bluuebunny/crossref_metadata_2025 huggingface dataset:
Total lactate dehydrogenase and its isoenzymes in serum in the presence of penicillamine and other sulfhydryl compounds.
Authors: Gershbein L L , Raikoff K G
Published: January 2020

Toward delineation of changes in total lactate dehydrogenase (LDH) and in the distribution of LDH isoenzymes as assessed by polyacrylamide disc electrophoresis, we inbucated human and rat sera with various agents, notably sulfhydryl compounds. Although artefacts were apparent when these agents were used without preliminary adjustment of pH, we saw little alteration in total unitage when one or two volumes of serum was mixed with one volume of any of several thiols, especially penicillamine, at an initial concentration of 0.4 mol/liter and pH 7.0-7.5. Under these conditions, penicillamine caused a loss in LDH-5 after incubation for 1 h at 25 degrees C together with small decreases in mobility of the other four isoenzymes toward the anode. A zymosan region appeared below the albumin and tracking dye area. With longer periods of incubation of rat serum with penicillamine or alpha-mercaptosuccinate, a novel band in the zymogram was noted just above the LDH-4 peak. The observations are discussed in terms of allosteric effectors.
Fluorometric estimation of triglycerides in serum by a modification of the method of Bucolo and David.
Authors: Rietz E B , Guilbault G G
Published: January 2020

An enzymic, flurometric method is described for determination of triglycerides (and glycerol) in blood serum, a modification of the method of Bucolo and David [Clin. Chem. 19, 476 (1973)]. Commercially available reagent kits are used. The rate of disappearance of NADH fluorescence at 460 nm (excitation wavelength, 365 nm) is monitored and related to serum triglyceride concentration, corrected for the content of free glycerol. We compared the results obtained fluorometrically to the ultraviolet spectrophotometric Boehringer Neutral Fat method used at Gentofte Hospital, Copenhagen. Instrument response and concentration were linearly related in the range 0.27 to 2.7 mmol of triglycerides per liter of serum with the fluorometric method. The CV was 0.9% for the fluorometric method, 3.7% for the spectrophotometric procedure. The fluorometric method requires less reagents, time, and calculations than does the spectrophotometric method.
Urinary free norepinephrine and dopamine determined by reverse-phase high-pressure liquid chromatography.
Authors: Mell L D , Gustafson A B
Published: January 2020

We used reverse-phase high-pressure liquid chromatography to measure free norepinephrine and dopamine simultaneously in human urine. Samples were treated with alumina, and the catecholamine(s) then eluted from it were directly injected onto a reverse-phase column (octadecyl-silica stationary phase), with 0.17 mol/liter acetic acid as the mobile phase and ultraviolet detection at 280 nm. The assay detects concentrations in urine as low as 5 mug/liter. Assay of 24-h urines (n = 10) gave within-run and day-to-day coefficients of variation of 3.7 and 4.7% for norepinephrine, and 2.6 and 3.5% for dopamine, respectively. Comparison studies with the traditional trihydroxyindole fluorometric method showed the liquid-chromatographic procedure to be more precise and subject to less interference. This relatively rapid procedure for urinary free norepinephrine and dopamine provides an efficient, reproducible method, readily adaptable to routine clinical use.
Interference of sodium azide with measurement of serum uric acid by the direct acid ferric reduction procedure.
Authors: Liu T Z , Khayam-Bashi H
Published: January 2020

We examined the effect of sodium azide on the quantitation of serum uric acid by the direct acid ferric reduction procedure. Ferric phenanthroline was used as redox indicator. Sodium azide, in a concentration commonly used as preservative (2 g/liter, 27.2 mmol/liter), increased the absorption at 505 nm and increased apparent uric acid values in specimens, as shown by calculations based on an azide-free standard. Spectral studies indicated that this interference was a result of the color produced by sodium azide in the reaction mixture. The mechanism for azide interference was the interaction of sodium azide and ferric ions to form ferric azide, which also absorbs extensively at 505 nm.
Micro-scale anticonvulsant assay with use of nitrogen/phosphorus detector and on-column methylation compared with a macro-scale procedure involving flame-ionization detection.
Authors: Least C J , Johnson G F , Solomon H M
Published: January 2020

We report a modified micro-scale gas-chromatographic procedure for determining phenobarbital, primidone, and diphenylhydantoin in serum with use of a nitrogen/phosphorus detector. Serum, 20 mul, is extracted into chloroform, the solvent is evaporated, and the residue dissolved in dilute (32 mmol/liter) trimethylanillinium hydroxide, which yields the methyl-derivatives of the drugs upon on-column injection. Within-run precision (CV) for the three drugs was 1.0, 2.1, and 1.4+, respectively, at concentrations of 19.2, 13.2, and 18.9 mg/liter; run-to-run precision at these concentrations was 4.4, 3.8, and 2.8%. Comparison of the 20-mul micro-scale procedure (y) with our conventional, flame-ionization macro-scale procedure (x), in which on-column methylation is used and which requires 1 ml of serum, gave the following respective results: y = 1.01 X -- 0.16 mg/liter, r = 0.992, y = 1.02 X + 0.29 mg/liter, r = 0.973; and y = 0.96x + 0.04 mg/liter, r = 0.996.
Diagnostic Effectiveness of Biochemical Liver-Function Tests, as Evaluated by Discriminant Function Analysis
Authors: Sher Paul Phillip
Published: January 2020

