bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concurrent immunoassay of C-reactive protein and orosomucoid by random-access analysis.
Authors: Pressac M , Magnier C , Aymard P 
Published: January 2020

Abstract
We describe turbidimetric methods for simultaneously determining C-reactive protein and orosomucoid in 33 microL of undiluted serum in the Technicon RA-1000, with multipoint calibration. Precision is good and results correlate favorably with those of nephelometry with the Beckman ICS (r = 0.98 for CRP, 0.99 for orosomucoid). Analyses are easy to perform, require infrequent calibration, and are suitable for routine and emergency analysis.
Ion-selective membrane electrodes for clinical use.
Authors: Oesch U , Ammann D , Simon W 
Published: January 2020

Abstract
We review ion-selective solvent polymeric membrane electrodes for clinical use. The particular requirements that the clinical application set on the membrane are discussed in terms of selectivity, stability, lifetime, and response time. The performance of currently available electrodes is reviewed, with consideration of actual problems that arise in clinical practice.
Normal reference intervals for free catecholamines and their acid metabolites in 24-h urines from children, as determined by liquid chromatography with amperometric detection.
Authors: Prémel-Cabic A , Turcant A , Allain P 
Published: January 2020

Abstract
We used two methods of reversed-phase liquid chromatography with amperometric detection, one for assay of unconjugated norepinephrine, epinephrine, and dopamine in urine, the other for determination of unconjugated vanillylmandelic acid and homovanillic acid. The catecholamines were extracted from urine by passage through a weak-cation exchange resin, then through alumina. Vanillylmandelic acid and homovanillic acid were isolated from urine by a two-step solvent-extraction procedure. The between-day CV was 5% for norepinephrine, 3% for epinephrine, 3% for dopamine, 4.5% for vanillylmandelic acid, and 6.4% for homovanillic acid. Reference ranges for these analytes in 76 children, ages 3-16 years, are reported.
Quantification of analyte and interferent by multipoint analysis.
Authors: Czervionke R L , Johnson G F , Nuwayhid N F , Feld R D 
Published: January 2020

Abstract
We have investigated the application of multipoint kinetic curve-fitting methods to the determination of an analyte in the presence of a single interferent. Our model system for the analyte-interferent was creatinine-acetoacetate as determined with the kinetic Jaffé method. We examined the utility of the following multipoint approaches: simultaneous equations, multivariable linear regression, and iterative multivariable nonlinear regression. With appropriate restrictions, all approaches could detect acetoacetate interference and quantify both creatinine and acetoacetate. A two-stage linear regression approach was both versatile and computationally simple. Interferent was detected in the first stage, and both analyte and interferent were quantified in the second stage if the interferent was assumed known and an adequate fit of the model to the data was obtained. Using the two-stage linear regression model, we obtained results for 10 ketotic patients that correlated well with results by enzymatic methods for creatinine (r = 0.976) and acetoacetate (r = 0.995); we also demonstrated that creatinine could be quantified in the presence of the antibiotic cefoxitin.
Routine measurement of calcium, magnesium, copper, zinc, and iron in urine and serum by inductively coupled plasma emission spectroscopy.
Authors: Nixon D E , Moyer T P , Johnson P , McCall J T , Ness A B , Fjerstad W H , Wehde M B 
Published: January 2020

Abstract
We describe an inductively coupled plasma atomic emission spectrometer that has been adapted to perform routine, simultaneous, direct analyses of calcium, magnesium, copper, zinc, and iron in serum or urine without sample digestion or pretreatment. The system, constructed with inexpensive, readily available components, can analyze 1-mL or smaller samples. Results correlate nearly perfectly with those derived by standard atomic absorption techniques (r = 0.98 to 0.997). Using certified serum and urine samples from various sources, we demonstrate that the instrument yields accurate results with a precision better than certified values. The instrument is sensitive to one order of magnitude less than the lower limit of the normal range in serum or urine for all elements tested, and responds linearly to concentrations two orders of magnitude higher than the upper limit of the normal range. With the system described here, these five elements can be assayed with the same or less technical effort than needed for a single element by atomic absorption.
Robotic sample preparation evaluated for the immunochemical determination of cardiac isoenzymes.
Authors: Castellani W J , Van Lente F , Chou D 
Published: January 2020

