bluuebunny/crossref_metadata_2025_split huggingface dataset:
A kinetic method for glucose that is insensitive to variations in temperature and enzyme activity.
Authors: Mieling G E , Pardue H L , Thompson J E , Smith R A 
Published: January 2020

Abstract
We have adapted for glucose determination a new approach to kinetic analyses [Anal. Chem. 50, 1611 (1978)]; it is 50-fold less dependent upon some experimental variables than is a more conventional rate method. Modification of a commercially available hexokinase/glucose-6-phosphate dehydrogenase reagent system for glucose provides that the rate of production of NADH be first-order in total glucose concentration within about 30 s after sample and reagent are mixed. In the kinetic method, absorbance vs. time data recorded after 30 s and a multiple-linear-regression program are used to compute the absorbance change that would occur if the reaction were monitored to completion. Results demonstrate a linear relationship between glucose concentration and computed absorbance change. Application of the method to 51 human sera without rigorous control of either temperature or reagent composition yielded a regression equation of y = 1.01x -0.3 when kinetic results (y) were compared with equilibrium results (x) for the same samples analyzed in a hospital laboratory.
Rapid analysis of bilirubin in neonatal serum. I. The binding of bilirubin to albumin.
Authors: Lu K C , Gooding K M , Regnier F E 
Published: January 2020

Abstract
Evaulation of the severity of jaundice in the neonate may be determined by measuring the reserve binding capacity of serum proteins for free bilirubin. Determination of protein-bound bilirubin has been labor intensive, necessitating multiple runs on gel-permeation chromatography columns or, more recently, enzyme assays or fluorescence quenching analysis. We present a method for quantitation of free bilirubin and of bilirubin-binding capacity of serum by liquid chromatography. A gel-permeation column binds free bilirubin while allowing passage and quantitation of protein-bound bilirubin. Subsequent injection of a desorbing agent releases the adsorbed bilirubin from the column, permitting quantitation of free bilirubin. Bound and free serum bilirubin may be determined directly in less than 15 min using 10 microL of serum. The binding of bilirubin to neonatal serum is seen to be quite different from the binding to adult serum. Ion-exchange chromatography of adult and neonatal serum samples shows that their protein profiles are radically different. This difference probably accounts for the binding characteristics.
Use of magnetic circular dichroism spectroscopy for biologic monitoring of occupational exposures to toxicants.
Authors: Zygowicz E R , Hollebone B R , Perkins H M 
Published: January 2020

Abstract
Zinc protoporphyrin is the predominent fluorescent porphyrin accumulating in erythrocytes as a result of chronic lead absorption or iron-deficiency anemia. Although diagnostic concentrations or thresholds for it in erythrocytes have been inferred, normal adult averages have not been established. We quantitatively assessed average zinc protoporphyrin values during an investigation into the usefulness of magnetic circular dichroism spectroscopy as an analytical technique for biologic monitoring of industrial toxicant exposures. Blood samples drawn from 55 employees not exposed to lead were analyzed for blood lead, hematocrit, and zinc protoporphyrin. Average concentrations of zinc protoporphyrin determined with a hematofluorometer were compared with results obtained by magnetic circular dichroism spectroscopy. The latter results were comparable in kind but superior in quality to those of fluorometry. The magnetized spectroscopy followed Beer’s Law at concentrations well below indigenous concentrations and was more sensitive than difference spectroscopy. Spectroscopic resolution of heme and zinc protoporphyrin moieties in a pyridine/NaOH mixture was complete.
New optical technique for measuring erythrocyte deformability with the ektacytometer.
Authors: Groner W , Mohandas N , Bessis M 
Published: January 2020

Abstract
The laser light scattered by erythrocytes subjected to a well-defined shear stess can be analyzed with the ektacytometer to obtain information regarding the changes in cell shape due to fluid shear. We describe an optical technique whereby an observed quantitative output derived from a mesurement of light intensity through a spatial filter is related to the change in cellular dimensions that were previously observed under similar fluid-shear conditions by use of microscopy and a cone-plate viscometer (rheoscope). We also present the predictions of a theoretical model (of the ektacytometer) based on approximations of light-scattering theory developed for nonspherical particles, and give preliminary results for the accuracy and sensitivity of this measurement of erythrocyte deformability. With this optical technique the instrumentation (ektacytometer) is made quite simple and suitable for use in the typical laboratory. This would allow a regular, quantitative assessment of this important blood cell quality, to supplement the data obtained from the complete blood count.
Application of "high-performance" liquid chromatography to the study of sphingolipidoses.
Authors: Ullman M D , Pyeritz R E , Moser H W , Wenger D A , Kolodny E H 
Published: January 2020

