bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioimmunoassay of erythropoietin: analytical performance and clinical use in hematology
Authors: Schlageter M H , Toubert M E , Podgorniak M P , Najean Y 
Published: January 2020

Abstract
We report here the performance of a recently commercialized radioimmunoassay kit for determining erythropoietin (EPO) in serum or plasma. The lower detection limit of the method was 3 U/L. Precision, analyzed by the variation coefficients between different assay runs and in the same experiment, was always less than 10%; accuracy was assessed by recovery and dilution tests. In anemic patients (hematocrit 18-39%), the concentration of EPO was logarithmically related to hematocrit. A relatively large dispersion of the results was noted, as reported by others with various RIAs. Patients with severe renal failure demonstrated a very low EPO value, whatever the degree of their anemia. In some chronic anemias resulting from malignancy, EPO concentrations were also relatively low. In the polycythemia vera group, the EPO mean was below normal for greater than 95% of the patients, whatever their clinical stage (first evaluation, relapse, or remission). In contrast, 91% of the patients with pure erythrocytosis had a normal or increased EPO value, even when the etiology was unknown. Measurement of EPO concentration may be useful for the clinical differentiation of myeloproliferative disorders and, subsequently, for their prognosis and choice of treatment.
Colorimetric liposome lysis for assay of anti-streptolysin O antibody
Authors: Kubotsu K , Ushio I , Yoshikawa K , Kida M , Ishikawa K , Matsuura S , Sakurabayashi I 
Published: January 2020

Abstract
We developed an automated colorimetric assay based on liposome lysis for measurement of the titer of anti-streptolysin O antibodies (ASO) in human sera by using liposomes in which alkaline phosphatase (EC 3.1.3.1) was entrapped. The assay involved the inhibition by ASO of liposome lysis caused by streptolysin O. The procedure was fully automated for use with a routine clinical automated analyzer. The inter- and intra-assay precision showed that results were reproducible. Potential interfering substances such as bilirubin, hemoglobin, and triglycerides did not affect the results. With this assay, results correlated well with those by the Rantz-Randall method and the latex agglutination method (r = 0.900 and 0.890, respectively). This automated colorimetric assay for ASO should be of use for diagnosing streptococcal infections.
A model for molecular screening of newborns: simultaneous detection of Duchenne/Becker muscular dystrophies and cystic fibrosis
Authors: Prior T W , Highsmith W E , Friedman K J , Perry T R , Scheuerbrandt G , Silverman L M 
Published: January 2020

Abstract
Gene mutations responsible for the majority of Duchenne/Becker muscular dystrophy (DMD/BMD) and cystic fibrosis (CF) chromosomes have been identified. We describe a DNA-based strategy, rather than the traditional biochemical assays, for screening newborns. DNA sequences spanning the CF mutation and several DMD/BMD deletion-prone exons are amplified simultaneously via a multiplex polymerase chain reaction. The gel is visually inspected for DMD/BMD deletions and then blotted and hybridized with allele-specific oligonucleotides to determine the presence or absence of the CF mutation. We determined that blood spots provide sufficient DNA for the molecular analysis, so the procedure can be used in screening programs of newborns.
Predicting effects of quality-control practices on the cost-effective operation of a stable, multitest analytical system
Authors: Westgard J O , Oryall J J , Koch D D 
Published: January 2020

Abstract
The cost-effective operation of an analytical system depends on quality-control (QC) practices such as the QC procedure itself (control rules, number of control measurements); the batch size or the run length; and the use of bracketed, nonbracketed, or pre-control modes of operation. Predictive value models that predict the defect rate and test yield of each test, as well as of the system as a whole, have been used to study these practices and to develop strategies for improving the quality and productivity of a multitest analyzer. Quality was optimized for most tests by achieving high error detection and low false rejection by the QC procedures. For a few tests where ideal QC performance could not be achieved, predictive models indicate that high quality is achieved, predictive models indicate that high quality is achieved as long as the observed stabilities (low frequencies of errors) of the measurement procedures are maintained. In our laboratories, productivity gains of 2.9% ($17,400/year) were achieved by changing QC procedures. Predictive models indicate that further gains are possible by increasing batch size and changing from bracketed to nonbracketed control operation. In general, the common practice of bracketed control on stable analytical systems may need to be re-examined owing to its effect on the cost of operation.
Time-resolved fluoroimmunoassay for unconjugated estrogen in urine: comparison with a fluorometric assay for total estrogen and application in an in vitro fertilization program
Authors: Thomas C M , van den Berg R J , Segers M F , Geelen L M , Hollanders J M , Doesburg W H , Houx P C 
Published: January 2020

