bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy and precision of five analog radioimmunoassays for free thyroxin compared.
Authors: Gow S M , Kellett H A , Toft A D , Beckett G J 
Published: January 2020

Abstract
We compared the precision of free thyroxin (FT4) measurements by kits involving analog RIA and the use of antibody-coated tubes (Becton Dickinson and Coat-A-Count), magnetic separation (Amerlex Magnetic and Corning Magic), or centrifugation of antibodies linked to solid beads (Amerlex). Results of kits with magnetic separation were the most reproducible. Amerlex, Amerlex Magnetic, and Becton Dickinson kits gave values comparing best with those obtained by direct equilibrium dialysis. Coat-A-Count and Corning Magic results differed significantly from dialysis values, both for patients' samples and kit standards. The kits had equal diagnostic efficiency in patients with suspected thyroid disease. On measurement of FT4 some patients were reclassified from "subclinical thyroid disease" to "overt disease." Most patients with triiodothyronine thyrotoxicosis had increased FT4. Several kit values were low for pregnant women and patients with nonthyroidal illness but the Amerlex and Amerlex Magnetic assays had fewer low results. The Amerlex Magnetic FT4 assay gave the best precision, agreement with the reference method, and diagnostic efficiency.
"Carryback": effect of viscous liquid controls on the preceding sample analyzed with the SMA II continuous-flow analyzer.
Authors: Winter S D , Kerr C , McAvoy M , Gallomore M D , Smith C , Lepoff R B 
Published: January 2020

Abstract
We systematically studied the "carryback" effect of ethylene glycol-based controls on the preceding sample on an SMA II continuous-flow analyzer. Including Beckman Level 1 unassayed liquid control material as a sample lowered the 12 analyte values of the preceding sample by an average of 2.7%, Level 2 (the most viscous) by an average of 4.4%, and Level 3 by 3.2%. Water-reconstituted lyophilized control material caused no carryback effect, but lyophilized control reconstituted with 330 mL/L ethylene glycol decreased the preceding sample's results by 4.1% (average carryback). We believe that carryback is caused by the drag placed on the sample line by a viscous sample, which decreases the volume of the preceding sample that is delivered to the reagent or pre-dilution mixing coils. Our findings were confirmed on another SMA II. Limited study of a SMAC analyzer gave inconclusive results, but further evaluation of continuous-flow systems for carryback is warranted. Carryback substantially increases total analytical variability.
Monoclonal antibody-based solid-phase immunoenzymometric assays for quantifying human immunoglobulin G and its subclasses in serum.
Authors: Papadea C , Check I J , Reimer C B 
Published: January 2020

Abstract
We developed quantitative immunoenzymometric assays for human IgG and its subclasses by using monoclonal antibodies, an avidin-biotin detection system and, as the calibrant, the U.S. National Reference Preparation for Specific Human Proteins. The assays are sensitive (detecting as little as 6 micrograms/L), precise (average inter-assay CV less than 11%), and vary linearly with concentrations over a five- to 10-fold range, depending on the monoclonal antibody. We evaluated 22 different monoclonal antibodies, many of which remained highly reactive when immobilized in wells of microtiter plates coated with bovine serum albumin-glutaraldehyde to "capture" total IgG or subclasses of IgG in the sample. We demonstrated the specificity of the most reactive antibodies by using a panel of 20 purified myeloma proteins. The sum of IgG subclass concentrations correlated well (r = 0.84, p less than 0.001) with the total IgG measured in sera from 63 apparently healthy adults (26 men, 37 women). We estimated 95 percentile reference intervals for the immunoglobulins in these subjects and determined the following mean percentage distributions of IgG subclasses: IgG1 49, IgG2 33, IgG3 9, and IgG4 7. The availability of these assays should facilitate studies of the clinical significance of the subclasses.
Free thyroxin and free triiodothyronine as measured by equilibrium dialysis and analog radioimmunoassay in serum of patients taking phenytoin and carbamazepine.
Authors: Liewendahl K , Tikanoja S , Helenius T , Majuri H 
Published: January 2020