Abstract
Quantitative high-performance liquid chromatographic analysis of perbenzoylated sphingolipids has been used to study the correlations of body chemistry to clinical phenomena. Plasma sphingolipids were isolated from 32 Gaucher (β-glucosidase deficiency) and six Fabry (α-galactosidase deficiency) patients by solvent partition and chromatographic separation on silicic acid columns. Plasma sphingolipids from a patient undergoing plasma-exchange were separated from interfering lipids with reversed-phase columns. Liquid-chromatographic analysis of sphingolipids provides useful supportive information for diagnoses because affected individuals are shown to possess increased circulating concentrations of the pathognomonic sphingolipid. We also used this technique to monitor sphingolipid concentrations in plasma and urine sediment during plasma exchange of a p atient with Fabry’s disease. Regular plasma exchanges produced and maintained decreased concentrations of sphingolipids in plasma, but near pre-exchange concentrations were observed within days after the therapy was terminated.
Enzyme immunoassay of hepatitis B surface antigen with use of the "Hepanostika" test kit and a new photometer, "Photo-Elisa 1".
Authors: Tanaka F , Nishi K , Arisue K , Hayashi C , Miyai K 
Published: January 2020

Abstract
We describe an enzyme immunoassay for hepatitis B surface antigen, with use of a Hepanostika test kit and "Photo-Elisa 1," a photometer capable of measuring small quantities of test material. Because the length of the optical path in the "Photo-Elisa 1" is only 1.2 mm, volumes as small as 15 micro L can be can be measured. Accuracy is enhanced through cancellation of background absorbance by measurement at two wavelengths. Results obtained with the kit compare well with those by radioimmunoassay. By substituting photometric reading for visual reading, Hepanostika provides a more nearly accurate screening test.
Diagnostic utility of C-terminal parathyrin measurement as compared with measurements of N-terminal parathyrin and calcium in serum.
Authors: Simon M , Cuan J 
Published: January 2020

Abstract
We compared results obtained from two parathyrin (parathyroid hormone) assays with differing specificities, using sera from 172 normal donors and from 98 patients with disorders of calcium regulation. Intact parathyrin was measured in both assays; the C-parathyrin assay also measured the 53-84 amino acid C-terminal hormone fragment; the N-parathyrin assay also measured the 1-34 N-terminal fragment. The reference interval for the C-parathyrin assay (860-3720 int. units/L; 430-1860 ng/L) was markedly higher than for the N-parathyrin assay (460-1260 int. units/L; 230-630 ng/L), a finding consistent with the longer half-life of C-parathyrin fragments in human circulation. Mean C-parathyrin in primary hyperparathyroid sera--5720 (SD 2760) int. units/L or 2860 (SD 1380) ng/L--clearly exceeded the reference interval and values for sera from patients with non-parathyroid malignancy [1740 (SD 760) int. units/L; 870 (SD 380) ng/L]. Secondary hyperparathyroid patients also had supranormal C-parathyrin values: 6100 (SD 2720) int. units/L; 3050 (SD 1360) ng/L. We found no consistent correlation between parathyrin and serum calcium in any clinical group. The two parathyrin assays showed about equal diagnostic power, but their results could not be used interchangeably in sequential monitoring of patients.
An immunochemical procedure for determination of mitochondrial aspartate aminotransferase in human serum.
Authors: Rej R 
Published: January 2020

