bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Liquid Chromatographic Analysis for Purine and Pyrimidine Bases in Hydrolysates of Nucleic Acid
Authors: Lakings Duane B , Gehrke Charles W
Published: January 2020

In this fast, simple method for analysis of microgram amounts of purine and pyrimidine bases in nucleic acid hydrolysates, RNA and DNA are optimally hydrolyzed in equal volumes of trifluoroacetic acid and formic acid, heated in a closed tube at 200°C for 1.5 h (for RNA) or at 150°C for 2.0 h (for DNA). The trifluoroacetic acid and formic acid are evaporated from the hydrolysates on a hot plate at 60°C, under a stream of pure nitrogen. The resulting nucleic acid bases are then silylated with a mixture of equal volumes of bis(trimethylsilyl)trifluoroacetamide and acetonitrile at 150°C for 15 min, and analyzed by gas-liquid chromatography on a column of SE-30 on Supelcoport.
Development and Evaluation of a High-Speed Continuous-Flow Analyzer
Authors: Evenson M A , Olson M A
Published: January 2020

A high-speed, high-performance, continuous-flow analyzer is described that operates at two to three times the usual analysis rate without necessitating corrections of the raw data and with no decrease in accuracy or precision. At faster speeds (180-300 samples/h) inductive sample interaction (%Ii), opposite in direction to carry-over, is for the first time quantitatively measured. A correction equation for %Ii was developed, and when it is applied to raw data, the accuracy of the results are significantly improved. Operating characteristics of the high-speed analyzer are described and the desirability of automatic computer corrections is discussed for the high-speed system.
Isolation of 2-Acetamido-1-β-(L-β-Aspartamido)-1,2-Dideoxy-D-Glucose from Normal Human Urine
Authors: Rowley Barbara O’Neill , Hamilton Paul B
Published: January 2020

A glycopeptide was isolated from normal human urine by fractionation on a column of Sephadex G-10 and preparative ion-exchange chromatography. Elution behavior during ion-exchange chromatography in two different solvent systems, amino acids formed upon hydrolysis, and migration on high-voltage electrophoresis and thin-layer chromatography were essentially identical for this substance and for authentic 2-acetamido-l-β-(L-β-aspartamido)-1,2-dideoxy-D-glucose. A technique was developed to permit analytical-scale fractionation of individual urines followed by analysis for this glycopeptide; urine from two normal individuals contained 7 and 11 µmol of 2-acetamido-1-β-(L-β-aspartamido)-1,2-dideoxy-D-glucose per liter.
Determination of Phenylbutazone in Plasma
Authors: Jähnchen Eberhard , Levy Gerhard
Published: January 2020

The permanganate oxidation method for the spectrophotometric determination of phenylbutazone has been modified and optimized to permit precise assays of phenylbutazone in small plasma samples. The assay is not affected by the presence of p-hydroxyphenylbutazone, the major metabolite of phenylbutazone. Weak bases are removed in the initial extraction procedure, and weak acids such as phenobarbital, warfarin, diphenylhydantoin, salicylic acid, and sulfadiazine do not interfere in the assay.
A Statistical Model for Assessing the Need for Medical Care in a Health Screening Program
Authors: Hartz Stuart C
Published: January 2020

This is a statistical model (the "multiple logistic model") for pooling data from many variables into a single probability estimate that a person examined in a health screening system requires medical care. Because discrete variables are frequently studied in health screening programs, the required assumption of multivariate normality of the predictor variables related to many statistical techniques is seldom fulfilled. A computing method is given that avoids this assumption by directly assuming the appropriateness of logistic function and obtains the corresponding maximum likelihood estimates (MLE) of the unknown parameters. Fisher’s linear discriminant function (LDF) may be used to provide the initial estimates of these parameters, which are necessary for the application of the MLE computing procedure. The algorithms to estimate these coefficients are discussed for both the LDF and MLE models, and an application of these methods to a set of data is presented and other applications of this procedure are proposed
Colorimetric Determination of 2,3-Diphosphoglycerate in Whole Blood
Authors: Luisada-Opper Anita V
Published: January 2020

A method for determining 2,3-diphosphoglycerate (DPG) is described that has been adapted for the clinical laboratory and does not require any special equipment. For eight controls, the average value obtained by this method was 4.19 ± 0.26 µmol of DPG per milliliter of red blood cells. The procedure is simple, quick, and reliable
Radiometric Assay of Citrate Condensing Enzyme (Citrate Synthetase) in Liver Tissue and Mitochondria
Authors: Dixit Padmakar K , Cuestas Raul
Published: January 2020

Citrate synthetase activity was determined in samples of commercially available citrate condensing enzyme. We measured the amount of radioactive citrate formed from the condensation of carbon-14 labeled acetyl CoA and oxaloacetate. The labeled citrate was oxidized by oxidative bromination; 14CO2 evolved was collected and represented the amount of citrate synthesized. Enzyme activity as low as 10-4 µmol/min was measured reproducibly with this procedure. Results obtained with this assay compared closely with those of a widely used spectrophotometric assay in which Ellman’s SH-coupling reagent [5,5-dithio-bis-(2-nitrobenzoate)] is coupled with CoA released during the reaction. Accuracy of labeled citrate determination in the presence of labeled acetate or pyruvate was excellent. The method can be used to determine citrate synthetase activity in skeletal muscle, liver, and isolated liver mitochondria, or to study the fate of labeled citrate injected into animals.
Rapid, Sensitive, and Selective Assay for Tryptophan in Serum
Authors: Guilbault George G , Froehlich Peter M
Published: January 2020

