Clinical Chemistry

Zettner,, Alfred

doi: 10.1093/clinchem/19.7.699pmid: N/A

Abstract The principles of competitive binding assays are reviewed, with emphasis on the differentiation of equilibrium vs. sequential saturation techniques. Three methods of equilibrium analysis are outlined that differ from each other in the relative concentrations of labeled ligand and binder used in the incubation system. The linearization of dose-response curves through the use of the logit plot is discussed. The importance of the knowledge of the effective affinity constant K for optimization of the assays is stressed, and two methods of estimating K are demonstrated with a digoxin-antidigoxin-antiserum system. sequential saturation techniques, logit plot in curve linearization, radioimmunoassay, estimating affinity constant, Scatchard plot This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Moore, John, W

doi: 10.1093/clinchem/19.7.706pmid: N/A

Abstract A method is described for the automated analysis of urinary 11-deoxy-17-oxo steroids from hydrolyzed conjugate extracts. Steroid conjugates are extracted manually on an Amberlite XAD-2 column and hydrolyzed with β-glucuronidase at 62°C for 90 min. After addition of alkali, the samples are transferred to the AutoAnalyzer where the steroids are extracted into isooctane and estimated colorimetrically by a modified Zimmerman reaction. 11-deoxy-17-oxo steroids, partition with isooctane, alcoholic m-dinitrobenzene, tetramethylammonium hydroxide, Zimmerman reaction This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Mejer, Luis, E;Blanchard, Roberta, C

doi: 10.1093/clinchem/19.7.710pmid: N/A

Abstract A method proposed by Kitabchi and Kitchell [Anal. Biochem. 34, 529 (1970)] for the fluorometric determination of plasma 11-hydroxycorticosteroids has been modified. It is simplified by eliminating centrifugations, by processing all samples consecutively (rather than in small groups), by using disposable test tubes, and by prealkalinizing standards and blanks as well as plasma samples. Specificity and sensitivity are increased by measuring fluorescence at 520 nm, with an excitation wavelength of 470 nm. Effects of prealkalinization and time of fluorescence development on final cortisol values were studied. Large fluorescence increases are possible after 60 min of fluorescence development. Cortisol recoveries were not changed by the use of phase-separating filter paper nor were cortisol values altered by partial aging of the fluorescence reagent. Sensitivity, specificity, accuracy, and precision of the proposed method are reported. screening procedure, normal values This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Mejer, Luis, E;Blanchard, Roberta, C

doi: 10.1093/clinchem/19.7.718pmid: N/A

Abstract We have investigated the specificity of the fluorometric method we proposed [Clin. Chem. 19, 710 (1973)] for plasma or serum 11-hydroxycorticosteroid determinations. The principal specific fluorogenic contaminants in the cortisol-containing extract of plasma, as detected by thin-layer chromatography and chemically, were triglycerides and total cholesterol. These contaminants contributed an average of 1.6 µg/dl to the total normal cortisol value. Fatty acids were also found, but did not fluoresce. Nonspecific serum fluorogens were quantitated at 1.3 ± 1.2 µg/dl. Cortisol, corticosterone, and fluorogenic contaminants represented an average of 62.0, 29.1, and 9.9%, respectively, of the total fluorometric plasma cortisol value obtained (expressed in terms of cortisol standard). A ratio of 8.3 ± 2.4 was found for cortisol/corticosterone when each component was determined in terms of its respective standard. Fluorescence scans of the plasma cortisol extract indicated cortisol to be the main component present, accompanied by minor fluorescent contaminants. This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Burnett, George, H;Conklin, Robert, L;Wasson, Gertrude, W;MacKinney, Archie, A

doi: 10.1093/clinchem/19.7.725pmid: N/A

Abstract Evaluation of commercial kits (3H and 125I digoxin) for the radioimmunoassay of digoxin showed that different normal plasma samples yielded significantly different standard assay curves. Such differences accounted for errors of from 0.6 to 1 ng under certain conditions. The usual internal assay controls do not correct for these conditions. Because such changes may represent the differences between toxic and nontoxic digoxin concentrations, further study of the commercial test procedures appears to be indicated. This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Margaret, LaVerne, Szabo,;Kenny,, A;Lee,, Winnie

doi: 10.1093/clinchem/19.7.727pmid: N/A

Abstract The use of a specific ion electrode for measuring sweat chloride has not been widely accepted because of poor precision and occasional falsely elevated chloride concentrations. We have studied this technique by using the Orion sweat-chloride instrument, and have eliminated these problems by modifying the methodology. An insufficient amount of sweat for determination with the electrode was responsible for both the imprecision and random inaccuracies. The following modifications eliminated these problems: (a) We freshly saturate felt pads with a solution of, per deciliter, 400 mg of pilocarpine nitrate and 1 g of NaHCO3 to replace the electrolyte pads supplied by the Orion Co. (b) The timed iontophoresis period commences after the meter indicates conduction of adequate current. (c) After iontophoresis, sweat is collected for 10 min under a plastic cap held over the induction area. Then chloride concentration is measured with the electrode. With these improvements in technique, the revised procedure should be as reliable as reference methodologies. iontophoresis, cystic fibrosis, diagnosis This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Turner, Adrian, K;Carroll, Carthage, J;Pinkus, Jack, L;Charles,, David;Chattoraj, Sati, C

