bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation and characterization of electrophoretic variants of human prostatic acid phosphatase.
Authors: Hibbard M D , McCarthy R C , Markowitz H 
Published: January 2020

Abstract
Prostatic acid phosphatase (EC 3.1.3.2) purified from benign hypertrophic prostate tissue was fractionated by preparative slab isoelectric focusing over a pH gradient of 3.16 to 7.16. Twenty-two of 29 fractions contained enzyme activity. We further examined each active fraction by determining the Michaelis-Menten constant and specific activity. The protein concentration used in the latter determination was estimated either spectrophotometrically or immunochemically by three different radioimmunoassays for the enzyme. Determination of specific activities for each fraction directly correlated enzyme activity with an immunochemical determination, which indicated the immunochemical relationships among different molecular species of the enzyme. We found that the Michaelis-Menten constants for the isolated fractions were similar to the Km value for purified, unfractionated enzyme. Most fractions analyzed by each immunoassay had similar specific activities; the few fractions with discrepant specific activities were found at either end of the pH gradient. The similarity in specific activities among the fractions indicates that RIAs involving polyclonal antisera detect all of the electrophoretic variants of the enzyme.
Prognostic value of combined data on enzymes and inflammation markers in plasma in cases of severe head injury.
Authors: Bourguignat A , Albert A , Férard G , Tulasne P A , Kempf I , Métais P 
Published: January 2020

Abstract
We measured certain enzyme activities (aldolase, aspartate aminotransferase, creatine kinase, and lactate dehydrogenase) and inflammation markers (alpha 1-antitrypsin, C-reactive protein, fibrinogen, and leukocytes) each day for four days in plasma of patients with severe head injury. The univariate prognostic efficiency of each biochemical parameter was assessed 24, 48, 72, and 96 h after trauma. By stepwise multivariate analysis applied every day, we found that (a) four variables, two enzymes (lactate dehydrogenase and aspartate aminotransferase) and two inflammation markers (C-reactive protein and leukocytes), sufficed to reliably predict the patient's outcome and (b) data recorded at 72 h best discriminated between survivors and nonsurvivors. A risk index based on the four selected variables and validated on a large control sample allowed the correct allocation of, respectively, 90% of survivors and 88% of nonsurvivors at 72 h. We discuss why results obtained at 72 h are more predictive than those obtained at any other of the times considered.
Clinical evaluation of two direct procedures for free thyroxin, and of free thyroxin index determined nonisotopically and by measuring thyroxin-binding globulin.
Authors: Waud J M , Chan D W , Drew H M , Oropeza M J , Sucupira M S , Scheinin B , Garrison G M , Mayo M , Taylor E , Stem J 
Published: January 2020

Abstract
We have investigated the clinical utility of two direct radioimmunoassays for free thyroxin, an enzyme-inhibition immunoassay, and a direct measurement of thyroxin-binding globulin (TBG) by radioassay. All assay methods correctly identified greater than or equal to 90% of euthyroid, hyperthyroid, and hypothyroid patients who had normal TBG concentrations. In patients with altered TBG concentrations, none of the assays correctly classified all categories of patients. However, the direct assays of free thyroxin concentrations were able to classify correctly more patients with altered TBG concentrations than did the free thyroxin index methods. The free thyroxin index methods evaluated may be acceptable for routine use, if the concentration of thyroxin and the measurement of TBG capacity are reported along with the index value. Patients with altered TBG concentrations included a group of euthyroid pregnant patients. Significant decreases in free thyroxin in the third trimester were detected by all the assays studied. For patients in the first and second trimester, the mean free thyroxin concentration measured varied with the assay method.
DNA interference with radioimmunoassay procedures.
Authors: Matsuo N , Koide S S 
Published: January 2020

Abstract
A bacterial factor preventing precipitation of immune complexes was purified from a culture of Streptococcus faecalis (AK strain) by gel filtration on Sephadex G-100 and Bio-Gel A-150m columns. The factor was identified as DNA on the basis of its ultraviolet absorption maximum at 260 nm, hydrolysis by deoxyribonuclease, Mr exceeding 1.5 X 10(8), and positive reaction with diphenylamine. DNA interferes with the immunoassay by preventing precipitation of immune complexes. Only double-stranded DNA and polynucleotides showed this property. Evidently, double-stranded DNA will give false-positive interference with the usual RIA procedures.
Radioimmunoassay for pancreatic polypeptide, and its age-related changes in concentration.
Authors: O'Hare M M , Daly J G , Buchanan K D 
Published: January 2020

