bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of dehydroepiandrosterone sulfate in plasma by a one-step enzyme immunoassay with a microtitre plate.
Authors: Dhar T K , Müller C , Schöneshöfer M 
Published: January 2020

Abstract
We have developed a rapid and cost-effective enzyme immunoassay for dehydroepiandrosterone sulfate (DHEA-S) in plasma, performed with samples on a microtitre plate within 2.5 h. No extraction or centrifugation steps are involved. The 3-hemisuccinate of dehydroepiandrosterone is labeled with horseradish peroxidase, then mixed with hydrogen peroxide substrate in the presence of the chromogen, tetramethylbenzidine. The detection limit of the assay is 12.5 pg of DHEA-S per well. Intra- and interassay CVs at three steroid concentrations (12.8, 1.28, and 0.16 mumol/L) ranged from 2.3 to 5.4% and 6.1 to 8.4%, respectively. Results correlated well (r = 0.95) with those of a radioimmunoassay with iodinated DHEA-S. The turnaround time for 41 samples (in duplicate) is 2.5 h, which includes 2 h of incubation time. The sensitivity of this one-step version and the linearity of its standard curve are equivalent to those of a less practicable two-step version. This technique may replace coated-tube enzyme immunoassays for routine use.
Fluorescence energy transfer immunoassay of digoxin in serum.
Authors: Plebani M , Burlina A 
Published: January 2020

Abstract
We have evaluated the reliability of the new fluorescence energy transfer immunoassay (FETI) for determining concentrations of digoxin in serum. The method demonstrated good stability of the standard curve and satisfactory precision in both within-and between-run assay. We have also found a significant correlation between FETI and two RIA methods (r=0.97). Furthermore, the association between results by FETI and by the EMIT method (a conventional enzyme immunoassay) was a linear one. Finally, the assay encountered no significant interference from endogenous substances (hemoglobin, bilirubin , and triglycerides).
Comparison of creatinine as determined with the Ames Seralyzer and by three Jaffé-based methods.
Authors: Kroll M H , Olson D , Rawe M , King C , Hagengruber C , Elin R J 
Published: January 2020

Abstract
We compared results for urinary creatinine, serum creatinine, and creatinine clearance, as determined with the Ames Seralyzer, with results determined with the Beckman ASTRA, the DuPont aca, and Technicon's AutoAnalyzer and SMAC. Results for urinary creatinine from the Seralyzer differed significantly (p less than 0.05) from those obtained with the ASTRA and AutoAnalyzer, but not with the aca. The Seralyzer results for serum creatinine were at least 1.0 mg/L higher (p less than 0.05) than by the other three methods. Results for creatinine clearance from the Seralyzer were 8 to 11 mL/min lower (p less than 0.05) than results by the other three methods. These differences are related to the positive interference by bilirubin in the Seralyzer creatinine method. We also evaluated 23 other compounds for interference with these methods for creatinine.
Analytical patterns and biochemical properties of macro creatine kinase type 2.
Authors: Stein W , Bohner J , Bahlinger M 
Published: January 2020

Abstract
Here we describe our findings for 105 patients' sera containing macro creatine kinase (CK) type 2, as confirmed by exclusion chromatography. Depending on the technique used for determining isoenzyme CKs (electrophoresis, ion-exchange chromatography, immunoinhibition), this variant CK shows characteristic patterns and interferes in CK-MB assays by different mechanisms and to various degrees, thus complicating test interpretation. Macro CK type 2 evidently is not of cytoplasmic origin; rather it is a separate CK activity of human serum, characterized by its heat stability and, especially, by its increased molecular mass and high energy of activation. These latter characteristics have never been associated with the normal-size, dimeric cytoplasmic CK isoenzymes, but are typical for mitochondrial CK isolated from human tissues. We conclude that mitochondrial CK released after severe cell damage usually appears in blood in macromolecular forms (macro CK type 2), not in a dimeric form.
Enzymatic determination of serum ethanol with membrane-bound dehydrogenase.
Authors: Takei H , Nakashima K , Adachi O , Shinagawa E , Ameyama M 
Published: January 2020

