bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Determination of pH, CO2 Content, and Cell Volume in 0.1 ml. Aliquots of Cutaneous Blood
Authors: Singer Richard B , Shohl Jane , Bluemle Dolores B
Published: January 2020

1. A modificationhas been described for the Shock and Hastings technic of determining simultaneously, in 0.1 ml. aliquots of blood, the pH,CO2. content, and packed cell volume. Advantages of the modification are collection and handling of the blood in a way that avoids the use of oil, and a modified design of the micropipets so that pH readings can be obtained in a filter photometer.

2. The standard error of measurement of a single reading was ±0.009 for the pH, and ±0.22mM/L. for the whole blood CO2. concentration. The reproducibility of the photocolorimetric pH measurement was slightly better than that obtainable with the most accurate commercially available glass electrode.

3. Results have been presented to show that blood can be handled in the presence of brief, limited, exposure to air with no detectable change in pH and only negligible change in CO2 content (decrease of less than 0.2 mM/L.). Errors attributable to collection and handling of cutaneous blood by this "virtual anaerobic" technic are not of significant magnitude.

4. Results have also been presented in confirmation of the fact that arterial and cutaneous blood are virtually identical in acid-base properties. A sample of as little as 0.5 ml. of cutaneous blood, analyzed by the microtechnic, provides the necessary and sufficient data for a description of the state of acid-base balance. This includes calculation of the physiologically important variables, arterial CO2 pressure, and whole-blood buffer base concentration, thus furnishing a measure of the respiratory factor and the metabolic factor in any acid-base disturbance. With a sample size of 1.5 ml. it is also possible to determine other individual constituents of plasma, such as sodium, chioride, and total protein.

5. The technic is useful in the study of clinical disturbances of acid-base balance, especially in infants and children.
A New Method for Scanning Electrophoretograms
Authors: Kabara Jon J , Zyskowski Diana , Pokornicki Helena
Published: January 2020

A new instrument is described for evaluating electrophoretograms on various media. The same densitometer can be used to evaluate spots on chromatographic strips and for colorimetric analysis of solutions. The versatility of this instrument makes it a useful adjunct to any analytical laboratory.
Simplified Ultramicro Determination of Carbon Dioxide Content Using the Natelson Microgasometer
Authors: Martinek Robert G
Published: January 2020

A rapid and greatly simplified method for the determination of serum carbon dioxide content, using the Natelson microgasometer, has been described.

Elimination of the absorption of carbon dioxide with alkali and the use of a single, unified reagent promote greater ease and facility of analysis, and insure greater precision.
An Improved Method for the Measurement of Urinary 17-Ketosteroids of Small Laboratory Animals
Authors: Ryan W T , Ferro W F , Beyler A L
Published: January 2020

A modified procedure for the estimation of urinary 17-ketosteroids includes the addition of formalin to urine before hot-acid hydrolysis and a separation of Zimmerman chromogen from nonspecific chromogen. Values of 17-ketosteroids are reported for the castrate rat and the intact guinea-pig following ACTH administration.
A Punched-Card Reference System for Biochemists
Authors: Weissman Norman
Published: January 2020

A simple binomial-code punched-card system for biochemists is described. Employing major and minor classifications, the system can handle a total of 812 subjects in two rows of 29 holes each. Enough theoretical and practical technics are illustrated to enable the novice to devise a system suited to his own needs.
Nomogram for Estimating Diffusible Serum Calcium
Authors: Hanna Ed A , Nicholas H O , Chamberlin James Allen
Published: January 2020

A method is presented for the construction and use of a nomogram for estimating the concentration of diffusible serum calcium from data obtained by determination of the total serum calcium and the albumin and globulin levels.
Enzyme Activities during Hepatic Injury Caused by Carbon Tetrachloride
Authors: Friedman Max M , Lapan Bernard
Published: January 2020

Rats injected with carbon tetrachloride show markedly elevated plasma glutamic oxalacetic transaminase and plasma fumarase but, at the same time, these enzyme activities do not decrease in the liver.

Three mechanisms are proposed which may account for the increase in plasma enzymes: first, a transfer of the enzyme systems from the necrotized liver cell to the plasma; second, the synthesis of plasma enzymes as the response to hepatic injury; third, disruption of the mitochondrion.
A Simple Method of Preparative Electrophoresis
Authors: Ressler Newton , Joseph Ramon R
Published: January 2020

A method of preparative electrophoresis is described. A volume of approximately 1 ml. of protein solution can be applied with the cell used. A "marker" solution, applied adjacent to the sample to be separated, indicates the positions of the protein bands during the migration. The procedure has the advantages of a high degree of recovery, simplicity of operation, and utilization of an electrophoretic cell which can also be applied to other electrophoretic procedures.
A Method for Determination of Magnesium in Serum and Urine
Authors: Sky-Peck Howard H
Published: January 2020

A method is described for a determination of magnesium in serum and urine. This method is based on the formation of a red color produced by a thiazole yellow-Mg(OH)2 complex in alkaline solution.
Quantitation of Some Abnormal Hemoglobins
Authors: Kelsey Jarel R , Kloss Robert A
Published: January 2020

A method is presented for identification and quantitation of abnormal hemoglobins. Electrophoretic fractionation with cellulose acetate is followed by elution of each fraction into Drabkin's solution. In the presence of Drabkin's solution hemoglobin is converted to cyanmethemoglobin and measured in any standard photometer at 540 mµ.
Gas Chromatographic Determination of Lower Alcohols in Biologic Samples
Authors: Lyons Harold , Bard Jacquelyn
Published: January 2020