Abstract
A time-resolved fluoroimmunoassay (TR-FIA) for unconjugated estrogens in human urine is described. 6-Keto-17 beta-estradiol-6-(O-carboxymethyl)oxime:bovine serum albumin is immobilized onto microtiter strip wells and the coated wells are incubated with 17 beta-estradiol standard preparations or unknowns with a polyclonal antiserum to 17 beta-estradiol-16,17-monosuccinyl:albumin. The antiserum-bound estrogen is detected by incubation with a europium-labeled anti-rabbit IgG that serves as both second antibody and tracer. After the immunoreactions, the bound portion of the labeled antiserum is quantified by dissociating the Eu3+ in a fluorescence-enhancement solution and measuring its fluorescence with a time-resolved fluorometer. The detection limit of the TR-FIA is 24 pmol of 17 beta-estradiol per liter; the analytical range extends to 1.8 nmol/L. This assay is a convenient alternative to radioimmunoassay and to the automated Kober-Ittrich fluorometry of total estrogen. Its advantages include short counting times; use of nonradioactive, stable reagents, all of which are commercially available; and more nearly complete automation. We conclude that this TR-FIA, compared with the Kober-Ittrich fluorometric assay (J Endocrinol 1957; 16:49-56), provides the clinician with equivalent information during follicular development therapy as part of an in vitro fertilization program.
Erythrocyte porphobilinogen deaminase activity in porphyria cutanea tarda
Authors: Siersema P D , de Rooij F W , Edixhoven-Bosdijk A , Wilson J H 
Published: January 2020

Abstract
Porphyria cutanea tarda (PCT) results from a metabolic block in heme synthesis at the level of uroporphyrinogen decarboxylase. We measured the activity of one of the enzymes preceding it in the heme biosynthetic pathway, porphobilinogen deaminase (PBGD; EC 4.3.1.8), in erythrocytes of 47 patients with symptomatic or asymptomatic familial or sporadic PCT. PBGD activity was significantly increased in all four PCT groups, compared with controls. To study the mechanism of this increased PBGD activity, we determined, using polyclonal antibodies, the amount of immuno-detectable PBGD per 100 units of PBGD activity (Ig PBGD/100 U) and the total amount of immuno-detectable PBGD (Ig PBGD) in erythrocytes from all 47 patients and from controls. In both familial and sporadic PCT, Ig PBGD/100 U was decreased compared with that in controls (P less than 0.05). Especially in asymptomatic patients of the familial PCT group there was an inverse correlation between increasing PBGD activity and Ig PBGD/100 U (r = -0.90). In familial PCT, and to a minor degree in sporadic PCT, an increase in PBGD activity was accompanied by an increased Ig PBGD, compared with controls (familial PCT: P less than 0.001, sporadic PCT: P less than 0.05). In familial and sporadic PCT an increase in erythrocyte PBGD activity can, at least partly, be explained by a diminished degradation of PBGD. In familial PCT, in the symptomatic group more than in the asymptomatic group, and to a minor degree in sporadic PCT, there is in addition an increase in the absolute amount of PBGD.
Proposed reference method for iron in serum used to evaluate two automated iron methods
Authors: Valcour A A , Krzymowski G , Onoroski M , Bowers G N , McComb R B 
Published: January 2020

Abstract
The manual Reference Method of the Centers for Disease Control for serum iron (CDC/RM/Fe) and a semiautomated adaptation of it were used to evaluate two working methods: one, a detergent solubilization procedure for the Roche Cobas-Bio analyzer, the other, the Kodak Ektachem 700 procedure, based on dry-film technology. The CDC/RM/Fe and its semiautomated version gave essentially the same results for 40 sera from hospital patients. This semiautomated version was in turn compared with the two working procedures in a study involving 200 patients. Each of the working methods correlated well with the semiautomated CDC/RM/Fe method. Separate recovery and interference studies indicated satisfactory analytical recovery of iron in all cases, but the detergent solubilization method was found to be susceptible to interference by hemoglobin, lipemia, and bilirubin.
Colorimetry and constant-potential coulometry determinations of transferrin-bound iron, total iron-binding capacity, and total iron in serum containing iron-dextran, with use of sodium dithionite and alumina columns
Authors: Jacobs J C , Alexander N M 
Published: January 2020

