bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is serum fructosamine assay specific for determination of glycated serum protein?
Authors: Schleicher E D , Mayer R , Wagner E M , Gerbitz K D 
Published: January 2020

Abstract
We compared the fructosamine activity in sera from healthy and diabetic subjects with the degree of protein glycation detected by a liquid-chromatographic method. The latter technique measures furosine as a specific product after hydrolysis of epsilon-amino-fructose-lysine. Our results indicate that the fructosamine assay measures the extent of glycation of purified human serum albumin correctly. On the other hand, we found no correlation between the two methods for sera from healthy subjects, although for diabetics' sera the values obtained with both methods were related. However, only about half of the reducing activity (fructosamine) was due to specific nonenzymatic glycation of proteins in healthy subjects and well-controlled diabetics. The remaining unspecific activity varied from serum to serum. It was not reducible with NaBH4 and was independent of the glycation of albumin, which normally accounts for about 80% of glycated serum proteins. The fructosamine assay is therefore of limited specificity for the exact measurement of glycated proteins in serum.
A rapid and accurate spectrofluorometric method for quantification and screening of urinary porphyrins.
Authors: Westerlund J , Pudek M , Schreiber W E 
Published: January 2020

Abstract
We describe a fluorescence method for screening and quantifying urinary porphyrins. New and effective approaches are used to oxidize prophyrinogens, correct the baseline, and ensure that uroporphyrin (uro) and coproporphyrin (copro) are equally detected, mole for mole. No preliminary purification is required. A 45-microL aliquot of urine is oxidized with 3 mmol/L iodine in 3 mol/L HCl to convert porphyrinogens to porphyrins, and then decolorized with 5 mL of 0.45 mmol/L sodium thiosulfate. An excitation scan is done from 350 nm to 440 nm, monitoring emission at 650 nm. Total porphyrin content is determined at the isosbestic point for uro and copro, and the mole fractions of uro and copro are estimated from the wavelength of the signal maximum. There is no interference from protein, glucose, bilirubin, or hemoglobin in high concentration. The limit of detection is less than 30 nmol/L and linearity is maintained up to 3200 nmol/L. Recoveries and precision are excellent. This is a rapid, sensitive screen for porphyrinuria as well as an accurate and precise quantitative method. We compared the method with existing methods and discuss some shortcomings common to many of them.
Laboratory evaluation of the Beckman Synchron CX3 clinical chemistry analyzer.
Authors: Peake M J , Pejakovic M , White G H 
Published: January 2020

Abstract
In this evaluation of the Beckman Synchron CX3, the multi-analyte clinical chemistry analyzer exhibited high precision, good linearity, and no carryover for each of the eight analytes measured. Results obtained correlated well with those produced by our routine instrumentation (Beckman Astra, Varian atomic absorption spectrophotometer). The instrument can process up to 75 samples per hour (600 tests per hour if all tests available are requested) and, after calibration, can provide urgent results for the complete panel of tests within 2 1/2 min. The performance characteristics of this instrument make it ideal as a routine or a "stat" analyzer for commonly requested tests in the clinical chemistry laboratory.
Getting involved in the legal system: choice or chance?
Authors: Labowitz D I 
Published: January 2020

Abstract
The legal system and the laboratory are becoming involved with each other on a daily basis today and the technologist is, willingly or unwillingly, being drawn into this unfamiliar arena. This article will explain some of the manner by which a part of that arena operates, specifically the trial courts. Whether civil or criminal, these courts are governed by rules and methods of operation for the persons in them. In the case of the laboratorian, the role is that of witness, and this article attempts to dispel any fears of that role and teaches how to best prepare for it.
A simple method for clinical assay of superoxide dismutase.
Authors: Sun Y , Oberley L W , Li Y 
Published: January 2020

Abstract
This assay for superoxide dismutase (SOD, EC 1.15.1.1) activity involves inhibition of nitroblue tetrazolium reduction, with xanthine-xanthine oxidase used as a superoxide generator. By using a reaction terminator, we can determine 40 samples within 55 min. One unit of activity of pure bovine liver Cu,ZnSOD and chicken liver MnSOD was expressed by 30 ng and 500 ng of protein, respectively. The mean concentrations of Cu,ZnSOD as measured by this method in blood from normal adults were 242 (SEM 4) mg/L in erythrocytes, 548 (SEM 20) micrograms/L in serum, and 173 (SEM 11) micrograms/L in plasma. The Cu,ZnSOD concentrations in serum and plasma of patients with cancer of the large intestine tended to be less and greater than these values, respectively, but not statistically significantly so.
Assessment of proton nuclear magnetic resonance spectroscopy for detection of malignancy.
Authors: Wilding P , Senior M B , Inubushi T , Ludwick M L 
Published: January 2020