Abstract
A general-purpose bench-top laboratory robot was programmed to perform sample preparation for immunoprecipitative and immunoinhibitory determinations of cardiac isoenzymes with commercial kits. Run size could be varied from 1 to 24 patients' samples, and was determined by the robot without prompting. The robot placed the processed samples into a sample rotor for dried transfer to a batch centrifugal analyzer. Robotic precision compared well with that of manual performance of the same procedures at four concentrations of lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 activity and at one of two concentrations of creatine kinase (EC 2.7.3.2.) isoenzyme MB activity; for the other creatine kinase MB concentration, use of the robot significantly improved precision. Results for 100 samples from patients after open-heart surgery were highly correlated with manually obtained results for both isoenzyme determinations (r less that 0.96 each). Time to completion for small run sizes for either approach was comparable about 25 min. For larger batches, robotic run time increased rapidly, to 169 min for 24 patients' samples vs 41 min by manual assay.
Chemometrics: an overview.
Authors: Deming S N 
Published: January 2020

Abstract
Chemometrics is broadly defined as the application of mathematical and statistical methods to chemistry. Because the mathematical and statistical aspects of chemistry require measured values, analytical chemists have been at the forefront of the "chemometric revolution." Using the analysis of variance as a paradigm, I present an overview of chemometrics as it is practiced today. Receiving special emphasis are: the design of experiments to acquire information from the relevant universe of possible measurements; the establishment of relationships among independent and dependent variables; the importance of minimizing purely experimental uncertainty; sequential simplex optimization; analysis of principal components; and cluster analysis.
Laboratory decision science applied to chemometrics: strategic testing of thyroid function.
Authors: Beck J R 
Published: January 2020

Abstract
Clinical decision analysis and cost-effectiveness analysis have begun to penetrate academic laboratory medicine. Decision science offers tools by which clinical chemical tests may be evaluated for their medical efficacy and economic feasibility. In the "treat, test, observe" paradigm it provides a framework for placing new laboratory tests in an appropriate clinical context. A general overview of the decision analysis method and the laboratory-oriented model is presented, with an application to the development of strategies for hospital-based testing of thyroid function.
The computer as a diagnostic consultant, with emphasis on use of laboratory data.
Authors: Myers J D 
Published: January 2020

Abstract
In this preliminary study concerning the applicability of expert computer systems, such as INTERNIST-I, to providing advice to clinical pathologists regarding patients' diagnoses and the pertinence of performing further laboratory tests, 32 complex cases, drawn from Case Records of the Massachusetts General Hospital, were analyzed diagnostically by computer, on the basis of clinical laboratory data only. Half (16 cases) were diagnosed correctly, but in 15 of the rest no diagnostic conclusion could be reached. However, no diagnostic errors were made. The study provides preliminary evidence that expert computer systems can be useful to clinical pathologists and clinical internists in guiding the laboratory workup of patients toward correct diagnosis.
Perspectives on the use of chemometrics in laboratory medicine.
Authors: Boyd J C 
Published: January 2020

Abstract
Today's automated laboratory instruments are capable of generating prodigious volumes of high-quality measurements. Increasingly, the powerful mathematical and statistical methods of chemometrics are being called upon to help reduce these measurements to useful information. Chemometric methods have been important in automating various data-intensive functions of the clinical laboratory, including analysis of cellular images, identification of bacteria and fungi on the basis of their metabolic and chemical properties, and identification of drugs and toxic substances from their mass spectra. These methods also appear promising in aiding both the selection and interpretation of laboratory tests for diagnosis, monitoring, and prognosis. In spite of the demonstrated potential of these methods, significant problems remain to be solved in the areas of measurement standardization, data-base collection, and user familiarity with these approaches before chemometric methods can be used most fully by the clinical laboratory.
Dry-reagent strips for measuring phenytoin in serum.
Authors: Sommer R , Nelson C , Greenquist A 
Published: January 2020