doi: 10.1093/clinchem/19.7.731pmid: N/A

Abstract Simultaneous measurement of cortisol, cortisone, and prednisolone is described. A dichloromethane extract of plasma is separated and purified by partition thin-layer chromatography and assayed by competitive protein binding. Using 0.2 ml of plasma, we could assay about 1 µg of these three steroids per 100 ml. We measured plasma corticosteroids in men on prednisone therapy, during ACTH stimulation, and in pregnant women at the time of delivery, and also in arterial and venous blood samples collected from the umbilical cord. Plasma concentrations of prednisolone (4.46 ± 1.07 µg/100 ml) were maximal 2 h after oral administration of prednisone (10 mg). Basal concentrations of cortisol and cortisone in these subjects were 10.50 ± 1.04 and 1.88 ± 0.69 (SD) µg/100 ml, respectively. The values decreased to less than 1 µg/100 ml 4 h after administration and returned to 12.82 ± 1.92 and 2.16 ± 0.49 µg/100 ml, respectively, by 24 h. After intramuscular injection of synthetic ACTH, values for cortisol and cortisone were maximal at 30 min, declining to pre-injection concentrations within 4 h. Plasma cortisol and cortisone values for maternal venous blood at delivery were 47.0 ± 8.5 and 7.1 ± 2.2, umbilical vein blood 4.9 ± 2.6 and 19.7 ± 2.8 and in blood from the umbilical arteries 7.3 ± 4.5 and 11.6 ± 4.9 µg/ 100 ml, respectively. Cortisol was higher (P < 0.05) in the umbilical arteries, cortisone (P < 0.01) in the umbilical vein. thin-layer chromatography, effects of ACTH, pregnancy, prednisone therapy, values for umbilical cord blood, corticosteroid-binding globulin This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Seidel,, Dietrich;Wieland,, Heinrich;Ruppert,, Claudia

doi: 10.1093/clinchem/19.7.737pmid: N/A

Abstract A method is described for making lipoprotein fractions visible by polyanion precipitation in situ in the gels after electrophoresis. With the new technique the pattern and its interpretation in the differential diagnosis of all primary forms of hyperlipoproteinemia is the same as for the other lipid-staining procedures. The new technique is simpler to perform, reliable, and provides the required information 60 min after electrophoresis. It also allows a very fast determination of the abnormal lipoprotein (LP-X) that characterizes cholestasis, without use of a specific antiserum. electrophoresis in agarose, in agar gel, in polyacrylamide, serum lipoprotein pattern, hyperlipoproteinemia, Ca-dextran sulfate as lipoprotein precipitant, immunodiffusion, LP-X, diagnosis of cholestasis This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Jiang,, Nai-Siang;Ryan, Robert, J;Albert,, A

doi: 10.1093/clinchem/19.7.740pmid: N/A

Abstract Radioimmunoassay of serum estrogen (sum of estrone and estradiol-17β) in 0.5 ml of human serum is described. After dilution of the serum, the estrogens are adsorbed on a Sephadex G-15 column in the presence of dilute HCl and then eluted with benzene. After evaporation of the benzene eluate, the estrogens are dissolved in bovine serum albumin (5 g/ liter solution, at pH 8.0). An aliquot of this solution is used for the assay. Serum estrogen concentrations (mean ± SD) were 69 ± 23 pg/ml in 105 normal men and 199 ± 146 pg/ml in 26 fertile women. In 109 postmenopausal women, estrogen was undetectable in seven sera, but in the remaining 102 it was 52 ± 30 pg/ml of serum. estrone plus estradiol in serum, column chromatography on Sephadex, normal values for men and women (pre- and postmenopausal), separation of free and antibody-bound hormone with use of dextran- and serum-coated charcoal, urinary estrogen, menstrual cyclic variations, assessment of gonadal function This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Bruton,, Joseph;Li,, Ting-Kai;Smith, Gerald, D

doi: 10.1093/clinchem/19.7.748pmid: N/A

Abstract A Porter and Silber procedure, a fluorometric procedure, a double-isotope derivative procedure, and a competitive protein-binding assay procedure were used to determine 17-hydroxycorticosteroids in plasma from normal individuals and from patients with endocrinopathies. Results from each of these procedures were intercompared. Results of the fluorometric procedure and the competitive protein-binding assay compared favorably with results obtained by the more elaborate and difficult double-isotope derivative method. The Porter and Silber method is less specific. This study should be a useful aid in comparing values with those of other laboratories and in selecting the most advantageous method for use by a particular laboratory. Porter-Silber, fluorometric, double-isotope derivative, and competitive protein-binding procedures intercompared This content is only available as a PDF. © 1973 The American Association of Clinical Chemists, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)