Abstract
We measured free thyroxin (FT4) and free triiodothyronine (FT3) in serum of patients taking the anti-epileptic drugs phenytoin and carbamazepine, both by equilibrium dialysis procedures and analog-type radioimmunoassays. By either assay, the mean concentration of FT4 was significantly decreased in patients receiving either drug, whereas their FT3 concentrations were normal or only slightly decreased. Adding therapeutic concentrations of these drugs in vitro to control sera had a small or no incremental effect on FT4 and FT3 as measured by either method, but adding greater concentrations of the drugs in vitro markedly increased the concentrations of the free hormones. These results indicate that the main mechanism of the decrease in concentrations of free thyroid hormones in serum during therapy with anticonvulsant drugs is not the displacement of hormones from their binding to plasma proteins. We also determined, using a new and sensitive immunoradiometric assay, that patients taking carbamazepine, but not those taking phenytoin, had significantly less thyrotropin in the serum.
Hyperamylasemia, specific pancreatic enzymes, and hypoxanthine during recovery from diabetic ketoacidosis.
Authors: Møller-Petersen J , Andersen P T , Hjørne N , Ditzel J 
Published: January 2020

Abstract
The contribution of the exocrine pancreas to hyperamylasemia in diabetic ketoacidosis was investigated by measuring total amylase, salivary and pancreatic isoamylases, cathodic trypsin-like immunoreactivity, and pancreatic lipase in 12 consecutive patients recovering from diabetic ketoacidosis. Hyperamylasemia was present in six of the patients [50%; expected incidence: 21.1-78.9% (95% confidence limits)]--in five with simultaneously increased activities of all three specific pancreatic enzymes, and in one with only increased salivary isoamylase. The serum concentration of hypoxanthine--an indicator of the cellular energy state--was above normal in all patients at admission. We found no differences in concentrations of hypoxanthine in serum of patients with or without hyperamylasemia or in patients with or without increases in the specific pancreatic enzymes. In none of the patients was the clinical course or the time--concentration curves of the pancreatic enzymes consistent with acute pancreatitis. The pathogenic mechanism leading to hyperamylasemia in diabetic ketoacidosis remains uncertain.
Effects of dextran on five biuret-based procedures for total protein in serum.
Authors: Barnes D B , Pierce G F , Lichti D , Landt M , Koenig J , Chan K M 
Published: January 2020

Abstract
We evaluated the effect of dextran on values for total protein in serum as measured by the biuret method with five widely used automated instruments: the American Monitor Parallel; the Du Pont aca II; the Roche Cobas-Bio; the Kodak Ektachem 400; and the Beckman Astra 8. Dextran concentrations as great as 25 or 30 g/L had relatively little or no influence on total protein measurements by the latter three instruments. Dextran concentrations exceeding 6 g/L caused falsely low results with the aca, whereas the Parallel gave falsely high results when the dextran concentration exceeded 2 g/L. The aca total protein procedure could be protected from the interference by dextran concentrations up to 30 g/L by injecting 0.4-0.8 mL of ethylene glycol directly into the reagent pack before sampling. However, we could not eliminate the interference with the Parallel procedure by any simple means; we thus recommend that it not be used for measuring total protein in serum samples from patients who are being treated with dextran.
Anti-IgG combined with rate nephelometry for measuring polyethylene glycol-precipitated circulating immune complexes.
Authors: Feldkamp C S , Levinson S S , Perry M , Amin V 
Published: January 2020

Abstract
Immune complexes from serum were assayed for IgG by a simple rate-nephelometric method after extraction with polyethylene glycol that removes monomeric IgG. A 30-min preincubation of the extracted material in reaction buffer before the anti-IgG is introduced eliminates falsely increased values owing to precipitation that increased baseline light scatter in the reaction buffer. We found good parallelism in the reaction of anti-IgG with the IgG calibrator, aggregated human globulin, or endogenous immune complex. Thus IgG can be used for calibration in place of aggregated human globulin, greatly simplifying the assay. A good correlation was found between the present assay and the C1q-binding test (r = 0.83). The present assay is both sensitive and reproducible. The extraction and assay are straightforward and can be completed in a single morning after an overnight precipitation. The reagents for extraction are easily prepared and inexpensive, and the materials for assay are available in kit form. We believe this approach to be well suited for many clinical laboratories to measure circulating immune complexes.
A monoclonal-antibody enzyme immunoassay for detection of hepatitis B surface antigen with use of a biotin-avidin system.
Authors: Liu Y S , Green A 
Published: January 2020

