µg/100 ml.
Determination of Glutamic Oxalacetic Transaminase Activity by Coupling of Oxalacetate with Diazonium Salts
Authors: Sax Sylvan M , Moore John J 
Published: January 2020

Abstract
A method for measuring serum glutamic oxalacetic transaminase activity is described, in which substrate concentrations are more nearly optimal than in previous colorimetric methods. By coupling the diazonium salt at a pH of 4.2, interference from α-oxoglutarate is negligible. Oxalacetate is produced at a linear rate to 180 I.U. Results correlate well with those obtained by a reference spectrophotometric method.
Determination of Unconjugated and Total N-Acetyl-p-aminophenol (NAPA) in Urine and Serum
Authors: Heirwegh Karel P M , Fevery Johan 
Published: January 2020

Abstract
A sensitive and accurate method is described for the determination of N-acetyl-p-aminophenol (NAPA) and its metabolites in urine and serum. In strongly acidic medium, p-aminophenol (PAP) resulting from differential extraction and acid hydrolysis of total NAPA and unconjugated NAPA, is diazotized and the diazonium salt coupled with N-(1-naphthyl)ethylenediamine (NED) in the presence of ethanol. The blue azo dye formed is determined spectrophotometrically. Application to liver disease is briefly reported.
Automated Method for the Determination of Serum Creatine Kinase Activity
Authors: Fleisher Gerard A 
Published: January 2020

Abstract
An automated (AutoAnalyzer) method for the colorimetric determination of creatine kinase activity in serum is described. This method includes reactivation of creatine kinase with cysteine, incubation of the active enzyme with creatine phosphate and adenosine diphosphate at 37.5°, and subsequent inactivation of enzyme and binding of cysteine by phenylmercuric borate. The enzymatically produced creatine is dialyzed against a solution of diacetyl and reacted with α-naphthol in an alkaline solution. The absorbance of the colored end product is measured at 550 mµ. Individual blanks are determined in the absence of adenosine diphosphate. Comparison of results obtained by this method and a manual procedure shows satisfactory agreement.
Porphyrin Patterns in Different Types of Porphyria
Authors: Chu T C , Chu Edith Ju-Hwa 
Published: January 2020

Abstract
Porphyrins from 38 cases of different types of porphyria were separated chromatographically and analyzed. Patients with different types of porphyria eliminated porphyrins with different patterns. Simple paper chromatography of the methyl ester of the total porphyrin of a urine sample revealed a chromatographic pattern of the porphyrins characteristic of the type of porphyria. The relative abundance of the heptacarboxylic and uroporphyrins in a sample also differentiated porphyria cutanea tarda from acute intermittent or congenital porphyria. The isomer compositions of the porphyrins were also disclosed. While one type of isomer might dominate one type of porphyria, the magnitude of predominance was by no means unanimous, or even reversed, among the porphyrins from uro- through the intermediates to coproporphyrins. For example, in cutanea tarda, Type I isomer dominates uro- and pentacarboxylic porphyrins, and Type Ill isomer dominates the hepta-, hexa- and coproporphyrins. The complexity of the enzymatic reaction involved in the decarboxylation of the porphyrins is thus indicated.
Kinetic Parameters of Continuous Flow Analysis
Authors: Thiers R E , Cole R R , Kirsch W J 
Published: January 2020

Abstract
Unlike systems of batch analysis, continuous flow systems possess kinetic parameters. Associated with the steady state are such measurements as noise level and drift. This study reports on kinetic parameters associated with the transient state between the steady states including time required to change from base-line steady state to sample steady state and vice versa, characteristics of this change, time interval between samples, proportionality of sampling and washing time, fraction of steady state reached in any given sampling time, and interaction between samples. The transition between steady states has been found to obey first order kinetics to a good first approximation. This observation enables correlation of all of the above listed properties in quantitative fashion using new characteristic constants for continuous flow-the half-wash time (W1/2) and the lag phase time (L). These parameters, well known in other contexts such as radioactivity, can be employed as "figures of merit" for any continuous flow system or component, can be utilized to calculate performance characteristics, and are useful in evaluating and optimizing over-all performance.
Method for the Determination of Acetylsalicylic Acid in the Blood
Authors: Routh J I , Shane N A , Arredondo E G , Paul W D 
Published: January 2020