I evaluated the diagnostic value of routinely ordered liver-function tests in 175 biopsy-proven cases of hepatic disease by use of stepwise discriminant analysis. The tests studied—total and "direct" bilirubin, alkaline phosphatase, lactate dehydrogenase, and aspartate aminotrans-ferase—correctly classified 45-73% of cases, depending on the homogeneity of the diagnostic groups. Aspartate aminotransferase and alkaline phosphatase were the best discriminators. When all tests were used in the most ho-mogeneous groups (tumors, cirrhosis, and hepatitis), there was a stepwise improvement in diagnostic accuracy from 51 to 73%.
Separation of Tissue and Serum Acid Phosphatase lsoenzymes by Ion-Exchange Column Chromatography
Authors: Mercer Donald W
Published: January 2020

I describe a simple, rapid ion-exchange column-chroma-tographic technique for separating the acid phosphatase (EC 3.1.3.2) isoenzymes in human serum and tissue. Ex¬tracts of platelets, spleen, liver, erythrocytes, and prostate were used to determine optimum conditions for separating these isoenzymes. Samples layered on mini-columns of DEAE-Sephadex A-50 were eluted stepwise with sodium chloride (100, 200, and 300 mmol/liter, buffered with tris(hydroxymethyl)aminomethane). Activity in column effluents was measured with p-nitrophenol phosphate as substrate, and their isoenzyme content was assessed by electrophoresis on polyacrylamide gel. Comparison of activity patterns so derived for various tissues revealed prostatic tissue to be a rich source of acid phosphatase isoenzyme 2 activity. Evaluation of sera from six patients with prostatic cancer revealed isoenzyme patterns with prominent amounts of isoenzyme 2 (3.8 to 27.6 U/liter). Sera from 10 healthy laboratory technicians contained isoenzyme 2 in the range of 0.3-0.5 U/liter. Samples from two patients with abnormally high activity owing to non¬prostatic conditions (Gaucher's disease and carcinoma of lung) exhibited less than 2 U of isoenzyme 2 per liter and acid phosphatase isoenzymes 3-5 that were 50- to 100-fold the normal range. Quantification of isoenzyme 2 by DEAE-Sephadex column chromatography as de¬scribed appears to provide a more sensitive and specific approach to diagnosis of prostatic cancer.
New Approach to Evaluation of Proteinuric States
Authors: Ellis Demetrius , Buffone Gregory J
Published: January 2020

We evaluated the use of immunonephelometric methods for measuring specific urinary proteins. Using a nephe¬lometer to detect light scattering (angle, 31'1, we mea¬sured some proteins immunonephelometrically in serum and aliquots of 24-h urines from 50 apparently healthy children, ages 2-17 years. The mean urinary excretion rate (mg/24 h) and the range of values was: for albumin 5.5 (range, 0-13.3), for transferrin 0.5 (0-1.9), for IgG 3.3 (0-12), and for a2-macroglobulin 0.6 (0-2.3). Direct comparison of the values for pathological urines with those for a reference population may offer more meaningful information concerning the integrity of the glomerular basement membrane than is provided by protein selectivity indices, and measuring a plasma protein such as albumin in urine may better define pathological proteinuria.
A Radioimmunoassay for Serum Ferritin
Authors: Luxton Allan W , Walker William H C , Gauldie Jack , Ali Mahmoud A M , Pelletier Catharine
Published: January 2020

We describe the development and evaluation of a serum ferritin radioimmunoassay, in which 125l-labeled ferritin and rabbit anti-ferritin antibody are used. Goat anti-rabbit gamma-globulin antibody, together with polyethylene glycol, is used as the separating reagent. The assay has a working range up to 500 µg of ferritin per litre, and a sample requirement of 75 µl of serum for assay at two dilutions. The assay requires 24 h. It has a sensitivity of 1.5 ,ug of ferritin per litre and a long-term precision (CV) of 13%. Reference intervals for a population of men were 18-330 µg/litre, with no marked age dependence, while those for a population of women older than 50 years were 18-200 Agate. Many apparently healthy women in the 20-50 year age group have much lower concentrations. Serum ferritin concentrations of <18 Agilitre are indicative of iron deficiency, defined as the absence of stainable iron in an aspirate of bone marrow.
Evaluation of a New Automatic Calcium Ion Analyzer
Authors: Madsen SØren , ⵁlgaard Klaus
Published: January 2020

We evaluated a new automatic analyzer for ionized cal¬cium (Ca2+), the Orion Model SS-20, based on a flow-through ion-exchange electrode. Ca2+ was measured in heparinized whole blood and serum. Within-day variation was 1.2%, day-to-day variation 1.6 %, and analytical re-covery 92.4%. Over the physiological range interference by K± and Mg2+ was negligible; major changes in ionic strength, induced by changes in Na+ concentration, made correction for a sodium error necessary. Within the physiological range, Ca2+ was inversely correlated to variations in pH. Therefore, to compare Ca2+ values, correction to an apparent pH of 7.40 should be made. The calcium binding effect of heparin was negligible when minimal (4.4 int. units/m1) concentrations of heparin were used. Storage of serum at 4 °C for one week resulted in a 4% decrease in apparent serum Ca2+, primarily owing to an increase in pH during storage. In normal material, mean values for blood- and serum-Ca2+ (1.10 and 1.07 mmol/liter, respectively) were close to results obtained by previous systems. Errors caused by disturbances in the fluid flow and non-function of half the electrodes we re¬ceived were the major inconveniences of the analyzer. We conclude that this new analyzer gives decisive advantages in measurement of Ca2+, making this important analysis possible as a routine laboratory test for the first time
Analysis for Procainamide and N-Acetyl Procainamide in Plasma or Serum by High-Performance Liquid Chromatography
Authors: Rocco Richard M , Abbott Donald C , Giese Roger W , Karger Barry L
Published: January 2020

