bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free-zone electrophoresis in glass capillaries.
Authors: Jorgenson J W , Lukacs K D 
Published: January 2020

Abstract
A simple theory of zone electrophoresis in open-tubular capillaries is developed. According to this theory, to achieve the highest resolution of zones, tubes with as small an inside diameter as possible should be used in combination with as high an applied voltage as feasible. To test this approach, we performed electrophoresis in glass capillaries with an internal diameter of 75 micron and a length of 100 cm. A special fluorescence detector was used to detect fluorescent zones while they migrated inside the capillary. With the application of 30 kV potentials to this system, rapid and efficient separations of amino acids, peptides, and urinary amines were demonstrated. In all cases fluorescent derivatives were necessary for detection. Preliminary results are encouraging, and with further development of sensitive detection devices, applications in clinical analyses may be feasible.
Automated in-line ratio-correcting filter fluorometer.
Authors: Khalil O S , Routh W S , Lingenfelter K , Carr D B , Ladouceur P 
Published: January 2020

Abstract
We have developed a novel optical arrangement for the Abbott VP bichromatic analyzer, converting it into a fluorometer upon insertion of a specially designed filter carriage. Fluorescence intensity is measured by using straight-through excitation geometry and is corrected for fluctuations in light-source intensity by using the attenuated transmitted beam through the solution as a reference. The modification allows switching from the absorbance to fluorescence mode without an auxiliary light source or a major hardware change. The detection limit for an experimental prototype was estimated as 192 pmol of fluorescein per liter. In an application to a fluorescence immunoassay for theophylline in patients' sera, the data (y) correlated well with results by an enzyme immunoassay procedure (EMIT), giving a correlation equation of y = 1.849 + 0.988x (r = 0.969). A fluorometric standard curve for glucose and some performance data are also presented.
An enzymic, reaction-rate assay for serum creatinine with a centrifugal analyzer.
Authors: Jaynes P K , Feld R D , Johnson G F 
Published: January 2020

Abstract
We describe a procedure for specific, rapid, kinetic determination of creatinine, in which a manual coupled-enzyme micro-scale assay is adapted to a centrifugal analyzer. The creatinine reaction is ultimately linked to NADH utilization, which is measured by the absorbance change at 340 nm. This procedure requires 15 microL of serum and the standard curve is linear to a creatinine concentration of 200 mg/L. A four-point kinetic algorithm allows the dynamic range of the assay to be extended without sacrificing sensitivity, and makes a separate serum blank unnecessary. The within-run precision (CV) for samples with a creatinine concentration of 11 and 52 mg/L was 5.6 and 2.4%, respectively; day-to-day CV for a creatinine concentration of 11 mg/L was 7.7% (n = 21). We compared this procedure with a kinetic Jaffé procedure, with excellent agreement (r = 0.996; y = 0.96x + 2.4 mg/L). Bilirubin, non-esterified fatty acids, and ketone bodies do not affect creatinine determinations by this method; thus the method is especially useful for monitoring the renal function of diabetics.
Detergent activation of the binding protein in the folate radioassay.
Authors: Hansen S I , Holm J , Lyngbye J 
Published: January 2020

Abstract
A minor cow's whey protein associated with beta-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a methotrexate-AH-Sepharose 4B affinity matrix. In contrast to beta-lactoglobulin, the purified protein did not bind folate unless the detergents cetyltrimethylammonium (10 mmol/L) or Triton X-100 (1 g/L) were present. Such detergent activation was not needed in the presence of serum. There seems to be a striking analogy between these phenomena and the well-known reactivation of certain purified membrane-derived enzymes by surfactants (lipids/detergents).
Evaluation of a commercially available radioimmunoassay kit for measurement of doxorubicin in plasma.
Authors: Piall E , Aherne G W , Marks V 
Published: January 2020