A procedure is described for the simultaneous determination of methanol, ethanol, and isopropanol in biologic samples, using a low-cost gas chromatograph. A combination of the use of anhydrous calcium sulfate (Drierite) absorption of most of the water in the sample followed by an n-butanol extraction of the alcohols from the solid absorbent is employed. This extraction technic is efficient and affords good sensitivity while eliminating the need for hydrogen flame detection and sample-port clean-out.
Studies on the Determination of Bile Pigments
Authors: Jacobs S L , Henry R J , Segalove M
Published: January 2020

Tests for total bilirubin on 10 icteric sera by 5 diazo procedures and a spectrophotometric method showed fair agreement with most samples but an occasional grossly discrepant result. Results for free and conjugated bilirubin by diazo methods, acetone precipitation, and extraction of serum with ethyl acetate and chloroform were widely discrepant. Problems in documentation of accuracy of such procedures are discussed. It is concluded that unavailability of reference standards of bilirubin conjugates poses a serious obstacle to solution of the analytical problems.
Studies on the Determination of Bile Pigments
Authors: Henry Richard J , Fernandez Alberto A , Berkman S
Published: January 2020

In an attempt to complete the standardization of the "quantitative" method for the determination of urobilinogen in urine, recoveries of added urobilin varied erratically between 50 and 80%. Experiments to demonstrate the cause of the low recoveries suggest that urobilin is altered in the reduction procedure by the presence of urine.
A Rapid Semiautomatic System of Chemical Analysis using True Microspecimens
Authors: Walter A Richard , Gerarde Horace W
Published: January 2020

This paper describes some biochemical applications of a self-filling, self-measuring, disposable, dilution micropipet. The device consists of a precision capillary in a plastic adapter and an attachable plastic bottle containing a premeasured volume of diluent or reagent. The human error in measuring microvolumes of liquid is elimimated by the self-filling, self-measuring action of the capillary. A quantitative transfer of sample to reagent is made by introducing the capillary into the bottle and rinsing the capillary by applying and releasing pressure on the walls of the container. The volume and composition of the reagent in the bottle can be varied depending on the test to be performed. An interesting application is its use as a disposable centrifuge tube containing a premeasured volume of stable deproteinizing agent. Other examples are determination of protein, bilirubin, serum sodium, and potassium, and predilution of serum or plasma for the microglucose determination using automatic chemical analysis.
Distribution of Ammonia in Cells and Plasma
Authors: Humoller F L , Barak A J , Holthaus J M
Published: January 2020

A method for the determination of plasma and whole blood ammonia is outlined which incorporates the desirable features of several older methods. By means of this method it has been demonstrated that the distribution of ammonia in erythrocytes and plasma of normal individuals is nearly equal to that of hydrogen ions. The ratio remains constant in cirrhosis, alkalemia, and ammonemia. It was observed in 82 consecutive admissions of cirrhotic patients that alkalemia was present in only a small percentage of the cases.
Macroglobulinemia: The Usefulness of DL-Penicillamine and Paper Electrophoresis in Diagnosis
Authors: Campbell Donald J , Boenisch Thomas
Published: January 2020

The change in mobility of an abnormal globulin peak during paper electrophoresis in the presence of DL-penicillamine is the most useful of simple procedures suggested for differentiation between macroglobulin and myeloma protein. However, not all cases indicating macroglobulin by this procedure will correlate with criteria based on ultracentrifuge analysis or antigenic reaction.
Tris (hydroxymethyl) Aminomethane as a Standard for Kjeldahl Nitrogen Analysis
Authors: Rodkey F Lee
Published: January 2020

Solutions of tris (hydroxymethyl) aminomethane (Tris) have been shown to be a convenient primary standard for the Kjeldahl analysis. This compound is readily available in analytical reagent grade and has all the desirable properties of a primary standard. It is unnecessary to protect the Tris solution from C02, as any reaction between Tris and this gas cannot be detected by the titrimetric procedures involved.
Cholesterol Measurement in Serum and in Plasma
Authors: Grande Francisco , Amatuzio Donald S , Wada Shohachi
Published: January 2020

The effect on the plasma cholesterol concentration of various anticoagulants added to the blood in dry form, as compared with that of serum, has been studied.

The amounts of anticoagulants used, per 5 ml. of blood, were: heparin, 2.5 mg.; oxalate mixture, 12 mg.; tetrasodium EDTA, 5 mg.; sodium oxalate, 12mg.; and ACD mixture, 5.3 mg. citric acid, 15.8 mg. Na citrate, and 17.6 mg. dextrose.

All these anticoagulants caused a decrease in the plasma cholesterol concentration. The mean cholesterol decrease (serum minus plasma) produced by heparin was only 4 mg./100 ml. (S.E., ± 1.24), but this difference was statistically significant. When the heparin was prepared by drying a solution of heparin in 0.9% NaCl a greater difference between serum and plasma was observed.

The cholesterol difference (serum minus plasma) producd by Na oxalate increases with increasing amounts of anticoagulant.