Abstract
In this solid-phase two-site enzyme immunoassay for hepatitis B surface antigen (HBsAg), three monoclonal anti-HBs are used: 5D3 (IgM) is immobilized on plastic beads; 5C3 (IgG2a) and 5C 11 (IgG1), labeled with biotin, are used as the first conjugate. Horseradish peroxidase covalently linked to avidin is the second conjugate. First, serum or plasma is incubated with the antibody-coated bead and biotin-labeled antibodies, simultaneously, at 45 degrees C for 1 h ("stat" procedure), 3 h ("standard" procedure), or 18 h ("overnight" procedure), during which HBsAg forms a complex with the solid-phase antibody and the biotinylated antibodies. The enzyme-conjugated avidin is then bound to the biotin on the antigen-antibody complex at 45 degrees C for 15 min ("stat") or 30 min (standard and overnight procedures). The beads are incubated with enzyme-substrate solution (H2O2 and o-phenylenediamine). Color developed is measured at 492 nm. All procedures satisfied third-generation HBsAg tests required by the FDA Office of Biologics, being sensitive both to ad and ay subtypes in subnanogram amounts. The assay is reactive with adw2, adw4, adr, ayw2, ayw3, and ayr subtypes and can detect viral determinants in HBsAg-anti-HBs immune complex form. Thus it provides a sensitive, simple, and reproducible alternative to radioimmunoassay.
Apparent binding of ionized calcium by various buffers.
Authors: Crowell J A , Bowers G N 
Published: January 2020

Abstract
Using different substance concentrations in an aqueous 1.25 mmol/L solution of CaCl2 plus NaCl to a final solution ionic strength of 160 mmol/L, we tested six buffers for their effect on measurements of ionized calcium (Ca2+). Measured Ca2+ decreased with increasing ionic strength and pH. Increasing concentrations of Tris caused a positive Ca2+ electrode bias; the other five buffers caused a negative Ca2+ electrode bias with increasing concentration. 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid ("HEPES") at 10 mmol/L maintained pH 7.39 in the aqueous reference solutions containing 0.75 to 2.50 mmol of CaCl2 per liter, and showed a linear Ca2+ response among three different suppliers of Ca2+ instruments; it is thus a suitable buffer for a reference solution.
An evaluation of the Du Pont aca IV: does it meet medical needs?
Authors: Lott J A , Abbott L B , Koch D D 
Published: January 2020

Abstract
A new bench-top analyzer from Du Pont, the "aca IV," was evaluated. To do so, we performed 10 different tests during an eight-week test period. The instrument is very precise (CVs less than 2%), results agree well with those obtained with the older acas (II and III), linearity is good in the clinically important ranges, and there is very little drift or carryover. From a medical-needs viewpoint, we found the analyzer satisfactory for all tests except possibly for calcium, for which the medical-needs criteria are so strict that few laboratories can meet them. We reached the latter conclusions by using a statistical model, described here, and from the predictive value of an abnormal test for populations with various prevalences of disease.
The upper limit of normal for thyrotropin is 3 or 4 milli-int. units/L.
Authors: Durham A P 
Published: January 2020

Abstract
Recently Musto et al. (Clin Chem 30: 329-330, 1984) noted that, despite the clinical importance of accurate measurement of thyrotropin at low concentrations, the upper limit of normal is well below the stated upper limit of normal of most commercial tests. Here I amplify their statement.
Preparation of urine samples for liquid-chromatographic determination of catecholamines: bonded-phase phenylboronic acid, cation-exchange resin, and alumina adsorbents compared.
Authors: Wu A H , Gornet T G 
Published: January 2020

Abstract
We compared results for the liquid-chromatographic determination of free norepinephrine and epinephrine in urine after purifying the catechols by the following methods: (a) acid-washed alumina, (b) weak cation-exchange resin (WCX), (c) a combination of weak cation-exchange resin followed by alumina (WCX-alumina), and (d) commercially available phenylboronic acid adsorbent. We evaluated analytical specificity, sensitivity, recovery, and turnaround time. The WCX-alumina combination produced the most sensitive and specific chromatograms for urinary catecholamines; the other methods took less processing time. Neither WCX nor alumina alone was suitable for routine work because of chromatographic interferences in a significant proportion of urines. The phenylboronic acid method is adequately sensitive and specific for norepinephrine and epinephrine, and samples can be assayed faster. Thus it provides a compromise between the high analytical performance of the WCX-alumina method and the speed of the WCX and alumina methods.
Rhabdomyolysis: two pediatric case reports.
Authors: Goldsmith B M , Hicks J M 
Published: January 2020