Abstract
After the parenteral administration of iron-dextran (imferon), the increased total iron concentrations in serum can be determined by atomic absorption spectroscopy and by colorimetric methods involving sodium dithionite, which reductively dissociates iron from the dextran complex. We report that constant-potential coulometry detects only about 55-70% of dextran-bound iron before dithionite reduction and variable amounts after reaction with the reducing agent. In addition, we have developed a procedure for determining transferrin-bound iron, total iron-binding capacity (TIBC), total iron, and dextran-bound iron with the Kodak Ektachem colorimetric system. In determining total serum iron, the sample is first mixed with sodium dithionite, which rapidly dissociates all dextran-bound iron, but does not remove iron from either transferrin or hemoglobin. After the mixture is applied to an Ektachem slide, transferrin-bound iron is released at pH 4 and is detected together with the iron previously bound to dextran. TIBC is determined by mixing serum with ferric citrate in moderate excess and filtering through a small alumina (Al2O3) column, which binds excess free iron and iron-dextran; the iron in the column eluate represents the TIBC. Transferrin-bound iron is determined by applying diluted serum without added ferric citrate to an alumina column and measuring the iron in the column eluate. Dextran-bound iron is equivalent to the difference between total and transferrin-bound iron. Using this method, we found that transferrin iron-binding sites are saturated in vitro by excess iron-dextran less efficiently than by ferric citrate.
Improved method for identifying alpha 1-antitrypsin Pi M subtypes by isoelectric focusing in agarose
Authors: Nowicki M L , Freier E F 
Published: January 2020

Abstract
We describe an improved method for the classification of alpha 1-antitrypsin variants by isoelectric focusing in agarose. Identification of the three Pi M subtypes can now be made by using a narrow-range carrier ampholyte (pH 4.2-4.9) and pretreating serum with dithioerythritol-iodoacetic acid to enhance band resolution. Phenotype results for two groups of Pi M homo- and heterozygotes are compared to illustrate the improved accuracy of the new method.
Deuterium enrichment of plasma determined by nuclear magnetic resonance spectroscopy: dilution kinetics of 2H2O and estimation of total body water
Authors: Brans Y W , Schwartz C A , Hood R J , Ksebati M B , Konduri G G 
Published: January 2020

Abstract
We demonstrate the feasibility of quantifying the abundance of 2H in plasma by nuclear magnetic resonance (NMR) spectroscopy. After adding internal standard (tert-butyl-d9 alcohol) to deproteinized plasma samples containing 2H2O, we determined the ratio of NMR peak areas for 2H2O and tert-butyl-d9 alcohol. This peak-area ratio was directly proportional to the exogenous 2H enrichment of plasma (difference between measured and naturally occurring 2H) between 0 and 0.272 atom % (r = 0.999). The coefficient of variation was 1.34% at an exogenous enrichment of 0.136 atom %. We applied this method to a study of the dilution kinetics of 2H2O to determine the optimal time and method of blood sampling for estimation of total body water content. The 2H enrichment of plasma stabilized by 4 h after intravenous injection of 2H2O, 1 g/kg of body weight, and fluctuated within 2-4% of the 4- to 8-h mean thereafter.
Simultaneous determination of acidic 3,4-dihydroxyphenylalanine metabolites and 5-hydroxyindole-3-acetic acid in urine by high-performance liquid chromatography
Authors: Stroomer A E , Overmars H , Abeling N G , van Gennip A H 
Published: January 2020

Abstract
We describe a simple and rapid quantitative method for the simultaneous determination of 3,4-dihydroxyphenylalanine acid metabolites and 5-hydroxyindole-3-acetic acid. After solvent extraction from acidified urine, the acids are analyzed by reversed-phase high-performance liquid chromatography. For detection and quantification, we used a fluorescence detector in combination with an amperometric detector to obtain a high degree of specificity. Sample preparation and chromatographic analysis can be completed within an hour. Results by the method correlate well with those by a previously used gas-chromatographic method, but the new method is faster and avoids the need for derivatization.
Improved phenotyping of apolipoprotein E: application to population frequency distribution
Authors: Hill J S , Pritchard P H 
Published: January 2020