A high-performance liquid chromatographic method is presented for simultaneous analysis for procainamide and N-acetyl procainamide in plasma or serum. The procedure involves internal-standard addition, organic extraction, and separation on a reversed-phase column. The detection limit for procainamide is 0.1 mg/liter and the calibration plot is linear to at least 30 mg/liter. Comparison with a colorimetric assay for procainamide gave a correlation coefficient of 0.989. We checked for interference by a large series of appropriate drugs, and found none, nor did icteric or lipemic sera present problems
Spectrophotofluorometric Assay for Isoniazid and Acetyl Isoniazid in Plasma Adapted to Pediatric Studies
Authors: Olson William A , Dayton Peter G , Israili Zafar H , Pruitt Albert W
Published: January 2020

We modified the micro-scale spectrophotofluorometric method of Miceli et al. [Biochem. Med. 12, 348 (1975)] for the assay of "apparent" isoniazid (isoniazid plus acid-labile hydrazones) to improve its clinical application. We also adapted the method for determination of acetyl isoniazid. Data are presented showing how long plasma containing isoniazid may validly be stored. The applicability of the method was demonstrated in studies on children and small animals.
Use of Tetramethylbenzidine in Plasma Hemoglobin Assay
Authors: Standefer J C , Vanderjagt Dorothy
Published: January 2020

Plasma hemoglobin can be assayed by substituting 3,3',5,5'-tetramethylbenzidine for benzidine (a carcinogen) as the chromogenic reducing substance. Sensitivity, precision, and accuracy compare well with methods in which benzidine is used. Plasma inhibition can be ac¬commodated by preincubation with hydrogen peroxide.
Interference with the Enzymic Measurement of Cholesterol in Serum by Use of Five Reagent Kits
Authors: Pesce Michael A , Bodourian Selma H
Published: January 2020

We describe the effects of uric acid, hemolysis, drugs, ascorbic acid, lipemia, and bilirubin on the enzymic measurement of cholesterol in serum by use of reagent kits from Abbott, Beckman, Boehringer Mannheim, Cal¬biochem, and Worthington. In all of these, the chromogen formed from the reaction of hydrogen peroxide with phenol and 4-aminoantipyrene is measured. The absorbance was measured at 500 nm vs. a serum blank for each kit—except Abbott's, with which the recorded absorbances were the differences between readings at 500 and 600 nm. With all reagent kits, there was no interference from uric acid up to 200 mg/liter, hemoglobin up to 1.0 g/liter, or drugs (clofibrate, phenobarbital, Ketochol, Ovral-28), but negative interferences from ascorbic acid. Except for the Abbott kit, the cholesterol values obtained for lipemic samples were lower than found with the comparison method [Abell et al., Stand. Methods Clin. Chem. 2, 26 (1958)]. With Abbott's reagent, for most lipemic samples, the values were the same. Bilirubin at concentrations of 200 mg/liter significantly decreased the cholesterol values with Beckman, Calbiochem, and Worthington reagent kits. With Boehringer Mannheim reagent a small negative in¬terference was observed and with Abbott reagent a small positive interference was observed when the bilirubin concentrations were 200 mg/liter.
Solid-phase enzyme immunoassay for hepatitis B surface antigen.
Authors: Wei R , Knight G J , Zimmerman D H , Bond H E
Published: January 2020

A solid-phase enzyme immunoassay is described for measuring hepatitis B surface antigen in human serum or plasma. Immunologically purified antibody labeled with horseradish peroxidase was used as the indicator. In the assay system, antibody-coated controlled-pore glass is used as a solid support and there are three sequential incubations, totaling 2 h, at room temperature. Results for serially diluted positive and reference sera compare favorably to radioimmunoassay in sensitivity and specificity.
Amylase activity in serum and urine: comparison of results by the amyloclastic, dyed-starch, and nephelometric techniques.
Authors: Lehane D P , Wissert P J , Lum G , Levy A L
Published: January 2020

We assayed serum and urine specimens for amylase activity by the nephelometric (I),dyed-starch (Amylochrome) (II), and mayloclastic (III) techniques. For serum, the correlation coefficients of the regression lines were: I vs. II, 0.978 (n = 106); I vs. III, 0.736 (n = 110); and II vs. III, 0.739 (n = 108). For urine, they were I vs. II, 0.938 (n = 49); and I vs. III, 0.752 (n = 46). Because calculation of the Kolmogorov-Smirnov statistic showed the distributions to be nongaussian, Spearman rank correlation coefficients were determined and showed that I and II correlated well but neither method correlated with III. The clinical data show that I and II gave above-normal activities in every case of pancreatitis, but III gave normal values in two of eight cases. In all cases, I and II were more sensitive, giving higher amylase activities (as compared with the upper limit of normal) than did III. The nephelometric procedure is most suitable for routine and emergency testing; the dyed-starch assay is equally sensitive and reliable, but less convenient. The amyloclastic procedure appears to be less reliable.
Canaline carbamoyltransferase in human liver as part of a metabolic cycle in which guanidino compounds are formed.
Authors: Natelson S , Koller A , Tseng H Y , Dods R F
Published: January 2020

