bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneity of chloramine T- and lactoperoxidase-radioiodinated human calcitonin.
Authors: Dermody W C , Levy A G , Davis P E , Plowman J K 
Published: January 2020

Abstract
Radioiodination reportedly damages peptides, but the nature of the damage has not been adequately examined. Utilizing isoelectric focusing, we examined the products of Chloramine T- and lactoperoxidase-directed radioiodinations of human calcitonin. Initially, the reaction products were purified by adsorption onto and elution from microfine silica (QUSO-G32). Radioiodination of the calcitonin by Chloramine T and lactoperoxidase produced a heterogeneous population of 125I-labeled peptides exhibiting apparent isoelectric points that were more acidic than that of unlabeled synthetic calcitonin. Variation in the products among radioiodinations and the inability of QUSO-G32 to resolve the components of the reaction mixture prompted our examination of alternative purification procedures. Anion-exchange chromatography on QAE-Sephadex effectively separated [125I]diiodotyrosine containing calcitonin from free iodine and [125I]iodolactoperoxidase. Our data indicate that: (a) radioiodination of human calcitonin by Chloramine T and lactoperoxidase induced alteration in the peptide as evidenced by isoelectric point, (b) specific [125I]iodopeptides vary in incidence and relative abundance among radioiodinations, (c) identification of the labeled amino acid in [125I]iodopeptides cannot ensure intergrity of the molecule, and (d) isoelectric focusing provides a method of comparing the products of peptide radioiodinations among laboratories.
Separation of bound from free hormone in radioimmunoassay of lutropin and follitropin.
Authors: Peterson M A , Swerdloff R S 
Published: January 2020

Abstract
A new technique in which polyethylene glycol is added to double-antibody assays of lutropin and follitropin eliminates the need for an incubation period during the separatory phase. After the antigen-first-antibody equilibrium reaction, the second antibody and polyethylene glycol (30 g/L final dilution) are added, the tubes are immediately centrifuged, each supernate is aspirated, and the precipitated antibody-bound hormone is counted. With this combined polyethylene glycol-second-antibody separatory method, the incubation time is shorter than the usual double-antibody separation procedure, but avoids the problem of high nonspecific precipitation, which occurs with polyethylene glycol alone. In addition, the combined separation technique allows the use of sera containing low titers of second antibody and use of smaller volumes of sera containing high titers of second antibodies, thus conserving second-antibody reagent.
X-ray fluorescence and potentiometry compared for determining iodine content of thyroid glands.
Authors: Puttemans F , Deconinck F , Jonckheer M , Vandeputte M , Massart D L 
Published: January 2020

Abstract
We compare results for iodine quantitation by x-ray fluorescence of excised thyroid glands with results of the quantitation by means of an original, newly developed chemical method, a Schöniger combustion technique, in which iodie is quantitated potentiometrically. Subsequently, we establish the accuracy and clinical suitability of the former technique in quantifying the intrathyroidal iodine.
Performance assessment of the GammafloTM automated radioimmunoassay system by assaying for digoxin.
Authors: Valdes R , Savory G , Bruns D , Renoe B , Savory J , Wills M R 
Published: January 2020

Abstract
We report an evaluation of the GammafloTM automated continuous-flow radioimmunoassay instrument in which we used a digoxin assay to assess system performance. System operation was based on combined continuous-flow and column-chromatographic techniques. No drift or carryover was detectable in 180 within-assay consecutive determinations performed at a rate of 42 determinations per hour (5 h of continuous operation). Within-assay and between-assay precision were less than 6% (coefficient of variation). The automated method correlated well (r = 0.960 and 0.952, respectively) with two established manual digoxin radioimmunoassay procedures. The data suggest this automated system offers a valid alternative to manual radioimmunoassay procedures in terms of overall precision, simplicity of operation, and sample throughout capacity.
A liquid chromatography-assisted assay for angiotensin-converting enzyme (peptidyl dipeptidase) in serum.
Authors: Chiknas S G 
Published: January 2020