Abstract
An immunochemical procedure is described for quantitation of mitochondrial aspartate aminotransferase (m-AspAT; EC 2.6.1.1) activity in human serum specimens. Antibodies directed against purified soluble aspartate aminotransferase (s-AspAT) from human erythrocytes were produced in rabbits and partly purified. Antibody sufficient for analyses of &gt; 6000 specimens could be obtained from 15 mL of rabbit antiserum; contaminant AspAT activity of the antibody preparation was &lt; 0.4 U/L. Addition of antibody directly to purified AspAT isoenzymes resulted in inhibition of s-AspAT but had no measurable effect upon m-AspAT. Antibody is incubated with serum in the presence of polyethylene glycol for 60 min at room temperature, then 60 min at 4 degrees C, and centrifuged (7000 x g, 4 degrees C, 15 min). No detectable s-AspAT activity remains in the supernatant fluid; thus m-AspAT activity can be measured directly. Precision, both within-day and day-to-day, was &lt; 1 U/L, or 3.0% of residual m-AspAT activity. The method completely removed 1200 U of purified s-AspAT activity per liter; addition of s-AspAT to serum in increasing concentrations of about 500 U/L had no effect upon the measurement of residual m-AspAT activity. Results of the procedure described showed excellent correlation with those by an alternative procedure involving antibodies directed against m-AspAT. Addition of both anti-s- and anti-m-AspAT antibodies resulted in complete removal of serum AspAT activity. Univalent Fab fragments prepared anti-s-AspAT antibodies were capable of directly inhibiting s-AspAT activity without precipitation. Although a homogeneous immunoinhibition assay was possible, the greater precision of the precipitation assay made it preferable.
Decrease in plasma glucose concentration during storage at -20 degrees C.
Authors: Giampietro O , Navalesi R , Buzzigoli G , Boni C , Benzi L 
Published: January 2020

Abstract
We measured glucose concentrations with the Beckman Glucose Analyzer, before and after storage at -20 degrees C for various intervals, in 228 plasma samples from oral glucose tolerance tests on 17 normal subjects and 21 patients with impaired carbohydrate tolerance, and also in 82 control samples collected daily, after overnight fast, from seven insulin-dependent diabetics. We found a significantly (p &lt; 0.001) positive relation between storage interval and percentage decrease in glucose concentration. Evidently, the longer plasma is stored, the greater the decrease in glucose.
Electrothermal atomic absorption spectrophotometry of cadmium in semen.
Authors: Wetzel L T , Bell J U 
Published: January 2020

Abstract
We describe the electrothermal atomic absorption spectrophotometry of cadmium in rabbit semen collected before and after seven days of subcutaneous administration of 0.5 mg of cadmium per kilogram body weight per day. The analytical technique involves combining an aliquot of an acid-digested semen sample with an equal volume of an (NH4)2HOP4 solution (50 g/L), to allow an increase in charring temperature, which results in more nearly complete destruction of matrix. Cadmium values as determined by this method correlated well with those determined by the method of standard additions. The dosing regimen resulted in a statistically significant (p &lt; 0.01) increase in cadmium concentrations in semen (and whole blood) sampled just after the last day of cadmium administration.
Counting efficiency of some commercially available liquid scintillators compared.
Authors: Gray P , van Reenen O , Potgieter G M 
Published: January 2020

Abstract
We investigated four commercially available liquid scintillators as to overall counting efficiency and quenching effect of added phosphate-buffered isotonic saline. They differed significantly in these respects. Evidently, characteristics of the scintillator used in radioimmunoassays where β-particle emitters are counted should be carefully examined if results are to be optimal.
Evaluation of enzyme immunoassay, radioassay, and radioimmunoassay of serum methotrexate, as compared with liquid chromatography.
Authors: Buice R G , Evans W E , Karas J , Nicholas C A , Sidhu P , Straughn A B , Meyer M C , Crom W R 
Published: January 2020

Abstract
We evaluated three commonly used clinical methods for measuring serum methotrexate: enzyme immunoassay (EMIT), radioassay, and radioimmunoassay. Because potentially interfering compounds can be resolved by liquid chromatography, this method was selected as the comparison method. Patients’ serum samples, taken during 24 h after 6-h high-dose infusions, contained methotrexate in concentrations ranging from 10(-7) to 10(-4) mol/L. Chromatograms revealed substantial amounts of 7-hydroxymethotrexate in all samples, actually exceeding methotrexate by 12 and 24 h. Nevertheless, analysis of variance revealed no significant differences in results by any of the four methods, nor did results by the three test methods differ significantly after being adjusted by analysis of covariance with liquid chromatography as the covariate. Evidently any of the four techniques is suitable for monitoring serum methotrexate for 24 h after high-dose therapy.
Simplified radioimmunoassay of bradykinin in human plasma.
Authors: Verma P S , Lorenz P E , Sander G E 
Published: January 2020