The decrease in plasma cholesterol concentration produced by the anticoagulants can be explained by changes of water distribution between cells and plasma, reflected by changes of hematocrit produced by the anticoagulant.
An Automated Procedure for the Simultaneous Determination of Calcium and Phosphorus
Authors: Kessler Gerald , Wolfman Morris
Published: January 2020

A completely automated method for the simultaneous or individual determination of calcium and phosphorus in serum and urine without preliminary sample treatment is reported. Separation of calcium and phosphorus from interfering materials is achieved by dialysis under acid conditions. The dialyzed calcium is determined colorimetrically using a metal complexing dye (cresolphthalein complexone) in an alkaline medium. Magnesium, phosphate, citrate, sulfate, etc., did not introduce significant errors under the test conditions. Inorganic phosphorus is determined by a modified Fiske-SubbaRow procedure. Reproducibility and recovery data as well as comparisons with manual methods are presented.
A Stable Murexide Reagent for the Estimation of Calcium in Micro Quantities of Serum
Authors: Spare Peter D
Published: January 2020

The effects of various solvents on the fading rate of alkaline murexide were studied. Glycerol, methanol, and propylene glycol were found to retard the fading rate of murexide at pH 12.0 to a considerable extent. Propylene glycol was the most satis-factory of these solvents. It was further noted that the fading rate of alkaline murexide in propylene glycol-water solution was directly proportional to the amount of water contained in the reagent, and that a reagent stable for at least 1 week at room temperature could be prepared.
A Useful Modification of the Prothrombin Time
Authors: Gollub S , Ulin A W
Published: January 2020

A useful modification of the prothrombin time test is described. It compares favorably with the usual Quick prothrombin time method in results and has the advantages of universal applicability, even for difficult or problem cases, and convenience for patient and physician.
Improved Quantitation of Cephalin-Cholesterol Flocculation Test
Authors: Martinek Robert G , Vimba Elvira , Mann Joseph D
Published: January 2020

A rapid turbidimetric method for the determination of cephalin-cholesterol flocculation is described. Greater specificity and photometric sensitivity have been achieved along with adequate precision.

The test is standardized with the conventional barium sulfate turbidity standards used for other laboratory procedures. Definition of results in turbidity units is proposed, and photometric standardization of the cephalin-cholesterol emulsion described. The stability of the emulsion is elucidated.

Comparison is made with a previously described quantitative method.
The Determination of Iodine in Biologic Material
Authors: Hoch H , Sinnett S L , McGavack T H
Published: January 2020

The chloric acid digestion of serum, followed by the ceric sulfate reduction test for iodine has been shown to give results reproducible to within ± 0.00035 µg. iodine per test sample (1) if the entire digestion tubes are kept hot during the combustion step so that products of incomplete oxidation are vaporized, (2) if the perchloric acid and sulfuric acid concentrations in the final digest are adjusted to 1.64 normal (16.5%) and 0.37 normal, respectively, (3) if attention is paid to the order of addition of the reagents, and (4) if the arsenite reagent is added within a fraction of a second. The method gave values for total serum iodine in 20 healthy subjects between 5 and 10.5 µg./100 ml.
Minor Hemoglobins in Erythrocytes
Authors: Hoch H , Barr G H
Published: January 2020

Two minor hemoglobins present in normal human erythrocytes have been separated by paper electrophoresis.

The concentration of the component which was more positively charged than the bulk hemoglobin ranged between 1.5 and 6 per cent of the total hemoglobin. The concentration of the other, more negatively charged, component could not be measured on account of incomplete separation, but was estimated to range from very low values to 5 per cent.

Globin added to the buffer was found to suppress the irreversible adsorption of hemoglobin on the filter paper and thus to eliminate "tailing."
Serum Lipase Determination
Authors: Bunch Leitha D , Emerson Richard L
Published: January 2020

A method for determining serum lipase activity requiring only 4 hours incubation at 37° is given. Olive oil in a phosphate buffer is the substrate. The values found in 57 healthy controls ranged between 0.06 and 0.87 units, with a mean of 0.31 ± 0.17 (S.D.). Some results are given for patients with pancreatitis, miscellaneous pathologic conditions, and healthy controls.
Azorubin in Aqueous and Methanolic Solutions
Authors: Friedman Howard S
Published: January 2020

A study of the spectrophotometric characteristics of azorubin in varying proportions of methanol and water has been presented.

The absorbence of azorubin in water was found to vary from 73 to 90 per cent of that in methanol, over a concentration range of 0.001 to 0.025 mg. per 2 ml. of test solution.

The absorbence of azorubin was found to be linear over the same range of concentration, and over the range from 0.1 to 10 mg. per 100 ml. of serum, using a final test dilution of 1 to 8.

The strong probability of the artefactual nature of "direct" and "total" serum bilirubin values has been demonstrated.
Determination of Oxalate in Urine
Authors: Hausman Estelle R , McAnally John S , Lewis George T
Published: January 2020

A method has been developed for the determination of oxalate in urine. This method has proved superior, in the experience of the authors, to the older titrimetric determination of this urinary component.
Glycylglycylglycine as a Synthetic Standard for Serum Protein Determination
Authors: Klein Bernard
Published: January 2020

Glycylglycylglycine was investigated as a reference standard for use in serum protein measurement by the biuret reaction. The tripeptide-biuret solution has a molar absorptivity of 96 at 565 nm, and absorbances at both 550 nm and 565 nm are proportional to concentration. By a manual reference procedure, the 550-nm absorbance of 1.0 g of tripeptide was equivalent to that given by 1.72 ± 0.03 g of human serum albumin or 1.43 ± 0.03 g of bovine serum albumin. By the Technicon N14b automated procedure, the absorbance of 1.0 g of tripeptide at 550 nm was equivalent to that of 1.81 ± 0.02 g of human serum albumin or 1.89 ± 0.03 g of bovine serum albumin. Results for serum protein analyses over the range 4.0 to 9.0 g/dl, when tripeptide or serum albumin was used to prepare calibration curves, showed mean differences of 0.15 g/dl in the manual mode and 0.08 g/dl in the automated mode.
Ion-Exchange Chromatography of Amino Acids in Sweat Collected from Healthy Subjects during Sauna Bathing
Authors: Gitlitz Peter H , Sunderman, F William , Hohnadel David C
Published: January 2020

