bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observational study of erythrocyte protoporphyrin screening test for detecting low lead exposure in children: impact of lowering the blood lead action threshold
Authors: Parsons PatrIck J , Reilly Andrew A , Hussain Azmat 
Published: January 2020

Abstract
We examined a retrospective sample of 1800 children on whom both erythrocyte protoporphyrin (EP) and blood lead (BPb) measurements were taken. The primary objective was to ascertain whether EP is a cost-effective screening test for low but increased BPb concentrations and to establish the optimal thresholds. The data did not provide evidence of an EP threshold at low BPb concentrations; however, the data did show a significant age effect. A subset of 500 children for whom both EP and hematocrit data were available showed no correlation between those variables. Age-specific operating characteristic curves, total error, and cost analyses are presented. The latter sets bounds on the relative cost of EP testing, above which only BPb determination should be performed. The implications of these findings are discussed in light of impending changes in U.S. federal guidelines for preventing lead poisoning in young children.
Practical method for optimizing radioimmunoassay detection and precision limits
Authors: Ezan ErIc , Tiberghien Chrlstoph , Dray Fernand 
Published: January 2020

Abstract
A model of the competitive radioimmunoassay standard curve, based on the Law of Mass Action, has been developed and used in conjunction with experimental and counting errors to predict the assay detection limit and precision profiles. We verified the model with hapten radioimmunoassays performed in our laboratory. The resulting computer program can be used to determine the optimum antiserum concentration--depending on its affinity--and labeled-antigen concentration--according to its specific activity and nonspecific binding. The graphical representation of this model provides radioimmunologists with a practical tool for assay optimization.
Standardization, specificity, and diagnostic sensitivity of four immunoassays for carcinoembryonic antigen
Authors: Börmer Ole P 
Published: January 2020

Abstract
Four "sandwich"-type immunoassays for carcinoembryonic antigen (CEA) based on monoclonal antibodies (Abbott CEA-RIA Monoclonal, Pharmacia/Wallac Delfia CEA kit, Roche CEA EIA Duomab 60, and our in-house immunoradiometric assay) were compared for 357 samples from colorectal cancer patients and samples from 48 patients with chronic liver disease or with acute, irrelevant diseases. Relative to a common 5 micrograms/L reference limit, all four assays agreed regarding classification in 92% to 94% of the samples in the colorectal cancer samples, with the Abbott and Roche assays giving slightly more "normal" values. Cross-testing of CEA standards and the 1st International Reference Preparation 73/601 showed that calibration differences could not be eliminated by the use of a common standard. It has been earlier demonstrated that the monoclonal antibodies in the Roche assay have an epitope group specificity slightly different from those of the other three assays. This can explain why the correlations involving the Roche assay were weaker (r = 0.84-0.87) than those obtained with the other assays (r = 0.94-0.97). I conclude that agreement between the assays studied is as good as can be expected when different antibodies are used; nevertheless, consistent discrepancies between assays in several patients still necessitate the use of the same assay during follow-up.
Iron, transferrin, and ferritin in cerebrospinal fluid of children
Authors: Gruener Nachman , Gozlan Orly , Goldstein Tamara , Davis Judith , Besner irit , Iancu Theodore C 
Published: January 2020

Abstract
We measured iron, ferritin, and transferrin in cerebrospinal fluid (CSF) of pediatric patients. Because the concentrations of iron and iron-binding proteins in CSF in these samples were lower than those ordinarily measured in older subjects, we had to modify the lower limit of detection of the methods used. The concentrations of these three analytes in patients with viral meningitis were higher than those in healthy infants and children.
Partial purification of endogenous digitalis-like compound(s) in cord blood
Authors: Balzan Sllvana , Ghione Serglo , Biver Pascal , Gazzetti Psolo , Montali Umberto 
Published: January 2020