Abstract
A simple procedure for phenotyping apolipoprotein (apo) E directly from plasma has been developed for use in the lipid clinic laboratory. In this new method, 10 microL of serum or plasma is pretreated with neuraminidase (EC 3.2.1.18), which removes the sialic acid residues from apo E and eliminates additional bands, thereby ensuring correct phenotype assignment. After a rapid delipidation step, the samples are focused in vertical polyacrylamide mini-slab gels and immunoblotted with a polyclonal goat anti-apo E antibody, followed by a Protein G-peroxidase conjugate. The accuracy of this method was confirmed by comparison with the established procedure of phenotyping by isoelectric focusing of delipidated very-low-density lipoprotein. In addition, sera from 203 subjects from Vancouver, selected without conscious bias, were used to determine the local distribution of the apo E alleles. We estimate that the relative frequencies of apo E alleles epsilon 2, epsilon 3, and epsilon 4 in this population are 0.086, 0.761, and 0.153, respectively. The speed and convenience of using minigels make this procedure ideal for clinical laboratory applications and large population studies.
Study of lipoprotein particles LpAI and LpAI:AII in patients before coronary bypass surgery
Authors: Coste-Burel M , Mainard F , Chivot L , Auget J L , Madec Y 
Published: January 2020

Abstract
Lipids, apolipoproteins, and LpAI and LpAI:AII particles were studied in 43 men (mean age 51, SD 7, years) 24 h before their coronary bypass surgery and in 54 control men (mean age 46 SD 9, years). LpAI and LpAI:AII were analyzed by electroimmunodiffusion and by a noncompetitive enzyme-linked immunoassay, respectively. Concentrations of LpAI and LpAI:AII in the bypass patients were significantly lower (P less than 0.001) than those in the controls. Apolipoprotein AI was significantly correlated with LpAI (P less than 0.001) and LpAI:AII (P less than 0.01) in controls, but only with LpAI:AII (P less than 0.001) in bypass patients. Discriminant analysis between controls and patients showed apolipoprotein AI to be the most powerful discriminant factor; the addition of LpAI and LpAI:AII did not improve discriminant power. We conclude that the determination of LpAI and LpAI:AII particles reflects metabolic disorders in patients but does not significantly influence the discrimination of such patients into risk groups.
Flexibility of noncompetitive avidin-biotin immunoassay: immunoassay of lutropin applied to different signal detection systems
Authors: Vilja P 
Published: January 2020

Abstract
I adapted the noncompetitive avidin-biotin immunoassay (NABA) of lutropin (LH) for use with radiometric, fluorometric, time-resolved fluorometric, and luminometric detection systems by changing the enzyme substrate or conjugating avidin with different labels. The corresponding methods were used to determine LH in 40 urine samples, and the results were compared with those obtained by an immunoenzymometric assay (IEMA), also based on the NABA principle. Scatter plots of the results showed a linear relation with high correlation coefficients (r = 0.972-0.983), and bias plots showed good agreement between the four comparison methods and the IEMA. The results indicate that the effectiveness of the NABA of LH is independent of the signal detection system. This means good flexibility for the user in choice of instrument and signal detection system.
Gradient centrifugation to isolate platelets for determination of trace elements by neutron-activation analysis
Authors: Bibow K , Mundal H H 
Published: January 2020

Abstract
A nonionic iodinated compound, Nycodenz, was used for density-gradient isolation of platelets before analysis for trace elements by instrumental neutron activation. The platelet samples were almost free from plasma and erythrocytes, and the trace element contribution from additives was insignificant for the elements investigated. The reproducibility of the trace element analysis in platelets attests to the usefulness of density-gradient separation. Platelet samples were obtained twice, three weeks apart, from 10 healthy young women (ages 24 +/- 2 years). The mean (SD) concentrations were as follows: Se, 0.62 (0.16) mg/L and 4.7 (1.4) ng/10(9) platelets; Zn, 44 (10) mg/L and 333 (80) ng/10(9) platelets; Rb, 3.0 (0.5) mg/L and 23 (5) ng/10(9) platelets; and Cs, 24 (5) micrograms/L and 0.18 (0.04) ng/10(9) platelets.
Impact of protein measurements on standardization of assays of apolipoproteins A-I and B1
Authors: Henderson L O , Powell M K , Smith S J , Hannon W H , Cooper G R , Marcovina S M 
Published: January 2020

