bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simplified Method for Plasma Zinc Determination by Atomic Absorption Spectrophotometry
Authors: Hackley Betty M , Smith James C , Halsted James A
Published: January 2020

A modified method is described for zinc determination in plasma by atomic absorption spectrophotometry using the Boling three-slot burner. Accurate analysis for the element was accomplished after merely diluting the plasma with deionized water (1 part plasma to 1 part water). Sample preparation time was thus greatly decreased. It was found that standards made up in water resulted in an error of 33%. However, standards prepared in 3% dextran solution gave results similar to those obtained with trichloracetic acid filtrates and water standards. Dextran was found not to be contaminated with zinc. The recovery of zinc added to plasma averaged 98.9%. Because of the simplicity of the method, sources of error and possibilities for contamination were reduced.
Acrylamide Gel Electrophoresis of Serum Proteins in Infancy and Pregnancy
Authors: Man Evelyn B , Whitehead Raymond J
Published: January 2020

Newborns have lower concentrations of certain serum protein fractions than do those children at age 1-2 years, and significant increases in estrogen-sensitive protein fractions are recognized in pregnancy. The acrylamide-gel vertical-slab electrophoretic technic requires minimal aliquots of serum and technically is not expensive. This technic appeared potentially useful in longitudinal comparisons of increasing protein fractions during infancy and as a screening test for absence of the normal gestational increases in estrogen-sensitive protein fractions in the α1-to α2-globulin zone.
An Automated Method for the Determination of Estrogens in Pregnancy
Authors: Ua Conaill D , Muir G G
Published: January 2020

Ittrich’s method for the determination of total estrogens in urine (1) was adapted for automation on the AutoAnalyzer, using a continuous digester module for the combined operation of phase exchange and color development.

The automated method gave good recovery and reproducibility, and correlated well with the manual method. It increased the capacity of this laboratory for estrogen determinations, improved the turnover rate, and reduced the labor involved to a minimum.
Regulation of Plasma Creatinine Concentration by Use of a Servo Control System
Authors: Harvey Rodney B , Bassingthwaighte James B , Heppner Richard L
Published: January 2020

A method for controlling the plasma creatinine concentration is described. This method uses continuous determination of the plasma creatinine concentration and a servomechanism which drives an infusion pump at a rate proportional to the difference between the actual and desired creatinine concentrations. The rate and volume of creatinine infusion necessary to maintain the desired plasma concentration provide information related to kidney function and the accumulation of creatinine in the body. Experiments using this technic and the method of data analysis are described. It has been shown that under certain conditions this technic may be used to estimate the renal clearance of creatinine and the size and nature of the space into which creatinine is distributed in the dog.
Method for Fully Automated Determination of Total Cholesterol in Blood Serum, Including Saponification and Extraction
Authors: van der Honing J , Saarloos C C , Stip J
Published: January 2020

A fully automated method has been developed for the determination of total cholesterol in blood serum, using the AutoAnalyzer system. According to the new method, based on the cholesterol determination of Abell et al. (1), the serum sample is saponified and subsequently extracted with carbon tetrachloride. After treatment with Liebermann-Burchard reagent, the amount of cholesterol is determined at 630 nm.

The method can be used for free and esterified cholesterol because saponification is carried out. The relationship between the new method and that of Abell et al. is linear. The correlation coefficient is 0.98 and the standard error 1.5%. According to the new method, 30 samples can be analyzed per hour.
Analysis of Pleural Effusions from Rats Exposed to High Concentrations of Oxygen
Authors: Robinson F R , Thomas A A , Rendon Leandro
Published: January 2020

Pleural effusions from rats exposed to high concentrations of oxygen for periods of up to 96 hr. were analyzed by routine clinical chemical methods. When compared to control rat serum, the values for glutamic oxalacetic transaminase, the albumin/ globulin ratio, potassium, and inorganic phosphate were higher in the pleural effusions. Alkaline phosphatase, total protein, albumin, and calcium values were higher in the control serum than in the pleural effusions, and there were no significant differences between the two fluids in the levels of lactate dehydrogenase and glutamic pyruvic transaminase.
Serum Amylases, Isoenzymes, and Pancreatitis I. Effect of Substrate Variation
Authors: Meites Samuel , Rogols Saul
Published: January 2020

Four plant starches were used to study human amylase activity in normal serum and urine, "pancreatitis" serum, duodenal fluid (secretin stimulated), saliva, and pancreatic extract. The starches were derived from waxy maize, high amylose corn, potato, and corn (pearl), and were lintnerized. It was shown that the rate of digestion of starch by each of the fluids tested depends on the plant starch selected as substrate. Digestion of waxy maize was most rapid. The advantages of using waxy maize as a substrate are indicated as a means of markedly enhancing the sensitivity of serum amylase determination. It was also found that normal serum, urine, and saliva digested potato starch at a greater rate than corn starch with few exceptions, while pancreatitis serum, secretin-stimulated duodenal fluid, and pancreatic extract digested corn starch at a greater rate than potato. These findings suggest that organ-specific amylases exist, and that plant starches might be used to distinguish them.
An Improved Procedure for the Determination of Serum Ethanol by Gas Chromatography
Authors: Savory John , Sunderman F William , Roszel Norris O , Mushak Paul
Published: January 2020

