bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonisotopic "sandwich" immunoassay of thyroglobulin in serum by the biotin-streptavidin technique: evaluation and comparison with an immunoradiometric assay.
Authors: Preissner C M , Klee G G , Krco C J 
Published: January 2020

Abstract
In this sequential assay, the thyroglobulin in serum binds to polystyrene beads coated with two mouse monoclonal antibodies. These beads then react with a rabbit polyclonal antibody, biotinylated sheep anti-rabbit IgG, streptavidin-horseradish peroxidase, and a peroxidase substrate to yield a colored product that is measured spectrophotometrically at 492 nm. The range of the standard curve is 1.6 to 100 micrograms/L. The detection limit of the assay is 1.2 micrograms/L. The interassay coefficient of variation is 14.0% at 6.2 micrograms/L, 5.7% at 32.7 micrograms/L; the intra-assay CVs range from 7.8% to 14.8%. The reference intervals are 2.7 to 42.1 micrograms/L for euthyroid persons and less than or equal to 5 micrograms/L for athyreotic patients not on thyroxin replacement therapy. Some autoantibodies to thyroglobulin cause thyroglobulin values to be falsely low. The concentration of autoantibodies is not correlated with the analytical recovery of human thyroglobulin. The coefficient of correlation between the measurement of thyroglobulin by this assay and by an immunoradiometric assay was 0.969 for 186 autoantibody-negative samples, 0.963 for 37 autoantibody-positive samples.
New one-step enzyme immunoassay for free thyroxin.
Authors: Kunst A , Seidenschwarz E , Bürk H , Schauer S , Haug H , Lehmann P , Ehrhardt V 
Published: January 2020

Abstract
This enzyme immunoassay for free thyroxin (FT4) involves simultaneous incubation of sample and thyroxin conjugated to horseradish peroxidase (EC 1.11.1.7) in antibody-coated tubes at room temperature. The test can be performed in 90 min. It is not influenced by variations in concentrations of thyroxin-binding globulin (TBG), thyroxin-binding prealbumin, or albumin. With increased concentrations of non-esterified fatty acids, the measured FT4 equivalent concentrations increase immediately, indicating displacement of endogenous thyroxin from its binding sites. FT4 values obtained with this assay for 110 samples, including sera with low albumin and high TBG as well as sera of patients treated with heparin, agreed well with those measured by a two-step radioimmunoassay and with the T4/TBG ratio. The measurable range of FT4 with our assay is 2.5 to 65 ng/L. Intra-assay CVs range from 3.4% to 2.2%, interassay CVs from 6.6% to 2.6% at concentrations of 9 to 45 ng of FT4 equivalent per liter.
Solid-phase enzymoimmunoassay of estrone in serum.
Authors: Folan J , Gosling J P , Fottrell P F 
Published: January 2020

Abstract
This rapid solid-phase enzymoimmunoassay for estrone in serum or plasma is done on microtiter plates after the serum is extracted with diethyl ether. No chromatographic or centrifugation steps are involved. The detection limit of the assay is 380 fg per well (28 pmol/L). Intra- and interassay coefficients of variation for the assay of low, medium, and high concentrations of estrone in plasma were respectively 4.4, 9.3; 2.3, 9.1; and 2.0, 6.3 percent. There was a good correlation (correlation coefficient 0.95) between estrone concentrations measured with this assay and with a commercial radioimmunoassay. The analytical procedure is simple, and one person can assay 80 serum samples per working day. We conclude that the assay is very suitable for serum estrone measurements and is more convenient than published radioimmunoassays.
Ten electrophoretic methods compared with a selected method for quantifying lactate dehydrogenase isoenzymes in serum.
Authors: Moses G C , Ross M L , Henderson A R 
Published: January 2020

Abstract
Using the Selected Method of McKenzie and Henderson (Selected Methods Clin Chem 1983;10:59-67) as a reference method, we compared the performance of 10 commercially available methods for determination of lactate dehydrogenase (LD, EC 1.1.1.27) isoenzymes. Results were expressed as percentage of total LD activity, as determined with two different types of densitometers shown to have an average difference less than 1.4% for each isoenzyme. All methods gave generally comparable results, as judged by Bland-Altman plots and correlation analyses. However, in general, estimates by the commercial methods for LD-1, LD-2, and LD-3 were lower, and for LD-4 and LD-5 were higher than with the Selected Method. The overall CV was less than 20% for all methods and isoenzymes, except for LD-4 and LD-5 by the Beckman Paragon, Helena LD-VIS, Gel LDH, Gel PC, and Iso Dot, Gelman LDH Isozyme, and Sebia Hydragel assays, for which it was greater than 20%. Overall, accuracy was best with the Helena Iso Dot and LD-VIS assays, followed by the Corning LD Flur assay; accuracy was poorest with the Gelman LDH Isozyme, Sebia Hydragel, and Beckman Paragon assays.
Abbott's fluorescence polarization immunoassay for cyclosporine and metabolites compared with the Sandoz "Sandimmune" RIA.
Authors: Sanghvi A , Diven W , Seltman H , Starzl T 
Published: January 2020

