bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taurine transport in epilepsy.
Authors: Goodman H O , Connolly B M , McLean W , Resnick M 
Published: January 2020

Abstract
Previous studies of plasma taurine concentrations in epileptics have yielded equivocal results. We measured plasma and urinary taurine in 41 epileptic and 68 control subjects and found plasma concentrations among epileptics to be comparable in general to those of controls, but that two or three classes of plasma taurine concentrations, possibly genetically regulated, occur in both epileptic and control subjects. Our previous studies and data from the present study on taurine excretion revealed three excretion classes under genetic control. The principal finding is that epileptics include disproportionate numbers of low excretors (high reabsorbers), who are presumptive homozygotes for the allele effecting higher reabsorption. If confirmed, these findings suggest that the transport of taurine, rather than absolute taurine concentration, may explain the efficacy of taurine administration in some epileptics but not in others. The locus involved may be one component in the polygenic diathesis to the idiopathic epilepsies.
A simplified assay for dihydroxylated vitamin D metabolites in human serum: application to hyper- and hypovitaminosis D.
Authors: Mason R S , Lissner D , Grunstein H S , Posen S 
Published: January 2020

Abstract
We describe a simplified assay for 24,25-and 1.25-dihydroxyvitamin D in human serum. It involves two preparative steps, and normal chick intestine is used in preparing cytosol-binding protein. Our results for 24,25-dihydroxyvitamin D include a reference interval of 2.9—16 nmol/L (1.2—6.7 microgram/L), a mean of 6.7 nmol/L (2.8 microgram/L), an intra-assay CV of 11%, and an interassay CV of 22%. For 1,25-dihydroxyvitamin D, these data were 29—168 pmol/L (12—70 ng/L), 86 pmol/L (36 ng/L), 12%, and 22%, respectively. In hypoparathyroid patients with vitamin D intoxication, mean concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum were significantly above normal; the 1,25-dihydroxyvitamin D concentrations were significantly below normal. Patients with malabsorption and/or post-gastrectomy states had significantly subnormal values for both 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum, and there was a significantly negative correlation between each of these biochemical values and the severity of osteomalacia. We also discuss cost effectiveness of assaying vitamin D metabolites in human serum.
Thyroxine-binding globulin capacity and concentration evaluated from blood spots on filter-paper in a screening program for neonatal hypothyroidism.
Authors: Dussault J H , Morissette J , Letarte J , Guyda H , Laberge C 
Published: January 2020

Abstract
We describe a simple method for evaluating thyroxine-binding globulin capacity and concentration from a single 1-cm blood spot on filter-paper used in a screening program for neonatal hypothyroidism. This method permits prompt diagnosis of about 90% of the infants with thyroxine-binding globulin deficiency in our abnormal low-thyroxine, low-thyrotropin population. There was excellent equivalence between results obtained by our method and by the method of Chopra et al. (J. Clin. Endocrinol. Metab. 35:565, 1972), and minimal overlap between the population with low thyroxine-binding globulin and the low-thyroxine, normal thyrotropin population. We recommend this method to all programs in which a primary thyroxine measurement is used in screening for congenital hypothyroidism.
Enzymic color development of urinary 3 alpha-hydroxysteroids on thin-layer chromatograms.
Authors: Yamaguchi Y 
Published: January 2020

Abstract
I describe the use of 3 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.50) for enzymic color development of 3 alpha-hydroxysteroids. Urinary 3 alpha-hydroxysteroids are converted to 3-ketosteroids by the enzyme, and the NADH formed is reacted with 2-p-iodophenyl-3-p-nitrophenyl-5-phenyl-tetrazolium chloride and "diaphorase" to form the colored formazan. The dye so formed on a thin layer chromatographic plate is measured by densitometoric scanning. I illustrate use of this method by showing results for urinary excretion of 3 alpha-hydroxysteroids by some various sorts of patients.
Measurement of anticonvulsants in serum by reversed-phase ion-pair liquid chromatography.
Authors: Christofides J A , Fry D E 
Published: January 2020