We have developed a rapid, selective, and sensitive fluorometric procedure for measuring tryptophan in serum. This assay is based on the facile reaction of tryptophan with aqueous formaldehyde; the concentration of the amino acid is measured from the diminution in its fluorescence as the reaction proceeds. Compared to other assay procedures, this procedure has the advantage of being sensitive to the amino acid, but unresponsive to other indole derivatives such as tryptamine and 5-hydroxytryptamine. Concentrations of tryptophan as low as 0.5 mg/liter may be assayed in 15 min.
Determination of Total Urinary Protein, Combining Lowry Sensitivity and Biuret Specificity
Authors: Doetsch Karl , Gadsden Richard H
Published: January 2020

A highly sensitive method with specificity for the peptide chain backbone was developed for determination of total urinary protein. Interfering substances are removed by gel filtration and cupric ions are stoichiometrically bound to the peptide bonds of protein by the biuret reaction. Ion-exchange characteristics of the gel are neutralized, allowing protein—copper complex to be separated from excess cupric ions by a second gel filtration step. Copper bound to peptide bonds is colorimetrically determined by use of sodium diethyldithiocarbamate. Nonprotein substances do not interfere unless they simultaneously bind to protein and chelate copper. As little as 1 mg of total protein per deciliter can be determined in heterogeneous biological fluids such as urine.
Spurious Elevation of Apparent Lactate Dehydrogenase Activity Caused by Triamterene
Authors: Chainuvati T , Harinasuta U , Zimmerman H J
Published: January 2020

Triamterene induced spurious elevations in serum lactate dehydrogenase activity, as assayed by an automated fluorometric method; the enzyme activities were normal when measured spectrophotometrically. Solutions of the drug in normal serum or physiological saline, without addition of substrate or coenzyme, yielded high values for apparent "enzyme" activity by the fluorometric assay.
Solid-Phase Radioimmunoassay for Digoxin
Authors: Line William F , Siegel Stanley J , Kwong Anda , Frank Clifford , Ernst Roberta
Published: January 2020

Anti-digoxin serum was conjugated to agarose or to organo-functional glass beads. The immunoadsorbents were compared to each other and to the soluble antibody, with respect to coupling efficiency and retention of immunological activity. We found that the antisera coupled to a glass-isothiocyanate retained about 50% of its immunological activity upon attachment. This derivative was superior to one prepared by coupling to CNBr-activated agarose, in which the attached protein retained 7% of its activity; and one prepared by coupling the protein to alkylamino glass using a water soluble carbodiimide, in which the attached antiserum retained only 1.5% of its original activity.
Use of Horseradish Peroxidase in Identification of Serum Antibodies and Immune Complexes
Authors: Murphy William M , Deodhar Sharad D , Cawley Leo P
Published: January 2020

We made 202 examinations on specimens from 78 patients, to evaluate the application of horseradish peroxidase-labeled antisera as compared to fluorescein-labeled material in a clinical immunology laboratory. Various circulating and tissue-fixed antibodies were identified by both techniques. The horseradish peroxidase technique can be substituted for the fluorescein isothiocyanate method for the evaluation of anti-nuclear antibody and anti-mitochondrial antibody without loss of specificity or sensitivity. Although the results are comparable, fluorescein isothiocyanate appears to be slightly more sensitive in the detection of the other circulating and tissue-fixed human antibodies examined. Further refinements in preparation and technique could well lead to the fluorescein method being replaced by horseradish peroxidase staining in the future.
Rapid, Simplified Continuous-Flow Colorimetry of Serum Triglycerides
Authors: Holub William R
Published: January 2020

A new modified, semi-automated method for triglyceride assay is described. The sampling rate is rapid (60/h) with acceptable inter-sample wash. Color and triglyceride concentration are linearly related up to 500 mg/dl. The modifications were: heated reactions were eliminated, a short Kel-F coil was used for transesterification, arrangements were made for simultaneous debubbling and phase separating. Both comparison with another semi-automated procedure and recovery values indicate the acceptability of this proposed method for use in routine clinical laboratories.
Conditions for a Radioimmunoassay of Serum Parathyroid Hormone
Authors: McCann Daisy S , Prunty JoAnn , Rigg Gerald , Arnstein Robert
Published: January 2020

A radioimmunoassay for parathyroid hormone is described that circumvents some previous difficulties. Parathyroid hormone binds strongly to other serum components. Consequently, a "control" curve is set up for each specimen, the specimen consisting of serum, diluent, and radiolabel, but no antibody. Final calculations are then based on the difference between the control curve and the curve obtained by incubating serum, diluent, radiolabel, and antibody. The lack of parallelism between various sample curves makes it almost mandatory that curves derived from at least 12 dilutions of serum be included for each specimen.
Polyacrylamide-Gel Disc-Electrophoresis as a Screening Procedure for Serum Lipoprotein Abnormalities
Authors: Naito Herbert K , Wada Mitsuo , Ehrhart L A , Lewis Lena A
Published: January 2020

A polyacrylamide-gel disc-electrophoresis system is described that is suitable for screening sera with a wide range of lipid concentrations, and the results agree with analytical ultracentrifugation data. The lipoprotein pattern so obtained was compared with that obtained by other recognized electrophoretic procedures. Lipoprotein determinations were done by polyacrylamide gel electrophoresis, for 125 patients, to determine its merit as a clinical screening method for lipoprotein abnormalities as compared to the paper-electrophoretic method. The lipid dye and riboflavin concentration of the gels used give a background that makes it easy to detect chylomicra in the sample gel and allows for densitometric semiquantitation of the lipoprotein fractions. The method is reliable, precise, and accurate.
Automated Kinetic Spectrophotometric Assays of Enzyme Activities of Human Cerebrospinal Fluid: Methods and Reference Values
Authors: Sharpe David M , Wilcock A Ross , Goldberg David M
Published: January 2020