A modification of the gas chromatographic procedure of Natelson and Stellate has been developed which enables analyses of serum ethanol to be performed with increased sensitivity, precision, and convenience. Serum (50 µl.) is dehydrated by injection onto anhydrous copper sulfate in a stoppered tube at 80° in a water-jacketed rotary mixing apparatus. After 2 min., ethanol vapor is swept by a stream of helium into a gas chromatographic column packed with a mixture of Flexol 8N8, diisodecylphthalate, propyleneglycol 600, and firebrick C-22. Ethanol emerges from the column after a mean retention time of 6.7 min. and is measured by a hydrogen-flame ionization detector. The coefficient of variation of replicate analyses is 2.0%. The recovery of ethanol added to serum is 98.7 ± 3.8%. The limit of sensitivity for the detection of ethanol in serum is 0.1 mg./100 ml., and assay can be made in the presence of constituents which are normally present in serum, and volatile compounds which are commonly encountered in clinical toxicology. Analyses of serum ethanol by gas chromatography provide close correlations with measurements by the alcohol dehydrogenase reaction.
Redefinition of the Normal Range for Serum Sodium
Authors: Payne R B , Levell M J
Published: January 2020

The serum sodium concentrations of three groups of patients selected from laboratory records and of one group of outpatients selected for a prospective study were examined. The mean serum sodium concentration of inpatients with normal serum urea concentrations was 8.5 mEq./ L. lower than that of a group of healthy normal subjects. Part of this difference (2.6 mEq./L.) could be attributed to a nonspecific effect of illness. It was not possible to demonstrate any effect due to the hospital environment, but the results do not exclude the possibility of such an effect. It was concluded that all or most of the remaining difference was due to weighting of the inpatient data by low values of pathologic significance; the proportion of these low values was too great to allow a normal range to be extracted from the data by statistical methods.

The concept of the normal range is discussed. It is suggested that two ranges are required for serum sodium, a normal range (137-147 mEq./L. in this laboratory) to make assertions about alterations in specific diseases, and a range derived from patients likely to have no manifest disturbances of salt and water metabolism (135-144 mEq./ L.) to detect such disturbances.
Blood-Clotting Enzymology
Authors: Seegers Walter H , McCoy Lowell , Marciniak Ewa
Published: January 2020

During the past quarter century perhaps no single phenomenon has attracted so much attention in biology and medicine as blood clotting. It plays a role in numerous clinical conditions where it was not taken into account previously. Knowledge of the basic mechanisms recently passed through a tumulous stage of growth, but is now delineated in terms of simple enzymology. Most of the components have been obtained in purified form. There are three main events: the formation of autoprothrombin C (F-Xa, thrombokinase), the formation of thrombin, and the formation of fibrin. Prothrombin itself is a more marvelous protein than was predicted. It is a protein aggregate that contains the precursor of thrombin, the precursor of autoprothrombin C, as well as accessory protein. When blood coagulation is initiated by tissue injury, large amounts of autoprothrombin C activity arise in the presence of calcium ions and tissue thromboplastin. When there is no tissue injury, small amounts of autoprothrombin C are produced by platelet cofactor I (F-VIII, AHF) which functions with the lipids of platelets. Autoprothrombin C is the enzyme which produces thrombin activity, and being a part of the prothrombin aggregate it is in close proximity to the specific bond(s) that must be split to get thrombin activity. Although autoprothrombin C alone is sufficient to produce thrombin, the reaction is greatly accelerated by plasma Ac-globulin (F-V), lipids from platelets, and calcium ions. The acceleration produced by components functioning in pairs and relays makes possible the essential integration with the anatomic location of resources. Tissue materials pair with plasma resources to produce autoprothrombin C, and then they pair with another plasma component (Ac-globulin) to make autoprothrombin C function. In the absence of tissue injury, platelet materials pair with plasma resources to produce autoprothrombin C, and then platelets again work with another plasma component (Ac-globulin) to support the function of autoprothrombin C. Platelets are essential because their lipids are needed for the formation of autoprothrombin C, as well as for accelerating its function. Whatever involves platelets can be the stimulus to accelerate blood clotting; this includes Hageman factor. Platelets are the true point of beginning for the first step in blood clotting and are involved in the second and third. Vitamin K deficiency, or counteraction of Vitamin K by Dicumarol reduces prothrombin synthesis by the liver. As a consequence the precursor of thrombin, the precursor of autoprothrombin C, and the accessory protein of the molecular aggregate which constitutes prothrombin is reduced in concentration. It has been found possible to produce abnormal conditinos experimentally and have relatively more of the precursor of thrombin released to the blood than is normally associated with the precursor of autoprothrombin C. Up to the point of incorporation to form a single prothrombin molecule, the synthesis of subunits proceeds by separately operating mechanisms.
Estimation of Creatinine by the Jaffe Reaction
Authors: Husdan Harry , Rapoport Abraham
Published: January 2020

Total chromogen, true, and AutoAnalyzer methods of measuring serum and urine creatinine by the Jaffe reaction were investigated. Some factors influencing this reaction were examined. These included wavelength, blank, linearity, and conditions of color development. Modifications of the three methods were made and their precision, recovery, and sample stability determined. The interference of ketones and glucose were measured. Finally, the values obtained by the three methods on the same samples of serum and urine were compared statistically.
Premature Infants: Analysis of Serum During the First Seven Weeks
Authors: Thomas Jack L , Reichelderfer Thomas E
Published: January 2020