Amino acids were measured by ion-exchange liquid chromatography in sweat samples obtained from 22 healthy men during sauna bathing. Amino acids were also measured in plasma (collected before breakfast) and urine (24-h collections) from the same subjects. Serine, ornithine, citrulline, and aspartic acid were present in sweat in mean concentrations >10-fold their mean concentrations in plasma. In contrast, glutamine, cystine, α-aminobutyric acid, and α-aminoadipic acid were present in sweat in mean concentrations that were <0.2 times their mean concentrations in plasma. Concentrations of specific amino acids in sweat bore no apparent relationship to their concentrations in urine. Thus, citrulline was abundant in sweat, whereas only traces of citrulline were found in urine. Conversely, glutamine, taurine, cystine, and several other amino acids were abundant in urine but were present in very low or undetectable concentrations in sweat samples. This study indicates that the physiological mechanisms controlling excretion of amino acids in sweat differ fundamentally from those regulating renal excretion of amino acids.
Measurement of Glucose-6-phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase Activites in Erythrocytes by Use of a Centrifugal Analyzer
Authors: Nicholson John F , Bodourian Selma H , Pesce Michael A
Published: January 2020

We describe an accurate automated method for measuring activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) in erythrocytes with a centrifugal analyzer. Blood is collected in microhematocrit tubes, centrifuged, and the erythrocytes are lysed with digitonin. Glucose-6-phosphate dehydrogenase activity is determined by mixing the hemolysate with glucose-6-phosphate, NADP+, and 6-phosphogluconate dehydrogenase #{ 233} (EC 1.1.1.44) in triethanolamine—EDTA buffer at pH 7.6, and measuring the rate of NADPH production for 3 min. Under these conditions 2 mol of NADPH are produced per mole of glucose-6-phosphate oxidized, ensuring the accuracy of the method and increasing its sensitivity. Activity is referred to hemoglobin, measured as cyanmethemoglobin. Activity of glucose-6-phosphate dehydrogenase added to hemolysates was well accounted for. Results obtained by our method and by the method of Bishop [J. Lab. Clin. Med. 68, 149 (1966)] are virtually identical. Our method requires a small amount of blood and is accurate and rapid; thus it is well suited for use in surveying large populations for glucose-6-phosphate dehydrogenase deficiency. A simple modification of the method may be used to determine the activity of 6-phosphogluconate dehydrogenase.
Palmitic Acid Content of Amniotic Fluid Lecithin as an Index to Fetal Lung Maturity
Authors: Russell Paul T , Miller W J , McLain C R
Published: January 2020

A method is described for evaluating functional maturity of the fetal lung by measuring the palmitic acid content of amniotic fluid lecithin. The proportion of palmitic acid in total lecithin fatty acids correlated well (r = .87) with the pulmonary status of the newborn in the neonatal period. Palmitic acid values of less than 20% correlated with respiratory distress in 21 of 24 pregnancies; values greater than 20% correlated with pulmonary maturity in 39 of 40 pregnancies. Blood in the amniotic fluid does not adversely affect the validity of values for palmitic acid. Advantages of this method for predicting fetal maturity are discussed.
Routine Micromethod for Determination of Oxalic Acid in Urine by Atomic Absorption Spectrophotometry
Authors: Menachè R
Published: January 2020

The method of Gitelson et al. was modified to a microscale procedure and adapted for atomic absorption spectrophotometry. Oxalic acid in urine is precipitated with excess of calcium ions at pH 5. The excess of calcium present in the supernate and the total calcium added and present in the urine at pH 2 are determined by atomic absorption spectrophotometry. The oxalic acid present in the precipitate is calculated indirectly from the difference between the two determinations of calcium. This method is useful for routine determination of urinary oxalic acid.
Pyruvate as Substrate in the Determination of Serum Lactate Dehydrogenase Isoenzyme Activity
Authors: McKenzie Doris , Henderson A R
Published: January 2020

Lactate dehydrogenase isoenzyme activity is usually assessed, after the isoenzymes have been separated, by reactions involving lactate as the substrate. We describe a method for their assessment with pyruvate as the substrate. Precision is adequate as compared to the conventional methodology. Application of this type of approach (measurement of a decrease in fluorescence) to determination of other serum isoenzymes is briefly described.
Increased Synthesis of Lactate Dehydrogenase "H" Subunit by a Malignant Tumor
Authors: Henderson Arthur R , Ahmad Dildar , McKenzie Doris
Published: January 2020

In a patient with a rapidly growing malignant teratoma in the anterior mediastinum, the only biochemical abnormality detected at first was an abnormally high serum lactate dehydrogenase (EC 1.1.1.27) activity, almost 50% of the activity being present in lactate dehydrogenase isoenzyme-1 (LD1). At the time of death, the total lactate dehydrogenase activity had increased still further, 77% of it being in the LD1 fraction. Both the tumor and its hepatic metastases were shown to have a supranormally active LD1 fraction. These patterns appear to be attributable to an increased synthesis of the "H" subunit by the tumor.
Standardization of Serum Ceruloplasmin Concentrations in International Enzyme Units with o-Dianisidine Dihydrochloride as Substrate
Authors: Lehmann H Peter , Schosinsky Karl H , Beeler Myrton F
Published: January 2020