Abstract
A new procedure for measuring cyclosporine in plasma has been introduced by Abbott Laboratories, involving their TDx instrumentation and fluorescence polarization immunoassay. Radioimmunoassay (RIA) and high-performance liquid chromatography are currently the conventional methods for measuring cyclosporine in plasma and whole blood. In an effort to find a method that will decrease the radioactive hazard, the reagent and supply cost, and the labor requirements associated with RIA procedures, we used specimens from transplantation patients to compare the Abbott assay with the Sandoz Sandimmune assay. We believe that the Abbott assay offers some advantages over the Sandimmune RIA procedure, providing a reliable but simpler and less hazardous technology.
Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. I. Effect of free fatty acids.
Authors: Csako G , Zweig M H , Glickman J , Kestner J , Ruddel M 
Published: January 2020

Abstract
We examined the effect of endogenous free fatty acids (FFA) on the measurement of free thyroxin (FT4) by five different methodologies represented in 16 different assays in a large number of patients with nonthyroidal illness (NTI). Some, but not all, one-step (analog) FT4 RIAs negatively correlated with FFA concentration. All two-step FT4 RIAs, equilibrium dialysis FT4, and the dialyzable (free) fraction of T4 positively correlated. In contrast, a binding-rate-based FT4 RIA, FT4 indices based on T3 macroaggregated albumin uptake, and T4/TBG ratios did not correlate. We also analyzed the FT4-FFA relationship with a second, more sensitive approach by correlating test results with FFA/albumin molar ratio as an estimate of the "excess" (nonalbumin bound) FFA. We found that all FT4 RIAs, equilibrium dialysis FT4, FT4 indices based on T3 uptake, the dialyzable fraction of labeled T4 in equilibrium dialysis, the fraction of labeled T4 bound to solid phase antibody in the binding-rate-based RIA, and T3 uptake correlated with the FFA/albumin molar ratio. This FFA dependency was comparable among all the various techniques and was relatively small. Thus, increases or decreases in FT4 results due to varying FFA (and albumin) concentrations are highly likely with most currently available methods (only the T4/TBG ratio did not reveal FFA-dependency), but the magnitude of changes varies with the "excess" FFA.
Four nonisotopic immunoassays of free thyroxin evaluated.
Authors: Perdrisot R , Bounaud M P , Bounaud J Y , Jallet P 
Published: January 2020

Abstract
We evaluated four new nonisotopic immunoassays of free thyroxin (FT4)--Amerlite FT4 (Amersham International), Magic Lite FT4 (Ciba Corning Diagnostics), Stratus FT4 (Dade--Baxter Travenol), and FT4 Enzelsa (Compagnie ORIS Industrie)--by comparison with two FT4 radioimmunoassays: Amerlex and Sclavo. Inter- and intra-assay coefficients of variation were less than 10% in the working range and there was no significant interaction between the tracer conjugate and albumin. All methods except Enzelsa gave results equivalent to those obtained with the Sclavo chromatographic technique. In a population consisting of 325 euthyroid subjects and 111 hyperthyroid and 61 hypothyroid patients without any treatment, we observed slight overlaps between the hyperthyroid and euthyroid populations and diagnostic sensitivities were approximately 0.95 and 0.80 for hyperthyroidism and hypothyroidism. In specific populations (69 patients with chronic renal failure, 20 patients in intensive-care, 17 patients treated with heparin, and 27 pregnant women), results were quantitatively similar to those obtained by the Sclavo assay. We conclude that these nonisotopic methods are a valid alternative to current radioisotopic commercial methods.
Measurement of cyclosporine concentrations in whole blood: HPLC and radioimmunoassay with a specific monoclonal antibody and 3H- or 125I-labeled ligand compared.
Authors: Wolf B A , Daft M C , Koenig J W , Flye M W , Turk J W , Scott M G 
Published: January 2020