Abstract
Increasing evidence indicates the presence of endogenous digitalis-like compound(s) in human body fluids. In this preliminary report, we describe a study of the partial purification by HPLC of these compounds in the plasma of neonates (who have particularly high concentrations of this substance) and adults. Plasma samples from neonates (cord blood) and adults, lyophilized and extracted with methanol, were applied on a 300 x 3.9 mm C18 Nova Pak column and eluted with a mobile phase of acetonitrile/methanol/water (17/17/66 or 14/14/72 by vol) and, after 30 min, with 100% methanol. We assayed eluted fractions for inhibitory activity of 86Rb uptake and for digoxin-like immunoreactivity. The elution profile revealed a first peak of inhibitory activity of 86Rb uptake at the beginning of the chromatography; another peak was eluted with the 100% methanol. The two peaks also cross-reacted with antidigoxin antibodies. Because the second peak could possibly reflect the nonspecific interference of various lipophilic compounds, we focused our attention on the first peak. For these fractions dose-response curves for 86Rb uptake and for displacement of digoxin were parallel, respectively, to those of ouabain and digoxin, suggesting similarities of digoxin-like immunoreactive substance to cardiac glycosides. Similar chromatographic profiles were also obtained for plasma from adults, suggesting that the endogenous glycoside-like compound(s) in the neonate may be the same as those in the adult.
Relationships between the proton nuclear magnetic resonance properties of plasma lipoproteins and cancer
Authors: Otvos J D , Jeyarajah E J , Hayes L W , Freedman D S , Janjan N A , Anderson T 
Published: January 2020

Abstract
We conducted a comprehensive investigation of the origin of nuclear magnetic resonance (NMR) lineshape variability of plasma lipids among healthy individuals and those with cancer. The methyl and methylene resonances of lipid in human plasma, whose linewidths have been reported to correlate with the presence of malignancy, are composed of the overlapping resonances of "mobile" protons from the major lipoproteins (very-low-, low-, and high-density lipoproteins). We tested two hypotheses for the origin of the narrower plasma linewidths observed for cancer patients: (a) malignancy-associated differences in the spectral properties (chemical shift, lineshape) of one or more of the lipoproteins, and (b) differences in the fraction of lipoprotein lipid giving rise to detectable NMR signal. Analysis of the concentrations of lipoprotein lipid and of 500 MHz NMR spectra of the lipoprotein constituents in greater than 100 plasma samples failed to provide support for either hypothesis. Although linewidths were found to be significantly narrower for the cancer group, the difference is entirely attributable to differences in the concentrations of the lipoproteins.
Determination of product shelf life and activation energy for five drugs of abuse
Authors: Anderson Geoffrey , Scott Milda 
Published: January 2020

Abstract
Estimating the shelf life of reagents and controls is a critical step in evaluating new formulations. We describe several stability assessment techniques, giving particular attention to experimental design. Activation energy was experimentally determined for five major drugs of abuse and metabolites: morphine, 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid, amphetamine, phencyclidine, and benzoylecgonine. The use of activation energy in establishing shelf life is illustrated for SENTRY (Hycor Biomedical Inc.) Drugs of Abuse Screen Control, a liquid urine-based product.
Direct measurement of high-density lipoprotein cholesterol by the reflotron assay with no manual precipitation step
Authors: Ng Ronald H , Sparks Katherine M , Statland Bernard E 
Published: January 2020

Abstract
We evaluated the quantification of high-density lipoprotein (HDL) cholesterol in plasma with the Boehringer Mannheim Reflotron reflectance photometric analyzer. The Reflotron is designed for testing in small to medium-size laboratories and physicians' offices. This HDL method does not require a manual precipitation step because the reagent tab contains dextran sulfate (Mr 50,000) and magnesium acetate. It takes 90 s to complete an analysis of 30 microL of plasma. Within-day standard deviations (SDs) were 0.02-0.04 mmol/L (6-16 mg/L). Total SDs over a three-month period were 0.03-0.06 mmol/L (11-23 mg/L). The Reflotron values averaged 0.02 mmol/L (6 mg/L) or 1.3% lower than the Hitachi 737 values; the standard error of the estimate (Sy.x) was 0.07 mmol/L (29 mg/L).
Dry reagent technology for rapid, convenient measurements of blood coagulation and fibrinolysis
Authors: Oberhardt Bruce J , Dermott Sharon C , Taylor Murdock , Alkadi Zaid Y , Abruzzini Anthony F , Gresalfi Nancy J 
Published: January 2020