We describe a method for calculating the absorptivity (in terms of substrate consumed) of the colored solution obtained when o-dianisidine dihydrochloride is oxidized by ceruloplasmin. By oxidizing o-dianisidine dihydrochloride with known amounts of hydrogen peroxide we could determine that the molar reacting ratio of o-dianisidine to hydrogen peroxide is 2:1. So calculated, absorptivity is 9.6 ml µmol-1 cm-1, the figure used to estimate ceruloplasmin oxidase activity in terms of International Units.
Parameters Affecting a Rapid Method In Which Sephadex Is Used to Determine the Percentage of Free Thyroxine in Serum
Authors: Levinson Stanley S , Rieder Sidney V
Published: January 2020

In this method, Sephadex is used to assess the percentage of free thyroxine in undiluted sera. We demonstrate that if temperature and amount of Sephadex are kept constant, reproducibility is excellent. When Sephadex is exposed to serum, equilibration between thyroxine and thyroxine-binding components of the system is instantaneous. Because it is so rapid, it is not possible to measure the true physiological fraction of free thyroxine in serum with any free-thyroxine-binding resin, but the method does give an accurate measure of fluctuations in percentage of free thyroxine, as indicated by the high correlation with values for percentage of free thyroxine as determined by equilibrium dialysis and by the appropriate response to additions of exogenous thyroxine and dilution of the serum.
Evaluation of a New Device for Rapidly Separating Serum or Plasma from Blood
Authors: Mathies James C
Published: January 2020

I have evaluated the suitability of a new device for the rapid and efficient separation of cell-free serum or plasma from whole blood. Thirty-four clinical chemistry procedures were used in the analysis of 750 paired blood samples. One sample from each pair was processed by double centrifugation, the other by single centrifugation with the new device. Differences between means for the paired samples were evaluated by Student's t-test. At a significance level of P ≤ 0.05, only uric acid, lactate dehydrogenase, lactate dehydrogenase isoenzyme 2, and CO2 show a statistically significant difference between the two separation procedures. These differences do not appear to be of sufficient magnitude to preclude use of the device in the clinical chemistry laboratory.
Sources of Error in Determining Lead in Blood by Atomic Absorption Spectrophotometry
Authors: Kopito Louis E , Davis Michael A , Shwachman Harry
Published: January 2020

203Pb was used to monitor sample-preparation techniques used in four atomic absorption methods for determination of lead in blood. Sources of error and their magnitude were identified and measured for each of the following analytical procedures: precipitation with trichloroacetic acid, separation with ammonium pyrrolidine dithiocarbonate into methyl isobutyl ketone, digestion with acids, and coprecipitation with bismuth and direct analysis after a "nonextraction" procedure. The determination of lead in blood supplemented with inorganic lead was compared with that of naturally bound lead obtained from experimentally poisoned animals. Because of differences in in vivo and in vitro lead binding, recovery of added inorganic lead may not accurately reflect the fate of endogenous lead in some analytical procedures.
New Method for Rapid Determination of Carboxyhemoglobin by Use of Double-Wavelength Spectrophotometry
Authors: Ramieri Alfred , Jatlow Peter , Seligson David
Published: January 2020

We have developed a simple method for rapid determination of carboxyhemoglobin concentration in blood, by use of double-wavelength spectrophotometry. The absorbance of both oxyhemoglobin and reduced hemoglobin are instrumentally nulled out in this procedure, so that the absorption signal reflects HbCO and only a single spectrophotometric reading is required. This procedure is accurate in the range encountered in ambulatory persons as well as in the "toxic" range. Results correlated well with the dithionite reduction procedure. The stability of carboxyhemoglobin in solution was investigated and concentrations of carbon monoxide in groups of smokers and nonsmokers were determined.
Use of the Carbon Rod Atomizer for Direct Analysis of Lead in Blood
Authors: Kubasik Norman P , Volosin Michael T
Published: January 2020

A method is described for direct analysis of lead in blood utilizing the carbon rod atomizer. Aliquots of whole blood are analyzed without pre-treatment. Results are comparable to those for a similar non-flame technique in which whole blood samples were prediluted with "Triton X-100." The small sample volumes required and the minimal sample preparation further diminish the possibility of spurious contamination.
Faster and Easier Radioimmunoassay of Digoxin
Authors: Drewes Patricia A , Pileggi Vincent J
Published: January 2020

We describe an improved radioimmunoassay method for serum digoxin, with 125I as tracer, to eliminate the problems that endanger the validity of this assay: apparent instability of tracer, time-dependence of charcoal separation of free and bound fractions, and influence of sample-to-sample differences on results. Principal innovations leading to a more rugged and reliable test are the use of (a) a stable [125I] tyros ine-methyl-ester of digoxin, (b) ammonium sulfate to separate bound and free fractions, (c) a fresh serum pool for the standard curve, and (d) individual specimen blanks. Results compare favorably with those of the properly-controlled, original tritium method of Smith et al. [New Engi. J. Med. 281, 1212 (1969)] in terms of digoxin values, while the method excels it in convenience and speed. Between-run precision is 11% (CV) over the range of interest (mean, 2.7 µg/liter), sensitivity is 0.2 µg/liter, and recovery of added digoxin averages 102%.
Dual-Precipitation Method for Lipoprotein Quantitation: Improvement by Membrane Ultrafiltration of Lipemic Samples
Authors: Wilson Dana E , Done Gregory A
Published: January 2020

