bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rate-nephelometric inhibition immunoassay of phenytoin and phenobarbital.
Authors: Finley P R , Dye J A , Williams R J , Lichti D A 
Published: January 2020

Abstract
A proposed rate-nephelometric inhibition immunoassay of phenytoin and phenobarbital in human serum involves the sequential addition to buffer of 42-microL aliquots of sample containing the hapten (drug) of interest, a hapten conjugate (drug-equine apoferritin), and specific antibody to the hapten. The drug and the drug conjugate compete for the binding sites on the antibody. The free hapten-antibody complex is soluble and so does not scatter light, whereas the complex of antibody and drug conjugate is insoluble and thus scatters light. The latter immunoprecipitation is competitively inhibited by free hapten. Thus the higher the concentration of free hapten present, the fewer immunoprecipitin complexes are formed, and the less light scatter. Precision, accuracy, linearity, analytical recovery, and comparison with patients' samples assayed with the DuPont aca were excellent. There was no significant interference from hemolysis, icterus, or lipemia. Many potentially interfering drugs and metabolites were checked for cross reactivity, with negative results. Reaction times range from 30 to 50 s.
Kinetic potentiometric determination of creatinine in serum with a picrate ion-selective membrane electrode.
Authors: Diamandis E P , Hadjiioannou T P 
Published: January 2020

Abstract
We describe a new kinetic method for potentiometric determination of creatinine in serum, based on the creatinine--picrate reaction in alkaline medium (Jaffé reaction). The reaction is monitored with a picrate-selective electrode, and the increase in electrode potential during 270 s is measured and related directly to the creatinine concentration. Small cation-exchange columns are used to separate creatinine from interfering substances. Analytical recovery of creatinine added to serum was 100.7%. Results for a series of samples compared well with results obtained with a spectrophotometric method (r = 0.994).
Kinetic latex agglutinometry II: a rapid, quantitative assay for factor VIII antigen.
Authors: Crane L J 
Published: January 2020

Abstract
A rapid method for measuring factor VIII antigen in plasma is presented, based upon optical measurement of the rate of agglutination of a stirred suspension of latex particles coated with anti-factor VIII immunoglobulin, when mixed with plasma containing factor VIII antigen. A log-log relationship exists between factor VIII concentration and the reciprocal of the time required for a fixed absorbance change. The assay is rapid, requiring less than 3 min for normal plasma, involves stable reagents, and can be performed with conventional instrumentation. Antigen values in normal plasma a well as plasma from patients with von Willebrand's disease (angiohemophilia) correlate well with values measured by electroimmunoassay or by radioimmunoassay.
Continuous-flow enzyme immunoassay for thyroxine in serum.
Authors: Nolan J P , DiBenedetto G , Tarsa N J 
Published: January 2020

Abstract
We have evaluated a fully automated thyroxine assay involving the use of a homogeneous enzyme assay and a Technicon AutoAnalyzer II continuous flow system. Comparison by regression analysis with a thyroxine radioimmunoassay kit method gave a slope of 0.82 and a y-intercept of 7.81 micrograms/L (SE 0.86 microgram/L, r = 0.95). Within-run precision yielded CVs of 1.0-6.1%, between-day CVs were 2.0-14.4%; within-day precision showed a mean variance of 7.81 micrograms/L. Mean analytical recovery was 96.1%. Bilirubin, hemoglobin, and lipemia interfered with quantitation of results when their concentrations exceeded 50 mg/L, 300 mg/L, and 5 g/L, respectively. The reference interval for euthyroid status was calculated to be 50-110 micrograms/L. Sensitivity was 5.0 micrograms/L with a mean carryover of 1.65%. Current reagent and labor costs for enzyme immunoassay ($0.40) were less than for the manual radioimmunoassay procedure ($0.40) were less than for the manual radioimmunoassay procedure ($1.70). The assay is economical, simple to perform, and amenable to high-throughput thyroid screening in the routine laboratory.
Lactate dehydrogenase isoenzyme 1 with the centrifugal analyzer after immunochemical removal of other isoenzymes.
Authors: Bruns D E , Emerson J C , Bertholf R L , Hill K E , Savory J 
Published: January 2020