Optimum conditions with respect to pH and molarity of phosphate buffer, and the concentrations of substrates, coenzymes, and exogenous enzyme, were defined at 37°C for activity of aspartate transaminase and lactate dehydrogenase of human cerebrospinal fluid (CSF), as measured by optical kinetic assays at 340 nm. The resulting methods, and a previously published procedure for malate dehydrogenase activity applicable to human CSF, were adapted for use with an automatic reaction-rate monitor. Within-batch and between-batch precision of all methods was satisfactory, and repeated estimations in seven subjects showed good agreement. Freezing samples decreased their activity by 5 to 10%, but thereafter no further losses occurred at -20°C for as long as three months. Injection of up to 12 ml of air during encephalography had no major effect. Reference values, derived from subjects with no neurological or simple chronic degenerative CNS disease, suggested that the upper limits (in U/liter) are: aspartate transaminase, 13.5; lactate dehydrogenase, 40; malate dehydrogenase, 58.
Estimation of Norms from a Controlled Sample Survey. II. Influence of Body Habitus, Oral Contraceptives, and Other Factors on Values for the Normal Range Derived from the SMA 12/60 Screening Group of Tests
Authors: Winkelman J W , Cannon D C , Pileggi V J , Reed A H
Published: January 2020

Sera from 423 clinically normal men and 557 clinically normal women, ages 20 to 49, were analyzed on the "AutoAnalyzer 12/60" (Technicon Corp.). The results were grouped by sex of the subject and subgrouped according to body habitus (overweight, normal weight, or underweight), region of residence in U. S., and other variables. Among subgroups, statistically significant differences in normal range limits were sought. Notable findings include (a) lactate dehydrogenase activities tend to be lower in winter, (b) women taking oral contraceptive medications have diminished albumin and inorganic phosphorus concentrations, and (c) overweight but otherwise clinically normal individuals tend to have higher uric acid values than do healthy individuals of normal weight.
Free Calcium in Serum. I. Determination with the Ion-Specific Electrode, and Factors Affecting the Results
Authors: Ladenson Jack H , Bowers George N
Published: January 2020

Free (ionic) calcium in human serum was measured with a commercially available ion-specific electrode, together with a saturated-KCl salt bridge, a saturated-calomel reference electrode, and a direct-reading electrometer. Effects of sodium, potassium, and magnesium on the electrode values for calcium were assessed and a rationale demonstrated for the use of calcium standards containing 140 mmol of NaCl, 5 mmol of KCl, and 0.55 mmol of MgCl2 per liter. Trypsin, triethanolamine, and heparin bind calcium; therefore, their use is to be avoided. Variability is greatly decreased if the serum is from a fasting subject and if the collection tube is completely filled, transported on ice, and handled anaerobically. The range for free calcium for 86 apparently healthy adults was 1.175-1.375 mmol/liter when measured at 25°C. The precision (coefficient of variation) of duplicates was 0.6%; the long-term precision ≃2.0%.
Sensitive Fluorescence Monitoring of Aromatic Acids after Anion—Exchange Chromatography of Body Fluids
Authors: Katz S , Pitt W W , Jones G
Published: January 2020

A simple, sensitive system has been developed for detecting oxidizable compounds that are eluted from chromatographic columns. It relies upon the production of fluorescent cerium(III) by the reaction of eluted compounds with cerium(IV) solution. When coupled with a modified ultraviolet-monitored anion-exchange chromatograph, this system provides excellent resolution and sensitivity in the analytical determination of aromatic organic acids.
Homogeneous Enzyme Immunoassay for Opiates in Urine
Authors: Schneider Richard S , Lindquist Peggy , Wong Emmy Tong-in , Rubenstein Kenneth E , Ullman Edwin F
Published: January 2020

An assay technique, homogeneous enzyme immunoassay, is described for the quantitative determination of morphine derivatives in biological fluids. An enzyme is labeled with morphine. When the enzyme-labeled morphine is bound by antimorphine antibodies, the enzyme is rendered inactive. Free morphine competes with enzyme—morphine for antibody binding sites preventing inhibition of enzyme activity. Enzyme activity is thus directly related to the concentration of free morphine.

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Where the enzyme used is lysozyme, the assay can detect 0.5 µg of morphine per milliliter of urine with >95% confidence (CV, 5.0% at 0.5 µg/ml morphine). The technique gave nearly twice as many confirmed positives as did thin-layer chromatography in a comparative study of urines from a methadone maintenance program. The immediacy of the results (assay time: <1 min) permits use of the assay in hospital emergency rooms, law-enforcement facilities, and methadone treatment programs.
Use of Stable Isotopes in Measuring Low Concentrations of Drugs and Drug Metabolites by GC—MS—COM Procedures
Authors: Horning M G , Nowlin J , Lertratanangkoon K , Stillwell R N , Stillwell W G , Hill R M
Published: January 2020

Certain drugs in urine, plasma, breast milk, and amniotic fluid have been quantitatively analyzed in the picogram to nanogram range by selective ion detection with two gas chromatograph—mass spectrometer—computer systems: an LKB 9000/PDP 12 operated in the electron impact mode and a Finnigan 1015/PDP 8/I operated in the chemical ionization mode. With the latter system, it is possible to monitor several drugs and drug metabolites and an internal standard in a single temperature-programmed analysis. Internal standards labeled with stable isotopes are preferred for selective ion detection. Diphenylhydantoin-2,4,5-13C has been used to quantify diphenylhydantoin, and pentobarbital-2,4(6) ,5-13C has been used to quantify amobarbital, secobarbital, caffeine, meperidine ("Demerol"), and phenobarbital in 50-200 µl samples of plasma and breast milk.
Relationships among Urinary Aminoimidazolecarboxamide in Urine and Folate, and Vitamin B12 Concentrations in Serum
Authors: Harrison J W , Slade B A , Shaw W
Published: January 2020