Serum values were determined on 60 premature infants whose birth weights ranged from 1500 to 1750 gm. At 1 week of age each infant was placed into one of six categories and given a feeding schedule according to a predetermined formula sequence and arrangement. Three formulas varying in mineral, caloric, and protein concentrations were used. Analyses for sodium, potassium, chloride, carbon dioxide, phosphorus, total protein, albumin, calcium, and urea nitrogen were carried out on blood drawn at 1, 3, 5, and 7 weeks of age. A comparison of levels during the same age period among the experimental groups was made.
Identification of Urinary Constituents Isolated by Anion-Exchange Chromatography
Authors: Burtis C A , Warren K S
Published: January 2020

High-pressure, anion exchange chromatography of urine has resolved more than 100 UV-absorbing urinary constituents. Three methods have been used to identify these constituents: (1) chromatographic properties of standards, (2) spectrometric analysis of isolated urinary constituents, and (3) chemical testing of the isolated urinary constituents.
Determination of Urinary Constituents in Solutions by Least-Squares Resolution of Ultraviolet Spectrums
Authors: Davis W , Schonfeld E , Kibbey A H
Published: January 2020

Least-squares resolution of ultraviolet (UV) spectrums has been tested as a method for determining the concentration of each UV-absorbing urinary component in a multicomponent solution. The tests reported here involved solutions containing 4-12 components chosen from 17 reference materials: p-aminobenzoic, anthranilic, ascorbic, ferulic, hippuric, p-hydroxybenzoic, uric, vanillic, and xanthurenic acids, and adenine, creatinine, cytosine, ergothioneine, hypoxanthine, indican, N-methylnicotinamide, and tryptophan. Spectrums of these reference and multicomponent solutions were measured from 1900 to 4000 Â, rather than over the more usual range of 2200 to 4000 Â; concentrations of individual components in unbuffered water solutions were in the range 0.4-100 mg./L. While the maximum number of solutes capable of being analyzed by this method cannot be given, this brief study shows that as many as 10 UV-absorbing urinary components could be determined quantitatively by least-squares resolution of the spectrum of the solution. All of the 17 species used in this study showed absorption in the region 1900-2200 Â; measurements in this region contributed greatly to the accuracy with which concentrations could be calculated.
Formaldehyde-Forming Drugs and Urinary 17-Hydroxycorticosteroids
Authors: Braverman Lewis E , Reinstein Harold , Loayza Humberto , Pomfret David
Published: January 2020

An apparent elevation of urinary 17-hydroxycorticosteroids may be found in the urine of patients receiving the formaldehyde-forming drug Mandelamine (methenamine mandelate), when the assay procedure depends on the formation of colored compounds with phenylhydrazine as determined at 1 wavelength (410 mµ). This false elevation may be eliminated by reading absorption at 3 wavelengths and using the Allen correction. However, the determination of 17-ketogenic steroids is not influenced by the presence of formaldehyde in the urine. Administration of Mandelamine or other formaldehyde-forming drugs should be stopped prior to the collection of urine in order to eliminate a potential source of error in determining 17-hydroxycorticosteroid excretion.
Detection of Human Inborn Errors of Metabolism by Examination of Urinary Metabolites
Authors: Seegmiller J Edwin
Published: January 2020

An increasing number of recessively inherited human diseases are being explained in terms of a missing or defective enzyme. The resulting aberration of metabolism is reflected, in many cases, in an altered composition of metabolites in the urine and other body fluids. Progress in this field is dependent on making the initial association between a familial disease and an aberration of body chemistry. The development of comprehensive analytic systems for the detection of abnormal quantities or kinds of metabolites in biologic fluids obtained from patients with inherited diseases should greatly facilitate this process. Biochemical characterization, at an enzyme level, then becomes possible and is essential for improved diagnosis and rational approaches to treatment of the disease.
The Coulometric Determination of Glucose in Human Serum
Authors: Simon Robert K , Christian Gary D , Purdy William C
Published: January 2020

The coulometric titration method is combined with the use of an enzymatic analytic reagent for the determination of glucose in human serum. The glucose in 25 µl. of serum is determined in a protein-free filtrate (PFF) with an accuracy of ± 3% and a coefficient of variation of approximately 2%. The procedure routinely covers a concentration range of 25-250 mg/100 ml. Calibrations are linear to at least 450 mg./100 ml. with zero intercept. Glucose oxidase specifically catalyzes the aerobic oxidation of glucose to hydrogen peroxide. The peroxide reacts with iodide, in the presence of molybdenum (VI) catalyst, to form iodine. A known excess of thiosulfate reduces the iodine as it is produced. The reagents and the sample are incubated at 25.0° and pH 5.1. After 15 min., the pH is adjusted to 8.0 with phosphate reagent to stop the enzymatic reaction. The residual thiosulfate is titrated coulometrically with iodine at pH 8.0 to a dead-stop end point at a generating current of 0.4825 ma. The difference between the sample and thiosulfate reagent titers is proportional to the glucose concentration. The method is empirical. Peroxide-reducing impurities in the glucose oxidase preparation and mutarotation equilibrium prevent the complete recovery of glucose under the conditions of the experiment. Calibrations are reproducible from day to day and week to week. Reagents and the PFF constitute a negligible titration blank. Only 1 calculation is necessary. A simplified apparatus and procedure for the preparation of PFF’s permits 15 manual determinations per hour. Coulometric assays of commercial serum controls are accurate to within 3-4%. Data indicate that the precision of the coulometric method exceeds that of the Auto-Analyzer, Folin-Wu, Glucostat, and Nelson-Somogyi procedures. The proposed method is free from interferences at normal serum levels.
SYMPOSIUM ON URINARY CONSTITUENTS OF LOW MOLECULAR WEIGHT Session III
Authors: Bush Ian E
Published: January 2020