Abstract
We describe a centrifugal analyzer method for measuring the LD-1 isoenzyme of lactate dehydrogenase (EC 1.1.1.27) in serum, after immunochemical precipitation of the other four isoenzymes. Enzymic activity was measured kinetically at 30 degrees C with the pyruvate-to-lactate assay. The method for LD-1 was linear to 1000 U/L. The precision (CV) of the assay was 1.0--2.2% within-run and 3.1--4.5% day-to-day. The reference interval was 26--73 U/L (n = 51), corresponding to 21--35% of total LD activity.
Complementary use of amperometric and spectrophotometric detection for concurrent monitoring of serum tryptophan metabolites by reversed-phase liquid chromatography.
Authors: Krstulovic A M , Friedman M J , Sinclair P R , Felice J 
Published: January 2020

Abstract
We describe an improved reversed-phase liquid-chromatographic method for concurrent measurement of tryptophan and eight of its metabolites in serum. These were separated by gradient elution and detected both by ultraviolet absorption at 254 nm and amperometrically at an oxidation potential of +0.700 V vs Ag/Cl. Detection limits for the electrochemically-detected compounds were between 100 pg and 1.0 ng, and approximately 1-5 ng for the ultraviolet-absorbing compounds. Analytical recovery of the compounds after deproteinization (by ultrafiltration) varied between 65 and 95%. As little as 500 microL of serum is required. No interference(s) from other naturally occurring serum constituents were encountered. This highly sensitive method is relatively fast and offers a useful tool for diagnosis and treatment of diseases involving derangement in tryptophan metabolism.
Diagnosis of hemolytic disease by electrophoresis of erythrocyte lactate dehydrogenase isoenzymes on cellulose acetate or Agarose.
Authors: Van Lente F , Marchand A , Galen R S 
Published: January 2020

Abstract
We determined the LD-1/LD-2 isoenzyme ratio in hemolysates of erythrocytes by electrophoresis on cellulose acetate and on agarose. A ratio exceeding 1.0 was found with the former but not the latter. Results were similar for in vitro models of hemolytic disorders. Using cellulose acetate electrophoresis, we determined the predictive value of data on total LD activity and of the LD-1/LD-2 ratio in diagnosis of hemolytic disease in 100 patients. The sensitivity of the "flipped" LD-1/LD-2 ratio was only 58%, the specificity was 93%, and the predictive value was 74% for diagnosis of hemolytic disease. A normal total LD activity is highly predictive (92%) for ruling at the presence of hemolytic disease.
Circulating IgG-LD complex, dissociable by addition of NAD+.
Authors: Gorus F , Aelbrecht W , Van Camp B 
Published: January 2020

Abstract
Macromolecular LD (lactate dehydrogenase, EC 1.1.1.27) was present in the serum of a patient suffering from idiopathic fibrosis of the lung and presenting signs of autoimmune disease. By using gel filtration and affinity chromatography techniques, the vast majority of the patient's serum LD activity was shown to consist of LD-IgG complexes, which dissociated in the presence of added nicotinamide adenine dinucleotide (NAD+). Binding studies with tritiated NAD+ indicated that complex formation was not ascribable to a lack of circulating cofactor. The most likely explanation for the complex formation was the existence of LD binding sites on IgG molecules. The disruption of the complex by NAD+ might be explained by a competition between IgG molecules and NAD+ for the LD active site or by conformational changes induced in the LD molecules on binding of NAD+.
Direct determination of therapeutic concentrations of lithium in serum by flow-injection analysis with atomic absorption spectroscopic detection.
Authors: Rocks B F , Sherwood R A , Riley C 
Published: January 2020

Abstract
In this flow-injection system for direct determination of lithium in serum by atomic absorption spectroscopy, the 10-microL sample is manually injected into a continuously flowing non-segmented stream of de-ionized water, which is pumped, via a dispersion tube, to the spectrometer's nebulizer. Controlled dispersion of the sample zone, before it is introduced into the nebulizer, produces the required sample dilution. Effects of varying the length of the dispersion tube, the flow rate, and the sample size were studied. Analytical readout is obtained, in the form of transient peaks, 5 s after sample injection. It is necessary to include physiological concentrations of sodium and potassium in the standard because each of these cations enhances the lithium absorbance signal. Analytical recovery (98.5 to 101%) and CV (about 2%) are good, and results compare well with those obtained by aspiration of prediluted samples (n = 121, r = 0.99).
Isolation and preliminary characterization of a fraction of bilirubin in serum that is firmly bound to protein.
Authors: Lauff J J , Kasper M E , Wu T W , Ambrose R T 
Published: January 2020