Urinary aminoimidazolecarboxamide (AIC), serum folate, and serum vitamin B12 values were determined in 84 apparently healthy individuals. An automated system for determination of AIC in urine is described. Despite claims to the contrary, we found no evidence of a strong relationship between elevated (e.g., >1.3 µg/mg of creatinine) AIC excretion as reflected in a casual sample of urine and folate or vitamin B12 deficiency. Urinary AIC values ranged from 0.10 to 5.20 µg/mg of creatinine. The mean for the population examined was 1.36 ± 1.02 µg/mg of creatinine.
Automated Measurement of Urinary Iodine
Authors: Garry Philip J , Lashley D Wayne , Owen George M
Published: January 2020

We describe a simplified, automated method for screening urinary iodine. Digestion with strong acid is avoided by dialyzing urine and then directly analyzing iodine in the dialysate with the ceric ion—arsenious acid system. This method is particularly useful for analyzing large numbers of samples without loss in precision. Urinary iodine excretions are reported for 1224 children 1 to 6 years of age.
Gas-Chromatographic—Mass-Spectrometric Determination of Urinary Acid Profiles of Normal Young Adults. II. The Effect of Ethanol
Authors: Witten Thomas A , Levine Steven P , Killian Mary T , Boyle Peter J R , Markey Sanford P
Published: January 2020

Urinary acid metabolic profiles of 26 healthy young adults who were maintained on a palatable standard diet for three days have been studied by combined gas chromatography-mass spectrometry. Means and standard deviations of the excretion rates of individual, identified acids were determined after the ingestion of ethanol and compared to basal values previously reported. A significant net effect of ethanol was demonstrated for only six of the acids studied: α- and β-hydroxybutyric, adipic, β-methyladipic, p-hydroxyphenylacetic, and 2,5-furandicarboxylic acids.
Liquid-Scintillation Counting of [57Co]—Application to the Radioassay of Vitamin B12
Authors: Gutcho Sidney , Johnson James , McCarter Henry
Published: January 2020

Cobalt-57 can be measured in a liquid scintillation counting system. We describe the calibration of such a system for this gamma emitter. The counting procedure has been used in the radioassay of vitamin B12. Results of assays for which counting of bound radioisotope was done in a gamma scintillation spectrometer and in a liquid scintillation counter show that either counting system can be used for the measurement of [57Co].
Diagnostic Value of Routine Liver Tests
Authors: Winkel Per , Ramsøe Klavs , Lyngbye Jørgen , Tygstrup Niels
Published: January 2020

In 131 patients on a medical service and 97 patients on a surgical service, in whom a diagnosis of hepatobiliary disease was verified in the hospital, the diagnostic value of routine liver tests performed soon after admission was evaluated by stepwise discriminant analysis. By measurements of alanine aminotransferase, alkaline phosphatases, gamma globulin, prothrombin time, bilirubin, and albumin, half of the medical patients were correctly classified into one of seven diagnostic categories. Aminotransferase contributed most to the classification, being twice as effective as random allocation. Decreasing the number of diagnostic categories to three (hepatitis, fatty liver, and chronic liver disease) increased the frequency of correct allocation to 80%. The allocation of all the patients to seven medical and four surgical diagnostic categories by means of four tests (aminotransferase, alkaline phosphatases, prothrombin time, and bilirubin) was significantly improved by each step, with a misclassification rate of 55% when all tests were used. A reduction of the diagnostic groups to five (hepatitis, fatty liver, chronic liver disease, duct obstruction and tumor) increased the frequency of correct allocation to 63%. The analysis demonstrates the limited diagnostic effectiveness of routine liver tests when used alone. The absolute discrimination values depend on the a priori frequencies of the diagnostic groups investigated, and therefore may vary from time to time and from place to place.
Critical Assessment of Phospholipid Measurement in Amniotic Fluid
Authors: Badham Linda P , Worth Howard G J
Published: January 2020

We assessed several methods of inorganic phosphate assay for their suitability in estimating phospholipids in digested extracts of amniotic fluids. The extraction and digestion procedures used for phospholipids from amniotic fluid were also examined critically. The effect of contamination by blood or obstetric cream has been examined. Accordingly, we suggest a method for measuring total phospholipids in amniotic fluids, and results of it are compared with the lecithin/sphingomyelin ratio measurement in some clinical situations.
Rapid Estimation of Hemoglobin A2 without Chromatography or Electrophoresis
Authors: Morin Leo G
Published: January 2020

Hemoglobin A2 is batch fractionated with diethylaminoethyl Bio-Gel A (Bio-Rad Laboratories) equilibrated with a tris(hydroxymethyl)aminomethane HCl buffer (pH 7.68, 8.75 mmol/liter, 6.36 mmol of Cl- per liter). Hemoglobin A1 and F become bound to the resin, allowing the separation and quantitation of A2. Hemoglobin S alters the equilibrium condition, but adjustments are easily made so that A2 can be separated in the presence of S. The procedure is simpler than electrophoretic or chromatographic methods, requires 5 min, is accurate (A2 fraction is at least 94% A2, less than 6% A1), precise (SD ±0.24 for duplicates), and has a normal limit of 2.6 ± 1.02%.
Double-Antibody Radioimmunoassay of Serum Insulin: Effect of Use of Hormone-Depleted Human Serum
Authors: Silbert Cynthia K , Sawin Clark T
Published: January 2020