Abstract
A new reagent strip has been developed for measuring phenytoin in serum or plasma. It utilizes the chemistry of the Apoenzyme Reactivation Immunoassay System (ARIS) and is designed for use with the Seralyzer reflectance photometer. The 90-s test relies on comparison of strip reactivities with a two-point calibration line, which can be validly stored in the instrument for two weeks. Within-run CVs for controls at five concentrations ranged from 2.7 to 5.6%, between-run CVs from 2.3 to 6.3%. Phenytoin values obtained for clinical serum samples correlated well (r greater than 0.99) with those obtained by liquid chromatography or substrate-labeled fluorescent immunoassay. The speed and convenience of this assay for monitoring phenytoin in serum make it well suited for decentralized test sites such as emergency rooms, urgent-care centers, and physician's offices.
Effect of pretreating samples with boric acid before liquid-chromatographic determination of urinary catecholamines.
Authors: Degel F , Zuman P , Jandik P , Gilch G 
Published: January 2020

Abstract
Isolation of catecholamines on prepacked gravity-fed ion-exchange columns in conjunction with liquid-chromatographic separation is occasionally subject to disturbances of unknown origin, especially after injection of H3BO3 eluates from the ion-exchange columns onto the chromatography column. Peak spreading, sometimes even peak splitting, has been observed in many laboratories--effects easily confused with those sometimes caused by voided columns or by impurities. To elucidate the origins of these interferences, we performed a combined voltammetric and chromatographic investigation. We show that complexation of the catechol group by borate ions and dissociation of those pH-labile complexes in the course of the chromatographic separation is the cause of those peak distortions. Addition of a small volume of diluted HCI to the borate eluates eliminates such interference and leads to reproducible, easily interpretable chromatographic separations.
Screening for cerebrotendinous xanthomatosis by using an enzymatic assay for 7 alpha-hydroxylated steroids in urine.
Authors: Koopman B J , Van der Molen J C , Wolthers B G , Waterreus R J 
Published: January 2020

Abstract
We used a commercial enzymatic kit for measuring 7 alpha-hydroxylated bile acids to screen urines from normal subjects, liver-transplant recipients, and patients with various liver diseases, cerebro-hepato-renal syndrome, or cerebrotendinous xanthomatosis (CTX). Because of their high concentrations of 7 alpha-hydroxylated compounds excreted, the CTX patients were clearly distinguished from all other groups except for a slight overlap with the patients with cerebro-hepato-renal syndrome and liver-transplant recipients. Gas chromatography for bile alcohols completed the differential diagnosis.
Electrophoretic mobility, concentration, and activity of alpha 1-antitrypsin in serum of patients undergoing bone-marrow transplantation.
Authors: Mullins R E , Bennett B , Hunter R L 
Published: January 2020

Abstract
We have observed an electrophoretically abnormal, nonfunctional species of alpha 1-antitrypsin in serum from patients who were receiving bone-marrow transplants for treatment of leukemia or aplastic anemia. Three of four patients in whose serum this protein appeared died soon after; the fourth recovered, and the disappearance of the abnormal alpha 1-antitrypsin paralleled his recovery. This suggests that the inability to maintain functional activity of alpha 1-antitrypsin predisposes patients to life-threatening complications during recovery from bone-marrow transplants.
Modified lamellar body phospholipid assay compared with L/S ratio and phosphatidylglycerol assay for assessment of fetal pulmonary status.
Authors: Ivie W M , Novy M J , Reynolds J W , O'Grady P , Swanson J R 
Published: January 2020

Abstract
We used a modified lamellar body phospholipid (LB-PL) assay to evaluate the effect of sample processing and to evaluate the clinical efficacy of LB-PL determinations. Within-run and between-run CVs for the modified LB-PL assay respectively ranged from 2.9 to 6.7% and from 3.4 to 14.3%. Freezing and storage at -20 degrees C did not affect results for LB-PL (n = 12). Statistically significant amounts of lamellar bodies were lost on centrifugation, ranging from 20% at 150 X g to 54% at 1000 X g for 5 min. The LB-PL content, lecithin/sphingomyelin ratio, and phosphatidylglycerol content of 194 samples of amniotic fluid obtained within three days of delivery were compared for the assessment of fetal pulmonary maturity. Twenty-three neonates developed respiratory problems at or shortly after birth. With uncontaminated samples (n = 160), the LB-PL assay exhibited better specificity than the lecithin/sphingomyelin ratio (p less than 0.01, Chi square) or the phosphatidylglycerol assay (p less than 0.001, Chi square) for samples obtained after 36 weeks of gestation. Assay sensitivities did not differ significantly. Differences among assay predictive values were not significant.
Microbiological assay for vitamin B12 with use of a colistin-sulfate-resistant organism.
Authors: Kelleher B P , Walshe K G , Scott J M , O'Broin S D 
Published: January 2020