Abstract
Rapid coagulation and fibrinolysis assays suitable for use with an imprecisely measured sample volume (either whole blood or plasma) have been developed, utilizing a technology based on paramagnetic iron oxide particles (PIOP) that move in response to an oscillating magnetic field. PIOP are combined with appropriate test reagents for clotting and thrombolysis assays and formulated as dry reagents within a capillary test chamber. The minima and maxima of the PIOP oscillations define a two-sided waveform that provides kinetic information on fibrin polymerization and lysis. Subject to the chemistry of the dry reagent formulation, the resulting waveform can be used to define clotting time, lysis onset time, or fibrinogen variables. Applications to one-stage prothrombin time and one-stage activated partial thromboplastin time tests have yielded assays with consistently good correlations with other test methods. Applications to fibrinolysis studies have yielded global assays of thrombolytic activity, in that the assay results reflect the interactions of multiple factors associated with the effectiveness of thrombolytic therapy. Depending on the components utilized in a particular reagent formulation, one can derive information about the activity of such factors as fibrinogen, plasminogen, and related inhibitors, as well as the lytic agent being administered. Use of these assays in a clinical setting should provide a rapid, convenient alternative to conventional testing of coagulation variables and a reliable method for monitoring thrombolytic therapy.
Determination of creatinine in serum and urine by cation-exchange high-pressure liquid chromatography
Authors: Harmoinen Aimo , Sillanaukee Pekka , Jokela Hannu 
Published: January 2020

Abstract
We describe an HPLC method for quantifying creatinine, separating the analyte from other compounds in serum and urine by cation-exchange chromatography and measuring its absorbance at 234 nm. The precision of the method (CV) varied from 2.9% (mean creatinine concentration, 31 mumol/L) to 1.7% (361 mumol/L) within a series of assays and from 3.9% (34 mumol/L) to 2.4% (391 mumol/L) between series. A comparison with the Jaffé method, as performed with a Technicon SMA analyzer, gave the regression line yHPLC = 1.00xJaffé - 12.0 (n = 141, r = 0.998, and Syx = 19). Results also are comparable with those of an enzymatic method, if the enzymatic method is standardized with a serum-based standard when serum samples are measured. An aqueous standard has to be used for enzymatic determination of creatinine in urine.
Neuron-specific enolase concentrations in serum in benign liver diseases
Authors: Collazos Julio , Genollá Jose , Ruibal Alvaro 
Published: January 2020

Abstract
Neuron-specific enolase (EC 4.2.1.11; NSE), a glycolytic enzyme produced by neuronal and neuroendocrine cells, is used as a tumor marker of neuroendocrine cancers, especially small-cell lung cancer. We have evaluated the behavior of NSE in nonmalignant liver diseases in 161 patients who underwent a thorough clinical and biochemical evaluation. Nine of the 161 patients (5.6%)--three of the 86 cirrhotic patients (3.5%), and six of the 75 noncirrhotics (8%)--had abnormal concentrations of NSE. Of the numerous clinical and analytical factors considered, none correlated significantly with NSE. The low false-positive rate, similar to or even lower than for other benign diseases, and the absence of association with the numerous characteristics of liver diseases that we studied, support the lack of any substantial metabolism of NSE by the liver. Consequently, the coexistence of a benign liver disease does not limit the usefulness of this enzyme as a tumor marker.
Influence of monoclonal immunoglobulins in direct determinations of iron in serum
Authors: Bakker A J 
Published: January 2020

Abstract
I compared seven buffers and four chromogens for determining serum iron, to evaluate the frequency of falsely high or low concentrations of iron in 59 sera containing monoclonal immunoglobulins. The results for these direct assays with untreated sera were compared with those obtained by a proposed reference method (Br J Haematol 1978;38:291-4) with protein-free filtrates of the same sera. Sera with monoclonal immunoglobulins sometimes yielded erroneous results; the frequency of errors, which could be as much as 29% (17/59), depended on the composition of buffer and color reagent. Addition of thiourea or a detergent (Triton X-405) to some of the buffers lowered the frequency of errors, but did not abolish them. In only a few of the investigated buffer/chromogen combinations were no errors found. Detection of errors by analyzing the absorbance pattern after mixing sample and buffer was not always successful. Moreover, the presence and magnitude of errors bore no relationship to the type or the concentration of the monoclonal immunoglobulins. Unfortunately, the problem cannot be solved by a simple two- or threefold dilution of the sample.
Single procedure for detection, confirmation, and quantification of benzodiazepines in serum by liquid chromatography with photodiode-array detection
Authors: Puopolo P R , Pothier M E , Volpicelli S A , Flood J G 
Published: January 2020