Human serum can be depleted of insulin and growth hormone by treatment with dextran-coated charcoal or by dialysis, or both. Inclusion of such hormone-depleted serum in the standard curve of a double-antibody radioimmunoassay for immunoreactive insulin more nearly mimics the conditions under which an unknown human serum sample is assayed. Compared to the usual standard curve in which serum albumin is the only protein, the addition of hormone-depleted serum can cause an increase (by an average 64% under the conditions we used) in the absolute value for apparent insulin in serum. The effect of hormone-depleted serum should be tested in the standard curves of double-antibody radioimmunoassays and included routinely in these standard curves if it changes the results. When used in conjunction with an eventual reference standard for human insulin, this modification of the insulin assay may make the measured values of human serum insulin from different laboratories more comparable.
Hepatic Synthesis of Canavaninosuccinate from Ureidohomoserine and Aspartate, and Its Conversion to Guanidinosuccinate
Authors: Koller Anthony , Aldwin Lois , Natelson Samuel
Published: January 2020

This study continues the exploration of the mechanism for the formation of guanidinoacetate and guanidinosuccinate in the human [Clin. Chem. 21, 235 (1975)]. In this report we describe the formation of canavaninosuccinate from ureidohomoserine and aspartate by a human or bovine liver extract that had high argininosuccinate synthetase (EC 6.3.4.5) activity, and the subsequent formation of guanidinosuccinate by reductive cleavage. In the presence of ATP the optimum pH for the synthetic reaction is 8.4. This reaction can be carried out in either a tris(hydroxymethyl)aminomethane or borate buffer. Subsequent addition of dithiothreitol in the presence of Fe2+ resulted in the cleavage of some of the synthesized canavaninosuccinate to form guanidinosuccinate and homoserine. Synthesis of canavaninosuccinate was strongly inhibited by added argininosuccinate, less so by canavaninosuccinate, arginine, canavanine, glycine, or 2,3-dimercaptopropanol. The Km values for the substrates of the synthetic reaction are 3.6 x 10-4 mol/liter for aspartate, 1.6 x 10-3 mol/liter for ureidohomoserine, and 2.92 x 10-5 mol/liter for ATP. These values are higher than those obtained when the synthesis of argininosuccinate was studied, except for ATP, which yielded a lower value. All of the reactions in the proposed mechanism have now been demonstrated except for the synthesis of canaline from aspartate.
Kinetic Equations and Error Analysis for the Cholesterol—Sulfuric Acid Reaction
Authors: Hewitt Thomas E , Pardue Harry L
Published: January 2020

Quantitative data reported in an earlier paper have been used to evaluate kinetic equations for the reaction of cholesterol with sulfuric acid in acetic acid—acetic anhydride medium. The equations satisfy experimental observations to within 6% over a wide range of experimental conditions. The equations have been used to justify mathematically the empirically developed measurement procedures described earlier and to predict the errors that can be expected for time and temperature uncertainties.
Effect of Zinc Deficiency and Repletion on Thymidine Metabolism
Authors: Hsu Jeng M , Anthony William L
Published: January 2020

We studied the effect of zinc deficiency on thymidine metabolism in intact and wounded rats. Zinc deficiency was associated with significantly decreased incorporation of [methyl-3H]thymidine into skin DNA of both intact and wounded rats, as shown by liquid scintillation counting and autoradiography. With wounding, proliferation—as gauged by the labeling index—increased to about twice normal for zinc-supplemented rats, but 3.5-fold for zinc-deficient rats. However, despite the increased proliferation rate, wound-healing in deficient rats was always slower than in zinc-supplemented animals. Incorporation of 3H-labeled thymidine into spleen DNA at 2 and 4 h, and liver DNA at 4 h was also significantly less in zinc-deficient rats than in zinc-supplemented rats. Conversely, DNA synthesis was enhanced in the thymus gland of zinc-deficient rats. Further studies showed that significantly higher percentages of [methyl-14C]thymidine were oxidized by zinc-deficient rats. The specific involvement of the methyl group of thymidine was indicated by the observation of normal oxidations of [2-14C]thymidine. These findings support the view that zinc directly regulates DNA synthesis.
Computer Interface for Data Acquisition and Control of an SMA 12/60
Authors: Davis J E , Lewis J W
Published: January 2020

We present an approach to the computer enhancement of the "SMA 12/60" (Technicon Instruments Corp.). Practical and theoretical considerations led to a plugcompatible system, which did not require changes in the hydraulics or methodology of the SMA. Results obtained from eight channels of the SMA using the system as described show that a sample analysis rate of 120 per hour is feasible. A desirable consequence of the increased analysis rate is a 60% decrease in the required sample volume. Before the system can be used in a clinical environment, further development will be necessary, including detection algorithms for hydraulic malfunction.
Identification of Some Abnormal Metabolites in Plasma from Uremic Subjects
Authors: Bultitude Frederick W , Newham Simon J
Published: January 2020