Abstract
Water-suppressed proton nuclear magnetic resonance spectra were generated (by using 360 and 500 MHz systems) from human plasma and serum samples taken from 35 apparently healthy individuals, 52 patients with overt malignancies, and 37 patients with hypertriglyceridemia (triglycerides greater than 200 mg/dL or 2.26 mmol/L). The line widths from the lipoprotein-lipid methylene and methyl resonances at approximately 1.3 and 0.9 ppm were averaged by the method of Fossel et al. (N Engl J Med 1986;315:1369-76), but, contrary to their findings, we were unable to distinguish normal individuals from those with malignant tumors (e.g., mean +/- SD line width at 360 MHz: normal group = 32.9 +/- 3.6 Hz, malignant group = 28.3 +/- 4.9 Hz). The average line-width measurements (y), however, varied with the triglyceride content (x, mg/dL) of the plasma or serum as follows (logarithmic transformation of the data determined at 360 MHz and regression analysis): y = 110 (x-0.27). Data from both nonmalignant and malignant specimens fit this equation, the coefficient of correlation being -0.91. These findings suggest that considerable caution should be used in interpreting water-suppressed proton NMR spectra for cancer detection.
Urinary enzymes and low-molecular-mass proteins as indicators of diabetic nephropathy.
Authors: Jung K , Pergande M , Schimke E , Ratzmann K P , Ilius A 
Published: January 2020

Abstract
We measured the excretion rates of six urinary enzymes that either originate from the proximal renal tubule, like alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), and N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30), or that are typical low-molecular-mass proteins, like lysozyme (EC 3.2.1.17) and pancreatic ribonuclease (EC 3.1.27.5). These rates were compared with those of total protein and albumin in urine of 36 insulin-dependent diabetic men and 30 healthy men. Seventeen of the diabetics had "clinical proteinuria," defined as excretion of more than 7.5 g of protein per mole of urinary creatinine (group B). Group A comprised the 19 diabetics without proteinuria. Except for gamma-glutamyltransferase, the excretions of enzymes and proteins were significantly higher in diabetics than in controls and were greater in group B than in group A. N-Acetyl-beta-D-glucosaminidase was the analyte most often increased in group A (89%), followed by albumin and alkaline phosphatase (each 32%). All patients in group B showed increased excretion of N-acetyl-beta-D-glucosaminidase. We conclude from the comparative data that this enzyme may be useful as an early predictor of diabetic nephropathy.
Interference by endogenous glycerol in an enzymatic assay of phosphatidylglycerol in amniotic fluid.
Authors: Herold D A , Reed A E 
Published: January 2020

Abstract
We investigated the possibility of interference by endogenous glycerol with the enzymatic measurement of phosphatidylglycerol in amniotic fluid. Phosphatidylglycerol is an important indicator of fetal lung maturity. The concentrations of glycerol and phosphatidylglycerol in amniotic fluid were measured by using a coupled enzymatic assay with and without phospholipase D (EC 3.1.4.4). The precision of the assay was acceptable (within-run CV = 1.2%, between-run CV = 4.8%). Endogenous glycerol content was demonstrated to be approximately 10-20 times that of phosphatidylglycerol. This high proportion of endogenous glycerol in amniotic fluid would preclude the accurate enzymatic determination of amniotic fluid phosphatidylglycerol unless the glycerol is first removed. Nor can the actual phosphatidylglycerol concentration be determined by subtracting the endogenous glycerol concentration from the total glycerol, which includes that glycerol derived from phosphatidylglycerol. With a usual range of 9 +/- 7 mumol/L, the error for a given phosphatidylglycerol measurement of +/- 6.6 mumol/L (+/- 2 SD) clearly is too high for this assay to be clinically useful. There was no correlation between concentration of endogenous glycerol or apparent phosphatidylglycerol in amniotic fluid and the lecithin/sphingomyelin ratio of the sample.
Thyrotroph function assessed by sensitive measurement of thyrotropin with three immunoradiometric assay kits: analytical evaluation and comparison with the thyroliberin stimulation test.
Authors: Wians F H , Jacobson J M , Dev J , Heald J I , Ortiz G 
Published: January 2020