Abstract
In this enzymatic method for detecting ethanol in blood by use of membrane-bound microbial alcohol dehydrogenase (no EC no. assigned), the enzyme catalyzes the reaction irreversibly and the rate of oxidation can be monitored by spectrophotometry of the reduction of the indicator dye. No pyridine nucleotides such as NAD+ or NADP+ are used. The calibration curve is linear in the range of 0.1 to 4.0 g of ethanol per liter. Assays of 45 samples of serum having ethanol values ranging from 0.4 to 3.2 g/L by the described technique and a gas-chromatographic method gave respective means of 1.734 and 1.732 g/L (r = 0.954).
Fluorescent substances in uremic and normal serum.
Authors: Shaykh M , Bazilinski N , McCaul D S , Ahmed S , Dubin A , Musiala T , Dunea G 
Published: January 2020

Abstract
We measured the fluorescence, at various excitation (Ex) and emission (Em) wavelengths, of serum ultrafiltrates and fractions of serum resolved by chromatography on Sephadex G15, studying both normal subjects and patients in chronic renal failure requiring hemodialysis. We found hitherto undescribed fluorescence at Ex 380 nm/Em 440 nm and Ex 400 nm/Em 460 nm, the intensity being greatly increased in patients with chronic renal failure in comparison with normal subjects (p less than 0.005). This fluorescence persisted unaltered when serum was filtered through membranes having cutoffs ranging from 10 000 to 500 Da. Each serum fraction resolved by gel chromatography demonstrated a characteristic fluorescence, which was generally much more intense in uremics. The most intense fluorescence (Ex 380 nm/Em 440 nm and Ex 400 nm/Em 460 nm) was emitted in the higher-Mr fractions.
Elimination of the "chromogen oxidase" activity of bilirubin oxidase added to obviate bilirubin interference in hydrogen peroxide/peroxidase detecting systems.
Authors: Maguire G A 
Published: January 2020

Abstract
The use of bilirubin oxidase to remove interference by bilirubin in hydrogen peroxide/peroxidase detecting systems is hampered by its inherent "chromogen oxidase" activity (its ability to oxidize the chromogens used in the systems). This unwanted activity is greater than 99% inhibited by 0.5 mmol/L cyanide, 97% inhibited by 20 mmol/L azide. At these same concentrations, they inhibit bilirubin oxidase activity by 95% and 73%, respectively. Sequential addition of reagents allows the use of bilirubin oxidase without interference by the chromogen oxidase activity.
Direct-measurement ion-selective electrodes: analytical error in hyponatremia.
Authors: Cowell D C , McGrady P M 
Published: January 2020

Abstract
Using two commercial direct ion-selective-electrode sodium and potassium analyzers, we found lower sodium values in cases of hyponatremia as compared with those by flame emission spectrophotometry or indirect ion-selective-electrode analyzers. It is shown that these errors can be eliminated by modifying the calibrant, and that there is a requirement for internationally agreed-upon reference standards for use by manufacturers and laboratory personnel to assess analytical performance of these analyzers.
Injurious effect of EDTA contamination on colorimetry of serum iron.
Authors: Koopman B J , Hindriks F R , Lokerse Y G , Wolthers B G , Orverdijk J F 
Published: January 2020

Abstract
Colorimetry of iron in serum with Ferrozine (as used in the Technicon SMAC) or with bathophenanthroline (as used in the Du Pont aca) is influenced by EDTA, in contrast to such measurements with atomic absorption spectroscopy. Therefore EDTA contamination should be avoided with these colorimetric methods. If, however, contamination with EDTA is suspected, addition of zinc sulfate to serum or to the SMAC "ascorbic acid reagent" will cancel the influence of EDTA on measurements of iron in the SMAC.
Measurement of glycosylated whole-blood protein for assessing glucose control in diabetes: collection and storage of capillary blood on filter paper.
Authors: Little R R , Wiedmeyer H M , England J D , Knowler W C , Goldstein D E 
Published: January 2020

Abstract
We present data on the use of filter-paper blood collection for measurement of glycosylated whole-blood proteins (gWB) (hemoglobin and plasma proteins). A capillary blood sample, obtained by fingerprick, is spotted directly onto filter paper (Schleicher & Schuell 903). The blood spot is washed briefly with alcohol (ethanol or isopropanol) to remove free glucose and dried before shipment to the laboratory. In the laboratory, the blood is eluted from the paper and analyzed for gWB by a colorimetric method. The gWB is primarily a measure of glycosylated hemoglobin (gHb) with a small contribution from glycosylated plasma protein. Concentrations of gWB and gHb are highly correlated (r = 0.91). The filter-paper method offers advantages over currently available methods for quantifying gHb and may be particularly useful in screening for diabetes and for assessing glycemic control in patients from remote areas.
International survey of apolipoproteins A1 and B measurements (1983-1984).
Authors: Cooper G R , Smith S J , Wiebe D A , Kuchmak M , Hannon W H 
Published: January 2020