Abstract
We developed a reversed-phase chromatographic procedure for detecting benzodiazepines and other drugs in serum. A liquid-liquid extraction step with hexane/ethyl acetate isolates the drugs from serum; absolute recoveries are generally greater than 85%. Reconstituted extracts are chromatographed on a 4-microns (particle size) C18 column; 14 drugs and an internal standard (flunitrazepam) are separated in 8 min. Peak detection, purity checking, and identification are performed with a computerized photodiode-array detector. Run-to-run imprecision (CV) for many benzodiazepines is less than 3%. In a study of 126 specimens from Emergency Department patients, the procedure showed excellent agreement with a gas-chromatographic method involving either mass-spectrometric or flame-ionization detection. This single procedure provides rapid and accurate detection, quantification, and confirmation of benzodiazepines in serum.
Quantification of lipoprotein(a) in dried blood spots and screening for above-normal lipoprotein(a) concentrations in newborns
Authors: Van Biervliet J P , Michiels G , Rosseneu M 
Published: January 2020

Abstract
Lipoprotein(a) [Lp(a)] is considered an additional, independent, and largely genetically determined risk factor for the development of premature coronary heart disease. Analogous with increased Lp(a) concentrations that represent an additional risk factor in adults, above-normal concentrations of Lp(a) can be detected in five- to seven-day-old newborns. We describe a simple enzyme-linked immunosorbent assay for measuring Lp(a) in dried blood spots collected by heel-prick in five- to seven-day-old infants. Lp(a) could be quantitatively recovered from blood spots. We chose a cutoff value of 100 mg/L for identifying the newborns at risk, based on the Lp(a) distribution in 180 such infants.
Fibrinogen assays: a collaborative study of six different methods. C.I.S.M.E.L. Comitato Italiano per la Standardizzazione dei Metodi in Ematologia e Laboratorio
Authors: Palareti G , Maccaferri M , Manotti C , Tripodi A , Chantarangkul V , Rodeghiero F , Ruggeri M , Mannucci P M 
Published: January 2020

Abstract
This collaborative study, organized by the Hemostasis Subcommittee of C.I.S.M.E.L., evaluated the accuracy, precision, and comparability of the following six widely used fibrinogen assays: total clottable fibrinogen (Blombäck and Blombäck), clotting time (Von Clauss), turbidimetry (Ellis and Stransky), Chromotime System, prothrombin time (PT)-derived, and radial immunodiffusion (RID). The same frozen samples, with normal and high contents of fibrinogen, were examined in four laboratories. The methods were calibrated with an internal standard whose fibrinogen content was determined gravimetrically. Both the Von Clauss and the RID methods were reliable, accurate, and precise, if adequate calibration was used. The PT-derived method was highly reproducible, but had some problems with accuracy. We demonstrate that an adequate calibration procedure is indispensable for reliable fibrinogen measurements whatever method is used. Because neither the calibration procedures proposed by the manufacturers nor the use of lyophilized commercial plasmas is adequate for this purpose, we urge that an international standard for fibrinogen measurement be promptly established.
Body mass index and liver enzyme activity in serum
Authors: Salvaggio A , Periti M , Miano L , Tavanelli M , Marzorati D 
Published: January 2020

Abstract
The association between body mass index (BMI) and serum liver enzyme activity [gamma-glutamyltransferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST)] was studied in 3167 subjects, 2373 men and 794 women. The subjects were managers and employees, ages 18-64 years, who were examined during a program of preventive medicine. Analysis of covariance was used to compare the serum liver enzyme activities (expressed as natural logarithms) of the subjects, who were subdivided according to BMI, while also considering age, alcohol and cigarette consumption, and physical activity. In men, the percentage increase in the geometric mean of liver enzyme activity of the obese subjects (BMI greater than 30 kg/m2) compared with that of the normal subjects (BMI less than or equal to 25 kg/m2) was 47.7% (P less than 0.001) for GGT, 55.3% (P less than 0.001) for ALT, and 19.7% (P less than 0.001) for AST; in women, the increase was 63.2% (P less than 0.01) for GGT, 58.4% (P less than 0.001) for ALT, and 7.3% (P greater than 0.05) for AST. Thus, our observations demonstrate a relation between BMI and serum liver enzyme activity.
Factors affecting determinations of manganese in serum by atomic absorption spectrometry
Authors: Nève J , Leclercq N 
Published: January 2020