This and previous papers examine the reasons for the relationship between the concentrations of guanidino-succinate and guanidinoacetate in human urine. With the demonstration here that extracts of human liver-tissue can mediate ureidohomoserine formation from canaline [(2-amino-4-aminooxy)-butyric acid] and carbamoyl phosphate, all steps in a cycle proposed for the production of guanidinoacetate and guanidinosuccinate have been documented. This includes synthesis of canavaninosuccinate from aspartate and ureidohomoserine, reductive cleavage of canavaninosuccinate to form guanidinosuccinate and homoserine, or, alternatively, lytic action on canavaninosuccinate to form fumarate and canavanine, and transamidination to glycine to form guanidinoacetate, regenerating the canaline. We propose that canaline originates from aspartate, but the precise mechanism by which canaline is formed needs to be elucidated.
Immunochemical determination of human lysozyme by laser nephelometry.
Authors: Goudswaard J , Virella G
Published: January 2020

The methods currently available for quantitative determination of lysozyme are based on the capacity of the enzyme to lyse Micrococcus lysodeikticus. Previous attempts to develop immunochemical assays have been reported, but the sensitivity was inferior to that of the most widely used lysoplate method. We describe the development of a sensitive immunochemical method for lysozyme assay in which the recently developed laser nephelometer is used. The sensitivity so achieved is at least comparable to that of the lysoplate method, and in some circumstances better. Results obtained by the lysoplate assay and the nephelometric assay correlate well. Among the advantages of our method are easier handling of larger numbers of samples, quicker results, and the possibility of assaying enzymatically inactive forms of the enzyme.
Assessment of a method for measuring serum thyroxine by radioimmunoassay, with use of polyethylene glycol precipitation.
Authors: Farid N R , Kennedy C
Published: January 2020

We assessed the efficacy of a new thyroxine radioimmunoassay kit (Abott) in which polyethylene glycol is used to separate bound from free hormone. Mean serum thyroxine was 88 +/- 15 (+/-SD) microgram/liter for 96 normal persons. Results for hypothyroid and hyperthyroid persons were clearly separated from those for normal individuals. Women taking oral contraceptive preparations showed variable increases in their serum thyroxine values. The coefficient of variation ranged from 1 to 3% within assay and from 5.4 to 11% among different assays. Excellent parallelism was demonstrated between thyroxine values estimated by this method and those obtained either by competitive protein binding or by a separate radioimmunoassay for the hormone.
Separation of hydroxyproline-containing protein from C1q (a subcomponent of complement) in serum.
Authors: Rosano C L , Hurwitz C
Published: January 2020

Precipitation of the euglobulin fraction from serum separates C1q from another hydroxyproline-containing protein(s), which remains in the serum-minus-euglobulin fraction. The presence of C1q in the euglobulin fraction has been verified by radial immunodiffusion assay, by sensitivity to collagenase, by hydroxyproline content, and by electrofocusing. The presence of another hydroxyproline-containing protein(s) in the serum-minus-euglobulin fraction has been verified by the same criteria. The isoelectric pH range of C1q is 6.1-7.0; the isoelectric pH range of the other hydroxyproline-containing protein(s) is 4.2-5.5.
Impact of posture on the "reference range" for serum proteins and calcium.
Authors: Humphrey K R , Gruemer H D , Lott J A
Published: January 2020

The impact of water shifts due to changes in posture has been reinvestigated for serum protein and calcium concentrations in a young, healthy population. We found that generaly accepted normal ranges for total serum protein, and to a lesser degree for total serum calcium, are not acceptable as a reference range for a hospitalized population that is predominantly in a supine position. Our data indicate a smaller biological variability for total protein and calcium for a reference population in the recumbent posture as compared to the same population in the upright position.
Enzyme-coupled measurement of uric acid in serum with a centrifugal analyzer.
Authors: White R M , Cross R E , Savory J
Published: January 2020

An early-reading blank-corrected end-point determination of uric acid in serum has been developed for use with a centrifugal analyzer. The method is based on a modification of the uricase (urate:oxygen oxidoreductase, EC 1.7.3.3)/catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase EC 1.11.1.6)/aldehyde dehydrogenase (aldehyde:NAD(P)+ oxidoreductase, EC 1.2.1.5)-coupled analytical scheme reported by Haeckel [Z. Klin. Chem. Klin. Biochem. 14, 101 (1976)]. Sensitivity and precision of the method are excellent, and results compare well with those obtained by the Kageyama procedure [Clin. Chim. Acta 31, 421 (1971)].
Phospholipid composition of blood plasma, erythrocytes, and "ghosts" in sickle cell disease.
Authors: Schwarz H P , Dahlke M B , Dreisbach L
Published: January 2020

We examined the phospholipid composition of the plasma, of whole erythrocytes, and of "ghosts" of the erythrocytes from healthy volunteers, patients with sickle cell disease without crisis, and such patients in crisis, and found that phosphatidylglycerol in the plasma and "ghosts" was very significantly increased in sickle cell crisis but not in the absence of crisis. The significance of these findings is discussed.
Lysozyme determined in serum or urine by a simple nephelometric method.
Authors: Borgen J , Romslo I
Published: January 2020

We describe a nephelometric procedure for determination of lysozyme. A quantitative result is obtained in 2 to 3 min with 50 microliter of serum or urine. At a lysozyme concentration of 12.0 mg/liter, between-day precision was 3.4% and the analytical recovery 96.5-105.5%. The values obtained were a linear function of enzyme concentration below 50 mg/liter, and they agreed with those obtained by absorptiometric determination of the decrease in turbidity of a suspension of Micrococcus lysodeikticus.
A fetal intestinal-type alkaline phosphatase in hepatocellular carcinoma tissue.
Authors: Higashino K , Otani R , Kudo S , Yamamura Y
Published: January 2020