Abstract
I describe modification of the spectrophotometric assay described by Cushman and Cheung [biochem. Pharmacol. 20, 1637 (1971)] for serum angiotensin-converting enzyme, with use of "high-pressure" liquid chromatography to measure the hippuric acid end product. After reaction of 10 microL of untreated serum with the angiotensin-converting enzyme substrate analog hippuryl-L-histidyl-L-leucine, the hippuric acid produced is extracted into ethyl acetate and quantitated, relative to an added internal standard, by liquid chromatography. Total chromatographic running time is 3 min per sample, with a within-run CV of 4.3% and a day-to-day CV of 6.6%, for aliquots of plasma supplemented with 1 mmol of hippuric acid per liter. The measurements are linear for hippuric acid in amounts up to 20 nmol per assay. The presence of large quantities of lipid in the serum did not affect the accuracy of the determination.
Human corticotropin (ACTH) radioimmunoassay with synthetic 1--24 ACTH.
Authors: Kao P C , Jiang N S , Carpenter P C 
Published: January 2020

Abstract
A corticotropin antiserum was obtained from rabbits immunized with synthetic 1--24 corticotropin conjugated with bovine serum albumin. The antiserum did not cross react with synthetic alpha-melanotropin or with synthetic beta-endorphin and had a cross reactivity of 0.23% with human beta-lipotropin. We developed a radioimmunoassay with the antiserum obtained, in which we used polyethylene glycol in conjunction with a second precipitating antibody for fast (15-min) separation of antibody-bound and free corticotropin. The assay had a sensitivity of 16 ng/L and was validated on patients with various pituitary and adrenal diseases. From 103 normal subjects, the median value for corticotropin in specimens collected during the morning was 34 ng/L of plasma; the upper 95% confidence limit of the normal range was 98 ng/L.
Radial and linear thin-layer chromatographic prodedures compared for screening urines to detect oligosaccharidoses.
Authors: McLaren J , Ng W G 
Published: January 2020

Abstract
We describe a circular (radial) thin-layer chromatographic procedure for separating urinary oligosaccharides. Results were better than those obtained by a single linear development. Bands and specific patterns were finely resolved for various known oligosaccharidoses. The procedure provides a simple means of screening for these disorders.
Improved liquid-chromatographic method for determination of serum cortisol.
Authors: Kabra P M , Tsai L L , Marton L J 
Published: January 2020

Abstract
We describe a specific and precise method for measuring concentrations of cortisol in serum or plasma by liquid chromatography. Cortisol, together with an internal standard, equilenin, is extracted from 1 mL of serum or plasma and analyzed isocratically on a reversed-phase column with a mobile phase of acetonitrile/phosphate buffer (30/70, by vol.), at a flow rate of 2.0 mL/min. The eluted cortisol is detected by its absorption at 254 nm and quantitated by peak height measurements. Each analysis requires no longer than 15 min at the optimum column temperature of 50 degrees C. The lower limit of detection for cortisol is about 2 ng/sample for a standard solution; sensitivity is routinely 5 micrograms/L of serum. Analytical recoveries exceeded 95%, with good day-to-day precision (coefficients of variation between 4 and 7%). Of more than 50 drugs and steroids tested for possible interference, only the steroids cortisone, prednisone, and prednisolone may interfere with the analysis of cortisol.
Measurement of Erythrocyte 2,3-diphosphoglycerate with a centrifugal analyzer.
Authors: Hickey T M , Uddin D E , Kiesow L A 
Published: January 2020

Abstract
Intra-erythrocytic concentration of 2,3-diphosphoglycerate is a major determinant of the oxygen affinity of hemoglobin. We report here the adaptation of its assay to a centrifugal analyzer, with use of a commercially available reagent. Results are calculated by using the reagent-blank-corrected absorbance change at 340 nm between 120 and 300 s for the samples and a 2.5 mmol/L standard. Under these conditions the standard curve is linear to 5 mmol/L. The compound in a 101-fold aqueous hemolysate is stable for several weeks at either -4 or -70 degrees C. Assay sensitivity and precision are excellent and results agree well with those by the corresponding manual method.
D-Mannose in human serum, measured as its aldononitrile acetate derivative.
Authors: Monson T P , Wilkinson K P 
Published: January 2020

Abstract
We report a procedure for determining D-mannose in serum. After removal of proteins and lipids, the carbohydrate-containing fraction is treated to form the aldononitrile acetate derivative and analyzed by gas--liquid chromatography with a flame-ionization detector. D-Mannose and D-glucose had retention times of 31 and 34 min, respectively. Day-to-day reproducibilities (CV) of between 2 and 12% for mannose were attainable for quantities of 100--900 ng. Related hexoses and derivatives do not interfere. The sensitivity was such that 10 mg/L could be detected in a 0.1-mL sample of serum. This method may be of use in diagnosing invasive Candida infection.
Evaluation and application of magnetizable charcoal for separation in radioimmunoassays.
Authors: Al-Dujaili E A , Forrest G C , Edwards C R , Landon J 
Published: January 2020