Abstract
Pancreatic polypeptide (PP), a recently discovered pancreatic hormone, is potentially a marker for endocrine tumors. Consequently, we devised a radioimmunoassay for it, using antisera (raised in rabbits) to bovine PP, 125I-labeled bovine PP (purified by anion-exchange chromatography), and human PP standards. Concentrations circulating in fasting, normal subjects were measured. Statistical analysis of the results revealed a skewed distribution. An age-related increase was also observed. Evaluating PP concentrations in sera from 23 patients with endocrine tumors, we found increased values in a few cases of Zollinger-Ellison syndrome, medullary carcinoma of the thyroid, carcinoid syndrome, and one tumor producing vasoactive intestinal polypeptide (VIPoma). In contrast, values from five insulinomas and one glucagonoma were within the normal reference interval. Thus, an increased value for PP in a fasting individual may suggest the diagnosis of an endocrine tumor but is not a diagnostic prerequisite.
Concurrent measurement of theophylline and caffeine in neonates by an interference-free liquid-chromatographic method.
Authors: Ou C N , Frawley V L 
Published: January 2020

Abstract
A sensitive liquid-chromatographic method was developed for the simultaneous measurement of theophylline and caffeine within 6 min. The excellent resolution of the method allows the complete separation of theophylline, internal standard, and caffeine from frequently encountered interfering drugs including acetaminophen, acetazolamide, acetylsalicylate, ampicillin, 8-chlorotheophylline, cefazolin, cephalosporin C, cephalothin, cephapirin, chloramphenicol, dyphylline, metronidazole, 3-methylxanthine, salicylate, sulfadiazine, sulfamerizine, sulfamethazine, sulfamethoxazole, sulfisoxazole, and theobromine. The chromatographic system involves a Waters' Radial-Pak C18 reversed-phase column and acetonitrile in 0.1 mol/L potassium phosphate buffer, pH 4.0, (9.5/90.5 by vol) as the mobile phase. The method can detect theophylline or caffeine concentrations as low as 0.5 mg/L in 50 microL of serum. Precision and accuracy are excellent.
Separation of bound and free ligand by ethacridine (Rivanol) in thyroxin radioimmunoassay.
Authors: Bhupal V , Mani R S 
Published: January 2020

Abstract
In this simple and low-cost radioimmunoassay (RIA) procedure for thyroxin (T4), ethacridine (6,9-diamino-2-ethoxyacridine lactate; Rivanol) is used to separate antibody-bound ligand and free ligand. This acridine dye precipitates free T4 not bound to antibody. At pH 8.6, it precipitates more than 90% of 125I-labeled T4. Precipitation is rapid and is constant over the concentration range of 1 to 3 g of ethacridine per liter; time of addition and temperature are not critical. The inherent yellow color of the dye gives it the advantage of a color-coded reagent. Analysis of 65 serum samples by the proposed method and by a procedure involving polyethylene glycol gave similar results: correlation coefficient, 0.988; slope, 0.981; y-intercept, -1.42. Within- and between-assay variations (CV) were less than 5 and 6%, respectively.
A radioisotopic method for fructose-1-phosphate aldolase assay that facilitates diagnosis of hereditary fructose intolerance.
Authors: Shin Y S , Moro V , Doliwa H , Endres W 
Published: January 2020

Abstract
A sensitive new method in which D-[U-14C]fructose-1-phosphate is used for fructose-bisphosphate aldolase (EC 2.1.2.13) assay is described. The radioactive fructose-1-phosphate compound was prepared from [U-14C]fructose by use of partly purified fructokinase (EC 2.7.1.4). With this method we measured normal values for aldolase in human liver (2.4-10.0 nmol/min per mg of protein), kidney (3.6-3.8), and intestine (4.2-10.0) as well as Km values for fructose-1-phosphate (approximately 1.0-2.2 mmol/L). In patients with hereditary fructose intolerance the aldolase activity in liver and intestine was less than 10% of normal values. The Lineweaver-Burk plots for data from patients with hereditary fructose intolerance were hyperbolic, indicating a structural alteration in the enzyme.
Quality-control sera for routine determination of aluminum by electrothermal atomic absorption spectroscopy.
Authors: Leung F Y , Henderson A R 
Published: January 2020