Abstract
We have isolated from pathological sera a bilirubin fraction (delta) that is very tightly, if not covalently, bound to protein, most likely albumin. This delta fraction absorbed at a lambda max of 433 nm in the visible spectrum, between the lambda max of unconjugated (alpha) and that of conjugated (Bc) bilirubin when measured in solutions containing albumin. However, unlike the other bilirubin species, this fraction could not be separated from the proteins in serum by exhaustive ultrafiltration in the presence of caffeine/benzoate solution. In the Jendrassik-Grof diazo procedure for bilirubin analysis, the delta fraction gave a large direct reaction (76-89% of the total reaction). Yet, when relatively hydrophobic azo dyes were formed by reaction of the delta fraction with the diazonium salt of dichloroaniline, only 50% of the dyes were extractable from aqueous solution. On chromatography the rest remained associated with protein. Of the extractable dye, more than 70% was accounted for by two liquid-chromatographic peaks with retentions identical with those of azo dyes formed from unconjugated bilirubin. This delta fraction was not appreciably separated from protein by treatment with strong acid or base, or by prolonged digestion with various enzymes. Finally, in a highly denaturing solvent (urea/mercaptoethanol), this fraction was not dialyzable through a membrane with a 12 000-dalton cutoff.
Quantitation of haptens by homogeneous immunoprecipitation. 1. Automated analysis of gentamicin in serum.
Authors: Wu J W , Hoskin S , Riebe S M , Gifford J E , O'Neill S P 
Published: January 2020

Abstract
A new homogeneous immunoprecipitation inhibition assay has been developed to quantitate concentrations of hapten in human serum or plasma without the use of radioactive isotopes, enzymes, fluorescent markers, or laser nephelometers. This immunoprecipitation is based on spectrophotometric measurement of the inhibition by free hapten of the precipitating reaction between antihapten antibody and polyhaptenic antigen. The immunoprecipitation analysis of the antibiotic gentamicin in human serum is reported here. A serum test sample is mixed with gentamicin-human serum albumin polyhaptenic conjugate and rabbit antiserum to gentamicin on a centrifugal analyzer, and the subsequent reaction monitored for 3 min. No sample dilution or pretreatment is required. The within-run and between-run coefficients of variation are well below 10%. The results on patients' test samples correlate well with those obtained by commercially available radioimmunoassay and enzyme immunoassay kits.
Two-dimensional electrophoretic patterns of proteins of normal mucosa, polyps, and carcinomas of the large intestine.
Authors: Thorsrud A K , Vatn M H , Jellum E 
Published: January 2020

Abstract
Two-dimensional protein maps of biopsies from normal mucosa, tubular adenomas (polyps), and colonic carcinomas in humans have been studied in order to obtain information on the possible precancerous role of intestinal polyps. The maps are complex and several hundred protein spots are seen after staining with Coomassie Blue. Most of the spots are common to these three tissue types, but there are also differences. Polyps and carcinomas had a strikingly similar protein pattern, different from that of normal mucosa. There were negligible differences in the two-dimensional protein maps of tubular adenomas from patients who also had colonic cancer, as compared with adenomas from persons without carcinomas. The results lend further support to the hypothesis that polyps may be precursors of carcinomas of the large intestine.
Patterns for normal colon mucosa and colon adenocarcinoma compared by two-dimensional gel electrophoresis.
Authors: Tracy R P , Wold L E , Currie R M , Young D S 
Published: January 2020

Abstract
A two-dimensional gel "map" of the proteins in normal cells and transformed cells may well help establish the presence of putative tumor-specific protein antigens, which can be isolated and used as antigens. We so examined normal colon mucosa and colon adenocarcinoma, using a sensitive silver stain. Samples were promptly prepared after excision by rapidly trimming the tissue to a small, grossly homogeneous piece, which was frozen on solid CO2. Frozen histological sections and permanent mounts were also prepared for several areas, to document the cellular constitution and to grade the carcinoma. Sample preparation for electrophoresis is described. The DNA was pelleted by centrifugation (108 000 x g x 1.5 h). Little or no pellet was observed, indicating complete solubilization. Many of the tumors contained proteases, liberated during sample preparation, so protease inhibitors were included. A highly reproducible pattern was observed for normal mucosa. Comparison of the gels from paired samples with histological data allows many of the spots to be tentatively assigned to the different cell types present in the mucosa (epithelium, connective tissue, or muscularis mucosa) and, in most tumors analyzed, detection of a series of spots that are not detectable in the pattern for normal tissue. These apparently tumor-associated proteins may be of epithelial cell or stromal origin.
Characterization of allergen extracts by two-dimensional electrophoretic techniques: Micropolyspora faeni antigens.
Authors: Vesterberg O , Holmberg K 
Published: January 2020