Abstract
We compared cyclosporine concentrations in whole blood as measured by HPLC and by RIA with a monoclonal antibody specific for cyclosporine with 3H- or 125I-labeled cyclosporine ligand. The 3H-RIA kit slightly underestimated cyclosporine concentrations (greater than 600 micrograms/L) in comparison with HPLC. Over a wide range of concentrations, cyclosporine measured with the 125I-RIA kit correlated well with HPLC (slope = 0.99, n = 301, r = 0.98), observed for samples from recipients of kidney, heart, or liver allografts (respective slopes: 1.01, 0.93, and 1.00). The 125I-RIA standard curve was linear to 1000 micrograms of cyclosporine per liter. Inter- and intra-assay CVs for 125I-RIA measurements of cyclosporine were less than or equal to 7%. Evidently, the 125I-RIA kit involving a monoclonal antibody specific for cyclosporine is equivalent to the HPLC assay and can replace it for therapeutic drug monitoring of cyclosporine therapy.
Evaluation of the IFCC reference method for alanine aminotransferase: spurious blank ALT activity due to contamination of D-alanine with L-alanine, and recommendations for a correction.
Authors: Okorodudu A O , Pelletier P R , Valcour A A , Bowers G N , McComb R B 
Published: January 2020

Abstract
During an evaluation of the IFCC reference method for alanine aminotransferase (ALT, EC 2.6.1.2), we noted that the specimen blank activity reaction was markedly increased. Experience with five different lots of D-alanine from four commercial sources indicated that substantial and varying negative bias (up to -10%) could be introduced into the blank-corrected ALT activity, depending on the lot of D-alanine used. Although the IFCC procedure for ALT mentions the possibility of this L-alanine contamination, we believe that the degree of contamination in commercial reagents is underestimated. Analyzing the five lots of D-alanine for L-alanine, we found the magnitude of negative bias to be correlated directly with L-alanine contamination. Here, we describe a quick, sensitive assay based on coupled reactions of L-amino acid oxidase/peroxidase for quantifying L-alanine in the concentration range of 0-15 mmol/L without a sample-dilution step. Results by this alternative L-alanine assay agreed well with those recommended in the IFCC ALT procedure. Further examination suggested an even simpler solution to the L-alanine contamination problem, because we found no difference in the blank-corrected ALT activity determined in Tris HCl buffer, with or without D-alanine (free of L-alanine). We therefore propose that D-alanine be omitted from the IFCC reference ALT procedure.
Tumoral calcinosis: seasonal biochemical studies and chemical studies of eyelid lesion.
Authors: Bruns D E , Boskey A L , Lieb W , Conway B P , Savory J , Wills M R 
Published: January 2020

Abstract
We recently described (Arch Ophthalmol 1988; 106:725-6) the presence of unique calcific lesions in the eyelids of a young woman with a history of hyperphosphatemic tumoral calcinosis. Here we document that no immediate family members showed similar lesions and that none was hyperphosphatemic. Dental roentgenography revealed characteristic abnormalities in the patient that confirmed the clinical diagnosis of tumoral calcinosis. Seasonal biochemical studies demonstrated persistently increased concentrations of phosphorus and 1,25-dihydroxyvitamin D in her serum. A calcific eyelid excrescence removed from the patient, studied by x-ray diffraction, was found to consist of crystals of hydroxyapatite. Microprobe analysis indicated the major elements in the deposit to be Ca, P, S, and Cl, just as in the periarticular deposits found in tumoral calcinosis. The Ca concentration in the patient's tear fluid, measured by atomic absorption spectrometry, was within the range found in tears of healthy volunteers. Phosphorus was undetectable (less than 30 mumol/L) in tears of the patient and the volunteers. These findings suggest that the eyelid lesions represent a new manifestation of the pathological process that produces the characteristic periarticular calcific masses of tumoral calcinosis.
Increased concentrations of heparin cofactor II in diabetic patients, and possible effects on thrombin inhibition assay of antithrombin III.
Authors: Gram J , Jespersen J 
Published: January 2020