Abstract
We evaluated the analytical and clinical performance of three "sensitive" immunoradiometric assay (IRMA) kits (Tandem-R TSH HS, Hybritech, Inc.; EchoClonal TSH, Bio-Rad; Coat-A-Count TSH IRMA, Diagnostic Products Corp.) for measurement of thyrotropin (TSH) and compared their performance against a "regular" IRMA (ARIA-HT, Becton-Dickinson) to determine whether these assays might eliminate the need to perform the thyroliberin (TRF) stimulation test. We concluded that the Tandem and EchoClonal kits may obviate the need to perform TRF stimulation tests in some patients. Using only the basal TSH concentration to predict the TSH response to TRF, we found all three sensitive TSH assays to be useful for detecting abnormal thyrotroph function. Dose-response, linearity, analytical recovery, and specificity were acceptable for all kits, but intra-assay precision at very low TSH concentrations and analytical sensitivity differed considerably among the kits. Using the EchoClonal assay, we established a normal reference interval for TSH of 0.4-4.6 milli-int. units/L.
Semi-automated direct colorimetric measurement of creatine kinase isoenzyme MB activity after extraction from serum by use of a CK-MB-specific monoclonal antibody.
Authors: Landt Y , Vaidya H C , Porter S E , Whalen K , McClellan A , Amyx C , Parvin C A , Kessler G , Nahm M H , Dietzler D N 
Published: January 2020

Abstract
This semi-automated colorimetric assay for the MB isoenzyme of creatine kinase (EC 2.7.3.2) is based on a monoclonal antibody ("Conan-MB") specific for this isoenzyme and is a modification of a previously published method (Vaidya et al., Clin Chem 1986;32:657-63). A 0.64-cm bead coated with 2 to 3 micrograms of antibody is incubated with 100 microL of serum and 10 microL of 0.2 mol/L beta-mercaptoethanol for 1 h at room temperature, to extract CK-MB. The beads are washed with de-ionized water and incubated with CK substrate for 45 min at 37 degrees C. A solution containing trans-1,2-diaminocyclohexane-N,N,N', N'-tetraacetic acid, p-iodonitrotetrazolium violet, and diaphorase is added and the resulting colored product is measured at 492 nm. The standard curve is linear to 200 U of CK-MB per liter, and analytical recovery is 97-113%. Total assay CV for low (9.7 U/L) and high (50.7 U/L) quality-control materials was 14.1% (n = 1878) and 11.6% (n = 1842), respectively. CK-MB activity correlated well (r = 0.978, n = 226) with CK-MB measured by a two-site mass immunoassay, and 99.4% of samples with CK-MB greater than or equal to 12 U/L (n = 347) were verified by electrophoresis on agarose.
Drug testing in the military--technical and legal problems.
Authors: Irving J 
Published: January 2020

Abstract
The Armed Forces drug-testing program has been in operation since 1971. Since that time, its goals, capabilities, and methods of operation have undergone extensive evolution and change. As these laboratories developed, they helped to establish many of the currently accepted operating standards for drug screening. For laboratories considering entry into the business of drug screening, an examination of the evolution and current operation of the military laboratories will be of benefit. It will help to define the currently accepted standards and NIDA guidelines and assist them to avoid the types of problems that were encountered by the military laboratories.
Development and performance of a highly sensitive carboxyl-terminal-specific radioimmunoassay of calcitonin gene-related peptide.
Authors: Zaidi M , Girgis S I , MacIntyre I 
Published: January 2020

Abstract
The calcitonin genes encode a small family of peptides: the circulating hormone calcitonin; its flanking peptide, katacalcin; and a third novel peptide, calcitonin gene-related peptide (CGRP). CGRP is a potent vasodilator and a major circulating product from the calcitonin genes; it may be a physiologically important regulator of blood flow in humans. High concentrations of circulating CGRP are found in medullary thyroid carcinoma. We report the development and validation of a highly sensitive (detection limit 500 amol per tube) radioimmunoassay of CGRP involving a high-affinity antibody directed against the carboxyl terminus of the molecule and a highly pure tracer. The assay is precise, robust, and reproducible, and is therefore a potentially useful analytical method for studying the normal and abnormal physiology of this peptide.
Measurement of ferritin in serum by an indirect competitive enzyme-linked immunosorbant assay.
Authors: Polson R J , Kenna J G , Shears I P , Bomford A , Williams R 
Published: January 2020