Abstract
A method was developed for the routine determination of manganese in serum from healthy human subjects by graphite furnace atomic absorption spectrometry. We controlled the experimental conditions rigorously, from sampling to analysis, to minimize contamination and to conserve diluted samples. We optimized the procedure with two serum Reference Materials, one of which had a manganese concentration very close to what is thought to be the physiological concentration in humans. The best analytical performance was obtained by directly injecting into the furnace serum diluted with an equal volume of a solution containing Triton X-100 and sodium EDTA and calibrating by the standard additions procedure or by a calibration graph constructed in a similar matrix. The Zeeman background correction produced better accuracy and precision than did the classical deuterium correction. Within-run CV for a manganese concentration of 12.7 nmol/L in serum was 7.9%, and between-run precision was 16.1%. The mean (SD) serum manganese concentration in 31 healthy adults was 10.8 (SD 3.0) nmol/L. Sex and age of subjects did not affect concentrations.
Detection of toluenediamines in the urine of a patient with polyurethane-covered breast implants
Authors: Chan S C , Birdsell D C , Gradeen C Y 
Published: January 2020

Abstract
Breast prostheses are implanted for augmentation or during reconstructive surgery. One of the more commonly used prostheses is the polyurethane-sponge-covered silicone gel implant. Some clinicians are concerned about the safety of this product because the polyurethane foam disintegrates in vivo, and its subsequent fate is not known. Polyurethane is a polymer formed by reacting diisocyanates and polyols. This study indicates that the polymer sponge breaks down into its reactive monomers, 2,4- and 2,6-toluenediisocyanate, which are converted into their corresponding diamines. We present evidence of the excretion of the diamine metabolites in the urine of a patient implanted with polyurethane-covered prostheses.
Versatile, non-clotting-based heparin assay requiring no instrumentation
Authors: Chen Weiliam , Yang Victor C 
Published: January 2020

Abstract
A non-clotting-based heparin assay requiring no instrumentation has been developed by attaching protamine (a heparin antidote) to a porous filter paper strip and monitoring the subsequent capillary migration of heparin sample through the paper. The area of paper to which heparin adsorbed, which is proportional to the concentration of heparin in the sample, is made visible by spraying Methylene Blue NNX solution onto the paper strip when the sample reservoir has emptied. The dye interacts with heparin to cause a metachromatic shift of the dye's absorption maximum from blue to purple. Heparin concentrations in the samples are estimated according to the length of the purple region on the paper strip. Heparin in plasma (2 to 35 int. units/mL) can be differentiated in approximately 6 min. The plasma heparin values derived by the new method agree reasonably well with those obtained by conventional assays (r greater than 0.99, n = 48).
Relationship of serum estradiol and progesterone concentrations to the excretion profiles of their major urinary metabolites as measured by enzyme immunoassay and radioimmunoassay
Authors: Munro C J , Stabenfeldt G H , Cragun J R , Addiego L A , Overstreet J W , Lasley B L 
Published: January 2020

Abstract
Paired daily blood and urine samples were collected from 10 apparently healthy premenopausal women to compare the hormone profiles of estradiol (E2) and progesterone in serum with those of estrone conjugates (E1Conj) and pregnanediol-3-glucuronide (PdG) in urine. Serum hormones were measured by radioimmunoassay (RIA) kits, whereas the urinary steroid metabolites were assessed by both RIA and enzyme immunoassay (EIA). RIA and EIA values for urinary E1Conj and PdG were not different, and both methods produced urinary profiles that paralleled the profile of the parent steroid in serum. However, the simplicity, flexibility, and economy of EIA will make this method more widely applicable. Mean E1Conj values lagged behind concentrations of serum E2 by one day or less, whereas daily urinary PdG profiles lagged behind serum progesterone by one to two days. Mean urinary profiles of E1Conj were similar whether or not creatinine was used to adjust for urine volume; however, creatinine indexing was beneficial when urinary profiles in individual cycles were compared with changes of serum E2.