Abstract
We compared concentrations of antithrombin III (AT-III) in plasma, as determined by an immunological method and by a functional thrombin inhibition method, in the presence of heparin in 160 blood samples from Type I diabetics. Although the correlation was highly significant (P less than 0.001) between the results obtained by the two methods, our data demonstrated that results by the thrombin inhibition assay, 121 (SD 15)%, expressed as percentages of the results for a normal plasma pool, were significantly (P less than 0.001) higher than by the immunoreactive method, 104 (SD 15)%, indicating an overestimation of functionally active AT-III. Concentrations of functionally active AT-III determined by a factor Xa inhibition assay, 105 (SD 13)%, were in the same range as immunoreactive AT-III. Addition of IgG antiserum to normal pooled plasma quenched only about 90% of the AT-III activity determined by the thrombin inhibition assay, but all of the AT-III activity determined by a factor Xa inhibition assay. These results demonstrate that the factor Xa inhibition assay is more specific for the determination of AT-III than the thrombin inhibition assay. We suggest that the high concentrations of heparin cofactor II, 117 (SD 17)%, might have caused an overestimation of AT III in this group of patients with diabetes Type I, and should not be overlooked in other clinical situations.
Automated determination of cholinesterase activity in plasma and erythrocytes by flow-injection analysis, and application to identify subjects sensitive to succinylcholine.
Authors: Lainé-Cessac P , Turcant A , Allain P 
Published: January 2020

Abstract
This automated spectrophotometric method for determination of cholinesterase activity in erythrocytes and plasma is based on measurement of the choline produced at 30 degrees C by the hydrolysis of acetyl-, butyryl-, or succinylcholine. Blanks, standards, and samples are prepared by a Gilson robotic unit. Use of flow-injection analysis for detection allows use of smaller volumes of reagent and sample. We applied this method to the study of 91 healthy subjects and members of two families with succinylcholine sensitivity. Results with use of the three different substrates for determination of activity in plasma correlated well (r greater than 0.94). Results for plasma and erythrocytes from healthy subjects are lower in women less than 50 years old than in women greater than 50 years or men. Values for plasma obtained with succinylcholine substrate (range: 31 to 100 U/L) allow detection of very sensitive subjects--AA phenotypes (less than 10 U/L)--but do not distinguish the UA from the UU phenotype.
Two-site immunoenzymometric assay for the 52-kDa cathepsin D in cytosols of breast cancer tissues.
Authors: Rogier H , Freiss G , Besse M G , Cavalié-Barthez G , Garcia M , Pau B , Rochefort H , Paolucci F 
Published: January 2020

Abstract
We developed a solid-phase two-site immunoenzymometric assay (IEMA) of the estrogen-induced 52-kDa cathepsin D (EC 3.4.23.5) and its processed forms (48-kDa and 34-kDa proteins) in cytosols of breast cancer tissues, using two monoclonal antibodies directed against two different epitopes of these antigens. The first antibody is bound to a polystyrene microtiter well; the second is labeled with alkaline phosphatase. The assay involves a simultaneous incubation of the antigen with both antibodies, because we observed signal loss during sequential incubations. Alkaline phosphatase was chosen because other enzymes (peroxidase, beta-galactosidase) were inhibited by cytosol extraction buffers. The measurable range of 52-kDa-related proteins is from 0.3 to 6 nmol/L with precision (CVs) within and between runs of 3.9% and 15.8%, respectively. The sensitivity, accuracy, and rapid turnaround time of the two-site IEMA should facilitate the clinical evaluation of this new marker in oncology.
Critical analytical and clinical aspects of ionized calcium in neonates.
Authors: Wandrup J 
Published: January 2020

Abstract
Clinical diagnosis in neonates is often based primarily on biochemical data, because clinical symptoms are difficult to assess and inconclusive. A knowledge of the validity of the data would therefore seem very important. Practical technical assessments lead me to conclude that measurement of ionized calcium at actual pH in anaerobic capillary samples of whole blood, currently practicable, is an easy and optimal laboratory analysis when biologically significant data are required for assessment of acute disturbances in calcium homeostasis of neonates. Values are given for ionized calcium, describing the relations in cord and maternal blood in uncomplicated pregnancies at term. Recent published cross-sectional and longitudinal reference values for ionized calcium, measured during the first weeks in healthy full-term and preterm neonates, seem to provide a new basis for the diagnosis and management of early neonatal hypocalcemia.
Simple enzymatic method for determining 1,5-anhydro-D-glucitol in plasma for diagnosis of diabetes mellitus.
Authors: Yabuuchi M , Masuda M , Katoh K , Nakamura T , Akanuma H 
Published: January 2020