We examined 19 hepatoma tissues for alkaline phosphatase isoenzyme and found that six have both the Kasahara isoenzyme and an alkaline phosphatase with a unique electrophoretic mobility, in addition to the liver-type enzyme. From two of six carcinoma tissues, the abnormal enzyme was partly purified and subjected to a detailed analysis, which clarified that the abnormal enzyme resembled a fetal intestinal alkaline phosphatase in most of its enzymic and immunologic properties and also in properties that reflect enzyme structure. This fetal intestinal-type alkaline phosphatase was not found in 24 specimens of normal liver from adults. The relevance of fetal intestinal-type alkaline phosphatase to Kasahara isoenzyme and adult intestinal alkaline phosphatase is discussed. The fetal and adult intestinal alkaline phosphatases differ in electrophoretic mobility, heat stability, and reactivity with concanavalin A. The adult-type enzyme has two components; only the electrophoretically slower, neuraminidase-resistant one is described here.
Double-antibody radioimmunoassay for factor VIII-related antigen.
Authors: Green D , Reynolds N
Published: January 2020

A plasma protein required for the support of ristocetin-induced platelet aggregation was isolated from antihemophilic factor concentrate and radiolabeled with 125I. A double-antibody radioimmunoassay was developed, with use of specific rabbit anti-VIII related antigen serum and goat anti-rabbit globulin. The assay is sensitive, reproducible, and technically simple to perform. Values obtained in normal subjects ranged from 0.65 to 1.53 units, similar to our normal range for VIII coagulant activity (0.67-1.43 units). However, normal or increased values of VIII-related antigen were observed in VIII coagulant-deficient hemophiliacs. Also, concentrations of VII-related antigen significantly exceeded coagulant concentrations in several patients with liver disease or disseminated intravascular coagulation, or both. Of a broad selection of congenital coagulation disorders examined, only patients with von Willebrand's disease had decreased VIII-related antigen concentrations, and these corresponded to the lowered concentration of ristocetin cofactor in the patients. In three transfused patients, VII-related antigen values correlated with the concentration of the cofactor. Our results suggest that the radioimmunoassay of VIII-related antigen is a simple and valuable adjunct in the study of patients with clotting abnormalities.
The sulfophosphovanillin reaction for serum lipids: a reappraisal.
Authors: Johnson K R , Ellis G , Toothill C
Published: January 2020

New evidence is presented for the mechanism of this reaction, which is used in estimating lipids. The reaction occurs in two stages: (a) Stage 1 evidently involves an oxidation step, forming a specific type of carbonium ion called an alkenyl cation of the general formula R--C+--C==C--R' (previous evidence had indicated that a carbonium ion of general formula R--C+--R' was formed by protonation only.) (b) Stage 2 of the reaction was examined by nuclear magnetic resonance studies and by partition experiments, which have indicated that a vanillin phosphate ester is not formed as previously suggested. Comparative data from other acid-aldehyde reactions indicate that in this reaction 1,1-di(4-hydroxy-3-methoxy phenyl)ethylene ion is formed, a product compatible with the formation of an alkenyl cation at stage 1.
Simultaneously obtained skin-puncture serum, skin-puncture plasma, and venous serum compared, and effects of warming the skin before puncture.
Authors: Blumenfeld T A , Hertelendy W G , Ford S H
Published: January 2020

Specimens of skin-puncture serum and plasma and venous serum were simultaneously obtained from healthy adults and in each specimen the concentrations of 12 chemical constituents were measured. No clinically important difference was found in the concentrations of the constituents measured in skin-puncture serum and plasma with or without warming the skin before puncture. When the concentration of each of the measured constituents was compared in skin-puncture specimens and venous serum there were important differences in the concentrations of glucose, potassium, total protein, and calcium. Except for glucose, the concentrations of these were higher in venous serum. The degree of hemolysis was the same in skin-puncture serum and plasma, but less in venous serum. The greater hemolysis in skin-puncture specimens was not reflected in a clinically important increase in the values of lactate dehydrogenase and potassium. We conclude that there is a difference in the concentration of some chemical constituents in skin-puncture specimens and venous serum and that these differences should be considered when results for these types of specimens are compared.
Analytical performance and comparability of the determination of cholesterol by 12 Lipid-Research Clinics.
Authors: Lippel K , Ahmed S , Albers J J , Bachorik P , Cooper G , Helms R , Williams J
Published: January 2020

Twelve Lipid-Research Clinic laboratories performed automated cholesterol analyses on four control-serum pools of known cholesterol concentration, using the Liebermann-Burchard reaction. The analyses were done during a two-year period, with the same standards, methodology, and quality-control procedures. Estimates of analytical bias, variability, and short- and long-term trends for each instrument and for the entire group of LRC instruments are presented. High accuracy, precision, and interlaboratory comparability were achieved through the rigorous standardization and control of the entire analytical procedure. The significance of these results for long-term collaborative studies is discussed. Individual laboratory biases averaged from 0.5 to 2.0% below Abell-Kendall reference values. Between-run variability was about equal to within-run variability and inter-laboratory variation was substantially less than intra-laboratory variation. The total standard deviation for all instruments was about 0.04 g/liter. Only 8-15% of this variation was due to differences between instruments. The between-instrument standard deviation ranged from 0.011 to 0.015 g/liter; the between-run, within-instrument standard deviation ranged from 0.023 to 0.030 g/liter; and within-run standard deviation ranged from 0.023 to 0.028 g/liter. The significance of the achieved results for long-term collaborative studies is discussed.
Faster radioimmunoassay of angiotensin I at 37 degrees C.
Authors: Fyhrquist F , Puutula L
Published: January 2020