Abstract
A greatly simplified radioimmunoassay for bradykinin in human plasma is described. Current techniques require multiple chromatographic steps or extraction procedures with analytical recoveries of bradykinin of often less than 60%. We present a method in which bradykinin is separated from components of higher relative molecular mass (including kininogens) in a single step, by use of a column of Sephadex G-25 medium (PD-10). The mean analytical recovery of tritiated bradykinin added to plasma is 85.5% (SD, 3.5%). The sensitivity of this radioimmunoassay is 25 pg per assay tube, equivalent to 125 ng per liter of plasma. Twenty to 30 blood samples may be completely processed and assayed within 6 h. As determined with this technique, concentrations of bradykinin in plasma from apparently normal subjects ranged from 2.5 to 5.2 microgram/L (mean 4.2, SD 1.1 microgram/L); these values are consistent with previously reported normal values.
Methods for ligand-receptor assays in clinical chemistry.
Authors: Smith R G , Sestili M A 
Published: January 2020

Abstract
This is intended to be a practical review for the clinical chemist of the laboratory procedures most commonly used to quantitate hormone receptors in various cellular fractions. These procedures include use of charcoal adsorption and hydroxylapatite for intracellular receptors and of centrifugation and filtration for membrane receptors. We discuss the use of the Scatchard analysis to establish the steroid-receptor affinity and the quantity of steroid-receptor binding sites. Both pre- and post-labeled sucrose density gradient methods are outlined. One section is devoted to the direct and indirect methods used in nuclear “exchange” assays. Basic theory underlying each assay is presented, but, more importantly, we assess the advantages and disadvantages of each procedure. On the basis of this information, one may decide which assay is best suited for a particular laboratory and (or) specimen.
Properties and clinical significance of an alkaline phosphatase-lipoprotein-X complex.
Authors: Weijers R N 
Published: January 2020

Abstract
The existence of an alkaline phosphatase-lipoprotein-X complex was demonstrated as an abnormally moving band in the agar-agarose gel alkaline phosphatase pattern of sera from 58 patients in a group of 72 patients whose sera contained lipoprotein-X. The position of the abnormally moving band in the agar-agarose gel alkaline phosphatase pattern and the percentage of alkaline phosphatase activity in the complex in relation to the total serum alkaline phosphatase activity depend on the serum lipoprotein-X concentration. The presence of the complex is a reliable indicator for cholestasis and of limited value in the differentiation between intrahepatic and extrahepatic cholestasis.
Enzyme-linked immunoassay for placental lactogen in human serum.
Authors: MacDonald D J , Nicol K M , Belfield A , Shah M M , Mack D S 
Published: January 2020

Abstract
We describe an enzyme-linked immunoassay for measuring human placental lactogen (HPL) in serum. After suitable dilution, sera are pipetted into the wells of polyvinyl microtitre plates previously coated with anti-HPL. After incubation the sera are decanted, and replaced by a conjugate of horseradish peroxidase and anti-HPL. An amount of enzyme proportional to the concentration of HPL in the serum is bound to the wells via an antibody—HPL—antibody bridge. Peroxidase activity is measured by oxidation of o-phenylenediamine, the resulting color being related to the concentration of HPL. Results correlate well with those by radioimmunoassay (r = 0.96). Our between-assay coefficient of variation was 13%; no discernible effect of protein was observed. This 4-h assay can be used to monitor placental function in pregnancy.
Spectrophotometric determination of urinary oxalate with oxalate oxidase prepared from moss.
Authors: Laker M F , Hofmann A F , Meeuse B J 
Published: January 2020

Abstract
A novel spectrophotometric enzymic procedure for estimating oxalic acid in urine is described. Oxalate oxidase, prepared from moss species, converts oxalic acid to hydrogen peroxide and carbon dioxide. Hydrogen peroxide is determined enzymatically with horseradish peroxidase, by oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline; the resulting indamine due is determined spectrophotometrically at 595 nm. Interfering substances are removed by adsorption to ion-exchange resins and oxidation with charcoal, thus avoiding oxalate recovery problems accompanying oxalate isolation. The procedure is rapid, sensitive, linear, and precise. Results agreed well with those obtained with a widely used chemical technique.
Hypophosphatasia (adult form): quantitation of serum alkaline phosphatase isoenzyme activity in a large kindred.
Authors: Millán J L , Whyte M P , Avioli L V , Fishman W H 
Published: January 2020