Plasma lipoproteins can be measured by the clinical laboratory after the major lipoprotein classes have been separated by two precipitation steps, one of which is the aggregation of very-low-density lipoproteins (VLDL) by the detergent, sodium dodecyl sulfate. Lipoprotein concentrations are expressed in terms of the cholesterol concentration within each class. However, incomplete removal of aggregated VLDL has led to serious analytical errors in a few lipemic subjects. We tested the efficacy of a membrane ultrafiltration step in removal of aggregated VLDL in three patients with plasma triglyceride concentrations of 540 to 12 560 mg/dl. Preliminary membrane ultrafiltration to remove the aggregated VLDL improved the precision of the method and is recommended for the analysis of grossly lipemic samples.
Multivariate Analysis of Serum Protein Assays in Chronic Hepatitis and Postnecrotic Cirrhosis
Authors: Agostoni Angelo , Marasini Bianca , Stabilini Roberto , Del Ninno Ersilio , Pontello Mirella
Published: January 2020

Pre-albumin, albumin, orosomucoid, α-antitrypsin, α-macroglobulin, β1A-globulin, IgG, IgA, and IgM were assayed in the serum of patients with chronic persistent hepatitis, chronic aggressive hepatitis, and postnecrotic cirrhosis. When results were evaluated by multivariate analysis, a good discrimination was obtained, especially between chronic aggressive hepatitis and postnecrotic cirrhosis.
Gas-Liquid Chromatographic Procedure for Measurement of Methylphenidate Hydrochloride and Its Metabolite, Ritalinic Acid, in Urine
Authors: Wells Rhondda , Hammond Keith B , Rodgerson Denis O
Published: January 2020

A gas-liquid chromatographic procedure has been developed for measuring methylphenidate and its metabolite, ritalinic acid, in urine. The unchanged drug is extracted into chloroform from alkalinized urine together with an internal standard, diphenhydramine. The solvent is removed, the residue dissolved in ethanol, and aliquots are injected into a gas-chromatographic column containing 3% OV-17. Ritalinic acid is recovered from the urine by lyophilizing the aqueous phase remaining after the unchanged methylphenidate is extracted into chloroform. The ritalinic acid is methylated with diazomethane to form methylphenidate, which is then assayed as described. Recovery of methylphenidate added to normal urine was quantitative and reproducible (CV, 3.2%). Ritalinic acid added to drug-free urine was recovered with an efficiency of 90-98%, but somewhat less reproducibly (CV, 12.8%). No interfering substances were found in normal urines. Between 35-98% of a single therapeutic (10 mg) dose given to hyperkinetic children could be recovered from the urine collected during the 6 h immediately after the dose. Only a small proportion was excreted as the unchanged drug (0.8-11.0%), the remainder being excreted as ritalinic acid.
Detection and Measurement of Total Bilirubin in Serum, with Use of Surfactants as Solubilizing Agents
Authors: Pearlman Frederick C , Lee Robert T Y
Published: January 2020

We describe a new method for measuring total bilirubin in serum. Nonionic, cationic, or anionic surfactants can be used as solubilizing agents to promote the diazo coupling of indirect-reacting bilirubin. A representative surfactant—azobilirubin system is illustrated, in which absorbance is maximum at 560 nm and linear to a concentration of 200 mg of bilirubin per liter. At pH 2.5 and in the presence of Du ponol (an anionic surfactant), bilirubin is completely coupled within 6 mm at 37 °C. All ingredients required for an assay are combined in two dry reagents, which are stable for a year at room temperature. Sensitivity is comparable to that of procedures routinely used in clinical laboratories; precision, linearity, and stability of the reagents in solution are excellent. Results for fresh sera correlated well with those obtained by the Jendrassik—Grof method. Hemolysis is minimized and turbidity eliminated.
Mechanism of Interference by Uric Acid in the Glucose Oxidase/Peroxidase Method for Serum Glucose
Authors: Chinh Nguyen H
Published: January 2020

Uric acid lowers the value for glucose as determined by the "GOD-Perid" method. To localize the interference by uric acid, we investigated each step of the reaction. Bleaching of the final color is the only source of such interference.
Advantages and Disadvantages of Nephelometric Measurement of Serum Lipids
Authors: Baer Daniel M
Published: January 2020

Several technical difficulties diminish the usefulness of serum triglyceride estimation by the method of Stone and Thorp [Clin. Chim. Acta 14, 812 (1966)]. An artificial and somewhat unstable material is used in the standardization. Falsely elevated readings caused by scratched cuvettes are a frequent problem. Conventional quality-control procedures cannot be used because stable preparations are not available. Specimen stability is a greater problem than with conventional chemical methods. In spite of these difficulties, the method can be useful, if its limitations are recognized, in measurements made on nonfasting individuals.
Development and Application of a Radioimmunoassay for Plasma Glucagon
Authors: Sperling Mark A , DeLamater Paul V , Kazenelson Mirtha , Fiser Robert H , Fisher Delbert A
Published: January 2020