Abstract
We compared conventional charcoal separation of antibody-bound and free antigen with a novel method involving magnetizable particles containing charcoal. The magnetizable charcoal separation method was as effective as the conventional method for a wide range of radioimmunoassays, including those for several steroids and small polypeptide hormones. In a detailed comparison of conventional vs. magnetizable charcoal for radioimmunoassay of aldosterone, the magnetizable charcoal had several advantages: it did not require prior coating with dextran or protein, varied less with time and temperature, required no centrifugation, and took less time for separation. The correlation of results obtained with magnetizable and conventional charcoal separation was excellent (n = 89, r = 0.98, p less than 0.001), and the coefficient of variation for the separation with magnetizable charcoal was 0.5%.
Creatine kinase isoenzyme--antibody reactions in immuno-inhibition and immunonephelometry.
Authors: Morin L G 
Published: January 2020

Abstract
I have raised, in rabbits, antibodies against MM and BB isoenzymes of creatine kinase. The antibodies produced were homogeneous by Ouchterlony double immunodiffusion and did not cross react with their opposite antigens. Both antisera, however, appeared to be mixtures of antibodies, displaying different equivalences for activation, inactivation, and, possibly, precipitation. Inactivation studies indicated the presence of antibodies effective against dimer only and antibodies effective against monomer or dimer. Both antisera cross reacted with MB and displayed antibodies that appeared to block only half of the activity as well as antibodies that blocked all of the activity. The antisera produced were useful for measuring MB by both immuno-inhibition and immunonephelometry, but neither appears to be advantageous over current electrophoresis or ion-exchange methods. A comparison of decay of MB in patients between activity and mass measurements indicated that activity decay is about 12-fold faster than mass decay.
Creatine kinase BB: a new tumor-associated marker.
Authors: Silverman L M , Dermer G B , Zweig M H , Van Steirteghem A C , Tökés Z A 
Published: January 2020

Abstract
Creatine kinase isoenzyme BB (CK-BB) is found in the serum of patients with various types of cancer. Using both radioimmunoassay and agarose electrophoresis, we found abnormal amounts of this isoenzyme in the serum of 15 of 17 patients with untreated prostatic carcinoma. Among patients with other types of adenocarcinomas and metastatic disease, serum CK-BB was increased in most of those who were unresponsive to therapy. In benign or malignant prostate tissue and in malignant pleural effusions, cytoplasmic CK-BB as determined by immunoperoxidase staining was found in epithelial cells. Prostatic fluid had high concentrations of CK-BB, as did malignant, but not benign, pleural fluid supernates. We conclude that glandular epithelial cells contain CK-BB, which is released in benign and malignant states and may appear in higher concentrations in the circulation in malignant states. These conclusions are consistent with predictions we have made from a model experimental system concerning characteristics of possible tumor markers. The observations indicate a role for CK-BB as a tumor marker, particularly for adenocarcinoma of the prostate.
Separation of five isoenzymes of serum lactate dehydrogenase by discontinuous gradient elution from a miniature ion-exchange column.
Authors: Hsu M Y , Kohler M M , Barolia L , Bondar R J 
Published: January 2020

Abstract
We describe a simple, fast chromatographic technique for quantitatively separating the five isoenzymes of lactate dehydrogenase (LD; EC 1.1.1.27) in serum. A 250-microL serum sample is applied to a 6.0 x 0.7 cm column of QAE-Sephadex A-50 and eluted stepwise with five different buffers. The isoenzyme fractions, assayed by the method of Wroblewski and LaDue [Proc. Soc. Exp. Biol, Med. 90, 210 (1955)], are stable at room temperature for 24 h. For all five isoenzymes the average within-day coefficient of variation is 4.3%; the day-to-day CV for 20 days is 6.3%. Of some common potentially interfering substances tested, only sodium fluoride (238 mmol/L) was found to do so, by slowing the elution from the column and making the fractions turbid. The expected range in international (IUB) united and percent for each isoenzyme was determined from data on 73 men and 70 women. From these data we calculate, by a percentile estimate of a nongaussian distribution, a normal range of LD-1/LD-2 ratio of 0.55--0.87 for men and 0.52--0.91 for women. The LD isoenzyme patterns in both normal and above-normal samples of 147 sera, as evaluated by the present column method and by electrophoresis, correlated well.
An improved micromethod for theophylline determination by reversed-phase liquid chromatography.
Authors: Butrimovitz G P , Raisys V A 
Published: January 2020