We describe a method for comparing plasma samples from healthy subjects and from chronic uremic patients before and after dialysis. It was used to determine the nature of those metabolites that appear to characterize the uremic state. Preliminary fractionation of the metabolites by gel chromatography was followed by removal of the aqueous effluent by lyophilization and preparation of volatile trimethylsilyl derivatives, which were then examined by gas—liquid chromatography. Gas—liquid chromatography/mass spectrometry was used to characterize and identify individual metabolites. Gas—liquid chromatographic patterns of plasma from healthy and uremic subjects differ markedly, more so than do individual plasma samples within the same class of subjects. Concentrations of many metabolites are increased in uremia, but after dialysis of the patient's blood, the concentrations become about the same as those in healthy plasma. We have observed some 150-200 metabolites in each category of plasma. We have tentatively identified about a tenth of the compounds that appear to be specific to or increased in uremia, including lactic acid, glycerol, erythritol, erythronic acid, 2-deoxy erythro pentonic acid, arabinitol, arabinonic acid, inositol, and lactose. Some of these are present in concentrations >20 mg/liter and have not been previously reported as occurring in the uremic state.
Pictorial reporting of multiple thyroid function results.
Authors: Pain R W , Duncan B M
Published: January 2020

Clinicians experience difficulty in correctly interpreting the results of in vitro thyroid function tests in the presence of abnormalities of thyrobinding proteins or when results are borderline. This difficulty has been largely resolved in our laboratory by three innovations. First, the borderline areas for each of three routine tests of thyroid function (total thyroxine, thyrobinding index, and free thyroxine index) were accurately determined. Second, the results from this routine profile of three tests were displayed pictorially so as to produce patterns characteristic of various diagnostic situations, including euthyroidism in the presence of abnormalities of thyrobinding proteins. Third, interpretive comments and, in the case of borderline patterns, suggested further testing procedures were added to the report. Clinicians find the reporting system helpful and respond when additional tests are suggested. The system, operated manually at first, was later computerized.
Comparison of results by three kit methods for assay of serum gastrin.
Authors: Warner A , George H
Published: January 2020

We evaluated and compared Nuclear International, Schwarz/Mann, and Squibb kit methods for measurement of serum gastrin with respect to intra-run precision, analytical recovery of added gastrin, and values obtained for healthy fasting adults and for selected patients. As a result of this study, the Schwarz/Mann kit was chosen for use in our laboratory.
Radioimmunoassay for serum cortisol with 125I-labeled ligand: comparison of three methods.
Authors: Kumar M S , Safa A M , Deodhar S D
Published: January 2020

We evaluated a previously modified double-antibody radioimmunoassay for serum cortisol. It was compared with the conventional double-antibody method that includes the usual extraction step, and also with an antibody-coated tube method. In this modified method, cortisol was released from its binding globulin by enzymatic degradation rather than by extraction with ether, and a preincubated mixture of first and second antibody was used to separate antibody-bound cortisol from free. These two steps shortened total asssay time significantly. Results still correlated well (r = 0.87) with results by the conventional melthod, but the antibody-coated tube method gave lower results (r = 0.61). Because of its good correlation with the conventional method, this method was thought to be more accurate. In 52 normal subjects, mean cortisol concentrations at 0800 and 1700 hours were 161 +/- 52 (SD) mug/liter and 91 +/- 27 mug/liter, respectively. In 16 normal subjects, cortisol values before and after dexamethasone treatment (1 mg at midnight) were 134 +/- 53 mug/liter and less than 20 mug/liter. In the same subjects, cortisol concentrations before and 30 min and 60 min after Cortrosyn (synthetic corticotropin1-24, 0.25 mg) administration were 103 +/- 25, 205 +/- 45 and 223 +/- 51 mug/liter, respectively.
Serum ionic fluoride: normal range and relationship to age and sex.
Authors: Husdan H , Vogl R , Oreopoulos D , Gryfe C , Rapoport A
Published: January 2020

We used the Orion fluoride electrode system to determine the normal range of serum ionic fluoride concentrations and to investigate its relationship to sex and age (A). 87 normal men, aged 18-92 years (mean, 46 years), and 49 normal women, age 19-64 years (mean, 38 years), participated in the study. At the 95% confidence limits, males less than 45 years old had a normal range of 0.29 to 1.52 mumol/litre and males greater than or equal to 45 years old 0.29 + 0.0101 (A-45) to 1.52 + 0.0101 (A-45) mumol/litre. Females, however, had a normal range of 0.022A - 0.32 to 0.022A + 1.07 mumol/litre. A group of 51 men 18-44 years old was compared with a group of 36 men 46-92 years old. The mean serum F- of the older group was shown to be significantly greater (P less than 0.01) than that of the younger group. Factors related to serum ionic fluoride values are (a) tea as an important source of dietary F-, (b) the lack of significant variation during daytime hours, and (c) the lack of significant difference in concentration between serum and plsma F-.
How accurate are lactate dehydrogenase isoenzyme estimations by the thin-layer agarose fluorescent technique?
Authors: McKenzie D , Clark P I , Henderson A R
Published: January 2020

We offer an assessment of the accuracy of the thin-layer agarose fluorescent technique of Elevitch et al. [Am. J. Clin. Pathol. 46, 692 (1966)]. We used semi-purified human lactate dehydrogenase isoenzymes 1 and 5. Both the lactate lead to pyruvate and pyruvate lead to lactate assays [Clin. Chem. 20, 1462 (1974)] appear to give, within the errors of the techniques used, a substantially unbiased estimate of both LD-1 and LD-5, although this must remain a provisional conclusion until a definitive method of assay for the total and isoenzymic LD activities is created. Introducing a buffer into the substrate mixture (lactate lead to pyruvate assay) had no effect on these findings except at extremes of pH, when marked inaccuracies occurred.
Radioimmunoassay and enzyme immunoassay compared for determination of digoxin.
Authors: Sun L , Spiehler V
Published: January 2020