We applied a 1-h radioimmunoassay incubation at 37 degrees C in determining generated angiotensin I in an assay for plasma renin activity. Under these nonequilibrium conditions, 26% of the 125I-labeled angiotensin I was bound at zero dose of unlabeled angiotensin, as compared to 57% at equilibrium after 18 h at 4 degrees C. Sensitivity and useful range for the standard curve remained unchanged. Blanks were not altered. There was a good (r = .971) correlation between renin values in 120 plasma samples from hypertensive patients as measured with both procedures. With isoelectric focusing, we detected no damage to the labeled angiotensin I during incubation for 1 h at 37 degrees C in the presence of diluted plasma, disodium ethylenediaminetetraacetate, hydroxyquinoline, and neomycin. Analytical recovery of unlabeled angiotensin I added to the assay mixture was 98 +/- 2.3% (mean +/- SD). We conclude that our incubation conditions allow rapid and accurate assay of plasma renin activity to be completed in one working day.
Buffer-exchange column for rapid separation of carcinoembryonic antigen from perchloric acid.
Authors: Haagensen D E , Easterday R L , Stolle C A , Wells S A
Published: January 2020

A Sephadex G-50 medium (Pharmacia) buffer-exchange column has been developed for rapidly changing the medium for carcinoembryonic antigen from perchloric acid to acetate buffer. Analytical recovery of the extracted antigen exceeded 95%. Plasma for analysis can be so prepared and samples ready for analysis within an hour. The technique also results in uniform assay volume, thus eliminating this variable from the assay.
Plasma glucose measurement with the Yellow Springs Glucose Analyzer.
Authors: Chua K S , Tan I K
Published: January 2020

The Yellow Springs Glucose Analyzer, a device for the quantitative measurement of glucose concentrations, involves the use of immobilized glucose oxidase, incorporated on a membrane covering a hydrogen peroxide sensor. Operation of the instrument is simple. After an initial calibration, 25 microliter of plasma is injected into a reaction chamber. At 45 s a digital result for glucose is displayed. The within-batch coefficient of variation for the method is 1.2% or less for glucose concentrations of 0.94 to 3.98 g/liter. The between-batch coefficient of variation is 5.8% or less for glucose concentrations of 0.29 to 2.91 g/liter. Concentration and readout are linearly related to at least 4.6 g/liter. Analytical recoveries ranged from 100 to 102%. Carry-over was negligible. Values for glucose concentration obtained with the instrument compared well (r = 0.997) with those obtained with the Beckman Glucose Analyzer.
Lipoprotein cholesterol in the serum of children, as determined independently by two different methods.
Authors: Srinivasan S R , Ellefson R D , Whitaker C F , Berenson G S
Published: January 2020

We separately evaluated split specimens of serum for lipoprotein cholesterol in 38 five- to 14-year-old children, by the heparin/Ca2+ precipitation method and the ultracentrifugation/dextran sulfate precipitation method. Statistical analysis of the results indicated an excellent agreement (especially in beta- and alpha-lipoprotein cholesterol values) between results by the two methods. The percentage of alpha-lipoprotein cholesterol (mean +/- SD: 38.6 +/- 5.0) in children further confirmed the earlier observations that cholesterol derived from alpha-lipoprotein in children constitutes a relatively greater part of the serum total cholesterol than is true of adults.
Use of the Du Pont aca to measure cholesterol in high-density lipoprotein fractions prepared by the heparin/Mn2+ precipitation method.
Authors: Liedtke R J , Busby B , Batjer J D
Published: January 2020

The enzymatic cholesterol method used with the Du Pont aca has been modified to provide a reliable measurement of high-density lipoprotein cholesterol in serum after heparin/Mn2+ precipitation of the low- and very-low-density lipoproteins. Interference by Mn2+, equivalent to about 90 mg of cholesterol per liter, is decreased to less than 40 mg of cholesterol per liter by the presence of ethylenediaminetetraacetate (8 mmol/liter) in the diluent; the residual effect of Mn2+ is compensated by calibrating the aca with standards containing Mn2+ and heparin. With an 80-microliter sample, the sensitivity is 236 muA/mg per liter and linearity ranges from 50 to 1500 mg/liter. Average analytical recovery of cholesterol added to the high-density lipoprotein fraction was 103%. Diluted fractions give the expected results. Between-run reproducibility (CV) is 1.3 and 1.6% at 463 and 554 mg/liter. Correlation with the Lipid Research Clinics' procedure (25 samples) gave a regression line of y(aca) = 1.039x- 15, and a correlation coefficient of 0.997.
Evaluation of homogeneous enzyme immunoassay of serum thyroxine with use of bichromatic analysis.
Authors: Finley P R , Williams R J
Published: January 2020

We evaluated the homogeneous enzyme immunoassay ("EMIT") of serum thyroxine with use of an ABA- 100 Bichromatic Analyzer, modified with an auxiliary dispenser syringe and a dual probe assembly. The modification allows two reagents to be dispensed at one time. The sera must be pre-treated with 0.1 mol/liter NaOH. The procedure thereafter is entirely automated. Twenty-four patients' samples may be analyzed in 15 min of instrument time. Precision and accuracy are excellent, and results correlate well with those by radioimmunoassay.
Improved radiochemical assay for carnitine and its derivatives in plasma and tissue extracts.
Authors: Pace J A , Wannemacher R W , Neufeld H A
Published: January 2020

We describe the measurement of carnitine and short-chain and long-chain acylcarnitines in perchloric acid extracts of liver and muscle. [1-14C]Acetyl-CoA is used, and labeled acetylcarnitine is measured with a sensitivity of less than 1 to 50 nmol of L-carnitine per 50-microliter sample. Samples frozen at -20 degrees C lost no carnitine during several months. Analytical recovery of carnitine (5 nmol) added to 50-microliter perchloric acid extracts of liver was 103 +/- 2%. This method may be suitable for clinical applications such as screening patients with muscle and metabolic disorders.
Sensitive gas-chromatographic determination of fluphenazine in human plasma.
Authors: Franklin M , Wiles D H , Harvey D J
Published: January 2020