We report sensitive radioimmunoassay procedures for glucagon-like immunoreactivity and for pancreatic glucagon, with use of antisera generated in rabbits by the injection of glucagon covalently coupled to thyroglobulin. Optimum assay conditions were determined. These assays have absolute limits of sensitivity of 10 to 20 pg, an intra-assay coefficient of variation of 8%, and an inter-assay coefficient of variation of up to 22%. In human infants 30 minutes after birth, glucagon concentration was 227 ± 27 pg/ml (SEM), and glucagon-like immunoreactivity increased sharply with oral feeding. In children and adolescents, plasma glucagon concentrations during fasting, the increase in response to arginine stimulation, and the suppression after oral glucose loading were similar to values previously reported in adults. Problems inherent in the methodology for measuring plasma glucagon are discussed.
Measurement of IgG and Albumin Content of Cerebrospinal Fluid, and its Interpretation
Authors: Ganrot Karin , Laurell Carl-Bertil
Published: January 2020

A high correlation (r = 0.85) normally exists between the concentration of albumin and of IgG in cerebrospinal fluid (CSF). The correlation is still better (r = 0.96) if the concentrations of the two proteins are also measured in plasma and the CSF/ plasma ratios compared for albumin and IgG. The scatter diagram for these ratios in persons without disease of the nervous system is most useful as a reference when differentiating between local IgG production in the subarachnoid space and an increase in CSF protein for other reasons. The analysis can be performed on less than 0.1 ml of CSF, in contrast to agarose-gel electrophoresis, for which 5-10 ml is necessary.
Comparative Study of a Micro-Scale Test for Lead in Blood, for Use in Mass Screening Programs
Authors: Cooke Richard E , Glynn Kathryn L , Ullmann William W , Lurie Nicole , Lepow Martha
Published: January 2020

A procedure suitable for the mass screening of children for an undue body burden of lead was tested on 170 clinic patients. Capillary finger-prick blood, collected on filter paper, was analyzed for lead with an atomic absorption spectrophotometer with the Delves cup attachment. This method of analysis had first been judged to be accurate after a laboratory evaluation in which results were compared with those obtained by a dithizone procedure. In the present study, both capillary and venous bloods were obtained from the patients. Venous bloods were also analyzed by the filter paper disk method and by an atomic absorption spectrophotometric procedure requiring a 5-ml sample. Results show that the screening method described here will reliably identify those children with a significantly supranormal blood lead. Both sample collection and laboratory analysis are easier.
Evaluation of Glucose-6-Phosphate Dehydrogenase from Leuconostoc mesenteroides in the Hexokinase Method for Determining Glucose in Serum
Authors: Bondar Richard J L , Mead Donna C
Published: January 2020

The hexokinase (EC 2.7.1.1)/glucose-6-phosphate dehydrogenase (I) (EC 1.1.1.49) method of glucose analysis is highly accurate, precise, and sensitive when I from Leuconostoc mesenteroides and NAD+ are used. Coefficients of variation ranged from 0.68 to 8.9% for glucose standards between 0.56 and 27.7 mmol/liter. Recovery was 103 ± 10% for glucose standards added to sera of known glucose content. Although no substances investigated interfere with the test system when present at their normal or likely concentrations in serum, final reaction mixtures containing mannose (>0.28 mmol/liter), fructose (3.7 mmol/liter), or 2-deoxy-D-glucose (4.01 mmol/liter) inhibit the analysis. With all constituents lyophilized, the reagent mixture is stable for at least a year at 4 °C and for five days at 40 °C. Within-day reproducibility averaged 0.83%; day-to-day precision was 1.3%. We compared results of hexokinase/glucose procedures by using I from yeast (with NADP+) and from L. mesenteroides (with either NAD+ or NADP+ as coenzyme); there was complete correlation over a serum glucose range of 4 to 12 mmol/liter (72 to 217 mg/dl). Use of NAD+ with I from L. mesenteroides is advantageous because of the decreased cost and greater stability of the coenzyme.
Urinary Excretion of Non-nitrogenous Organic Acids by Healthy Infants and Children
Authors: Aksu Asian , Morrow Grant , Barness Lewis A
Published: January 2020

We have quantitated 14 non-nitrogenous organic acids in the urine of infants and children. Excretion values are calculated as total milligrams per day, milligrams per kilogram body weight per day, and milligrams per milligram of urinary creatinine. The correlation with creatinine excretion is high; thus, meaningful data can be obtained from casual samples of urines.
Specific Gravity of Blood and Plasma at 4 and 37 °C
Authors: Trudnowski Raymond J , Rico Rodolfo C
Published: January 2020

The specific gravity (relative density) of human whole blood and plasma from 25 healthy volunteers was determined gravimetrically. For whole blood it was found to be 1.0621 (95% confidence interval: 1.0652-1.0590) at 4 °C and 1.0506 (95% confidence interval: 1.0537-1.0475) at 37 °C. Plasma specific gravity was 1.0310 (95% confidence interval: 1.0324-1.0296) at 4 °C and 1.0205 (95% confidence interval: 1.0216-1.0193) at 37 °C. All of these values are referred to the density of water at 4 °C. We show the relationship between these values and those given in the literature for measurements at 25 °C. There was a small increase in whole blood specific gravity with increasing hematocrit, but it was not statistically significant over the 40-56 hematocrit range studied.
Reinterpretation of Hyperamylasemia in Diabetic Coma
Authors: Goldberg David M , Spooner Richard J , Knight Anthony H
Published: January 2020