Abstract
We describe a method for the simultaneous liquid-chromatographic determination of ethosuximide, ethylphenacemide, primidone, phenobarbital, carbamazepine, and phenytoin in serum. The drugs, together with an internal standard, are extracted into ethyl acetate at pH 7.0. The extract is analyzed isocratically at ambient temperature on a reversed-phase column of "SAS Hypersil" with a mobile phase of acetonitrile/tetrabutyl ammonium phosphate solution (2/8 by volume). The eluted drugs are detected by their absorption at 200 nm, and quantitated from their peak heights as compared with those of extracted standards. The day-to-day CV of the method varied between 5.1 and 9.6% for concentrations ranging from less than therapeutic to toxic. The results, when compared with those by gas chromatography, gave correlation coefficients of 0.936 for phenytoin, 0.977 for phenobarbital, and 0.939 for primidone. No drug interference was found except that amobarbital and ethylphenacemide co-chromatographed.
Pre-precipitated and solid-phase second antibody compared in radioimmunoassay.
Authors: Brown T R , Bagchi N , Ho T T , Mack R E 
Published: January 2020

Abstract
We describe simple methods for preparing and determining the titer of pre-precipitated second antibody. We compared the performance of this type of insolubilized second antibody with that of a commercially available solid-phase second antibody (DASP) for separation of reverse triiodothyronine (rT3) and for thyrotropin radioimmunoassays. Equilibrium time for both reagents was about 30 min, considerably briefer than for the usual second-antibody procedure. Within-assay precision was improved and percentages of nonspecific binding (mean and SD) were lower if pre-precipitated second antibody was used in both assays [rT3 pre-precipitate = 1.48 (SD 0.16), rT3 DASP = 3.76 (SD 0.22); thyrotropin pre-precipitate = 1.45 (SD 0.18), thyrotropin DASP = 3.45 (SD 0.26)]. The cost of DASP was three to 10 times that of pre-precipitated second antibody prepared with commercially available products.
Transient increase in serum creatine kinase isoenzyme BB activity after prostatectomy in a patient with massive benign prostatic hyperplasia.
Authors: Goodman Z D , Hamilton S R 
Published: January 2020

Abstract
The activity of creatine kinase isoenzyme BB (CK-BB) in serum is rarely abnormally high (i.e., detectable). An increase in immunoreactive CK-BB or CK-BB activity in patients with prostatic disease has been proposed as an indication of prostatic adenocarcinoma. Here we report the case of an elderly man with massive benign prostatic hyperplasia but no clinical or pathological evidence of prostatic adenocarcinoma, whose serum CK-BB activity was found by agarose gel electrophoresis to be 1 U/L (normal: 0%), 10% of his total CK activity. Serum CK-BB activity was further increased to 16 U/L (20% of total CK activity) 1 h after prostatectomy, but became undetectable by the second day after the operation. The findings suggest that: (a) the source of the serum CK-BB activity was the enlarged prostate gland; (b) abnormally high CK-BB activity in serum of men with prostatic disease does not necessarily indicate the presence of prostatic adenocarcinoma; and (c) myocardial injury could be erroneously diagnosed postoperatively in prostatectomy patients if CK isoenzyme methods are used that do not consistently separate "heart-specific" CK-MB from CK-BB.
Automated creatine kinase-MB estimation by immuno-inhibition: a clinical evaluation.
Authors: Delahunty T J , Foreback C C 
Published: January 2020

Abstract
We detected the presence of creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) in serum by using an immunoinhibition technique to inactivate the creatine kinase isoenzyme of muscle origin (CK-MM). The GEMSAEC centrifugal analyzer is ideally suited for this procedure because it rapidly mixes reagents and has a throughput of 60 samples/h. The within-run CV was acceptable when the CK-MB value was 7.5 U/L or more. CK-MM was totally inactivated up to 5000 U/L, a value well above that usually seen in myocardial-infarct patients. We assessed the predictability of the assay for detecting myocardial infarction among 120 coronary-care patients when 2% of total CK activity was considered diagnostic and compared the results with those obtained with an electrophoresis technique. The positive predictive value of the immunoinhibition assay was 97.8%, as compared to 92% with the CK electrophoresis technique, when lactate dehydrogenase (EC 1.1.1.27) isoenzyme results were included in both cases. The optimal negative predictive value was 95.1% with the immunoinhibition assay vs 98.2% with electrophoresis. We conclude that the immunoinhibition technique for estimating CK-MB can be automated to assess myocardial status rapidly, precisely, inexpensively, and sensitively.
Determination of urinary amino acids by liquid chromatography with “dabsyl chloride".
Authors: Lin J K , Wang C H 
Published: January 2020