Abstract
Several commercially available quality-control sera were analyzed for aluminum content by atomic absorption spectroscopy with a stabilized-temperature graphite furnace. The values obtained ranged between 4 and 1250 micrograms/L (0.148 to 46.235 mumol/L). No significant difference was detected for between-vial variation for four lots of quality-control sera (p greater than 0.05). Control sera stored in 1-mL polypropylene vials and frozen at -20 degrees C for up to six months showed no significant variation in aluminum content (p greater than 0.05), but those stored in their original glass containers had significantly increased aluminum content (p less than 0.001) over a four-week period.
Preparation of F(ab')2 fragments of immunoglobulin G.
Authors: Killion J J , Holtgrewe E M 
Published: January 2020

Abstract
We describe a simple protocol for the preparation of F(ab')2 fragments of immunoglobulin G, based upon the known Fc- binding properties of protein A-Sepharose. The fragment preparations of xenogeneic and allogeneic anti-IgG were noncytotoxic to intact target cells, and were able to block the cytotoxicity of intact antibody. This method should therefore be useful for functional studies not requiring biochemical homogeneity.
Coproporphyrin in urine of newborns with meconium aspiration syndrome.
Authors: Francoual J , Lindenbaum A , Dehan M , de Verneuil H , Nordmann Y , Leluc R 
Published: January 2020

Abstract
We evaluated coproporphyrin in the first urine passed by newborn infants with and without meconium aspiration, by spectrophotometric analysis and thin-layer and "high-performance" liquid chromatography. Urines of newborn infants without meconium aspiration contained only very small quantities of coproporphyrin, detected, after partial purification, by "high-performance" liquid chromatography. Urines of newborn infants with meconium aspiration contained large quantities of coproporphyrin, identified by all three techniques. Urinary coproporphyrin as measured spectrophotometrically correlates well with the "urinary meconium index," and the method is simple, rapid, and reliable, even for samples containing hemoglobin.
Clinical value of free-thyroxin measurements.
Authors: Braun B E , Müller M J , Seitz H J , Krieg M 
Published: January 2020

Abstract
Although discrepancies have been reported between free thyroxin (fT4) in serum and actual thyrometabolic status, the concentration of free thyroid hormones in blood is thought to be an important determinant of the thyrometabolic status of patients. Therefore, the diagnostic value of fT4 measurement has been emphasized. This prompted us to evaluate the diagnostic significance of direct fT4 measurement. We conclude that: (a) The different fT4 radioimmunoassays we examined did not excel the total thyroxin, fT4 index, or thyroxin/thyroxin-binding globulin ratio in the laboratory assessment of thyroid status and alterations in thyroid hormone-thyroxin-binding globulin relationships. (b) The fT4 values obtained by direct or indirect methods always shifted in parallel to total thyroxin with respect to borderline increased or decreased total thyroxin, subclinical hypothyroidism, isolated hypertriiodothyroninemia, and thyroxin substitution.
Solid-phase chemiluminescence immunoassay for plasma estradiol-17 beta during gonadotropin therapy compared with two radioimmunoassays.
Authors: De Boever J , Kohen F , Vandekerckhove D 
Published: January 2020

Abstract
Estradiol in plasma was determined with a simple solid-phase immunoassay based on chemiluminescence in patients undergoing ovulation induction. In the assay, we use a purified monoclonal antibody to estradiol-17 beta, with estradiol-6-carboxymethyl oxime-aminobutylethyl isoluminol as the chemiluminescent marker. The antibody is covalently coupled to polymer beads. Bound and free ligand are separated by simple centrifugation. Values so determined were compared with those determined with two different radioimmunoassay (RIA) methods, one involving the same monoclonal solid-phase antibody plus iodinated estradiol, 125I-RIA, the other a polyclonal antibody and tritiated estradiol, 3H-RIA. In the latter RIA, dextran-coated charcoal was used to separate bound and free ligand. Values determined by the three methods agreed well: for chemiluminescence vs 125I-RIA, r = 0.93; for chemiluminescence vs 3H-RIA, r = 0.94; for 125I-RIA vs 3H-RIA, r = 0.94. The three methods are similar in sensitivity, specificity, and precision. The present method is simple and reliable, taking advantage of the specificity and sensitivity intrinsic to the use of an antibody without the inconveniences associated with use of an isotopically labeled ligand.
Quality control of acid phosphatase assay improved by direct reconstitution of lyophilized control materials with citric acid.
Authors: Blick K E , Commens M J , Passey R B 
Published: January 2020