Abstract
We evaluated a commercially available (Diagnostic Biochemistry Inc.) doxorubicin 125I radioimmunoassay kit. This kit gave a high apparent doxorubicin concentration (greater than 12 micrograms/L), which was not linearly related to dilution, for two pools of normal human serum and plasma and also for samples collected from patients before they received the drug. In contrast, a doxorubicin 3H radioimmunoassay developed by us gave a low blank (2 micrograms/L), which was linearly related to dilution, for the same pools and patients' samples. Doxorubicin concentrations in the plasma of patients receiving the drug were compared by the two methods; the kit gave results five- to 10-fold those obtained with our assay. High nonspecific interference by serum and plasma as measured by the 125I radioimmunoassay must therefore be borne in mind by users of the kit, and we suggest that results should be corrected for these nonspecific effects.
Turnover rate of skeletal alkaline phosphatase in humans.
Authors: Posen S , Grunstein H S 
Published: January 2020

Abstract
Two patients with Paget's disease of bone were subjected to plasmapheresis. Alkaline phosphatase activities of serum declined sharply, but returned to preplasmapheresis values within eight to 10 days. The biological half-life of circulating skeletal alkaline phosphatase, as calculated from these experiments, is between 1.12 and 2.15 days.
Stability of frozen liquid control sera for assay of cholesterol in high-density lipoprotein.
Authors: Demacker P N , Hijmans A G , van Sommeren-Zondag D F , Jansen A P 
Published: January 2020

Abstract
Liquid serum pools with low-, normal-, or above-normal concentration of high-density lipoprotein cholesterol were prepared by selection and dilution of sera having low lipoprotein content or by enrichment with concentrated high-density lipoprotein. Stability of the serum pools depended on storage conditions. On storage between -2 and -12 degrees C, the high-density lipoprotein cholesterol content decreased. At a constant temperature of -19 to -21 degrees C the concentrations remained stable for more than 18 months. The imprecision (CV) of the high-density lipoprotein cholesterol assay during this period as established with enzymic cholesterol analysis (Clin. Chem. 26: 1780-1786, 1980) of these serum pools was between 2.7 and 4.8% (n = 51). Serum pools prepared and stored as described are suitable for internal quality-control procedures. In external quality-control trials these sera may be superior to the commercially available lyophilized lipid control sera.
Immunoinhibition and automated column chromatography compared for assay of creatine kinase isoenzyme MB in serum.
Authors: Bayer P M , Boehm M , Hajdusich P , Hotschek H , Koehn H , Unger W , Wider G 
Published: January 2020

Abstract
We examined sera from six different groups of patients for CK-MB activity by means of two commercially available tests, an immunoinhibition method (E. Merck) and the CK-MB test as used with the aca (Du Pont). In the first group of patients (suspicion of myocardial infarction) the correlation between the two methods was good: r = 0.9191, y = 1.068x -- 0.888, x = 18.7 U/L, y = 19.0 U/L. In the second group, patients with high adenylate kinase activity, no interference was detectable on the aca, whereas the immunoinhibition method yielded falsely high CK-MB values. The third group consisted of persons with macro-CK-BB in their serum. In the immunoinhibition test these patients usually showed a high CK-MB:total CK ratio, whereas such results were rarely found for the aca. The fourth group, patients with a different electrophoretic mobility of their CK-isoenzymes (migration of an active band towards the cathode), were detected by the immunoinhibition method (high ratio of CK-MB to total CK), but not with the aca. In the presence of free CK-BB (group five) the immunoinhibition test resulted in "falsely" high CK-MB values, whereas CK-BB was retained on the column of the aca. In skeletal muscle diseases (group six) results by the two methods differed, values for CK-MB on the aca being much higher. It was demonstrated experimentally that this was due to CK-MM with altered surface charge.
Radioimmunoassay and chemical ionization/mass spectrometry compared for plasma cortisol determination.
Authors: Lindberg C , Jönsson S , Hedner P , Gustafsson A 
Published: January 2020

Abstract
We describe a method for determination of cortisol in plasma and urine, based on chemical ionization/mass spectrometry with deuterium-labeled cortisol as the internal standard. The within-run precision (CV) was 2.5-5.7%, the between-run precision 4.6%. Results by this method were compared with those by a radioimmunological method (RIANEN Cortisol, New England Nuclear) for 395 plasma samples. The latter method gave significantly higher (approx. 25%) cortisol values.
Evaluation of four assay methods for determination of tobramycin in human serum.
Authors: Acton W J , Van Duyn O M , Allen L V , Flournoy D J 
Published: January 2020