Abstract
We describe a “high-performance” liquid-chromatographic procedure for measuring amino acids in 0.5 mL of urine. The procedure includes direct derivatization of amino acids in urine samples with “dabsyl chloride" (4-dimethylaminoazobenzene-4’-sulfonyl chloride). An aliquot of this dabsylated amino acid solution is analyzed on a muBondapak C18 column with ethanol/sodium acetate (20 mmol/L, pH 4.0) 4/6 (by vol.), as mobile phase. Dabsylated amino acids are detected by their absorbance at 425 nm and quantitated by measuring peak heights. The procedure allows for the reliable analysis of amino acids in urine at concentrations near 16 mg/L. The sensitivity of this analysis on column approaches 5 ng/sample. Higher urinary tryptophan concentrations were found in the urines of some cancer patients, whereas we saw no significant difference in urinary glycine between cancer patients and control subjects. The present method was shown to be a straightforward procedure for detecting phenylalanine in phenylketonuric urine. Extension of this procedure to screening for other inborn errors of aminoaciduria is recommended.
Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.
Authors: Winartasaputra H , Mallet V N , Kuan S S , Guilbault G G 
Published: January 2020

Abstract
We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.
Restoration of lead-inhibited 5-aminolevulinate dehydratase activity in whole blood by heat, zinc ion, and (or) dithiothreitol.
Authors: Sakai T , Yanagihara S , Ushio K 
Published: January 2020

Abstract
We examined effects of heat, zinc, ion, and dithiothreitol in restoring the activity of lead-inhibited-5-aminolevulinate dehydratase (EC 4.2.1.24). The ratio of non-activated to activated activity produced by dithiothreitol correlated well with blood lead concentration among 35 lead workers. The individual effects of heat, zinc, or dithiothreitol differ from each other in the shift of pH optimum as well as in the extent to which activity is restored. Dual or triple combinations of these agents show additive or complementary restoration of activity. The combination of heat and zinc or zinc and dithiothreitol expands the range of optimum concentration of zinc in restoring activity. Using these combinations of agents, we can expect more accurate evaluation of lead exposure than by measuring only activation of zinc. Although dithiothreitol most powerfully restores activity, it restores not only the activity inhibited by lead exposure but also the activity removed by oxidation of SH-groups in the enzyme molecule.
Albumin-bound fluorescence in serum of patients with chronic renal failure.
Authors: Schwertner H A , Hawthorne S B 
Published: January 2020

Abstract
A band that is strongly fluorescent and migrates electrophoretically with serum albumin is commonly found in electrophoretograms of sera from patients with chronic renal failure. We sought to determine whether the fluorescence originates from binding of certain still-unidentified metabolites or drugs, from an abnormal albumin species, or from some other protein entity. Molecular-exclusion column chromatography, polyacrylamide gel isoelectric focusing, and cellulose acetate electrophoresis, along with results of charcoal treatment and alcohol extraction, provided evidence that the fluorescence comes from fluorescent ligands tightly bound to albumin. The fluorescent intensity of the albumin fraction, isolated by molecular-exclusion chromatography, coincides with the albumin-associated fluorescence determined electrophoretically and with the intensities of the fluorescence emission spectrum for serum. A fluorescent species with an emission maximum of 415 ± 5 nm, separated by thin-layer chromatography, appears to account for the increased serum fluorescence.
Stability of standard curves prepared for EMIT homogeneous enzyme immunoassay kits stored at room temperature after reconstitution.
Authors: Bach P R , Larsen J W 
Published: January 2020