Abstract
We have developed a simple method for determination of 1,5-anhydro-D-glucitol in plasma, based on use of pyranose oxidase (EC 1.1.3.10), an enzyme with specificity toward pyranoid compounds such as 1,5-anhydro-D-glucitol and glucose. Plasma samples deproteinized with trichloroacetic acid are passed through a two-layer mini-column packed with strongly basic anion (OH- form, the upper layer) and strongly acidic cation (H+ form, the lower layer) exchange resins. 1,5-Anhydro-D-glucitol is efficiently recovered in the flow-through fraction, which is almost devoid of other sugars that are sensitive to pyranose oxidase. The hydrogen peroxide formed in the enzymatic oxidation of 1,5-anhydro-D-glucitol is detected by a standard method utilizing an enzymatic color-developing system. The overall assay system is highly specific for 1,5-anhydro-D-glucitol. The correlation between results obtained in the present method (x) and in the gas-liquid chromatographic (GLC) method (y) was: y = 1.062x-0.293 mg/L (r = 0.997, n = 49, Sxy = 10.78 mg/L). Compared with GLC, our method is simpler in the sample treatment step and quicker in the measuring step. The precisions of the two methods are comparable.
Distribution of thiobarbituric acid-reactive substances in lipoproteins and proteins in serum.
Authors: Bonnefont D , Legrand A , Peynet J , Emerit J , Delattre J , Galli A 
Published: January 2020

Abstract
We assessed the distribution of malondialdehyde (MDA) in lipoproteins and proteins in serum after using two procedures to separate the lipoproteins: sequential ultracentrifugation or selective precipitation with a sodium phosphotungstate and magnesium chloride reagent followed by ultracentrifugation of the supernate. MDA concentrations were determined by the thiobarbituric acid reaction and quantified by fluorometry. We found that 43% of the thiobarbituric acid-reactive substances (TBARS) was bound to the lipoproteins--27% to very-low- and low-density lipoproteins (VLDL-LDL) and 16% to high-density lipoproteins (HDL)--and from 11.5% to 15.8% to proteins, depending on the separation procedure. Residual unbound TBARS were located in the ultracentrifugation layers that contained no lipoproteins or proteins. The TBARS concentration in serum lipoproteins containing apolipoprotein B (i.e., VLDL-LDL) was the same after ultracentrifugation or selective precipitation. We therefore consider the precipitation method more suitable for routine TBARS determination in these lipoproteins, because it is easier to handle and faster. However, for determination of TBARS in HDL, selective precipitation requires subsequent ultracentrifugation at a density of 1.21 kg/L.
An interlaboratory comparison of control materials for use with hematofluorometers.
Authors: Parsons P J , Stanton N V , Gunter E W , Huff D , Meola J R , Reilly A A 
Published: January 2020

Abstract
This interlaboratory study was conducted to examine four erythrocyte protoporphyrin control materials from Aviv Biomedical, Helena Laboratories, Kaulson Laboratories, and the New York State Department of Health for use with hematofluorometers. Our principal aims were to monitor the stability of these materials at three different storage temperatures (room, refrigerator, freezer) and, where appropriate, to validate the manufacturer's target values. Measurements for the study were generated in three reference laboratories that used a total of five hematofluorometers, three from Environmental Science Associates and two from Aviv Biomedical. Each instrument was calibrated against a consensus acetic acid-ethyl acetate extraction procedure. We found the materials from Aviv to be the most stable, followed by the New York State material. However, the target values assigned by Aviv were not within the acceptable range determined by consensus. The target values assigned by Kaulson Laboratories for their materials did fall within the acceptable consensus range, but they were the least stable of the materials evaluated. The materials from Helena Laboratories were originally designed for use as calibrators with Helena's "ProtoFluor Z" hematofluorometer, which reports in different units. They were deemed unsuitable for use as control materials with the Aviv or Environmental Science Associates hematofluorometers because of the narrow range of values and the wide scatter of results.
An enzymatic method for oxalate automated with the Cobas Fara centrifugal analyzer.
Authors: Allen L C , Kadijevic L , Romaschin A D 
Published: January 2020

Abstract
Measurement of oxalate in urine has been automated for use with the Cobas Fara centrifugal analyzer. No sample pretreatment other than (a critical) pH adjustment is required. Between-run CVs were less than 4%. Results were linearly related to oxalate concentration to 1000 mumol/L. Ascorbic acid ingestion, up to 5 g of ascorbate daily, caused no demonstrable interference with the assay. This practical, automated method for assaying urinary oxalate is substantially faster than other chemical or enzymatic methods.