Abstract
This indirect competitive enzyme-linked immunosorbant assay (ELISA) for ferritin, unlike other currently available ELISAS, does not require use of an anti-ferritin antibody-enzyme conjugate. Designed for use on microtiter plates, the method has a precision and sensitivity similar to those of other immunoassays. The detection limit is 20 pg of ferritin per test (corresponding to 2.0 micrograms/L in serum samples). Comparison of results obtained on serum from 57 patients by this method with those from a conventional radioimmunoassay gave a correlation coefficient of 0.92.
Genetic analysis of systemic lupus erythematosus: 1. Detection of disease-associated variant proteins by two-dimensional gel electrophoresis.
Authors: Morito F , Ohta A , Kaneoka H , Nagayoshi T , Hilda M , Yamaguchi M 
Published: January 2020

Abstract
Various genetic studies indicate that development of systemic lupus erythematosus (SLE) is regulated by the mode of multifactorial inheritance, i.e., by the overall effect of polygenes and environmental factors. To elucidate some variant genes involved in the polygenic system responsible for onset of SLE, we resolved and measured the protein components of lymphocytes and sera from inactive-SLE patients, their relatives, and normal controls, using two-dimensional gel electrophoresis. Intercomparison of polypeptide patterns between patients and controls revealed three major variations, two detected in lymphocytes and one in sera. These variations were present in 66-82% of the patients, in 20-36% of the control group, and in 41-64% of the relatives. In addition, nearly half of SLE patients, but only one of 19 normal controls, possessed all three SLE-associated traits, suggesting that these variant proteins may reflect in part the genetic factors contributing to development of SLE.
Direct determination of selenium in serum by graphite-furnace atomic absorption spectrometry with deuterium background correction and a reduced palladium modifier: age-specific reference ranges.
Authors: Jacobson B E , Lockitch G 
Published: January 2020

Abstract
We describe the development of a direct method for determination of selenium in serum by graphite-furnace atomic absorption spectrophotometry with deuterium background correction. We include palladium modifier to stabilize selenium in the presence of a strong reducing agent. Spectral interferences from iron are not evident in this system. Because an analysis requires only 20 microL of serum or plasma, the method is applicable to neonatal populations. At a selenium concentration of 0.75 mumol/L (approximately the mean found in our pre-term infants), the within-run CV is 5.3%. For a concentration of 1.83 mumol/L, which approximates our normal adult mean, within-run and between-run CVs are 2.7% and 3.4%. Accuracy is demonstrated by analytical recoveries ranging from 96% to 102%. We present reference values for pre-term and term infants, and age-specific ranges for infants to adults.
Pre-analytical variation in alanine aminotransferase.
Authors: Ruby S G , Reiber N E , Lonser R E 
Published: January 2020

Abstract
To determine the effect of pre-analytical variation of alanine aminotransferase in blood specimens with normal activity concentrations of this enzyme, we stored serum and whole blood samples at 4 and 22 degrees C and assayed aliquots of each specimen at intervals up to 72 h. Analysis of variance revealed no statistically significant increase or decrease in activity of the enzyme for up to 72 h in either specimen type, whether stored at room temperature or refrigerated.
Amylase in urine as measured by a single-step chromolytic method.
Authors: Bertholf R L , Winn-Deen E S , Bruns D E 
Published: January 2020

Abstract
We studied a new single-step direct chromolytic method (Behring D.A.T.) for measuring urinary amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) activity, comparing results with those by a similar, but two-step, procedure that requires an auxiliary (coupling) enzyme. The two methods gave virtually identical relative responses to purified human pancreatic and salivary amylases. Assay of four quality-control materials to evaluate the total (day-to-day) precision of the new method yielded CVs of 4 to 7%, similar to those of the comparison method for each of the four quality-control samples. Amylase activity was measured by both methods in 110 random (i.e., untimed) urine specimens. Linear regression analysis provided a slope and y-intercept of 0.947 and 4 U/L (x = comparison method, y = direct method), respectively, and a standard error of the estimate of 25 U/L for specimens in which the amylase activities ranged from 11 to 1465 U/L (mean = 358 U/L) by the comparison method. The mean rate of amylase excretion in 2-h timed urine specimens from 95 healthy volunteers, as measured by the new method, was 7.18 (SD = 3.18) U/h, and the nonparametric (95% confidence interval) reference interval was 1.6 to 15.2 U/h. We consider the new method a promising alternative to other kinetic assays that require the use of auxiliary enzymes.
Comparison of Roche RIA, Roche EIA, Hybritech EIA, and Abbott EIA methods for measuring carcinoembryonic antigen.
Authors: Nisselbaum J S , Smith C A , Schwartz D , Schwartz M K 
Published: January 2020