Abstract
We used heat inactivation, L-phenylalanine inhibition, and electrophoresis on polyacrylamide gel and cellulose acetate membranes--with and without use of specific antisera against the liver-bone, intestinal, and placental isoenzymes--to distinguish and quantitate the different alkaline phosphatase isoenzymes in sera from 23 adult members of a kindred affected by the adult form of hypophosphatasia. Nine subjects had values for total activity more than two standard deviations below the mean values for age- and sex-matched normal persons. Bone isoenzyme was diminished in all nine, whereas liver isoenzyme was subnormal in only four. Phosphoethanolamine and phosphoserine in the urine of eight hypophosphatasemic individuals correlated inversely with both total and liver alkaline phosphatase activity in their serum, but not with the activity of the bone isoenzyme. Total activity in the serum of adult kindred members correlated best with the circulating liver isoenzyme activity. The findings suggest that altered hepatic metabolism is responsible for the increased urinary excretion of phosphoethanolamine, and perhaps phosphoserine, in hypophosphatasia.
Creatinine: a review.
Authors: Narayanan S , Appleton H D 
Published: January 2020

Abstract
Measurement of creatinine has many applications. We review the determination of urinary creatinine as a valid index of completeness of 24-h urine collection, the clinical utility of the determination of creatinine clearance ratios, and measurement of the ratio of the clearance of specific analytes, such as amylase, to the ratio of clearance of creatinine. The chemistry and variables that affect the Jaffé reaction are reviewed, and attempts at improvement of specificity are discussed. We also review and assess techniques other than the Jaffé reaction for measurement of creatinine.
Identification of fluorescent Pseudomonas species.
Authors: Shelly D C , Quarles J M , Warner I M 
Published: January 2020

Abstract
Fluorescent pseudomonads may be identified through examination of the fluorescence "profiles" of diffusible pigments released into the growth medium. The profiles are obtained in the form of an emission-excitation matrix, the elements of which correspond to fluorescence intensity as a function of multiple exciting and emitting wavelengths. Use of a rapid scanning fluorometer to acquire these data provides a relatively fast method for identification of the microorganisms after incubation. This procedure can potentially be expanded for the identification of other microorganisms.
Magnetizable solid-phase fluoroimmunoassay of phenytoin in disposable test tubes.
Authors: Kamel R S , Landon J , Smith D S 
Published: January 2020

Abstract
We developed a fluoroimmunoassay for phenytoin in serum or plasma, based on the magnetic separation technique. The method involves sheep anti-phenytoin serum coupled to magnetizable cellulose/iron oxide particles, with a fluorescein-labeled phenytoin analog as tracer. After magnetic sedimentation of the solid phase from assay mixtures, the free fraction of the tracer is aspirated, removing endogenous fluorophores and other interfering components of the sample. The antibody-bound tracer is then eluted from the solid phase into a methanolic buffer medium and quantitated fluorometrically. The entire procedure, including fluorometry, is performed within disposable polystyrene test tubes. The assay involves only simple reagents and equipment, and correlates closely with established radioimmunoassay (r = 0.97) and gas-liquid chromatographic (r = 0.98) techniques.
beta-Lipoprotein quantitation in cord blood spotted on filter paper: a screening test.
Authors: Vladutiu G D , Glueck C J , Schultz M T , McNeely S , Guthrie R 
Published: January 2020

Abstract
We describe an electroimmunodiffusion technique for measuring beta-lipoprotein in cord blood spotted on filter paper. A series of cord-blood samples, taken from 916 consecutive live-birth infants, was spotted directly onto filter paper and assayed for beta-lipoprotein. Eleven had above-normal beta-lipoprotein. Of these 11, seven were tested two to six months later, along with their parents, for total cholesterol and triglyceride concentrations. Five infants had increased cholesterol values, and four parents of these infants had either increased cholesterol or triglyceride values. We also measured beta-lipoprotein concentrations in 63 paired samples of dried cord-blood and three-day post-delivery blood specimens, routinely collected for phenylketonuria screening. We saw a significant correlation between results for the specimens, but detected no cases of increased beta-lipoprotein. beta-Lipoprotein assay in dried specimens of cord blood is simple, inexpensive, and potentially is useful in mass screening of newborns for familial type II and combined hyperlipidemia.