Abstract
In 1989 the Committee on Apolipoproteins of the International Federation of Clinical Chemistry and the Centers for Disease Control conducted an international survey of total-protein measurements of isolated low-density lipoproteins (LDL) and delipidated high-density lipoproteins (HDL), and of their relationships to the National Institute of Standards and Technology (NIST) bovine serum albumin (BSA) Standard Reference Material (SRM). Most of the 93 apolipoprotein laboratories surveyed use the Lowry total-protein method. Results reported with the LDL preparations demonstrated a large bias and variation among methods; those with delipidated HDL were not as great, but were similar to those for BSA. Performance improved appreciably with use of the Lowry-sodium dodecyl sulfate method and the NIST BSA SRM for protein measurement. The total CVs, including among-laboratory and within-laboratory errors, averaged approximately 50% and 23% for LDL, 17% and 11% for HDL, and 18% and 11% for BSA solutions by all methods and by the Lowry methods, respectively. Regardless of the methods used, greater variability of the protein measurements was seen with the normally occurring LDL than with the nonlipoprotein BSA or delipidated HDL. The mean CV values for all samples among laboratories averaged between 10% and 15% with the modified Lowry methods; the biuret method gave the highest among-laboratory CV, 34%; the Kjeldahl had the lowest, 7.7%. Use of the same methodology and primary nonapolipoprotein standard is essential for comparability of protein results for apolipoprotein primary standard solutions. This is especially true for apolipoprotein B, because its inherent properties and lability make protein analysis difficult. This study supports the use of a standardized selected Lowry-sodium dodecyl sulfate method traceable to quantitative amino acid analysis as a point of reference for determining the protein concentration of primary calibration reference materials for apolipoproteins.
Intestinal variant alkaline phosphatase in plasma in disease
Authors: Kuwana T , Rosalki S B 
Published: January 2020

Abstract
We investigated by enzyme electrophoresis after prolonged neuraminidase treatment the activity of "intestinal variant" (alpha 2-globulin mobility) alkaline phosphatase (EC 3.1.3.1; ALP) in the plasma of 189 patients selected for disorders (diabetes mellitus, liver cirrhosis, and chronic renal failure) with a known high frequency of increased plasma intestinal (beta-globulin mobility) ALP activity. The overall frequency of the variant ALP was 23.8%, whereas in the samples showing intestinal ALP it was 45.0%. The variant ALP was not observed in the absence of intestinal ALP, nor in patients of blood group A. Its frequency did not differ significantly between the different patient groups. Quantification of the variant ALP by densitometry was unsatisfactory but the quantity could be estimated by subtracting the intestinal ALP activity measured by electrophoresis from the activity determined by immunoassay with monoclonal antibody that reacts with both the intestinal and the variant forms. This indicated median activity of 12 U/L for the variant, approximately equal to that of the concomitant intestinal ALP. From the effects of papain and bromelain treatments, we suggest that "intestinal variant" represents intestinal ALP with attached membrane-binding domain.
Analysis of 8-methoxypsoralen by high-performance liquid chromatography
Authors: Ketchum C H , Robinson C A , Huang S T 
Published: January 2020

Abstract
We report a simple and rapid procedure for assaying 8-methoxypsoralen (8-MOP) in plasma by high-performance liquid chromatography (HPLC). The standard curve for the assay is linear for 8-MOP from 15 to 500 micrograms/L (y = 0.002x-0.01, r = 0.99) with a lower limit of detection of 1.5 micrograms/L. Intra-assay precision (CV) was 6.0% at the 100 micrograms/L concentration and 10.0% at 50 micrograms/L (n = 30 each). Interassay precision was 6.4% at 100 micrograms/L and 7.0% at 50 micrograms/L (n = 50 each). Extraction recovery of 8-MOP was 98%. Common antiarrhythmics, sedatives, and hypnotics were found not to interfere.