Abstract
We describe an improved micro-scale method for determining serum theophylline by reversed-phase liquid chromatography. Samples are deproteinized with two volumes of methanol containing beta-hydroxyethyltheophylline as an internal standard. The supernate is chromatographed with a methanol/sodium acetate buffer (15/85 by vol) mobile phase, and the amount of theophylline is calculated from the ratio between peak heights for theophylline and the internal standard at 273 nm. We also monitor for chemical interferences at 254 nm. We found no interferences from ampicillin, methicillin, cephalosporin, and cephalothin. None of the drugs tested or metabolites and compounds related to theophylline have been found to interfere. The method is rapid, accurate, sensitive, and specific for theophylline.
Homogeneous enzyme immunoassay for thyroxine compared with a radioimmunoassay technique.
Authors: Gustafsson J E 
Published: January 2020

Abstract
A homogeneous enzyme immunoassay (EMIT) for serum thyroxine determination has been evaluated. It was also compared to our routine method, a radioimmunoassay with use of a commercial kit, Tetra-Tab RIA. Within-day precision was very similar for the two methods, the CV ranging from about 2.5% at 150 nmol of thyroxine per liter to about 5.7% at 25 nmol/L. The two methods were compared by running 100 patients' serum samples. The resulting linear regression equation was: y = 1.088x - 17.9, with a correlation coefficient r = 0.979. The deviation from the theoretical line, y = x, wash shown to be primarily caused by the calibration of the methods, shown by running the EMIT calibrators in the radioimmunoassay method and vice versa. The choice of thyroxine method in the individual laboratory will then depend on considerations other than methodological factors.
Hyperxanthinemia interferes with serum uric acid determinations by the uricase method.
Authors: Hande K R , Perini F , Putterman G , Elin R 
Published: January 2020

Abstract
Serum xanthine concentrations as high as 148 mg/L were noted after treatment of a patient with Burkitt's lymphoma who was receiving allopurinol. These markedly above-normal values for xanthine led to spuriously low values for serum uric acid as measured by the uricase method. Rapid tumor lysis in patients who are receiving allopurinol may lead to marked hyperxanthinemia, which in turn may obscure hyperuricemia in such patients when the uricase method is used for uric acid analysis. In such situations, uric acid concentrations should be measured by the phosphotungstate colorimetric assay.
New developments in analysis of isoenzymes separated by "high-performance" liquid chromatography.
Authors: Schlabach T D , Fulton J A , Mockridge P B , Toren E C 
Published: January 2020

Abstract
We have developed two enzyme analyzers for use in "high-performance" liquid chromatography. In both systems two detectors are used, placed after the column effluent has been combined with assay reagent. In one system, an absorbance detector is placed before and after a post-column reaction coil. Peaks observed at one detector are subtracted from those at the other, to produce a two-point measurement of enzyme activity. The linear dynamic range was 17--1700 U/L for lactate dehydrogenase (EC 1.1.1.27). In the other system, two reaction coils were used and a single fluorescence detector was placed at the end of each coil. These coils were kept at different temperatures, and an automated switching valve diverted equal amounts of column effluent and reagent into both coils. The fluorescence readings were then subtracted to produce a differential measurement of enzyme activity. The linear dynamic range was 20--1000 U/L. We used both systems to chromatographically analyze lactate dehydrogenase isoenzymes, and could separately determine both the distribution and activity of sample isoenzymes.
High-performance liquid chromatography for ultraviolet-absorbing constituents in human urine.
Authors: Miyagi H , Miura J , Takata Y , Ganno S 
Published: January 2020

Abstract
Several liquid-chromatographic systems involving anion-exchange resins and linear acetate gradient elution have been reported previously for the analysis of ultraviolet-absorbing constituents in human urine. We describe a high-performance liquid-chromatographic system on which a macroreticular anion-exchange resin, and stepwise elution are used. Separations were more rapid with ammonium chloride/acetonitrile stepwise elution than with acetate stepwise elution, and urine constituents could be detected at 225 nm with the former system. Analytical conditions were convenient and the method has proven to be useful for routine clinical analysis.
Properties and uses of immobilized light-emitting enzyme systems from Beneckea harveyi.
Authors: Jablonski E , DeLuca M 
Published: January 2020