Abstract
In this simplified microbiological assay for serum vitamin B12, Lactobacillus leichmanii (NCIB 8117) adapted to tolerate high concentrations (500 mg/L) of the polymyxin antibiotic colistin sulfate is used. Results were similar in parallel experiments in which we used both the parent strain of L. leichmanii (NCIB 8117), and the new adapted strain. Evaluation of assay performance showed excellent analytical recovery of added cyanocobalamin (97%, SD 3%) and good interassay and intra-assay precision (CV less than 5%). This modified assay system obviates the need to sterilize culture medium and glassware. Consequently, assay manipulations may be carried out openly, without aseptic precautions. Moreover, this adapted organism would be suitable for use in an automated microbiological assay system.
Intra-individual variation of some analytes in serum of patients with insulin-dependent diabetes mellitus.
Authors: Hölzel W G 
Published: January 2020

Abstract
Biological intra-individual variation in concentrations of 16 clinical biochemical analytes in serum was estimated for 27 patients with insulin-dependent diabetes mellitus (IDDM), and results were compared with those for apparently healthy individuals. In general, the variation was significantly higher in the patients. The ratio of the average intra-individual variation in IDDM patients to that in normal subjects exceeded 2.0 for Na+, K+, creatinine, and alpha-amylase; 1.50 to 2.0 for Cl-, total protein, albumin, cholesterol, and hemoglobin; and 1.2 to 1.5 for urea, uric acid, high-density-lipoprotein cholesterol, and aspartate aminotransferase. This increased variability in IDDM patients may be caused by variations in osmotic diuresis. Average intra-individual variations were greater for women than for men for Na+, total protein, albumin, and hemoglobin. Individual values showed a gaussian distribution for all analytes, including enzymes and triglycerides. No intra-individual variation was time dependent. For practical purposes, decision-making criteria in monitoring IDDM can be derived from the estimated biological component of intra-individual variation and the analytical variation established for each laboratory.
Differentiation of renal from non-renal hematuria by microscopic examination of erythrocytes in urine.
Authors: Pillsworth T J , Haver V M , Abrass C K , Delaney C J 
Published: January 2020

Abstract
Recent studies indicate that hematuria of renal parenchymal origin can be differentiated from hematuria of other origin by the presence of dysmorphic urinary erythrocytes (cells exhibiting irregular membranes or small surface blebs). We investigated the utility of this simple screening assay in a routine clinical laboratory. Dysmorphic erythrocytes in urine from 69 patients (18 with renal-parenchymal disease) were quantified on unstained slides by medical technologists using phase-contrast microscopes. Samples stored at 4 degrees C or 23 degrees C for up to 5 h had no significant changes in percentages of dysmorphic erythrocytes (PDE). PDE was also not modified by urea nitrogen concentration, osmolality, or pH over the physiological ranges of these variables. Receiver-operating characteristic (ROC) curves indicated an optimal sensitivity of 88% and specifity of 94% at a decision level of 14% dysmorphic erythrocytes per high-power field. Thus, the presence of fewer than 14% dysmorphic cells is suggestive of extra-renal disease; more than 14% is suggestive of intra-renal disease.
Rapid assay of N-acetyl-beta-D-glucosaminidase isoenzymes in urine by ion-exchange chromatography.
Authors: Nicot G , Lachâtre G , Gonnet C , Dupuy J L , Valette J P 
Published: January 2020