Abstract
Current quality control of assays of acid phosphatase (EC 3.1.3.2) with thymolphthalein substrate is inadequate when certain control-suppliers' instructions are followed for reconstituting and stabilizing human lyophilized control material. If such materials are reconstituted with a citric acid solution, then stored frozen, control vial-to-vial variability is minimized, as are losses of activity in freshly reconstituted controls and losses during room-temperature storage of the control material. Effects of pH of the reconstituting solution on the acid phosphatase activity of human lyophilized controls are also discussed.
Multilayer film analysis for glucose in 1-microL samples of plasma.
Authors: Neeley W E , Zettner A 
Published: January 2020

Abstract
With the ultramicroanalytical system described here we can measure glucose in 1 microL of plasma or serum. The sample is placed on a dry, multilayer film element (Eastman Kodak), where a colored spot about 3.5 mm in diameter develops. The reflectance of these spots is measured with a reflectance digital matrix photometer that was conceived, designed, and constructed in our laboratory. The spot is illuminated with monochromatic light and its image is projected by a camera lens onto the photosensitive surface of a linear photodiode array containing 512 individual photodetectors. The photodetector signals are processed by a computer to obtain the reflectance and diameter of the spot. The latter is proportional to sample volume. Because the reflectance of the spot does not depend greatly on sample volume, accurate pipetting is not required. The coefficients of variation of repeatable glucose analyses were, for 400, 3000, and 5120 mg/L, 1.7, 2.3, and 2.8%, respectively. The correlation coefficient (r) between glucose analyses by our method (y) and with the Ektachem 400 (x) was 0.9918; the regression equation was y = 1.07x - 94.3 mg/L.
Advancing in tandem: clinical endocrinology and clinical chemistry.
Authors: Hershman J M 
Published: January 2020

Abstract
Here I review some of the recent accomplishments in clinical endocrinology and clinical chemistry, point out the direction of future work, and try to predict some of the advances of the next decade. Endocrinology, perhaps more than any other branch of clinical medicine, is rooted in biochemistry and physiology. Endocrinologists have been leaders in the development of methods, which have been adapted by clinical chemists for wider applications than those conceived originally. For the sake of brevity, I shall not recount the early history of endocrinology in this century--or the enormous progress since Starling coined the term "hormone" and stated the physiological role of these chemical messengers in 1905. Progress in endocrinology in recent years has been astounding.
Sensitive fluorometry of heat-stable alkaline phosphatase (Regan enzyme) activity in serum from smokers and nonsmokers.
Authors: Maslow W C , Muensch H A , Azama F , Schneider A S 
Published: January 2020

Abstract
We developed a simple, sensitive enzymatic assay involving the fluorogenic substrate naphthol AS-MX phosphate [(3-hydroxy-2-naphthoic acid 2,4-dimethylanilide) phosphate] to measure heat-stable alkaline phosphatase (EC 3.1.3.1), the Regan isoenzyme, in human serum. The day-to-day CV was 5.7% for a serum activity of 0.080 arbitrary units/L. Measurable amounts of enzyme were detected in most normal individuals. The mean for 51 nonsmokers was 0.068 (SD 0.037) arb. units/L; for 25 smokers it was 0.440 (SD 0.360) arb. units/L. Activity of this isoenzyme in smokers was as much as 10-fold the upper normal limit for nonsmokers. Activation of this tumor marker by smoking has not received attention hitherto. We conclude that a truly normal range can only be established among nonsmokers. The isoenzymes in smokers, nonsmokers, and pregnant women were similar in their heat stability, immunologic cross reactivity, and inhibition by L-phenylalanine.
Amniotic fluid fluorescence polarization value at physiological temperature: a marked improvement in assessing fetal lung maturity.
Authors: Barkai G , Mashiach S , Modan M , Serr D M , Lanir D , Lusky A , Goldman B , Shinitzky M 
Published: January 2020