Abstract
The shift in the UV spectral absorption curves of acetylsalicylic acid (ASA) and salicylic acid (SA) produced by a change in pH has been used in the development of a method for the quantitation of these compounds. The differential spectral absorption curve of ASA exhibits a maximum at 300 mµ, while that of SA shows a maximum at 319 mµ and an isosbestic point at 300 mµ. The method is simple and specific for ASA and capable of determining the concentration of the ASA and SA in the blood after the ingestion of 10 gr. of aspirin.
Comparison Between p-Nitrophenyl Glucuronide and Phenolphthalein Glucuronide as Substrates in the Assay of β-Glucuronidase
Authors: Szasz Gabor 
Published: January 2020

Abstract
The p-nitrophenyl glucuronide method for the determination of β-glucuronidase activity is compared with the phenolphthalein glucuronide method in a variety of diseases. It is shown that linear correlation exists between the two methods. The presence of isoenzymes, which would hydrolyze the substrates at different rates, is therefore excluded. The reaction conditions for the phenolphthalein glucuronide method are investigated and improved upon. Normal values for both methods in milliunits per milliliter are presented. The advantages of the p-nitrophenyl glucuronide method are indicated.
Fluorometric Determination of Zinc in Biologic Fluids
Authors: Mahanand D , Houck J C 
Published: January 2020

Abstract
The 8-quinolinol complexes of zinc at pH 8.0 (in universal buffer) are stabilized by gum arabic and demonstrate a marked fluorescence at 517 mµ when excited at 375 mµ. Under these conditions only zinc—not magnesium or calcium at physiologic concentrations—can be determined in plasma and urine. Adult plasma has 94 ± 7 µg. zinc per 100 ml. while the plasma of children contains 108 ± 15g./100 ml.
The Colorimetric Estimation of Plasma Amino Nitrogen with DNFB
Authors: Goodwin Jesse F 
Published: January 2020

Abstract
A simple procedure for the estimation of plasma amino nitrogen based on the reaction of amino groups with 2,4-dinitrofluorobenzene (DNFB) and subsequent measurement of the dinitrophenyl (DNP) amino derivatives at 420 mµ is presented. Elevated concentrations of bilirubin, hemoglobin, and the major nonprotein and nonamino acid nitrogen components of plasma do not seriously interfere. The proposed procedure compares favorably with a corresponding ninhydrin technic for plasma amino nitrogen. The mean plasma amino nitrogen values and range for a group of adults (age 18-50 years) by the proposed method is 5.56 mg./100 ml. (3.6-7.0 mg./100 ml.) compared to 4.12 mg./100 ml. (3.6-5.2 mg./100 ml.) for a group of children (age 2-10 years). Values from a group of children with sickle cell anemia showed no significant variance with the normal population. Optimum conditions for quantitation of plasma amino nitrogen along with other procedural parameters are presented.
One-Dimensional Paper Chromatographic Method for Determination of Urinary Homovanillic Acid
Authors: Duke Phillip S , Demopoulos Harry B 
Published: January 2020

Abstract
A one-dimensional paper chromatographic method is presented for determination of urinary homovanillic acid. The method is faster and gives higher values than does two-dimensional chromatography. Urinary homovanillic acid values are given for patients with metastatic malignant melanoma and for presumed normals. Homovanillic acid level was elevated in the case of amelanotic melanoma. Determinations of urinary homovanillic acid may be a valuable adjunct to the therapy and study of metastatic malignant melanoma.
Systematic Screening for Abnormal Urinary Constituents
Authors: Young D S 
Published: January 2020