Abstract
We describe a new method for separating and measuring urinary N-acetyl-beta-D-glucosaminidase isoenzymes by "high-performance" liquid chromatography. Isoenzymes are eluted from the anion-exchange column with a one-step linear gradient of NaCl solution. For continuous post-column quantification of the activities of these isoenzymes, we use an on-line post-column reactor and 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide as substrate; the methylumbelliferone formed in this reaction is quantified fluorimetrically. We discuss the effects of varying different components of the assay: NaCl concentration, the pH of the mobile phase and of the reaction reagent, substrate concentration, incubation temperature, and the geometry of the post-column reactor.
Determination, by radioimmunoassay, of the mass of lactate dehydrogenase isoenzyme 1 in human serum and of its rate of removal from serum after a myocardial infarction.
Authors: Smith D A , Leung F Y , Jablonsky G , Henderson A R 
Published: January 2020

Abstract
In this radioimmunoassay of lactate dehydrogenase-1 (LD-1; EC 1.1.1.27) in human serum we use a commercial LD-1-selective assay system and a goat antiserum. We have determined the fractional rate of disappearance from serum and the half-life of LD-1, in terms of both enzyme activity and enzyme mass, in 21 myocardial infarction patients. Our evidence suggests that this isoenzyme is inactivated in serum. Furthermore, our data suggest that the conventionally accepted half-life of about 110 h for serum LD-1 activity may grossly overestimate the actual LD-1 half-life in many post-myocardial infarction patients.
Electrophoresis and the isomune-LD and LD-1 immuno methods compared for measurement of lactate dehydrogenase isoenzyme-1.
Authors: Ranjan P , Karcher R E , Epstein E , Kiechle F L 
Published: January 2020

Abstract
We evaluated three different methods for measuring lactate dehydrogenase (EC 1.1.1.27) isoenzyme LD-1 activity--agarose gel electrophoresis and two immunoassays, Isomune-LD (Roche) and LD-1 Immuno (Seragen)--in patients' samples for which measurement of creatine kinase-MB was ordered. Regression analyses of the comparisons gave the following results: LD-1 (%) from Isomune-LD (y) vs electrophoresis (x) (n = 51), y = 1.05x + 1.99, r = 0.92; LD-1 (%) from LD-1 Immuno (y) vs electrophoresis (n = 27), y = 1.05x + 3.94, r = 0.88; LD-1 (%) from LD-1 Immuno (y) vs Isomune-LD (x) (n = 41), y = 1.06x + 0.48, r = 0.95. Comparison by Student's paired t-test yielded significant differences between the mean values by electrophoresis and both Isomune-LD (P less than 0.005) and LD-1 Immuno (P less than 0.001), but no significant difference between the two immunoassays (P greater than 0.2). Analyzing these results by the overlap index, we conclude that electrophoresis shows the best clinical correlation followed, in order, by the Isomune-LD and the LD-1 Immuno methods. Both immunoassays are simpler and more rapid than electrophoresis, but in our hands the Isomune-LD method demonstrated greater precision and better correlation with electrophoretic values.
Evaluation of a fully automated centrifugal analyzer for performance of hemostasis tests.
Authors: Chantarangkul V , Tripodi A , Mannucci P M 
Published: January 2020

Abstract
We have evaluated the performance of a centrifugal analyzer, specifically designed for hemostasis tests, for methods based on clotting time as measured by light scattering, or based on splitting of chromogenic substrates. The results were compared with those obtained with a semiautomated coagulometer (clotting tests) or with a manually operated photometer (chromogenic tests). In general, the results with the centrifugal analyzer were at least as precise as those of the comparative methods, with greater output and ease of operation. Disadvantages of the instrument are its partial incompatibility with some commercial reagents and the relative rigidity of the operational parameters, which hinder its use for research.
Single-reagent polarization fluoroimmunoassay of methamphetamine in urine.
Authors: Eremin S A , Gallacher G , Lotey H , Smith D S , Landon J 
Published: January 2020

Abstract
We developed a polarization fluoroimmunoassay for the specific detection of methamphetamine in urine. Sheep antiserum raised against methamphetamine was premixed with a fluorescein-labeled amphetamine tracer in a single reagent. The use of labeled amphetamine gave a more sensitive and more specific assay than did the use of a labeled methamphetamine tracer. The assay system had equal sensitivity for the d- and l-isomers of methamphetamine while the cross reactivity of amphetamine and other structurally related compounds was 3% or less. With a positive/negative cutoff concentration set at 1 mg/L, the polarization fluoroimmunoassay reliably identified human urines that had been reported positive for methamphetamine by an established gas-liquid chromatographic method.