Abstract
Determination of fetal lung maturity by measurement of the fluorescence polarization (P) value of the amniotic fluid at room temperature has become the method of choice in an increasing number of perinatal units because of its simplicity and relatively high predictive value. Nevertheless, its power to discriminate between cases with and without hyaline membrane disease (HMD) needs improvement. To this end, we assessed the discriminative power of the P value at the physiological temperature of 37 degrees C (P37) as compared with the power at 25 degrees C (P25). The study group consisted of 288 consecutive cases at risk for preterm delivery. Samples from all 288 cases were measured at 25 degrees C and samples from 112 of these were measured concurrently at 37 degrees C as well. HMD occurred in 27 infants of the total group, nine of whom belonged to the subgroup tested at both temperatures. When sensitivity was fixed at 100% the specificity of P37 was 97% as compared to 79% for P25 (p less than 0.001). The percentage of cases with infants free of HMD who had borderline P values was also significantly smaller: 1% vs 21%, respectively (p less than 0.001). Although data on more HMD cases are needed to establish the precise threshold of lung maturity for P37, we conclude that P37 is a considerably better discriminator for fetal lung maturity determination than P25.
Centrifugal analyzer used for enzyme immunoassay of progesterone and choriomammotropin.
Authors: Terouanne B , Marchand J , Calzolari C , Monnier J , Nicolas J C , Pau B , Descomps B 
Published: January 2020

Abstract
Recently we developed an enzyme immunoassay involving the use of steroid delta-isomerase (EC 5.3.3.1) as enzyme label and exclusion-affinity chromatography for rapid separation of free antigen-enzyme conjugate that bound to antibodies (J. Immunol. Methods 35: 267-284, 1980). Here we describe an automated version of this procedure, for immunoassay of progesterone and choriomammotropin (human placental lactogen) in serum with the use of a centrifugal analyzer. After incubation, suitable dilutions of sera or extract plus antiserum, conjugate, and double antibody were filtered on an estradiol affinity gel-filtration column; the enzyme activity of the filtrates was determined with the centrifugal analyzer. Results correlate well with those obtained by radioimmunoassay: r (progesterone) = 0.980, r (choriomammotropin) = 0.940. The within-run and between-run precision, specificity, sensitivity, accuracy, and speed of this system make it a useful tool for immunoassay.
Effect of albumin concentration on the assay of serum free thyroxin by equilibrium radioimmunoassay with labeled thyroxin analog (Amerlex Free T4).
Authors: Amino N , Nishi K , Nakatani K , Mizuta H , Ichihara K , Tanizawa O , Miyai K 
Published: January 2020

Abstract
Serum free thyroxin (FT4) in normal nonpregnant and pregnant subjects was measured by radioimmunoassay (RIA) with Amerlex FT4 RIA (Amersham International) and LiquiSol FT4 RIA (Damon Diagnostics) kits. Amerlex FT4 values in serum from pregnant women were lower than those in serum from nonpregnant women, but LiquiSol FT4 values were similar in serum from both groups. Amerlex FT4 values were directly correlated with the concentrations of albumin in serum and inversely correlated with those of thyroxin-binding globulin, but not with prealbumin concentrations. No significant correlations were observed between LiquiSol FT4 values and serum concentrations of thyroxin-binding proteins. Amerlex FT4 values were normal in patients with excess, deficient, or decreased thyroxin-binding globulin. Albumin added to serum samples increased Amerlex FT4 values but not LiquiSol FT4 values. Albumin inhibited the binding of labeled thyroxin analog to the solid-phase thyroxin antibody. These data indicate that the albumin concentration influences FT4 values as measured by an RIA involving a thyroxin analog and that Amerlex FT4 values should be carefully interpreted when the patient has an abnormal concentration of serum albumin.
Proportion of hemoglobin S in blood, as determined from solubility measurements.
Authors: Bowie L J , Dohnal J C 
Published: January 2020

Abstract
We exploited the concentration dependence of hemoglobin S on its solubility in concentrated phosphate buffer to determine the percentage of hemoglobin S or hemoglobin A in whole blood or hemolysates. A sample is incubated for 1 h at 37 degrees C in "SickleQuik" (General Diagnostics) tubes, and the absorbance of the aqueous phase is then measured at 555 nm and 650 nm, the latter wavelength to correct for turbidity. The fractional hemoglobin S or hemoglobin A content is read from standard-curve data on mixtures of hemoglobin A and hemoglobin S. Such curves can be prepared with the use of hemoglobin A alone, because under our conditions all hemoglobin S is precipitated. The curve is reproducible for up to three weeks. Day-to-day CVs ranged from 1.8% at 10% hemoglobin S to 8.1% at 68% hemoglobin S. For similar concentration ranges, day-to-day CVs for electrophoresis, with densitometry, ranged from 4.9% to 18%. Results on 29 patients are presented. We recommend the method for rapid quantification of hemoglobin S percentage for patients with sickle cell disease in acute-care situations.