Abstract
Thermophilic actinomycetes and saprobic fungi are important in the etiology of allergic occupational diseases such as "farmer's lung" disease. Each such organism produces several protein antigens. Inhaled, these antigens stimulate production of antibodies. Detection of precipitating antibodies has been useful in the diagnosis of diseases so induced. Characterization of allergen extracts from microorganisms associated with these diseases is important, to improve the sensitivity and precision of the precipitin analysis. For this purpose we submitted crude allergen extracts to electrophoresis and isoelectric focusing in agarose gels. Staining the gels revealed many protein components in each extract, especially after isoelectric focusing. After separation in one dimension, a lane of gel was cut out and the proteins were electrophoresed at right angles into another gel, which contained antibodies. Several arcs of immunoprecipitates, indicating different antigens, were seen. This technique ("crossed immunoelectrofocusing") has earlier been used with polyacrylamide in the first dimension, but it is improved by using instead agarose of a special quality. Further to improve the quantification, we isolated pieces of gel containing the proteins of interest and used them as samples in zone immunoelectrophoresis assay. This method is straightforward, easy to evaluate, and about 100-fold as sensitive as radial immunodiffusion. The amount of protein in each sample is usually proportional to the distance from the upper gel surface to the front of each immunoprecipitate. The increased sensitivity allows study of many hitherto unexamined antigens.
Chloroquine and its metabolites in human cord blood, neonatal blood, and urine after maternal medication.
Authors: Essien E E , Afamefuna G C 
Published: January 2020

Abstract
Chloroquine, its N-dealkylated metabolites, and chloroquine N-oxides were detected in the urine of pregnant women who were receiving chloroquine medication whereas chloroquine and its nonpolar metabolites, desethyl- and didesethylchloroquine and 7-chloro-4-aminoquinoline, have been found in the neonates' urine, blood, and cord blood. We used thin-layer chromatography to separate chloroquine and its metabolites after their extraction from biological fluids. These compounds were identified by comparing their chromatographic and ultraviolet spectrophotometric characteristics with those of reference compounds. That chloroquine and its relatively nonpolar metabolites (including one without the alkyl side-chain, 7-chloro-4-aminoquinoline) cross the placenta is demonstrated by the presence of these compounds in the cord blood, neonatal systemic blood, and neonatal urine. The selective transfer of the compounds in the cord blood, neonatal system blood, and neonatal urine. The selective transfer of the compounds across the placenta and the clinical implications of these findings are discussed.
Stability of immunologic activity of human prostatic acid phosphatase in serum.
Authors: Chen I W , Sperling M I , Maxon H R , Kaplan L A 
Published: January 2020

Abstract
The stability of the immunologic activity of human serum prostatic acid phosphatase (iPAP;EC 3.1.3.2) under various storage conditions was evaluated. Although more stable than the enzymic activity of serum PAP, serum iPAP was inactivated rapidly at room temperature at neutral and especially at alkaline pH. Purified iPAP in a phosphate buffer (pH 7.5) was stable for at least three days at room temperature but showed instability similar to that of serum iPAP when added to heat-treated serum (30 min at 56 degrees C, pH 8.3). Addition of a protease inhibitor, a sulfhydryl agent, or a chelating agent failed to preserve iPAP. Acidification of serum with an acetate buffer (5 mol/L, pH 5.0), 20 microliters/mL of serum, protected but could not restore serum iPAP activity. When stored at 24 degrees C, serum iPAP was most stable at pH 6.5. Acidification had little effect on PAP values by radioimmunoassay, iPAP values from acidified and unacidified serum samples being essentially the same. We recommend that blood samples drawn for PAP immunoassays be kept at 4 degrees C and that serum samples be separated and acidified as soon as practical. For long-term storage, acidified serum samples should be kept in small aliquots at -20 or -70 degrees C.
Liquid-chromatographic direct determination of phenylalanine and tyrosine in serum or plasma, with application to patients with phenylketonuria.
Authors: Hilton M A 
Published: January 2020