A summary of the strategy and progress in devising a general system of biochemical analysis based on the direct photometry, or "scanning" of thin-media chromatograms is presented. Recent results suggest that the method is as precise and as accurate as other types of quantitative chromatography. It is capable of reasonably easy adoption by workers previously unfamiliar with the basic technic and apparatus. It has been subjected to more rigorous quality control by blind and double-blind trials concurrent with ordinary routine work than is usual, and has passed these tests adequately. Data processing by a small, relatively inexpensive digital computer is capable of handling the data produced by the central apparatus of the method. The sensitivity of newer instruments using well-established fluorescence reactions compares very favorably with that of flame-ionization detectors in gas-liquid chromatography but not with the electron-capture detector as yet.
Manual Fluorometric Paper Disc Method for Determining Tyrosine in Blood
Authors: Searle Bernard G , Li Miyako , Briggs Jamalabo , Segall Paul , Widelock Daniel , Davidow Bernard
Published: January 2020

A spectrophotofluorometric method is described for the determination of tyrosine in blood dried on filter paper discs. It has been found that by immersing the paper disc containing the dried blood in aqueous trichloracetic acid, the blood proteins remain bound to the paper and the amino acid is eluted into the aqueous phase. This method of assay is based on the principle that tyrosine reacts with α-nitroso-β-naphthol to form a highly fluorescent product.
Determination of Uric Acid An Automated Phosphotungstate Method Using NaOH as the Alkali
Authors: Wheat James L
Published: January 2020

An automated method is described for the determination of serum uric acid using sodium hydroxide alone as the alkalinizing agent in the uric acid-phosphotungstate reaction. Turbidity is not a problem and antiturbidity reagents are not needed. At the rate of 40 samples per hour, there is good sensitivity and good correlation with a manual urea-cyanide method. Quality control shows a standard deviation of ± 0.1 mg./100 ml.
Ionic Activities of Sodium, Potassium, and Chloride in Human Serum
Authors: Dahms Harold , Rock Robert , Seligson David
Published: January 2020

Ionic activities of sodium, potassium, and chloride in serums of 26 hospitalized patients were determined with ion-specific electrodes. Comparison of the activities with the corresponding concentrations shows that the two most important parameters influencing the molar activity coefficients of these ions are the water content of serum and the binding between albumin and chloride. Quantitative expressions for activity-concentration conversion factors are given. Calculations show that the conversion factors vary significantly in disease states due to changes in protein.
Acid Hydrolases in Plasma in Gaucher’s Disease
Authors: Ockerman P A , Kohlin P
Published: January 2020

Acid hydrolytic enzymes were measured in plasma from 6 patients with Gaucher’s disease. Markedly increased values were found not only for acid phosphatase, as expected, but also for β-acetylglucosaminidase and β-glucuronidase. The activity of β-galactosidase and α-fucosidase was slightly increased, and that of α-mannosidase was normal.
A New and Rapid Determination of Pyridinium Aldoximes in Blood and Urine
Authors: Groff William A , Ellin Robert I
Published: January 2020

A rapid and accurate method for analyzing pyridinium oximes—N-methylpyridinium-2-aldoxime chloride, N,N'-trimethylene-(pyridinium-4-aldoxime) dihalide, and N,N'-oxydimethyl-(pyridinium-4-aldoxime) dichloride—in plasma, urine, and whole blood is described. The method is completely automated and requires small sample volumes. Concentrations ranging from 3 to 120 µEq./L. in biologic fluids can be determined at a rate of 40 samples per hour. This technic can be applied to oximes which are unstable in basic solution. The average variation of the oxime concentration used to establish calibration curves, as determined by the ratio of the standard deviation to the mean, was ± 1.5%. Plasma and albumin increase the transfer rate of the oximes through the dialyzing membrane. Theoretical concentrations to explain this phenomenon are presented.
Bilirubin and the Polarographic Brdicka Reaction
Authors: Puranen Jouni
Published: January 2020

Bilirubin added to serum suppresses the protein double wave of the polarographic Brdicka reaction. This effect might be due to the blocking of the -SH groups of albumin by bilirubin.
Application of a Continuous Spectrophotometric Assay for 5'Nucleotidase Activity in Normal Subjects and Patients with Liver and Bone Disease
Authors: Belfield Alan , Goldberg David M
Published: January 2020