We describe a method for quantitative determination of fluphenazine in human plasma, based on gas chromatography of its trimethylsilyl derivative and the use of a structurally similar internal standard. We determined its concentrations in plasma of four patients who were receiving the drug intramuscularly as its decanoate, in doses ranging from 12.5 to 250 mg; the concentrations in the plasma of these patients ranged from 0.25 to 11.8 microgram/liter. The precision (CV) of the method over the range 2 to 17 microgram/liter was 6.8% when fluphenazine was extracted from 5 ml of plasma. Of 18 other drugs tested, only thioridazine and the cis and trans forms of flupenthixol interfere with the determination.
Automated metabolic profiling of organic acids in human urine. II. Analysis of urine samples from "healthy" adults, sick children, and children with neuroblastoma.
Authors: Gates S C , Sweeley C C , Krivit W , DeWitt D , Blaisdell B E
Published: January 2020

Normalized median, minimum, and maximum values (analytical concentration factors) are given for 134 organic acids in urine of nine adult control subjects, five juvenile control subjects, and five children with neuroblastoma. The organic acids, separated by anion-exchange chromatography, were analyzed by a gas chromatograph-mass spectrometer-computer system. Sixty substances in this fraction are positively identified, and, of these, mean absolute concentrations are listed for 20. An additional 81 substances, sought but not found by this method, and 16 other substances found in a subset of these urines by another analytical method, are also listed. Measured retention indices on 5% OV-17 and a selected discriminating ion are given for each of the total of 231 compounds. Results are compared for the three groups of subjects, and the value of normalizing the data is discussed.
Evaluation of a glassy-carbon electrode for amperometric detection of selected methylxanthines in serum after their separation by reversed-phase chromatography.
Authors: Lewis E C , Johnson D C
Published: January 2020

We examined the relative merits of direct-current, pulse, and differential pulse amperometry at a flow-through, glassy-carbon electrode used in monitoring column chromatography. We give a rapid, simple procedure for determining theophylline (1,3-dimethylxanthine) in 20--100 microliter of blood serum. Interference by 1,7-dimethylxanthine, a metabolite of caffeine, is compared for photometric and amperometric detection, and some advantages of combined photometric and amperometric detection are discussed.
Negative-ion mass spectrometry of amphetamine congeners.
Authors: Mårde Y , Ryhage R
Published: January 2020

Negative-ion chemical ionization mass spectrometry with a conventional combined gas chromatograph-mass spectrometer has been used for the analysis of amphetamine-like compounds. Ammonia was used as the reagent gas, which gives rise to few but specific sample-fragment ions, such as (M--1)- as the base peak, m/z 91, and a smaller peak corresponding to the end part of the side chain. Five reference compounds and a urine sample from an overdose case were analyzed. Comparative positive-ion chemical ionization reference spectra were also recorded.
Measurement of three aminoglycosiee antibiotics with a single radioimmunoassay system.
Authors: Ashby C D , Lewis J E , Nelson J C
Published: January 2020

A versatile radioimmunoassay procedure has been developed to specifically assay gentamicin, tobramycin, or amikacin. Iodinated derivatives of these three antibiotics were prepared by a modified Bolton and Hunter procedure. A single reagent system composed of a pool of three very specific antisera was used in the procedure. The antisera combination did not alter the specificity of the procedure. Validation of the assay of the three antibiotics included studies of parallelism, accuracy, precision, reproducibility, and method comparison with other radioimmunoassay procedures involving single antiserum systems. We discuss the application of this multiple assay capability to other procedures involving use of immunochemicals.
Neonatal thyroxine screening by use of a single-tube solid-phase radioimmunoassay.
Authors: Bell A B , Coleman L H
Published: January 2020

Filter paper discs saturated with dried blood can be used in the Immunotube solid-phase thyroxine radioimmunoassay. This assay utilizes polypropylene tubes to which antibody to thyroxine is covalently bound. The filter paper standards and samples are placed in the tubes, followed by an assay buffer that contains I125-labeled thyroxine and compounds to displace thyroxine from its binding proteins. After incubation, bound and free thyroxine are separated by aspirating or decanting the disc and buffer from the tube. The test can be used with 0.32 cm (1/8 inch) or 0.64 cm(1/4 inch) discs, and gives quantitative results that correlate well with those for serum samples. The intra-assay coefficient of variation is less than 10%. The assay may readily be mechanized with existing disc-punching equipment, and results of its use in mass screening programs are described.
Is serum cholinesterase activity a predictor of succinyl choline sensitivity? An assessment of four methods.
Authors: Evans R T , Wroe J
Published: January 2020

Four methods for measuring serum cholinesterase activity have been applied to sera of normal individuals and of patients shown to be sensitive to short-acting muscle relaxants of the succinyldicholine type. They have been assessed according to their ability to differentiate between sensitive and insensitive individuals on the basis of enzyme activity measurements alone. The method described, based upon that of Dietz et al. [Clin. Chem. 19, 1309 (1973)], in which propionylthiocholine is used as substrate, is best for this purpose, being capable of identifying over 90% of affected individuals with no false positives. Acetylcholine and butyrylthiocholine are slightly inferior substrates in this respect, and benzoylcholine gives little useful information.
Non-equilibrium enzyme immunoassay of gentamicin.
Authors: Mattiasson B , Svensson K , Borrebaeck C , Jonsson S , Kronvall G
Published: January 2020