Abstract
We report here results of a worldwide survey of apolipoprotein (apo) A1 and B measurements. A lyophilized pool of human serum was developed for the survey to test its suitability as a candidate Reference Material. Seventy-five laboratories from 18 countries responded to invitations to participate. Using several methods, they evaluated the mass concentration of apo A1 and B in the proposed Reference Material. The bias between laboratories and between analytical methods was then characterized. Fifty-five laboratories reported results before the deadline on measurement of at least one apolipoprotein by one method. Variation in apo A1 and B among collaborators constituted the largest source of error in the study (68% of the total variation for apo A1, 73% for apo B). Variation among method means was not significant for apo A1, but for apo B it constituted 20% of the total variation. Differences due to vials or in replicate measurements within vials were found to constitute 6% or less of the total variability. Within-laboratory, among-vial, and among-replicate CV values were less than 5% for the study. These results suggest that future standardization efforts can be successful.
Quality control of lipid measurements in epidemiological studies: the U.S. Air Force HEART program.
Authors: Hainline A , Hill P , Garbaczewski L , Winn C 
Published: January 2020

Abstract
A special standardization and quality assurance program, similar to that created for the Lipid Research Clinics Program (LRC), was developed for the American Health Foundation Laboratory by the Centers for Disease Control (CDC) to assure the quality of lipid measurements in the U.S. Air Force Health Evaluation and Risk Tabulation (HEART) Program. This study was designed to test the feasibility of reducing the incidence of heart disease in active-duty U.S. Air Force personnel through life-study intervention. During the 18-month study, CDC provided serum calibrators and reference materials for internal control and an external surveillance program for measurements of total cholesterol (TC) and high-density-lipoprotein cholesterol (HDLC). The Laboratory, using an automated enzymic method to measure cholesterol, achieved an overall goal for accuracy of less than 2% error (av systematic error, -30.6 mg/L) for TC, as measured on nine reference pools for which values were assigned by CDC. The average bias of measurements of HDLC with heparin-manganese to separate the lipoproteins in five CDC reference pools was -4.6 mg/L. Bias was estimated relative to the values assigned to the reference materials by the CDC reference methods for TC and HDLC. The average CV for TC was 0.89%, for HDLC 2.66%. Accuracy of cholesterol measurements can be assured over time with a standardization and quality-assurance program that incorporates accurately labeled reference materials for calibration, internal quality control, and external surveillance.
Facilitated determination of ionized calcium.
Authors: Urban P , Buchmann B , Scheidegger D 
Published: January 2020

Abstract
Using a calcium-containing heparin preparation for anticoagulation, we determined [Ca2+], the mean concentration of ionized calcium, in whole blood of 120 healthy blood-donors to be 1.23 (SD 0.04) mmol/L. Similarly, for 50 intensive-care patients selected without conscious bias, the correlation between [Ca2+] in serum (mean 1.15, SD 0.10 mmol/L) and in whole-blood samples anticoagulated with the same heparin preparation (mean 1.15, SD 0.09 mmol/L) was very good (r = 0.95). Storing samples anaerobically on ice for as long as 2 h did not alter whole-blood [Ca2+]. On the other hand, various concentrations of calcium-free heparin preparations all induced a significant decrease in measured [Ca2+]. By using whole-blood samples, rather than plasma or serum, for [Ca2+] determination with a calcium-selective electrode, repetitive measurements can be made with simple handling procedures, facilitating rapid implementation of appropriate therapeutic measures for critically ill patients.
Carboxyhemoglobin determination by second-derivative spectroscopy.
Authors: Parks J , Worth H G 
Published: January 2020

Abstract
In this procedure hemoglobin is converted to its reduced form and the magnitude of the zero-order spectral shift of the reduced hemoglobin peak at 430 nm to the carboxyhemoglobin peak at 418 nm is determined by second-derivative spectrum analysis. The method is simple, straightforward to set up, and rapid. A result may be obtained within 15 min of receiving the sample. It is sufficiently sensitive to differentiate carboxyhemoglobin concentration in the blood of smokers and nonsmokers.
Hyperlipoproteinemia with albumin-lipid complex: a novel type of hyperlipoproteinemia associated with insulin-resistant diabetes mellitus.
Authors: Habbal Z M , Apelian A Z 
Published: January 2020