Abstract
Four assay procedures for tobramycin in serum--enzyme immunoassay (I), substrate-labeled fluorescent immunoassay (II), radioimmunoassay (III), and bioassay (IV)--were compared and evaluated by replicate and analytical recovery studies. I and II were about 50% more precise than III and IV. II was substantially more nearly accurate than the other methods and also gave the best reproducibility (correlation coefficient 0.992 between-day). The least expensive method was IV. Ease of handling favored I and II. Overall, we find II to be the most acceptable procedure for use in the clinical laboratory.
Laser nephelometry and radial immunodiffusion compared for immunoglobulin quantification in pathological sera.
Authors: Cloppet H , Francina A , Coquelin H , Boucaud-Maître Y , Hutinel P , Creyssel R 
Published: January 2020

Abstract
We evaluated nephelometers from Behring, Hyland, and Beckman for IgG, IgA, and IgM quantitation in sera from patients with monoclonal gammopathies. The intra-batch precision of each instrument for each immunoglobulin class and for different concentrations of the same immunoglobulin was compared to the one obtained with the radial immunodiffusion method. No nephelometer showed a clearly better precision. The correlation with cellulose acetate electrophoresis was good for each of the three nephelometers. The mean value by the radial immunodiffusion method was higher than corresponding determinations by nephelometry.
Liquid-chromatographic determination of urinary 5-hydroxy-3-indoleacetic acid, with fluorescence detection.
Authors: Rosano T G , Meola J M , Swift T A 
Published: January 2020

Abstract
We describe and evaluate a procedure for measuring urinary 5-hydroxy-3-indoleacetic acid by "high-performance" liquid chromatography. After a simple organic extraction, the analyte and internal standard are chromatographed on a reversed-phase column and are detected by native fluorescence. The detection limit (3 ng per injection), between-day precision (CV 5.2%), absolute recovery (70%), analytical recovery (99%), and working linear range (up to 15 mg/L) have been determined. Compared with colorimetric results with nitrosonaphthol, values obtained with the chromatographic method are significantly lower. Reference values and clinical experience with the method are reported. The method is simple, free from interferences, and suitable for use in routine analysis in the clinical laboratory.
1-naphthyl phosphate: specifications for high-quality substrate for measuring prostatic acid phosphatase activity.
Authors: Bowers J L , Bowers G N 
Published: January 2020

Abstract
Ten lots of sodium 1-naphthyl phosphate were compared by spectrophotometry, high-performance liquid chromatography, and kinetic measurements of the activity of human prostatic acid phosphatase (EC 3.1.3.2) in serum. Two lots were readily identified as the 2-naphthyl phosphate salt by spectrophotometry and liquid chromatography. Four of the remaining eight lots of sodium 1-naphthyl phosphate met the following specifications: (a) sodium 1-naphthyl phosphate content greater than 80% by A286nm measurements (epsilon286nm1-NP = 5630 L.mol-1.cm-1) and by enzymic conversion to 1-naphthol (epsilon332nm1-N = 7560 L.mol-1.cm-1), (b) free 1-naphthol less than 3 mmol/mol, (c) inorganic phosphate less than 10 mmol/mol, and (d) the catalytic activity concentration greater than 98% maximum by absorbance assay and greater than 90% maximum by spectrofluorometric assay during simultaneous comparisons of several substrates. The need for detailed specifications and the testing of each batch of sodium 1-naphthyl phosphate is readily demonstrated by this study.
Comparison of two isotope dilution/mass spectrometric methods for determination of total serum cholesterol.
Authors: Schaffer R , Sniegoski L T , Welch M J , White V E , Cohen A , Hertz H S , Mandel J , Paule R C , Svensson L , Björkhem I , Blomstrand R 
Published: January 2020

Abstract
Isotope dilution/mass spectrometric methods for total serum cholesterol, developed separately at the Karolinska Institutet (KI) and the National Bureau of Standards (NBS), were compared by applying them to a common set of serum pools. A search for the cause of a systematic difference of a few percent in results from the two methods revealed that the KI cholesterol standard contained lathosterol, which interfered with the calibration of the method. With NBS Standard Reference Material cholesterol used for new analyses at the KI, the average difference in mean values dropped to 0.2%. The NBS results are more precise. This is attributed to the protocols NBS used for sample preparation and mass spectrometry. However, these protocols make the NBS method more complex and time-consuming. A recent critical article on the use of this technique for total cholesterol is also examined.
Radioimmunoassay for pregnancy-associated plasma protein A.
Authors: Sinosich M J , Teisner B , Folkersen J , Saunders D M , Grudzinskas J G 
Published: January 2020