Abstract
Using 600 clinical specimens, we compared the concordance of four methods for carcinoembryonic antigen: the Roche RIA (I); the Roche EIA (II); Hybritech EIA (III); and Abbott EIA (IV). EDTA-treated plasma was used for Methods I and II and serum for Methods III and IV. However, no significant difference was found between results for serum and plasma in Method II. The normal reference interval (in micrograms/L) was I (222 specimens), 1.94 +/- 1.54; II (57 specimens), 0.8 +/- 0.5; III (100 specimens), 2.94 +/- 2.47; and IV (614 specimens), less than 5.0. The precision of all four methods was acceptable. Concordance among all of the methods exceeded 90%.
Are increases in thyroxin-binding globulin in patients with acute hepatitis ascribable to synthesis by regenerating hepatocytes?
Authors: Shigemasa C , Tanaka T , Mitani Y , Ueta Y , Taniguchi S , Urabe K , Adachi T , Yoshida A , Abe K , Mashiba H 
Published: January 2020

Abstract
We describe a case of liver cirrhosis lacking the expected increase in serum thyroxin (T4)-binding globulin (TBG) despite abrupt, severe increases in aspartate and alanine aminotransferases (ASAT and ALAT) in serum. Sequential change in serum T4, triiodothyronine (T3), and TBG concentrations were also measured retrospectively in serum of 10 hospitalized patients with acute viral hepatitis. Although their mean T4 and TBG concentrations significantly exceeded those in 40 normal subjects (P less than 0.002 and P less than 0.001, respectively), these values were within the normal reference intervals in five patients. ASAT and ALAT concentrations were not significantly different in patients with increased TBG and patients with normal TBG, whereas mean concentrations of serum albumin and cholinesterase and mean prothrombin times (in percent) in the former group were significantly higher than those in the latter group (P less than 0.05, P less than 0.05, and P less than 0.001, respectively). For 60 samples with increased ASAT and ALAT, TBG and albumin or cholinesterase correlated significantly (r = 0.49, P less than 0.001 and r = 0.50, P less than 0.001, respectively), but not TBG and ASAT or ALAT. Collectively, these results suggest that the increase in serum TBG in acute hepatitis may reflect its synthesis in regenerating hepatocytes rather than a simple leakage from damaged hepatocytes.
Is there a practical alternative to therapeutic drug monitoring in therapy with tricyclic antidepressants?
Authors: Dawling S 
Published: January 2020

Abstract
Optimization of tricyclic antidepressant (TCA) therapy by dosage adjustments made in response to inappropriate concentrations in plasma or side effects can be extremely slow owing to the long half-lives of these drugs. I examine the practicality of alternative methods of arriving quickly and reliably at an adequate starting dosage. The clearance of a single test dose from plasma has been used to select individualized dosages before commencing therapy, but this takes several days and requires computer-assisted calculation of clearance. A simpler technique is to measure the concentration in a single timed plasma sample as an index of metabolism, and to infer the required dosage directly from a nomogram. Ideally, the nomograms should be interchangeable between patient populations and independent of the analytical method used, and the drug must have linear kinetics. Furthermore, TCAs are metabolized by common routes--demethylation and hydroxylation--so one might apply a single tolerance test for the entire class of drugs. Hydroxylation of TCAs can also be correlated with that of debrisoquine. The debrisoquine clearance test is non-invasive, faster, and analytically less demanding than TCA measurements. In the absence of rigid therapeutic ranges, tests that identify abnormally slow metabolizers may well be invaluable in preventing iatrogenic poisoning. Despite the usefulness of these methods in establishing effective initial dosages, their continued success depends upon good compliance, the maintenance of the patient's concurrent drug therapy, and a stable physical condition. In the non-ideal world, therefore, TDM cannot be dispensed with, but must be seen as an essential part of effective TCA treatment, based ultimately of course on sound clinical judgement.