Abstract
We describe a new phenotype of hyperlipoproteinemia in two members of a family with a high degree of consanguinity. Both have a history of uncontrolled diabetes mellitus without ketoacidosis, and a family history of coronary artery disease at a relatively early age. A high degree of insulin resistance was found. The abnormal lipoprotein(s) has alpha-lipoprotein mobility on cellulose acetate electrophoresis and has a relative density of less than 1.006 as determined by ultracentrifugation of serum collected after a short fast. The fraction isolated by ultracentrifugation contains about half of the serum cholesterol and triglycerides and most of the phospholipids; the major protein component is albumin. Immunoelectrophoresis showed low concentrations of beta-lipoproteins in both sera, and two abnormal precipitin bands against monospecific antiserum to antilipoprotein A; a third member of the family showed only one abnormal precipitin band against the same antibody. We tentatively propose an abnormal gene(s) as the underlying mechanism. The insulin-resistant diabetes mellitus, probably inherited separately, may aggravate the hyperlipidemia.
Particle-counting immunoassay (PACIA) of pregnancy-specific beta 1-glycoprotein, a possible marker of various malignancies and Crohn's ileitis.
Authors: Fagnart O C , Mareschal J C , Cambiaso C L , Masson P L 
Published: January 2020

Abstract
Pregnancy-specific beta 1-glycoprotein (SP1) was assayed by particle-counting immunoassay (PACIA) with a sensitivity of 1 microgram/L. In serum from 50 men, the SP1 concentration was less than 1 microgram/L, whereas three of the specimens from 46 nonpregnant women had values exceeding 1 microgram/L. In 29% of 950 consecutive patients' sera, SP1 concentrations exceeded 1 microgram/L--in sarcoma (six of six), in malignant hemopathies (101/127, 80%) such as myeloma (20/26, 92%) and acute myeloblastic leukemia (23/27, 90%), and in various other types of cancer (11/19, 58%) except for bronchial epithelioma, which did not lead to any significant increase of SP1 in the five patients examined. The concentration of SP1 was also frequently increased in patients with Crohn's ileitis (28/43, 65%) but not in patients with other inflammatory disorders.
Estimation of thyroxin, triiodothyronine, thyrotropin, free thyroxin, and triiodothyronine uptake by use of magnetic-particle solid phases.
Authors: Witherspoon L R , Shuler S E , Gilbert S 
Published: January 2020

Abstract
We evaluated solid-phase radioassays involving small, uniform magnetic particles (MAGIC, Corning Medical), obtaining data on total serum thyroxin (T4), triiodothyronine (T3), thyrotropin (TSH), free thyroxin (FT4), and T3 uptake for a total of 301 serum samples from euthyroid patients; patients receiving replacement thyroxin; patients receiving estrogen, or who were pregnant; hyperthyroid, hypothyroid, and nonthyroidally ill patients; and patients receiving salicylates, phenytoin, or heparin. We found each procedure to be technically simple and precise (between-assay CVs for T4 2.8-8.2%, T3 9-7.4%, TSH 2.9-4.5%, FT4 3.6-11%, T3 uptake 2.2-3.7%). The magnetic separations are rapid (2 to 5 min), reproducible, and complete. Each MAGIC assay produced clinically appropriate results. These assay systems offer the convenience associated with noncentrifugation assays and excellent analytical performance.
Radiochemical microassay of delta-aminolevulinic acid dehydratase activity in whole blood and bone marrow.
Authors: Kondo M , Urata G 
Published: January 2020

Abstract
We describe an assay for delta-aminolevulinic acid dehydratase (EC 4.2.1.24) activity. Radioactive [14C]porphobilinogen, formed by action of this enzyme on [14C]delta-aminolevulinic acid, is purified by passage through an ion-exchange chromatographic column before measurement with a liquid scintillation counter. The radioactive substance in the final solution was identified as solely [14C]porphobilinogen by paper-chromatographic analysis. The present assay procedure requires only a 0.1-microL sample of blood and is about 100-fold more sensitive than the conventional colorimetric methods involving Ehrlich's reagent. Using this method, we found that activity of this enzyme in the bone marrow of rats decreases abruptly and sharply two weeks after birth.
Chemiluminescence enzyme immunoassay for thyroxin with use of glucose oxidase and a bis(2,4,6-trichlorophenyl)oxalate-fluorescent dye system.
Authors: Arakawa H , Maeda M , Tsuji A 
Published: January 2020