Serum 5'nucleotidase activity has been measured by a coupled kinetic assay in which adenosine formed by hydrolysis of adenosine 5'-monophosphate in the presence of 150-fold excess of β-glycerophosphate is converted to inosine by adenosine deaminase, with a consequent decrease in absorbance at 265 nm. The method gives activity in proportion to enzyme concentration so long as the rate of decrease of absorbance at 265 nm does not exceed 0.025/min, and not more than 30% of the substrate is consumed. The normal range established in 517 healthy adults was 0-15 mU/ml. A significant correlation between enzyme activity and age was found in females but not in males. Raised levels of 5'nucleotidase activity were found in 92% of patients with obstructive jaundice, 70% of patients with parenchymal liver disease, 81% of patients with hepatic metastases, and 11% of patients with bone disease. The estimation is useful in aiding the elucidation of raised serum alkaline phosphatase activity, and is of value as a liver function test, but is not as frequently increased as alkaline phosphatase in all classes of hepatobiliary disease.
A Simplified Fluorometric Method for Determination of Plasma Methotrexate
Authors: Chakrabarti Siba G , Bernstein I A
Published: January 2020

A method is described for the determination of plasma methotrexate at low concentrations. The method consists of a single fluorescence measurement on plasma proteinfree filtrates after oxidation of the drug with KMnO4 at controlled pH. The complete release of the drug into plasma filtrates is accomplished by heating the reaction mixture in a boiling water bath with occasional stirring.
An Automated Method for Serum Calcium Utilizing Ethylene Diamine Tetraacetic Acid
Authors: Burr Robert G
Published: January 2020

An improved method of estimating serum calcium by the AutoAnalyzer using the reagent glyoxal-bis-(2-hydroxyanil) is described. Sensitivity and accuracy in the physiological range are increased by the use of ethylene diamine tetraacetic acid. Results correlate well with an established manual procedure and there is no interference from magnesium or phosphate.
A Summation Technic for Serum Total Lipids
Authors: Cheek Chandler S , Wease Dorothy F
Published: January 2020

An efficient summation technic for the quantitation of total lipid from the results of the cholesterol, phospholipid, and triglycerides determinations is compared to the phenol turbidity and gravimetric method. Also considered is the total lipid value calculated from the cholesterol and triglyceride concentrations.
An Improved Automatic Technic for the In-Vitro Assessment of Thyroid Status
Authors: Webber C E , Johnstone J H , Garnett E S
Published: January 2020

The correlation between the direct assessment of 125I-triiodothyronine binding and the PBI level is given after using an improved automatic procedure for 125l-T3.
Derivatographic Thermal Analysis of Renal Tract Calculi
Authors: Strates B , Georgacopoulou C
Published: January 2020

Attention is drawn to the possibility of using the technic of thermal derivatography for structure and main constituent analysis of biologic concretions, with special reference to renal tract calculi.
Studies on Manganese
Authors: Mahoney John P , Sargent Kathleen , Greland Margaret , Small Walter
Published: January 2020

Atomic absorption spectrophotometry offers a method applicable to the determination of serum manganese in clinical research. The signal-to-noise ratio is great enough to yield precise data even with 10X scale expansion. The method has the required sensitivity for the measurement of the concentrations encountered in human serum, even though the signals produced are very small. It requires a few manipulative steps, and the possibility of contamination is kept to a minimum. Interference from other materials usually present in the matrix does not present a problem.

The mean manganese concentration in the serum of normal fasting human subjects was 2.4 ± 0.7 µg/100 ml without any variation between the sexes. The concentration in the same individual does not vary over long periods of time. Initial observations do not indicate diurnal variation.

Large quantities of manganese administered to two normal individuals for 3 and 8 weeks, respectively, did not produce a detectable change in the serum manganese concentrations.

Studies are underway to adapt the method to the determination of manganese in blood cells and other tissues.
Fluorometric Determination of Histidine
Authors: Ambrose John A , Crimm Allan , Burton Joe , Paullin Kathleen , Ross Charlotte
Published: January 2020

An accurate and precise fluorometric procedure was developed for the determination of histidine based on the observation that o-phthalaldehyde forms a fluorophor with the analogous compound, histamine. The precision of the method was improved, and the fluorophor was stabilized for days by the addition of a phosphoric acid reagent.
A New Method for Serum Iron and Total Iron-Binding Capacity by Atomic Absorption Spectrophotometry
Authors: Olson Arthur D , Hamlin W B
Published: January 2020

A new, atomic absorption spectrophotometric method for serum iron and iron-binding capacity is described, which utilizes 20% (w/v) TCA plus heating at 90° for 15 min. This procedure liberates the ferric iron; precipitates the protein, facilitating removal by centrifugation; and avoids significant interferences by contaminating hemoglobin iron. The method is highly specific, accurate, and has the additional feature of requiring less time than most colorimetric or atomic absorption methods employing chelation and extraction.
Automated Fluorometric Determination of Glucose-6-Phosphate Dehydrogenase (G6PD) and 6-Phosphogluconate Dehydrogenase (6PGD) Activities in Red Blood Cells
Authors: Tan I K , Whitehead T P
Published: January 2020

An automated fluorometric microtechnic, suitable for screening purposes, has been developed for the quantitative determination of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) levels in red blood cells. The method is rapid, simple, and precise. It uses 50 µl whole-blood (capillary) samples and is based on the measurement of natural fluorescence emitted by the NADPH generated during the enzymatic reactions.
Evaluation of a New System for the Kinetic Measurement of Serum Glutamic Oxalacetic Transaminase
Authors: Winsten Seymour , Wilkinson J Henry , Boutwell Joseph H
Published: January 2020