Abstract
Bacterial luciferase and NADH:FMN oxidoreductase have been immobilized onto arylamine glass beads. These immobilized enzymes can detect as little as 0.2 pmol of NADH per assay sample. Glucose-6-phosphate dehydrogenase has been co-immobilized with these enzymes, and with this system it is possible to quantitate 1 pmol of glucose 6-phosphate. By co-immobilizing a fourth enzyme, hexokinase, onto the glass beads, the system can reproducibly detect 20 pmol of glucose per liter. These immobilized enzyme systems are potentially superior to soluble enzymes by being reusable and much more stable. We compared the light-emitting properties of the immobilized enzyme systems with that of an equivalent mixture of the soluble enzymes. The most striking difference was the apparently more efficient conversion of NADH or glucose 6-phosphate to light by the immobilized enzymes. We used hydroxysteroid dehydrogenase in developing a soluble coupled system for the assay of androsterone and testosterone. The lower limit of detection was 100 pmol.
Flow-injection analysis with chemiluminescence detection.
Authors: Rule G , Seitz W R 
Published: January 2020

Abstract
In "flow-injection analysis," the sample is inserted into a stream of reagent by use of a sample-injection valve. Mixing occurs downstream from the valve in a coil of tubing. With chemiluminescence detection this coil is positioned in front of a photomultiplier. We have evaluated the system for detection of hydrogen peroxide, using the luminol reaction with cupric ion as a catalyst. The effects of flow rate, sample volume, and reaction kinetics on the magnitude, duration, and repeatability of the chemiluminescent response have been evaluated. Precisions of 1 to 2% relative standard deviation on replicate measurements are readily achievable. A sample throughput of six samples per minute is possible with very little peak overlap. This detection system can be coupled to any process in which peroxide is generated.
Mechanism of interference by hemoglobin in the determination of total bilirubin. I. Method of Malloy-Evelyn.
Authors: Shull B C , Lees H , Li P K 
Published: January 2020

Abstract
Oxyhemoglobin is the species of hemoglobin in erythrocyte hemolysates that inhibits the diazo reaction. Ferric hemoglobin derivatives and species with relatively low molecular mass do not interfere. Conversion of oxyhemoglobin to acid hematin under assay reaction conditions is associated with rapid destruction of bilirubin, which accounts for the diazo reaction error. The most probable mechanism for this destruction of bilirubin is an oxidative reaction involving H2O2, formed in the oxidation of hemoglobin, and acid hematin acting as a pseudoperoxidase. We could find no evidence for other mechanisms of interference such as spectral error or azobilirubin destruction. Addition of potassium iodide, 4.0 mmol/L final concentration in the reaction mixture, eliminates interference from hemoglobin added to give concentrations as great as 10 g/L. It also eliminated the effects of hemolysis in the method of Ertingshausen et al. (Clin. Chem. 19: 1366, 1973), in which ethylene glycol is used as the accelerator.
"High-pressure" liquid chromatography of sulfisoxazole and N4-acetylsulfisoxazole in body fluids.
Authors: Jung D , Oie S 
Published: January 2020

Abstract
We describe a simple, rapid chromatographic method for separating and quantitatively determining sulfisoxazole and its N4-acetyl metabolite in plasma and urine. A 100-micro L sample of plasma or urine is combined with 200 micro L of a solution containing 12 mg/L of the internal standard, N4-acetylsulfamethoxazole, in absolute methanol and centrifuged to obtain a clear supernatant solution. This solution is then eluted through a 10-micron microparticulate column with a mobile phase of 32/68 (by vol) methanol/sodium acetate buffer (0.01 mol/L, pH 4.7), at a flow rate of 1.2 mL/min. The eluted sompounds are detected by their absorption at 254 nm. We calculated concentration from the peak-height ratios of sulfisoxazole or N4-acetylsulfisoxazole to N4-acetylsulfamethoxazole. The peak-height ratio was linear with concentration in the range 0.05--200 mg/L for both drug and metabolite in plasma and urine. Because this assay can be completed within 30 min of obtaining a blood or urine sample, it should be a valuable tool in clinical drug monitoring and pharmacokinetic studies.