Patients' sera were analyzed for digoxin by using two different radioimmunoassays and an enzyme immunoassay. Quantitative results obtained by enzyme immunoassay (I) were compared to results obtained on aliquots of the same sample by the radioimmunoassays (II and III). The correlation coefficients were: I vs. II 0.90, n=108; I vs. III 0.94, n=102; and II vs. III 0.95, n=158. Day-to-day precision (10 days) on a low control (1.3 mug/liter) and a high control 3.0 mg/liter), expressed as coefficients of variation, were: I, 13% and 7.8%, II, 4.0% and 4.7%; and III, 8.9% and 4.2%. Ten digoxin-supplemented samples (0-8 mug/liter) were analyzed by the three methods. Correlation coefficients were: supplemented sample vs. I, O.99; supplemented sample vs. II, 0.97; supplemented sample vs. III, 0.98.
Sample Stability: A Suggested Definition and Medthod of Determination
Authors: Thiers Ralph E , wu Gaw T , Reed Allen H , Oliver Lawrence K
Published: January 2020

Volume 22

p 52, colunm 1: In two palces, "γ-GT/ml" should read "γ-GT/CC." In Figures 2 through 4 in this paper, the "X800" in the legend refers to the original magnification.

p 179: In Table 2, in the —20 °C experiment, the "test statistic" of samples 5 through 18 should be more negative by 0.5 and that of sample 24 should be —7.0 rather then —5.0. These change do not affect the conclusions.

p 197, column 1: In the first full paragraph, reference "(2)" should read "(21)."

p 777: In Figure 1, structures B and C should not contain an endocyclic double bond (structure A is correct)-i.e., the double bonds at the tops of the seven membered ring should be single bonds.

p 833: Corrections to this Table are detailed in a Letter to the Editor, p 1751, q.v.

p 1324: The drawing for Figure 2 has been interchanged with the drawing in the upper half of Figure 9, p 1327.

p 1427: Richard S. Schifreen should be listed as an author.

p 1745, column 1: The [3H]cortisl belongs to ref. 1, and was not supplied by Diagnostic Products Corp.

p 1751, column 3, first paragraph: 9.7 mg/liter should read 0.7 mg/liter.
Evaluation of a discrete-sample computer-directed clinical analyzer.
Authors: Forrester R L , Collinge W , Hashimoto P , Worrall J
Published: January 2020

The operational characteristics of the Gilford System 3500 were evaluated for six months as to accuracy, precision, carry-over, reliability, and ease of operation. Accuracy was evaluated by comparison to manual methods of established accuracy. The tests evaluated and their respective correlation coefficients are as follows: glucose (0.99), blood urea nitrogen (0.99), calcium (0.97), total bilirubin (0.99), aspartate aminotransferase (0.97), alkaline phosphatase (0.98), albumin (0.96), and total protein (0.96). Within-run precision (CV) for three commercial calibration sera of differing analyte concentrations (low, intermediate, and high) were respectively: 0.69, 1.02, 1.18; 5.4, 1.2, 1.09; 0.83, 0.77, 0.86; 5.9, 1.0, 0.86; 6.4, 5.2, 2.1; 3.7, 1.5, 1.3; 0.0, 1.4, 0.97; and 1.2, 1.3, 0.75. Day-to-day precision, similarly evaluated during 101-164 days, met accepted criteria for clinically acceptable precision. Carry-over for each of the eight tests was less than 1%. Instrument reliability has been excellent, and training time is short. In summary, we have found the Gilford System 3500 to be sufficiently precise and fast, easy to operate, highly accurate, and flexible.
Stability of fatty acids in hyperlipoproteinemic plasma during long-term storage.
Authors: Hirsch E Z , Slivka S , Gibbons A P
Published: January 2020

Aliquots of hyperlipoproteinemic plasma were stored at -20 degrees C in a nitrogen atmosphere with added disodium ethylenediaminetetraacetate for up to one year, to determine the stability of fatty acids in the four major lipid classes under these conditions. Assays were performed at zero time and at 2, 5, and 12 months. No uniform fatty acid change was found. Minor statistically significant changes were found in total triglyceride fatty acids and in some of the individual fatty acids in cholesterol esters, phospholipid, and free fatty acids. These minor changes could not be accounted for by plasma lipid concentrations, lipolysis, or fatty acid peroxidation. Evidently, plasma can be stored in this manner for as long as a year without substantial change in fatty acids in any of the four major lipid classes.
Preparation of optically clear lyophilized human serum for use in preparing control material.
Authors: Proksch G J , Bonderman D P
Published: January 2020

We describe a simple, rapid process--which includes the specific precipitation of pre-beta and beta-lipoproteins with dextran sulfate and divalent metal ions--for preparing an optically clear human serum that retains its clarity upon reconstitution with water after having been frozen and lyophilized. Such serum contains the normal constituents of human serum, except for the removed lipoproteins. The process causes no apparent interference with results of analyses for 22 of the more commonly measured constituents. Fresh or aged pooled serum or blood-bank plasma containing acid-citrate-dextrose or citrate-phosphate-dextrose are equally suitable as raw materials. This stabilized serum is an excellent matrix for use in preparing standards and quality-control material for assay of components of human serum.
Kinetic determination of serum lipase activity with the Abbott ABA-100.
Authors: Feld R D , Witte D L , Barrett D A
Published: January 2020

A turbidimetric procedure for lipase has been adapted for use on the Abbott Bichromatic Analyzer (ABA-100). The method is rapid and results compared well with those by the more traditional method of Cherry and Crandall [Am. J. Physiol. 100, 266 (1932)]. Advantages of this method include shorter incubation time (2 min), smaller sample size (50 mul), neglible interference from bilirubin, and greater dynamic range (to eightfold normal).
Radioimmunoassay of antibiotics and chemotherapeutic agents.
Authors: Broughton A , Strong J E
Published: January 2020