Abstract
A specific and highly sensitive radioimmunoassay for determination of pregnancy-associated plasma protein A in human serum is described. The minimum detection limit for this protein was 2.9 micrograms/L. The within- and between-assay coefficients of variation were 4.0 and 4.5%, respectively. The circulating protein was detected within 32 days of conception in eight normal pregnancies and within 21 days in a twin pregnancy. Circulating concentrations in the mother at term were consistently higher (10-fold) than in matched amniotic fluid; none was detected in the umbilical circulation. This protein was also detected in the circulation of patients with hydatiform mole. This assay will permit investigations into the clinical evaluation of measurements of the protein during early pregnancy and trophoblastic disease.
Simultaneous measurement of plasma apolipoproteins A-I and B by electroimmunoassay.
Authors: Fruchart J C , Kora I , Cachera C , Clavey V , Duthilleul P , Moschetto Y 
Published: January 2020

Abstract
We describe a simplified electroimmunoassay for quantification of human apolipoproteins A-I and B on prepared plates. A solution of agarose at 55 degrees C, containing hydroxyethylcellulose and antibodies, is poured onto a plastic film and allowed to gel. Wells are punched in the gels and the plates are dried for storage. Before use, they are rehydrated and buffered. We use succinylated Sudan Black to prestain lipoprotein fractions of plasma. After electrophoresing samples of plasma or standards for 3 h at 4 degrees C at 12.5 V/cm, we measure the peak heights and read the results from a standard curve prepared by using calibrated sera of known apolipoprotein B and A-I content as secondary standard. The within- and between-assay coefficients of variation were less than 4% in all cases. Results correlated well with those obtained by classic electroimmunodiffusion. Subjects with confirmed atherosclerotic lesions had significantly (p less than 10(-9)) lower ratios of apolipoprotein A-I to apolipoprotein B, compared with ratios in controls.
Influence of erythrocyte iodothyronine-binding proteins on radioimmunoassay of thyroxin in dried blood spots.
Authors: Sadler W A , Lynskey C P 
Published: January 2020

Abstract
Three erythrocyte proteins, one identified as hemoglobin, bind thyroid hormones. Using a dextran/charcoal radioimmunoassay for thyroxin in dried blood spots, we demonstrate that such binding differs with the buffer used. Barbital, phosphate, and borate buffers significantly enhance the binding more than glycine and tris(hydroxymethyl)methylamine buffers. Binding is not affected by agents commonly used to inhibit thyroxin binding to serum proteins. A highly significant nonlinear direct relationship between sample storage (temperature and duration) and increased thyroxin-erythrocyte binding is documented, together with an associated decrease in assayed concentrations of thyroxin. However, concomitant serial measurement of thyroxin with polyethylene glycol and combined double-antibody/polyethylene glycol radioimmunoassays produced no evidence of interference by erythrocyte proteins in the radioimmune reaction. We conclude that erythrocyte proteins act only as low-affinity secondary binders in radioimmunoassay for thyroxin.
Development and validation of a new radioimmunoassay for parathyrin (PTH).
Authors: Kao P C , Jiang N S , Klee G G , Purnell D C 
Published: January 2020

Abstract
A radioimmunoassay for human parathyrin has been developed and characterized with whole-molecule (residues 1-84) human parathyrin and with the 1-34, 44-68, and 53-84 amino acid residue fragments of it. The antiserum used reacted with the whole molecule and with the 44-68 and 53-84 fragments, but not with the 1-34 fragment. Parathyrin concentrations in the serum of 118 normal subjects and of 112 patients with surgically proved primary hyperparathyroidism were determined with this assay. The mean results were 39 (SD 13) microL-Eq/mL for the normals and 111 (SD 77) microL-Eq/mL for the patients with primary hyperparathyroidism (p less than 0.0005). The upper 95% confidence limit of the normal range was 60 microL-Eq/mL. For 54 patients with primary hyperparathyroidism, the preoperative values for serum parathyrin, calcium, and phosphate--but not creatinine--were statistically different from the postoperative values (paired t-test, p less than 0.0005). Normal subjects showed significant (p less than 0.0005) differences in serum calcium concentrations but not in parathyrin concentrations, compared with concentrations found in cancer patients and patients who had thiazide-induced hypercalcemia. Phosphate concentration in serum, although not a specific indicator of disease, is a valuable clue to the diagnosis of primary hyperparathyroidism.
Hemoglobin A1C by isoelectric focusing.
Authors: Simon M , Cuan J 
Published: January 2020