Abstract
We examined the stability of standard curves obtained with use of homogeneous enzyme immunoassay reagents (EMIT; Syva Corp., Palo Alto, CA) for assay of lidocaine, procainamide, N-acetylprocainamide, gentamicin, and theophylline, when stored at room temperature (23-24 degrees C) after reconstitution of the lyophilized materials. Standards were run and curves obtained for as long as 16 days after reconstitution. All standard curves were acceptable, according to the criteria specified in Syva product literature. Absorbance changes for all calibrators, including the zero calibrator, increased gradually with time. Increases of non-zero calibrators were largely offset by a parallel increase in the zero calibrator, such that the quantity delta A--delta A0 was very nearly constant with time. Standard curves based on the quantity delta A--delta A0 can be used for longer than curves based only on delta A.
Method for determination of hydrogen peroxide, with its application illustrated by glucose assay.
Authors: Graf E , Penniston J T 
Published: January 2020

Abstract
We describe a simple colorimetric method for determining micromolar quantities of hydrogen peroxide, based on the oxidation of iodide in the presence of ammonium molybdate and photometry of the resulting blue starch-iodine complex. Color development is linearly dependent on analyte concentration, but only slightly time dependent, and the color of the complex formed is stable for several hours. In the range of wavelengths that may be used (570 to 630 nm), lack of interference from other biological compounds makes this method seem suitable for routine analyses. As one illustrative application of the method we quantitated glucose by measuring hydrogen peroxide produced from it by glucose oxidase catalysis. This method of quantitating glucose is more than five times as sensitive as the commonly used dianisidine method. With the appropriate hydrogen peroxide-producing oxidases, this method may be used to directly measure amino acids, purines, uric acid, xanthine, and hypoxanthine.
Interferences appearing in fluorometrically measured liquid-chromatographic profiles of creatine kinase isoenzymes in serum.
Authors: Schlabach T D , Fulton J A , Mockridge P B , Toren E C 
Published: January 2020

Abstract
We observed nonenzymic peaks when serum isoenzymes of lactate dehydrogenase (EC 1.1.1.27; LD) and creatine kinase (EC 2.7.3.2.; CK) were separated by “high-performance” liquid chromatography and detected by continuously monitoring the column effluent for enzyme activity. Such background peaks were particularly apparent in CK isoenzyme profiles obtained from human sera. We observed two nonenzymic peaks with fluorescence detection, one in the CK-MB region, the other in the CK-BB region. Serum albumin was a major component in the artifactual CK-MB peak, with lipoprotein as a minor component. We present evidence that the material responsible for the other peak fluoresced quite strongly and is mostly pre-albumin.
Liquid-chromatographic separation and on-line bioluminescence detection of creatine kinase isoenzymes.
Authors: Bostick W D , Denton M S , Dinsmore S R 
Published: January 2020

Abstract
We separated isoenzymes of creatine kinase by anion-exchange chromatography, with use of an elution of gradient containing lithium acetate (0.1 to 0.6 mol/L). A stream splitter was used to divert a 5% side stream of column effluent, which was subsequently mixed with the reagents necessary for bioluminescence assay of the separated isoenzymes. The use of the stream splitter greatly decreased the rate of consumption of reagent and, when combined with a peristaltic pumping system, permitted independent control of the side-stream flow rate. Thus both the residence interval in a delay coil in which the ATP reaction product is formed and the bioluminescence response could be increased. Bioluminescence emission was monitored in a flow-through fluorometer without use of an external light source or filters. Separation and detection of the isoenzymes of creative kinase were rapid, sensitive, and highly selective. The incremental decrease of bioluminescence response owing to inhibition by the ions in the eluent was less than 31% across the entire gradient.
High-purity 4-nitrophenol: purification, characterization, and specifications for use as a spectrophotometric reference material.
Authors: Bowers G N , McComb R B , Christensen R G , Schaffer R 
Published: January 2020