We describe a fast, accurate non-equilibrium enzyme immunoassay for serum gentamicin. With use of isokinetic conditions an assay takes a total of 12 min, including regeneration of the immunosorbent. The coefficient of correlation between the present method and conventional microbiological assays was 0.98.
Interlaboratory Comparison of Lead and Cadmium in Blood, Urine, and Aqueous Solutions
Authors: Paulev Poul-Erik , Solgaard Poul , Tjell Jens Christian
Published: January 2020

Analysis for lead and cadmium in biological liquids (blood and urine) is difficult. Results of such analyses from five laboratories are compared for samples with known additions of lead and cadmium. The data, evaluated in terms of inter- and intralaboratory reproducibility and accuracy, suggest that laboratories should voluntarily participate in quality control programs. Users of routine laboratories are advised to use their own quality control program.
Simultaneous gas-chromatographic analysis for diazepam and its major metabolite, desmethyldiazepam, with use of double internal standardization.
Authors: Greenblatt D J
Published: January 2020

Electron-capture gas-liquid chromatography was used for simultaneous quantitation of plasma diazepam (I) and its major metabolite, desmethyldiazepam(II). Because concentrations of I can greatly exceed those of II after single doses of I, two benzodiazepine-analog internal standards were added to all samples, thereby allowing reliable quantitation of high concentrations of I and low concentrations of II. After extraction at neutral pH with benzene (containing isoamyl alcohol), the organic extract is evaporated and the residue is reconstituted in a small volume of solvent and chromatographed on a 3% OV-17 column. The sensitivity limits are 2 to 3 ng of I or II per milliliter of original sample, with a CV for identical samples of less than 5%. The applicability of the method to single-dose pharmacokinetic studies of I in humans is illustrated.
Interlaboratory comparison of lead and cadmium in blood, urine, and aqueous solutions.
Authors: Paulev P E , Solgaard P , Tjell J C
Published: January 2020

Analysis for lead and cadmium in biological liquids (blood and urine) is difficult. Results of such analyses from five laboratories are compared for samples with known additions of lead and cadmium. The data, evaluated in terms of inter- and intralaboratory reproducibility and accuracy, suggest that laboratories should voluntarily participate in quality control programs. Users of routine laboratories are advised to use their own quality control program.
A one-tube micromethod for radioimmunoassay of plasma cortisol.
Authors: Ellis G , Morris R
Published: January 2020

A micro-scale method is presented for measurement of cortisol. Serum or plasma, 2 microliter, is diluted with buffer and the solution heated at 60 degrees C in the presence of high-affinity antibody and [3H] cortisol. Corticosteroid-binding globulin in the serum is denatured, releasing cortisol and making it available to the antibody, which is stable during the incubation. After cooling, ammonium sulfate solution is added, followed by a toluene-based scintillant that does not dissolve in the aqueous phase. The vial is shaken to extract the free cortisol into the scintillant. Antibody bound cortisol remains in the aqueous phase and does not produce any scintillation. The amount of [3H] cortisol that is free at the end of the incubation, and which therefore gives rise to the measured counts, is related to the concentration of cortisol in the original serum, and may be calculated from a standard curve. The assay is sensitive and precise. Ranges are presented for normal and pathologic subjects.
Modification of the choriogonadotropin beta-subunit radioimmunoassay for determination of urinary choriogonadotropin.
Authors: McCready J , Braunstein G D , Helm D , Wade M E
Published: January 2020

The choriogonadotropin beta-subunit radioimminoassay has been used extensively to measure human choriogonadotropin in the sera of pregnant women and individuals with trophoblastic and nontrophoblastic tumors. Unmodified, this method cannot be used to measure choriogonadotropin in urine because of interfering substances. We circumvented the non-parallelism between the standards and serial dilutions of urine containing choriogonadotropin by adding pooled urine from men to the standard tubes and limiting the volume of urine to 100 microliter. This modified assay has a sensitivity of 3 int. units/liter of urine and is specific for choriogonadotropin concentrations of 40 int. units/liter of urine. Analytical recovery of choriogonadotropin added to urine ranged from 96 to 105%. The within-assay CV was 7.6%; the between-assay CV was 11.8%. Concentrations of choriogonadotropin in concurrently collected serum and urine samples from pregnant women correlated well. The test can be performed within 24 h by using the double-antibody method for separating bound from free hormone, or in 3 h with a dioxane method. The assay is about 20-fold more sensitive than the 2-min or 2-h slide and tube pregnancy tests, and seven-to 12-fold more sensitive than the radioreceptor assay.
Trace elements in scalp-hair of persons with multiple sclerosis and of normal individuals.
Authors: Ryan D E , Holzbecher J , Stuart D C
Published: January 2020

Scalp-hair samples from 40 multiple sclerosis patients and 42 controls were analyzed by neutron activation analysis, with a SLOWPOKE reactor as the neutron source. Ag, Al, As, Au, Ba, Br, Ca, Cl, Cu, l, K, Mg, Mn, Na, S, Sb, Se, Sr, V, and Zn were determined in samples of about 0.1 g. Highly significant differences (99% confidence) were observed between the two groups in concentrations of Cu, l, Mn, S, Se, and V.
Mechanized micro-scale determination of protein in platelet pellet sonicates.
Authors: Haff A C
Published: January 2020

With the method described here, samples can be assayed at the rate of 40/h, with increased reproducibility. As described, the method covers an analytical range of 1 to 7 g/liter, but it can be readily adapted to measure different ranges of concentration in other protein preparations.