Abstract
A scheme is described for the systematic screening for amino acids and sugars in urine. High-voltage electrophoresis is used to separate amino acids, and thin-layer chromatography is used for sugar separation. In each case the separated constituents are stained and scanned in a densitometer, and a profile is constructed for comparison against normal profiles.
Determination of Glutethimide (Doriden) and Its Metabolites in Biologic Specimens
Authors: Sunshine Irving , Maes Robert , Faracci Rosalie 
Published: January 2020

Abstract
A gas chromatographic method for the quantitative determination of glutethimide was developed. This method was applied to samples obtained from patients who were comatose because of acute glutethimide intoxication. The results obtained from this procedure were compared with those obtained by using an ultraviolet method. The patients’ clinical conditions were assessed and correlated with the blood concentrations of glutethimide. The samples were processed to isolate glutethimide, as well as its metabolites. The metabolites were separated using thin-layer chromatography and were checked for purity by both thin-layer and gas chromatography.
Stability of δ-Aminolevulinic Acid and Porphobilinogen in Urine Under Varying Conditions
Authors: Bossenmaier Irene , Cardinal Ruth 
Published: January 2020

Abstract
A study was made on the stability of δ-aminolevulinic acid and porphobilinogen in urine. Data are presented showing that both substances can be preserved in the same sample by adjusting the pH to 6-7 and storing at -20° for periods up to 1 month, or at 4° for periods up to 2 weeks. As previously shown (1), these conditions are also satisfactory for preservation of coproporphyrin.
A Rapid Electrochemical Technic for Measuring Carbon Dioxide Content of Blood
Authors: Reyes Robert J , Neville J Ryan 
Published: January 2020

Abstract
An electrochemical technic for measuring carbon dioxide (CO2) content in whole blood has been devised and evaluated. The method requires a membrane-covered pH electrode for the CO2 measurements. This electrode system permits rapid determination of CO2 content in blood samples of less than 1 ml. The measurement is performed by hemolyzing and acidifying a blood sample in such a manner that the released CO2 goes into physical solution. The increase of tension caused by this physically dissolved CO2 is measured by exposing the sample to a previously calibrated electrode. While use of the technic requires some compromise with accuracy (standard deviation of replicate samples = 0.76 volume/100 ml. compared with 0.12 volume/100 ml. for the Van Slyke manometric procedure), its convenience may outweigh this consideration in certain routine applications.
Removal of Inorganic Iodide in the Automated Serum Protein-Bound Iodine Determination
Authors: Ahuja Jagan N , Kaplan Alex , Van Dreal Paul 
Published: January 2020

Abstract
Values for serum protein-bound iodine (PBI) concentration obtained by the AutoAnalyzer method are too high because of the failure of the batch (Technicon) process to completely remove inorganic iodide. The Technicon method removes about 98% of the inorganic iodide; this incomplete adsorption of inorganic iodide would give falsely elevated PBI values in serums with high iodide concentrations.
A rapid, economical method for removing serum inorganic iodide to the extent of 99.8% by a single pass of serum through a small column packed with an anion-exchange resin is described. Using Dowex-1 x 8, 20-50 mesh, 2 ml. of serum is filtered in 30 sec. directly into an AutoAnalyzer sample cup. Filtration through the column eliminates all possibility of clogging the sample probe with either resin beads or serum clots. The column method requires a little less serum than the batch process.
Determination of N-Acetyl-p-Aminophenol in Plasma
Authors: Routh J I , Shane N A , Arredondo E G , Paul W D 
Published: January 2020

Abstract
Two methods for the determination of N-acetyl-p-aminophenol (APAP) in plasma that differ in principle from the diazotization procedure of Brodie and Axelrod (1) are described. One method based on the differential absorption peak of APAP at 266 mµ, which corresponds to the isosbestic point of common drugs such as acetylsalicylic and salicylic acids, is simple and most specific for APAP. The other method employs a free-radical dye diphenylpicrylhydrazyl which extracts a hydrogen atom from the APAP molecule and is progressively decolorized. The dye method is the least complex and most sensitive. All three methods exhibited satisfactory replication, recovery of added APAP, and comparable plasma levels of the drug.