Abstract
With this method, picomole amounts of phenylalanine and tyrosine can be rapidly separated and directly measured by absorbance at 206 nm. As little as 25 microliters of serum or plasma suffices. Plasma is deproteinized and 20 microliters of the supernate, representing 1.8 microliters of plasma, is applied to a reversed-phase column and eluted isocratically with a solution containing methanol and H3PO4, pH 2.4. The tyrosine and phenylalanine peaks appear at 6 and 10 min, respectively. We used the method to measure phenylalanine in plasma from six children with phenylketonuria.
Why we need better test evaluations.
Authors: Zweig M H , Robertson E A 
Published: January 2020

Abstract
A laboratory test is clinically useful only if it successfully answers a question of consequence to patient management. Unfortunately, the results and conclusions of many published test evaluations are misleading or of uncertain validity because common-sense principles of study design are overlooked. This is illustrated by examples from recent literature. We suggest that tests should be evaluated with prospective studies of patients representative of the population for which the test will ultimately be used. The clinical question to be addressed by the test should be clearly stated, and then answered for each patient by means independent of the test being evaluated. When comparing tests with each other, decision levels should be chosen to give either the same sensitivity or specificity for each. The use of soundly designed protocols for the clinical evaluation of tests provides the information needed to select the most effective tests.
Enzyme immunoassay for factor VIII-related antigen.
Authors: Cejka J 
Published: January 2020

Abstract
I describe a simple enzyme-linked immunosorbent assay (ELISA) for the quantitation of Factor VIII-related antigen in plasma with use of commercially available peroxidase-labeled antiserum and solid-phase support. Regression analysis of 85 plasma samples analyzed by this technique (y) and by a commonly used electroimmunoassay (Anal. Biochem. 15: 45-52, 1966) (x) gave the equation y = 0.223 + 0.77x (r = 0.973). The present method was also compared with enzyme immunoassay in which a phosphatase-labeled antiserum prepared in our laboratory was used; the correlation between the two assays was very good. The simplicity and specificity of the ELISA technique should make it a useful alternative to the more difficult and time-consuming Laurell method.
Urinary urea: are currently available methods adequate for revival of an almost abandoned test?
Authors: Eckfeldt J , Levine A S , Greiner C , Kershaw M 
Published: January 2020

Abstract
Measurement of urinary urea excretion has been suggested as a means of estimating nitrogen balance in hospitalized patients who are malnourished. Because proficiency-testing surveys show gross variations in mean urea as determined by various automated methods and extremely poor precision occasionally, we compared urinary urea measurements and ammonia interference in three widely used methods. The coupled urease/glutamate dehydrogenase method (used in the DuPont aca) showed positive interference from ammonia, as expected; with the diacetylmonoxime (Technicon (12/60) and the urease conductivity (Beckman ASTRA) methods we saw no such interference. Generally, interference by ammonia is less than 10%, but (rarely) it may exceed 25%. However, if urine specimens are properly diluted and potential sources of interference recognized, all three methods appear capable of providing clinically useful data.
Idiopathic hemochromatosis: serum ferritin concentrations during therapy by phlebotomy.
Authors: Garry P J , Saiki J H 
Published: January 2020

Abstract
We report the case of a 54-year-old man who presented with symptoms of idiopathic hemochromatosis, an inherited disorder involving regulation of iron absorption. These symptoms usually do not appear until total body iron content reaches 15 g, about threefold normal. Therapy involves mobilization and removal of excess stored iron through weekly or twice-weekly phlebotomies of 500 mL, until the hemoglobin concentration becomes less than 110 g/L and remains there for several weeks, or until serum ferritin concentrations indicate that almost all the stored iron has been removed (ferritin less than 12 micrograms/L). Here, concentrations of ferritin in serum were used as an index to iron overload and removal of stored iron. We report changes in hemoglobin, serum ferritin, iron, and total iron-binding capacity during the course of removing by phlebotomy more than 20 g of iron from a patient with idiopathic hemochromatosis.