Abstract
We report two pediatric cases of rhabdomyolysis. This disease involves the destruction of skeletal muscle, which can present with myalgia and a brown-pigmented urine. The first patient presented with acute renal failure, hypertension, and hyponatremia. The second patient was pyrexic, hypernatremic, and hypokalemic, and later developed hypertension. Evidence of rhabdomyolysis in both patients included dark, o-tolidine-positive urine, granular casts in the urinary sediment, and grossly increased activities of creatine kinase (greater than 60 000 U/L) in serum. An uncommonly recognized entity in the pediatric age group, rhabdomyolysis often presents as an acute disease with severe onset but can be diagnosed with relatively simple laboratory tests.
Light chain disease and massive proteinuria.
Authors: Lessard F , Bannon P , Lepage R , Joly J G 
Published: January 2020

Abstract
We describe the case of a 64-year-old man with lambda type light chain disease, in whom panhypogammaglobulinemia was associated with anemia, massive Bence Jones proteinuria (24.6 g/L), and renal failure. Lambda type light chains were present in the serum.
Hypergastrinemia--a risk factor for myocardial infarction?
Authors: Lindstedt G , Bengtsson C , Lapidus L , Nyström E 
Published: January 2020

Abstract
We determined gastrin and pepsinogen I in serum samples obtained in 1968-69 from 256 women (175 women 54 years old and 81 women 60 years old when sampled). The concentration of gastrin in serum was significantly (p less than 0.01) and positively correlated with the incidence of myocardial infarction during a 12-year follow-up, with age taken into account as a background variable in multivariate analysis. It was not correlated with overall mortality or with the 12-year incidences of angina pectoris, electrocardiographic changes indicating ischemic heart disease, or stroke. The correlation with myocardial infarction was independent of smoking, systolic blood pressure, indices of obesity, concentrations of blood glucose during fasting and of serum triglycerides and cholesterol, and of the presence of diabetes mellitus at screening or during follow-up. Serum gastrin was significantly (p less than 0.05) related to body mass index (positive age-specific relation) and to smoking (negative age-specific relation). These findings may provide a new aspect to analysis of risk factors for myocardial infarction.
Radioenzymic determination of homocysteine in plasma and urine.
Authors: Refsum H , Helland S , Ueland P M 
Published: January 2020

Abstract
Using a modification of the radioenzymic assay described previously (J Biol Chem 259: 2360-2364, 1984) we measured homocysteine in freshly prepared plasma and urine from volunteers. The concentration of free homocysteine--i.e., the amount measurable in plasma after deproteinization by strong acid--was 2.27 (SEM 0.11) mumol/L for 18 men and 1.95 (SEM 0.13) mumol/L for 16 women (p greater than 0.05, not significant). About 70% of the total homocysteine in human plasma was associated with plasma proteins, and was precipitated with strong acid. The concentration of protein-bound homocysteine in plasma was 6.51 (SEM 0.32) mumol/L for men and 7.29 (SEM 0.65) mumol/L for women, a significantly (p less than 0.01) different spread. Homocysteine was rapidly released from plasma proteins in the presence of a reducing agent, dithioerythritol. By gel filtration of plasma on a "high-performance" liquid-chromatographic column, albumin was shown to be the sole carrier of homocysteine in plasma. Because the fraction bound to protein as determined by this procedure equaled that obtained by precipitation of plasma proteins with acid, we conclude that homocysteine is bound to albumin in vivo. The concentration of homocysteine in urine ranged from 3.5 to 9.5 mumol/L, about 6 mumol of homocysteine being excreted per 24 h.
Immunoenzymometric assay for insulin involving column chromatography and insulin immobilized on Sepharose.
Authors: Yamamoto R , Kimura S , Hattori S , Matsuura A , Hayakawa T 
Published: January 2020

Abstract
This practical assay for measuring insulin involves use of a 4 X 8 mm chromatographic column. Serum samples are incubated at 30 degrees C for 1 h with beta-D-galactosidase-labeled antibody to insulin, then passed through the 0.1-mL column containing insulin immobilized on Sepharose 4B. After the column is washed to remove the bound label, the buffer in the column is replaced with a solution of o-nitrophenyl-beta-D-galactoside. The column is then incubated at 30 degrees C for 1 h, the enzyme reaction is stopped by washing the column with sodium carbonate solution, and the absorbance of the eluate is measured at 420 nm. Results obtained by this method were compared with those by a radioimmunoassay and a solid-phase enzyme immunoassay.
Macroamylase immunoglobulins show high affinity for animal and human amylases.
Authors: Urdal P , Landaas S , Kierulf P , Strømme J H 
Published: January 2020