A new spectrophotometric method for the determination of serum glutamic oxalacetic transaminase§ (SGOT) is described which uses standardized technics and prepackaged reagents. A study was made of this new method in three laboratories and was compared with the routine methods, using identical serum specimens. The new procedure gave good reproducibility and precision. In all methods studied there was evidence of failure of linearity of response at the two highest activity levels examined.
Specific Binding Radioassay of Serum Thyroxine
Authors: Nobel Sidney , Barnhart Fay
Published: January 2020

Adaptation of the Murphy and Jachan method for serum thyroxine for routine use in a clinical chemistry laboratory is described. Details in the original paper have been amplified, and operations such as mixing, resin addition, and temperature control modified in the direction of greater precision and simplicity. A comparison study was made of the performance of the method in our laboratory with the reported performance in the laboratory of the original authors. In agreement with Murphy and coworkers and Cassidy et al, it was found that conditions could be established whereby the method was both reproducible and capable of yielding significant diagnostic information in the presence of iodinated radiographic compounds.
Effect of Bilirubin and Lipemia on an Automated Method for Serum Cholesterol
Authors: Moline Carolyn , Barron Edward J
Published: January 2020

A simple automated procedure for total serum cholesterol, employing a stable Liebermann-Burchard reagent, was tested. The method has good precision, and results agree well with extraction methods for total cholesterol on normal serums. Serum samples with elevated bilirubin levels gave cholesterol values which were too high and which could not always be corrected for. Lipemic serums in some instances gave results which were too low when compared to other methods.
A Simple and Sensitive Method for the Measurement of Deoxycytidylate Deaminase Activity
Authors: Ressler Newton
Published: January 2020

A method for the assay of deCMP deaminasef based upon the measurement of ammonia formation by means of the Berthelot reaction is described. Saturating con-centrations of substrate are used. The activity is linear with time for several hours, and with enzyme concentration. Composition of the incubation medium, repro-ducibility, and enzyme stability are studied. The method is reasonably simple to perform, reproducible, and sensitive. Values obtained with some normal tissues and serum are presented, and the possible significance of measurable activity in human serum is discussed.
Automatic Discrete Sample Processing: Automation in a Clinical Chemistry Laboratory Based on Discrete Sample Handling and Computerized Data Processing
Authors: Westlake George , McKay Donald K , Surh Philip , Seligson David
Published: January 2020

It is our belief that a general-purpose digital computer that receives and processes the electrical signal from an analytic instrument to its final step, and then processes the latter to produce a patient report, is an essential tool of the clinical laboratory. The present report concerns the development of a discrete-sample-handling analytic instrument that was designed to interface with a computer. A description is given of the entire system that includes the interface, multiplexing, sample identification, and operational characteristics of the instrument. Some advantages of discrete sample handling in analytic chemistry are accuracy, speed, ease of adaptation to computers, use of small amounts of sample, stepwise analysis of analytic method, and ease of trouble-shooting.
Quantification of Protein Solutions with Trinitrobenzenesulfonic Acid
Authors: Goodwin Jesse F , Choi Siu-Ying
Published: January 2020

Trinitrobenzenesulfonic acid (TNBS) may be used for quantifying dilute solutions of protein. The trinitrophenyl protein—sulfite complexes resulting from reaction of TNBS with protein in the presence of sulfite are highly colored and exhibit maximum spectral absorbance at 420 nm. The TNBS protein—sulfite complex is formed by a simple two-stage condensation and complexation reaction. Protein in concentrations as low as 20 µg may be detected by the reaction. The method devised for protein quantification compares favorably with an ultraviolet spectrophotometric method and the conventional biuret procedure. Bilirubin and hemoglobin interference with the TNBS method is negligible. The procedure is useful for measuring total protein and globulin in serum and cerebrospinal fluid and also for measuring minor serum protein components. Procedural parameters and factors affecting the measurement of protein by the TNBS—sulfite reaction are presented.
Chemical Basis of the Carbamidodiacetyl Micromethod for Estimation of Urea, Citrulline, and Carbamyl Derivatives
Authors: Veniamin Michael P , Vakirtzi-Lemonias Catherine
Published: January 2020

The chemical pathway of the carbamidodiacetyl colorimetric assay was investigated. The experimental variables that were studied include reaction temperature, heating time, and the ratio of the mineral acid mixture to the reactants. Evidence is presented establishing the involvement of either 7- or 8-methyl, or 7,8-dimethyltetrahydroimidazo(4,5-d)imidazole-2,5-diones as chromogens, all three being equally acceptable.
New Chromogenic Substrate for Determination of Serum Amylase Activity
Authors: Klein Bernard , Foreman James A , Searcy Ronald L
Published: January 2020

A rapid assay for serum amylase activity has been developed based on the use of a new chromogenic substrate—Cibachron Blue—amylose. The procedure requires 0.1 ml of serum and measures the production of soluble chromogen, the formation of which is linear with enzyme activity. Normal human serum has a mean amylase activity of 118 ± 37 (SD) mg dye/100 ml/15 min or, in international units, 78 ± 24 (SD) µg dye/min/ml. Excellent correlation was observed with a saccharometric amylase procedure.
Amino Acid Composition of Serum Albumin in Normal Individuals And in Patients with Rheumatoid Arthritis
Authors: Denko Charles W , Purser D Barrie , Johnson Ralph M
Published: January 2020