Theapeutic monitoring of drugs has become of major importance and has stimulated development of new assay systems. Chemotherapeutic agents, many of which are toxic, have until recently been assayed by microbiological systems or other complex techniques that are impractical for a clinical laboratory. Radioimmunoassays have now been developed for some of these agents. We review the techniques for producing hapten protein conjugates and radiolabeling at specific sites on the drug molecule, and the use of these assays in clinical medicine and pharmacology.
Radioimmunoassay, enzyme immunoassay, spectrophotometry, and gas-liquid chromatography compared for determination of phenobarbital and diphenylhydantoin.
Authors: Spiehler V , Sun L , Miyada D S , Sarandis S G , Walwick E R , Klein M W , Jordan D B , Jessen B
Published: January 2020

Sera from epileptic patients were assayed for phenobarbital and diphenylhydantoin by four different analytical procedures. Quantitative results obtained by radioimmunoassay (I) and enzyme immunoassay (II) were compared to each other and to the results obtained on aliquots of the same sample by gas-liquid chromatography (III) and ultraviolet spectrophotometry (IV). For phenobarbital the correlation coefficients were I vs. II, 0.909; I vs. III, 0.947; II vs. III, 0.917; I vs. IV, 0.950; II vs. IV, 0.953. For diphenylhydantoin the correlation coefficients were I vs. II, 0.953; I vs. III, 0.951; II vs. III, 0.957; I vs. IV, 0.862; II vs. IV, 0.898. The immunoassays can be substituted for liquid chromatography or ultraviolet spectrophotometry without changing the resulting clinical interpretations.
Liquid chromatographic method for monitoring therapeutic concentrations of L-dopa and dopamine in serum.
Authors: Riggin R M , Alcorn R L , Kissinger P T
Published: January 2020

We describe a new method for the simultaneous assay of 3,4-dihydroxyphenylalanine (L-dopa) and dopamine in serum. Both compounds have been determined quantitatively at concentrations as low as 10 mug/liter with a coefficient of variation of less than 4%. Peak heights were linearly related to concentration up to 10 mg/liter for each compound. Assay of human sera gave within-run and day-to-day coefficients of variation of 2.8% and 3.1% for L-dopa, and 2.9% and 3.7% for dopamine. The linear relationship between readings nA, y-axis) and concentration (mug/liter) is described by the following equations: y = (21.0 +/- 0.082)x + (0.46 +/- 0.31 SD) for L-dopa and y = (17.0 +/- 0.10)x + (0.08 +/- 0.04 SD) for dopamine. The procedure combines liquid/solid extraction, liquid chromatography, and controlled-potential electrochemistry. The simplicity, sensitivity, and accuracy of this method make it suitable for routine clinical analysis of serum samples to optimize bioavailability for individual patients. After the extraction procedure is completed, samples can be analyzed at the rate of 10/h.
Relative merits of some methods for amphetamine assay in biological fluids.
Authors: Bost R O , Sutheimer C A , Sunshine I
Published: January 2020

We describe principles and details that we use for amphetamine determination in blood and urine by photometric, thin-layer chromatographic, gas-chromatographic, and immunologic (EMIT and radioimmunoassay) procedures. Results, interferences, stabilities, and economic considerations are intercompared and recommendations are made.
Determination of ionized calcium in serum that has been exposed to air.
Authors: Wybenga D R , Ibbott F A , Cannon D C
Published: January 2020

We examined changes in ionized calcium concentration in serum after its exposure to air. Samples with total protein concentrations ranging from 50 to 90 g/liter were equilibrated with CO2 in nitrogen (5/95, by vol) or CO2 alone, to produce pH values of 7.0 to 8.0. Ionized calcium was then measured with an Orion flow-through electrode system. Curves relating pH and ionized calcium concentration had statistically identical slopes regardless of protein concentration. A factor was derived, based on pH change, for correcting values for ionized calcium in serum exposed to air, and its validity was confirmed by comparing corrected values for samples allowed to stand at ambient temperature (23 degrees C) without anaerobic precautions with values initially obtained on anaerobic aliquots of the same samples.
Automated approach to radioimmunoassays of somatotropin (human growth hormone) and insulin.
Authors: Green G , Dyce D , Gimovsky A , Lo D H
Published: January 2020

The adaptation of human somatotropin and insulin assays to the automated Centria radioimmunoassay system [Clin. Chem. 21, 1305 (1975)] is reported. For the somatotropin assay, reaction conditions include a borate/bovine serum albumin buffer (pH 8.4) AND 20-H Incubation at 4 degrees C. Assay results for clinical samples compared favorably (correlation coefficient = 0.930) with values obtained from a reference laboratory. The means determined for 92 patients' samples were 4.3 mug/liter (reference laboratory) and 5.1 mug/liter (Centria). Intra- and inter-run precision ranged from 3.2 to 15.9%. For the insulin assay, a phosphate/bovine serum albumin buffer (pH 7.4) is used, with a 20-h incubation at 4 degrees C. Previously analyzed insulin samples from a reference laboratory were determined by the Centria analyzer with excellent correlation (r = 0.965). Means for patients' samples were 43.0 milli (USP) units of insulin per liter (reference laboratory) and 47.5 milliunits of insulin per liter (Centria). In both assays an anionicexchange gel is used in the separation step. The criterion of parallelism, an indication of the validity of a radioimmunoassay, was satisfied in both assays. The Centria radioimmunoassay system offers the advantage of automating all the critical steps of these radioimmunoassays.