Abstract
We have examined the affinity shown by the immunoglobulin fraction from each of five sera containing macroamylase for amylases from different sources: human saliva or human, porcine, or ovine pancreas. High affinity constants, 0.4 X 10(10) to 7.2 X 10(10) L/mol, were found in competitive binding experiments with human or porcine pancreatic amylase. All but one serum yielded linear Scatchard plots, indicating that in most sera the amylase-binding immunoglobulins are homogeneous, possibly monoclonal. The immunoglobulin fractions from different sera differed in their specificity: two of them bound all four types of amylases, whereas two bound only one type. Three of the five immunoglobulin fractions showed considerably higher affinity towards one or both of the animal amylases than towards the human ones, and may be primarily directed against some animal amylase.
Fluorometric assay for phospholipase A2 in serum.
Authors: Thuren T , Virtanen J A , Lalla M , Kinnunen P K 
Published: January 2020

Abstract
In this fluorometric assay for phospholipase A2 (EC 3.1.1.4) in serum we use the fluorescent phospholipid analog 1-octacosanyl-2-(pyren-1-yl)hexanoyl-sn-glycero-3-phosphatid yl monomethyl ester as substrate. The optimized conditions are: 28 mumol of the substrate per liter of Tris buffer (20 mmol/L, pH 7.4). The hydrolytic reaction is allowed to proceed for 30 min at 37 degrees C. The fluorescent reaction product, (pyren-1-yl)hexanoic acid, is then separated from the unreacted substrate by liquid-liquid phase partition. The concentration of the liberated fatty acid analog is determined fluorometrically. The detection limit is approximately 6 pmol min-1 mL-1. Forty duplicate samples can be assayed in about 2 h. The activity of this enzyme in serum of 20 healthy volunteers averaged 69 pmol min-1 mL-1. For seven patients with clinically diagnosed pancreatitis the average activity was 1092 pmol min-1 mL-1.
Evaluation of a benchtop capillary gas chromatograph-mass spectrometer for clinical toxicology.
Authors: Deutsch D G , Bergert R J 
Published: January 2020

Abstract
We evaluated the Hewlett-Packard 5995B benchtop capillary gas chromatograph-mass spectrometer (GC-MS) for its ability to identify drugs commonly detected and (or) measured in the clinical toxicology laboratory. Initial experiments indicated that the instrument as originally configured, with an isolation valve between the gas chromatograph and mass spectrometer, was unsatisfactory for the identification of hypnotics-sedatives. However, with the capillary inserted directly into the ion source, we could detect 10 ng of these drugs on a total-ion chromatogram. The software programs cause the instrument to be highly automated. In terms of ease of operation and speed it was found suitable for use in a routine clinical laboratory. Chromatography of urine extracts on the capillary gas chromatograph-mass spectrometer yielded excellent resolution of parent compounds and metabolites (e.g., diphenhydramine together with approximately four metabolites and propoxyphene with four metabolites). However, the manufacturer's computer program used to evaluate the quality of the match between the experimental mass spectra and the 375 drug reference spectra was only moderately successful in identifying unknown compounds. The ability of this capillary GC-MS to identify most compounds with a high degree of confidence will be increased by enlarging the library to include more drugs and metabolites and by using a more reliable computerized matching program.
A radioimmunoassay for 18-hydroxycortisol in plasma and urine.
Authors: Corrie J E , Edwards C R , Budd P S 
Published: January 2020

Abstract
Increased excretion of 18-hydroxycortisol has been proposed as a specific biochemical marker for differential diagnosis of primary aldosteronism. We describe the development of a direct RIA with an 125I label that permits measurement of the steroid in less than or equal to 0.5 microL of urine or less than or equal to 25 microL of plasma. For control subjects, the mean concentrations of 18-hydroxycortisol in urine and plasma were 310 (SD 178) nmol/24 h (n = 32) and 2.27 (SD 0.80) nmol/L (n = 37), respectively; patients with Conn's adenoma or glucocorticoid-remediable aldosteronism had values for urine in the range 1084 to 6534 nmol/24 h and concentrations in plasma ranging from 6.49 to 31.20 nmol/L. Patients with idiopathic zona glomerulosa hyperplasia had values for urine and plasma ranging from 353 to 734 nmol/24 h and from 0.26 to 6.60 nmol/L, respectively. Concentrations of 18-hydroxycortisol in urine clearly discriminate patients with idiopathic hyperplasia from those with other forms of primary aldosteronism, but further work is required to assess the diagnostic accuracy of determinations in plasma.