A modern automated technique has been used to re-evaluate the older standard classic methods for studying the amino acid composition of human albumin. Previous published data have been derived from pooled samples that included persons of unknown clinical status. In this study normal values were determined for albumin derived from healthy volunteers and purified by electrophoresis on polyacrylamide gel. Patients with rheumatoid arthritis were similarly evaluated. No differences attributable to age were found. Albumin from women contained 20% more threonine than did albumin from men. Patients with rheumatoid arthritis had more phenylalanine and less lysine in their albumin than did normal persons. No such differences in composition of structural proteins have been previously demonstrated. It is unlikely that the substitution of one amino acid for another in molecules of this size could arise by chance during protein synthesis.
Optimization of Radioimmunoassay for Human Growth Hormone by the Charcoal-Dextran Technique
Authors: Meek Joseph C , Stoskopf Mary M , Bolinger Robert E
Published: January 2020

The effect of serum on the radioimmunoassay for human growth hormone was tested by use of the double-antibody technique and the charcoal-coated dextran technique. With the double-antibody technique, serum effects a falsely high reading for unknowns, while with the charcoal-dextran technique it causes falsely low values to be obtained. Part of the anomaly with the charcoal-dextran technique is the result of adsorption of small molecular fragments of radiolabeled hormone onto serum proteins of higher molecular weight. These fragments can be eliminated by frequent repurification of the labeled hormone. Another part is not related to purity of the label but is corrected by subtracting values for serum blanks that contain no antibody. The use of antiserum to human growth hormone prepared in the goat is more sensitive than that prepared in the guinea pig.
An Artifact in the Analysis of Oxygenated Blood for Its Low Carbon Monoxide Content
Authors: Lee Rodkey F , Collison Harold A
Published: January 2020

A sensitive gas chromatographic method for blood CO determination was used to analyze samples of reduced and oxygenated blood having identical low CO content. Oxygenated blood always released more CO than did the reduced samples when neutral ferricyanide was used as oxidant. Several reagents for CO release from blood were applied to both oxygenated and reduced samples. CO release by K3Fe(CN)6 from oxygen-free blood or COHb solutions was complete and constant from pH 1.5 to 6. Values of extra CO released from oxygenated samples varied from 0.003 vol % at pH 1.5 to over 0.015 vol % at pH 6. The least amounts of excess CO were produced between pH 2 and 4.5. Neutral K2Cr2O7 causes less excess CO formation than does K3Fe(CN)6, but the rate of reaction with COHb is low. Neutral KMnO4 and acid K2Cr2O7 cause extreme formation of excess CO from blood in amounts many times the amount of COHb present. Acid KIO3 effectively releases CO from COHb solutions and reduced blood, but causes more excess CO formation from oxygenated blood than K3Fe(CN)6. When CO is released in citric acid with K3Fe(CN)6 at a pH of about 3.5, the CO released from oxygenated blood is only about 0.001 vol % greater than that released from reduced samples. These differences indicate formation of small amounts of CO during reactions used to release CO from blood. Reduced hemoglobin and carboxyhemoglobin appear to be much more stable to these procedures than is oxyhemoglobin.
Quantitative Determination of Chlorpromazine Metabolites in Urine
Authors: Turner William J , Turano Patricia A , March James E
Published: January 2020

A simple, rapid, precise, and accurate method is described for the simultaneous and quantitative determination of conjugated and unconjugated chlorpromazine metabolites in urine. It depends on reduction of sulfoxides to sulfides, and oxidation of sulfides to ion radicals in a solution of Fe+3 (10-3N) in 18N H2SO4. Absorbance is measured at 422, 530, 565, and 700 nm, and concentration of metabolites is calculated by substituting values obtained in appropriate equations. Our data for urines (from schizophrenic men chronically medicated with chlorpromazine) generally agree with those of other workers.
Thin-Layer Chromatography of Urinary Carbohydrates
Authors: Young D S , Jackson Agathe J
Published: January 2020

Ten procedures for thin-layer chromatography of carbohydrates in urine were compared. The procedures differ considerably in their sensitivity and ability to separate sugars of clinical importance. A procedure was developed that permitted several sugars to be identified in normal urine samples without prior desalting or concentration. Celite was used as adsorbent, anisaldehyde as location reagent. The procedure is simple and reproducible, and is readily modifed for quantification of sugars by thin-layer densitometry.
Biological and Analytic Components of Variation in Long-Term Studies of Serum Constituents in Normal Subjects
Authors: Cotlove Ernest , Harris Eugene K , Williams George Z
Published: January 2020

Biological components of variation for each of 15 serum constituents have been estimated in 68 normal subjects by weekly measurements over several months, and concurrent measurements on invariant human serum pools. Intra-individual coefficient of variation was smallest, less than 2%, for Na, Cl, Ca, Mg; 3 to 4% for CO2, albumin, and total protein; 5 to 7% for K, glucose, cholesterol, and phosphate; and largest, 9 to 12%, for uric acid, urea nitrogen, SGOT, and LDH. Inter-individual variation was larger than intra-individual variation for all 15 tests except Cl, CO2, and K. Analytic deviation was as large as or larger than biological (intra- or inter-individual) variability for constituents, such as calcium, which are under precise homeostatic control, thus producing artifactual widening in the observed normal range and obscuring the borderline between normal and abnormal results. Limits of tolerable variability in laboratory procedures are proposed, based on composite intra- and inter-individual variation, that would permit medically significant deviations in results to be detected. Such limits were exceeded by current methodology in at least half the 15 tests.
Measurement of Total Calcium in Serum by Atomic Absorption Spectrophotometry, with Use of a Strontium Internal Reference
Authors: Pybus John , Feldman Fredric J , Bowers George N
Published: January 2020