Serum enzyme activity was sequentially determined in 10 consecutive patients with diabetic ketoacidosis, of whom all had increased β-glucuronidase activity, eight had increased amylase activity, and four had increased acid phosphatase activity. Activity of amylase and that of the two lysosomal enzymes were poorly correlated, irrespective of whether peak activities or activities of all samples were considered. Of 37 cases with acute viral hepatitis, serum β-glucuronidase activity was increased in 33 and amylase activity in four, and the correlation between the two was poor. Study of normal human liver showed that the ratio of its mean enzymatic activity to the upper normal limit for serum was less than 1.0 for amylase, and approximately 80 and 6000 for acid phosphatase and β-glucuronidase, respectively. The hepatocyte cannot be the source of an increased serum amylase activity, and we question whether lysosomes are concerned in its release from other tissues.
Immunochemical Measurement of Lipoprotein-X
Authors: Kostner Gerhard M , Petek Walter , Holasek Anton
Published: January 2020

Lipoprotein-X, an abnormal lipoprotein that is specific for cholestasis, was quantitated by immunochemical methods. Interfering lipoproteins also present in normal serum and sharing antigenic determinants with lipoprotein-X were removed before the sample was applied, by precipitation with purified anti-lipoprotein B or a γ-globulin fraction of specific lipoprotein B antiserum. On Laurell electrophoresis, peak height was linearly related to lipoprotein-X concentration in the range 0.20-10 g/liter of serum. Sensitivity could be increased further by staining the plates. The coefficient of variation was less than 5%. Single radial immunodiffusion (Mancini et al. technique) was somewhat less sensitive and accurate. Results were available after 3 h by Laurell's electroimmunodiffusion technique, and after 72 h by the technique of Mancini et al. Equivalent results were obtained for samples of lipoprotein-X of extrahepatic or intrahepatic origin.
Use of Co-Current Dialysis in an Improved Estimation of Free Thyroxine in Serum
Authors: Strickler Herbert S , Link Susan S , Grauer Robert C
Published: January 2020

A new method is described for measuring free thyroxine in serum, in which co-current dialysis is used to simplify and speed the determination. The patient's serum is mixed with 125I-labeled thyroxine and buffer (28 ml of serum per deciliter) and co-currently dialyzed for 15 min against a mixture of pooled serum (8 ml/dl) in buffer. After dialysis, the free thyroxine of the patient's serum, which is now bound to the protein of the recipient stream (pooled serum), is precipitated with trichloroacetic acid. The radioactivity of this precipitate and of an undialyzed serum aliquot is measured, to obtain the total count. Use of pooled serum and trichloroacetic acid eliminates the need for the amounts of carrier thyroxine required in most other methods. The procedure is both simple and rapid (3 to 4 samples/unit/h). The values for free thyroxine correlate well with those obtained by the method of Lee and Pileggi [Clin. Chem. 17, 166 (1971)] and by others participating in the proficiency program of the College of American Pathologists.
Clinical Evaluation of a Rapid Screening Test for Sickle Cell Trait (S[unknown]) and Sickle Cell Anemia (SS)
Authors: Louderback Allan L , Youhne Young , Fontana Anthony , Natland Martin
Published: January 2020

The need for a rapid screening procedure that differentiates both sickle-cell trait (S[unknown]) and sickle-cell anemia (SS) in a single test system has led to the development of a new 10-min screening test. The "Sickle-I.D." system is based on a modification of the sodium dithionite hemoglobin solubility test. It is composed of three reagents and requires 0.1 ml of whole blood. Two independent blind clinical comparisons of this new procedure with hemoglobin electrophoresis (4328 samples) revealed an accuracy of 99.8% in identification and differentiation of sicklecell trait and sickle-cell anemia. Together with confirmation of positives by hemoglobin electrophoresis, this new procedure provides rapid and accurate screening for sickle-cell trait (S[unknown]) and sickle-cell anemia (SS).
Stability in Urea as a Measure of Cardiac Lactate Dehydrogenase on the Centrifugal Analyzer
Authors: Hanson Naomi Quast , Freier Esther F
Published: January 2020

Kinetic methods are described for determination of total, heat-stable, and urea-stable lactate dehydrogenase (EC 1.1.1.27) activity on the centrifugal analyzer. In the urea-stable method we present, 2.6 molar urea is used to differentiate lactate dehydrogenase originating from heart and liver. This urea concentration, greater than that used by most other investigators, better differentiates between cardiac and liver lactate dehydrogenase and is as sensitive and specific for cardiac lactate dehydrogenase as the heatstable method; excellent correlation was obtained on 200 specimens assayed by both methods. The ureastable method has the advantages of speed and simplicity, better precision, and decreased serum volume, and is, therefore, preferred to the heat-stable method for determination of cardiac lactate dehydrogenase isoenzymes.
Use of a "Three-Isoenzyme Diagram" in Assessing Activity of Alkaline Phosphatase Isoenzymes
Authors: Kim Jae C , Stastny Milos , Manning John P
Published: January 2020

A "three-isoenzyme diagram" has been devised to visualize the alkaline phosphatase profile quickly. Activities of the individual isoenzymes can then be estimated from the diagram. Each vertex represents a pure alkaline phosphatase isoenzyme, thus forming a triangle with three alkaline phosphatase isoenzymes, each side of the triangle describing the concentration ratio of a binary mixture of the respective isoenzymes. The validity of the three-isoenzyme diagram was tested by mixing three sets of two abnormal sera in three proportions. Results show that linearity and proportionality agree with what would be assessed from the diagram.