Abstract
We describe specifications for high-purity 4-nitrophenol, which is suitable for spectrophotometric standardization. Such a reference material is needed in clinical enzymology to establish the proper molar absorptivity of 4-nitrophenol under final reaction conditions, particularly for measuring alkaline phosphatase activity in human serum. Some lots of 4-nitrophenol available commercially met these specifications, but several did not. The latter can be purified to meet our specifications by recrystallization or sublimation. The molar absorptivity of 4-nitrophenol (35 μmol/L) IN 10 mmol/L NaOH at 25 °C at 401 nm is 18380 +/− 90 L.mol−1.cm−1.
Cortisol directly determined in serum by fluoroimmunoassay with magnetizable solid phase.
Authors: Pourfarzaneh M , White G W , Landon J , Smith D S 
Published: January 2020

Abstract
We developed a direct fluoroimmunoassay for cortisol in serum. This method involves cortisol labeled at the 3 position with fluorescein, and antibodies to cortisol coupled to magnetizable cellulose/iron oxide particles. Sodium salicylate is used as a blocking agent to prevent interference from endogenous binding proteins in serum. Serum sample and labeled cortisol are incubated with the antibody-coupled solid phase for 30 min. The solid phase is then separated and washed to remove free labeled cortisol and endogenous fluorophores of the sample. Finally we elute the antibody-bound fraction of the labeled cortisol into an alkaline methanolic medium and measure its fluorescence. The separation, wash, and elution steps are facilitated by magnetic sedimentation. The assay is sufficiently sensitive, specific, and reliable for routine use and correlates acceptably (r = 0.92) with an established radioimmunoassay. Precision (CV) ranged from 4 to 10% in experiments on three pooled sera; analytical recovery for sera supplemented with as much as 360 μg of cortisol per liter was 91 to 109%.
Measuring thyroxine and thyrotropin simultaneously in a dried blood sample on filter paper, to screen for neonatal hypothyroidism.
Authors: Nagataki S , Ishibashi K , Ohsawa R , Suwa S , Tsukamoto N , Takahashi T , Obara Y , Liao Y Y 
Published: January 2020

Abstract
We have developed a highly sensitive radioimmunoassay of thyroxine and thyrotropin for mass screening for neonatal hypothyroidism. This assay involves a single disc (3 mm diameter) of dried blood on filter paper. The minimum detectable concentrations are 15 pg/tube (10 microgram/L) for thyroxine and 15 nano-int. units/tube (10 milli-int. units/L) for thyrotropin; intra- and interassay CV’s are &lt; 15% in both assays. The high sensitivity of this method is due to use of labeled thyroxine with high specific activity (3 kCi/g) and of an anti-thyrotropin serum with high affinity (Keq = 7.8 × 10(11) L/mol). With this method, 11337 newborns were screened; a follow-up study revealed that only newborns with both high thyrotropin and low thyroxine concentrations had permanent hypothyroidism. We conclude that this method is sensitive, simple, and reliable and that the recall rate with this method is much lower than that of tests for measuring thyroxine or thyrotropin alone.
A coupled-enzyme equilibrium method for measuring urea in serum: optimization and evaluation of the AACC study group on urea candidate reference method.
Authors: Sampson E J , Baird M A , Burtis C A , Smith E M , Witte D L , Bayse D D 
Published: January 2020

Abstract
We describe a coupled-enzyme equilibrium method for measuring urea in serum, which is performed on supernates prepared by treating each specimen with Ba(OH)2 and ZnSO4 (Somogyi reagent). Analytical recovery of [14C]urea added to a variety of matrices was essentially complete (mean, 100.6%) for the supernates after precipitation. Nine variables were univariately examined in arriving at the reaction conditions for the method: glutamate dehydrogenase, urease, 2-oxoglutarate, ADP, Tris . HCI, NADH, EDTA, pH, and temperature. The reagent is stable for at least 48 days at--20 degrees C and for 23 days at 4 degrees C. Mean analytical recovery of urea (14 mmol/L) added to seven different specimens (three different matrices) was 100.8%. The analytical linear range of the method extends to 30 mmol of urea per liter. Of 22 potential interferents, only bilirubin at 1 mmol/L (580 mg/L), hemoglobin at 10 g/L, and hydroxyurea at 6 mmol/L showed more than 2% interference. We discuss precision and effects of specimen dilution, and compare results for 100 human serum specimens with those measured for the same specimens with four other urea methods. We examined the effects of measuring a blank, consisting of sample and reagent without urease, with each specimen.