A method for total calcium in serum was optimized, a dual double-beam atomic absorption spectrophotometer being used, with strontium as an internal reference. The effect of HCl and lanthanum concentrations on the signals of both calcium and strontium was determined. The final analysis was unaffected by known sources of interference in serum at a 50-fold dilution of serum in 50 mmolar HCl containing 10 mmol LaCl3 and 0.12 mmol of SrCl2 per liter. Within-run precision for 30 replicate analyses performed during 30 min gave a relative standard deviation (RSD) of 0.36% for the internal strontium reference mode vs. 0.72% RSD for the single-channel mode. Nine consecutive multiconcentration control pools were measured repeatedly for two years; the median RSD was 2.3%. With meticulous technique, long-term variability for total calcium in serum approached 1%. Accuracy is believed to be limited only by the precision, since systematic bias was not detected from recovery studies and comparisons with results of ashing procedures or oxalate precipitation techniques.
Direct Potentiometric Measurement of Potassium in Blood Serum with Liquid Ion-Exchange Electrode
Authors: Wise W M , Kurey M J , Baum G
Published: January 2020

A new liquid ion-exchange electrode is described which has a selectivity for K+ over Na+ of 93:1 in 0.1 mol/kg solutions. Its response is Nernstian in the range 5 x 10-4 to 5 x 10-1 mol KCl per kg. The dip-type electrode responds to small changes in K+ in mixed salt solutions containing the same quantities of KCl and NaCl as human blood serum. A miniaturized form of the electrode was adapted to a capillary flow-through system for blood sera. It gives results for K+ in the normal range that agree with flame photometric values without correction for Na+ in the concentrations normally present. The effect of pH on the K+ response and the response of the electrode to Mg++, Ca++, NH4+, Rb+, and Cs+ are also illustrated.
Quantitation of Plasma Testosterone by Improved Competitive Protein-Binding Technique
Authors: Demetriou J A , Austin F G
Published: January 2020

A method is described for quantitation of testosterone in plasma from females and males. The principal operations of extraction, chromatographic fractionation, and competitive protein-binding assay can be completed for eight duplicate samples in a single day. Experimental data used in the development of the test and the rationale for the specific operations and conditions are presented. The specificity of the method was established by comparing plasma testosterone concentrations determined by the double isotope derivative technique. Concentrations are reported for normal female and male subjects, and for patients with hirsutism, adrenal hyperplasia, Klinefelter’s syndrome, and other endocrine conditions.
Determination of Free Thyroxine in Serum by Low-Temperature Equilibrium Dialysis
Authors: Fang Victor S , Selenkow Herbert A
Published: January 2020

Equilibrium dialysis of thyroxine (T4) in diluted serum at low temperature gives consistent and reproducible values for the dialyzable fraction (DF) of this hormone. The quantity of serum required for the determination is minimized by dilution, which is technically advantageous. Variations caused by temperature, dialysis time, dilution of serum, buffer system, and stability of 125I-T4 could be controlled by parallel use of a normal reference serum in each experiment. The reference serum was assigned a DF value of 0.04%, which was corrected by a factor derived from the ratio of assigned DF to the observed DF calculated from the experimental data for this reference serum. This correction factor permits the observed DF results for concurrent unknown samples to be related to the values for the DF of the normal reference serum. The free thyroxine concentration is calculated from the product of the DF and the total serum thyroxine concentration as determined by competitive binding analysis. The method is convenient for use in clinical laboratories, and data for free thyroxine obtained from patients with metabolic thyroid disorders are diagnostically discriminatory.
Semiautomated Method for Serum Pepsinogen Determination
Authors: Wenger Julius , Munro Miranda
Published: January 2020

An automated fluorometric determination of tyrosine has been adapted to the measurement of pepsinogen in body fluids. Preparation of the hemoglobin substrate and methods of incubation are similar to those previously described. The major technical improvement is the elimination of precipitation and filtration; instead, dialysis has been incorporated into the automated procedure for determination of tyrosine and tyrosine-containing peptides. This method provides a reliable, simple technique for use with large numbers of serum specimens.
Contribution of Estriol to Total Urinary Estrogens during Pregnancy
Authors: Hobkirk R , Anuman-Rajadhon Y , Nilsen M , Blahey P R
Published: January 2020

Estriol accounts for an average of 74% of the principal Kober-positive steroids in the urine of 13 women during uncomplicated pregnancies. This proportion is independent of the stage of pregnancy, from 20 weeks until term. The average ratio of estriol to ring-D α-ketols (mainly 16α-hydroxyestrone and 16-ketoestradiol-17β) is about 5:1 over the same period. In 17 pregnant women with diabetes, urinary estriol averaged 63% of the "total steroids" during a similar period, and the average ratio of estriol to ring-D α-ketols was 3:1. The quantitative importance of these ketolic steroids may introduce a problem in deciding whether to measure estriol or "total estrogens" when evaluating fetal viability in complicated pregnancies.