Abstract
We separated the hemoglobins in an unwashed erythrocyte hemolysate according to their isoelectric points on a thin-layer horizontal polyacrylamide gel containing ampholyte (40 g/L) over a pH gradient of 6-8. We scanned the fixed, unstained gels by microdensitometry and calculated the percentage of hemoglobin A1C. The overall CV (between-run imprecision) for a normal hemolysate (mean, 5.2% of total hemoglobin) stored at -70 degrees C was 12.6%. An above-normal pooled specimen (mean 8.5%) showed an overall CV of 8.4%. We confirmed that hemoglobins S, C, and F do not interfere; acetylated F co-migrates with A1C. The mean A1C percentage in non-diabetic adults was 4.9%, the reference interval 3.9-6.4%. The mean values for diabetics in various degrees of control were 7.6% in the group rated "good," 9.9% in the "fair" group, and 12.2% in the "poor" group. Results for patients' samples (y) were compared with results by cation-exchange chromatography (x). The slope was 1.0 and the intercept was 2.2%. The percentage of hemoglobin A1C in erythrocytes remains constant for seven days in samples stored at 30 degrees C.
New spectrophotometric method for the determination of hemoglobin A1 compared with a microcolumn technique.
Authors: Wålinder O , Ronquist G , Fager P J 
Published: January 2020

Abstract
We compared a spectrophotometric kit method (Glycospec) for determination of glycosylated hemoglobin (HbA1) with a microcolumn kit method (Bio-Rad). The Glycospec method is based on the change in absorbance when phytic acid binds to hemoglobin A. With glycosylated hemoglobin there is no such change because the binding is blocked by the sugar moiety. Inter-assay CVs were 2-6% for both methods. In healthy subjects the mean (+/- SD) value for HbAl was about 1% higher with the spectrophotometric than the microcolumn method. For samples from 122 diabetics the correlation between values for HbAl obtained with the two methods was acceptable (r = 0.89), although the spectrophotometric technique yielded 2-4% higher values, a difference at least partly due to the absence of 2,3-diphosphoglycerate from the spectrophotometric standards. Adding 1.8 mmol of it per liter to these standards caused displacement of the standard curve; HbAl values then agreed well with those of the microcolumn method. The spectrophotometric procedure is easily automated, and therefore is well suited for large-scale analyses if problems with standards and calibration can be solved.
Evaluation and comparison of immunoinhibition and immunoprecipitation methods for differentiating MB and BB from macro forms of creatine kinase isoenzymes in patients and healthy individuals.
Authors: Wu A H , Bowers G N 
Published: January 2020

Abstract
We compared results for measurements of creatine kinase isoenzyme MB (CK-MB) by immunoinhibition vs immunoprecipitation, using sera from 53 normal healthy individuals, 55 patients with increased CK-MB associated with acute myocardial infarction, and 42 patients whose blood exhibited one or more abnormal forms of CK by electrophoresis. These last 42 patients, selected from a group of 91 cases exhibiting abnormal forms as detected in a screening of 5000 hospitalized and clinic patients, include: (a) CK-BB bound to IgG (macro CK type 1), (b) a polymeric complex of mitochondrial CK (macro CK type 2), (c) abnormally high activity of free CK-BB isoenzyme, and (d) persistent increases of CK-MB from patients without myocardial infarction. These abnormal forms occur in less than 2% of all patients and are exceedingly rare in patients with acute myocardial infarction. Therefore, the vast majority of CK-MB analyses can be performed rapidly and efficiently by immunoinhibition, which has analytical sensitivity, is associated with high clinical sensitivity, and is easily automated for a low cost per test. In contrast, immunoprecipitation is a more specific analytical measurement of CK-MB but is less efficient and more costly.