Abstract
In this chemiluminescence enzyme immunoassay for thyroxin, glucose oxidase (EC 1.1.3.4) is the enzyme label and the bound and free fractions are separated by the double-antibody solid-phase technique. In the assay of enzyme activity, hydrogen peroxide generated from glucose substrate is measured by its chemiluminescence reaction with bis(2,4,6-trichlorophenyl)oxalate and 8-anilino-1-naphthalene-sulfonic acid. The measurable range of thyroxin is 2.5 to 200 micrograms/L. The coefficients of variation for thyroxin concentrations of 43.2 and 12.8 micrograms/L were 7.0% and 8.6% (intra-assay), and 6.4% and 12.3% (interassay), respectively. The proposed method is applicable to large-scale preliminary screening of neonates for congenital hypothyroidism, with samples consisting of dried blood spotted on filter paper.
Headspace measurement of ethanol in blood by gas chromatography with a modified autosampler.
Authors: Penton Z 
Published: January 2020

Abstract
An autosampler intended for liquid injection into a gas chromatograph was modified to serve as an automatic headspace sampler by replacing the syringe with a 100-microL gas-tight syringe and shortening the needle that normally enters the vials for sampling. Instead of the usual 1.0 to 1.5 mL of liquid sample, the vials contained 200 microL of liquid; the vapor above the liquid was injected into the gas chromatograph. Blood samples from California drivers were analyzed for ethanol by using the modified autosampler and the values were compared with those obtained by two other methods: the Smith modified version of the Widmark diffusion desiccation oxidation method (J Lab Clin Med 38: 762, 1951) and direct injection of diluted blood into the gas chromatograph. The correlation coefficient between the headspace method described in this paper and the titration method was 0.984; with direct injection, 0.997.
Steroid receptor analysis by size-exclusion liquid chromatography: considerations for the clinical laboratory.
Authors: Pavlik E J , Nelson K , van Nagell J R , Robinson J C , Hanson M B , Donaldson E S , Flanigan R C , Kenady D E 
Published: January 2020

Abstract
Steroid receptor activity can be more quickly estimated by size-exclusion chromatography than by conventional analysis on sucrose gradients, and profiles of receptor activity are better resolved. Here we discuss several factors affecting this form of analysis in clinical laboratories. The composition of the elution buffer influences steroid receptor elution and recovery: high ionic strength, neutral pH, and the presence of dimethylformamide are important. Of the TSK-SW (Beckman) size-exclusion chromatographic columns we considered, the TSK-G2000SW column appeared to be the most appropriate. "Reference" elution profiles are presented for several marker proteins and estrogen receptor forms generated under different sample-treatment conditions. In examining the sensitivity of receptor analyses by this method, we used fresh rodent preparations, a commercial receptor reference (Estrocept), and human tumor material obtained by needle biopsy. We also compared frozen and lyophilized receptor preparations with fresh ones.
Multiple forms of gamma-glutamyltransferase: a clinical study.
Authors: Wenham P R , Horn D B , Smith A F 
Published: January 2020

Abstract
We have measured the amounts of different molecular forms of gamma-glutamyltransferase (EC 2.3.2.2), leucine aminopeptidase (EC 3.4.11.2), and alkaline phosphatase (EC 3.1.3.1) in serum of patients with different types of liver disease. A high-molecular-mass (greater than 1 000 000 Da) form of gamma-glutamyltransferase and of each of the other enzymes is present in greatest amounts in patients with jaundice from extrahepatic obstruction. A gamma-glutamyltransferase form of intermediate molecular mass (250 000 to 500 000 Da) is present in the serum from most patients with liver disease and can be separated by electrophoresis into several bands. We found that one of these bands predominated in patients with extrahepatic obstructive jaundice, whereas the others predominated in patients with other liver diseases. Electrophoresis of serum gamma-glutamyltransferase may be of clinical value in distinguishing extrahepatic from intrahepatic causes of jaundice.
Amniotic fluid acetylcholinesterase activity and alpha-fetoprotein in chromosomal anomalies and neural tube defects.
Authors: Buamah P K , Skillen A W , Harrison J , Davison V 
Published: January 2020

Abstract
Measurement of alpha-fetoprotein concentration and acetylcholinesterase activity in amniotic fluid can be used to identify chromosomal defects as well as neural tube defects. In seven cases of trisomy 21 and one case of partial trisomy 3, alpha-fetoprotein concentrations were below the reference range but values for acetylcholinesterase activity were normal for the appropriate gestational age. One case of trisomy 13 had an increase in acetylcholinesterase activity and normal alpha-fetoprotein concentration.