bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and certification of human hair powder reference material.
Authors: Okamoto K , Morita M , Quan H , Uehiro T , Fuwa K 
Published: January 2020

Abstract
Human hair powder reference material was prepared and certified for elemental composition. Human scalp hair (from Japanese men) was washed in a non-ionic detergent solution in an ultrasonic cleaner, dried, ground in an agate ball mill, sieved through a polyethylene net, blended, bottled (1100 vials, 2 g each), and finally sterilized by 60Co radiation. The prepared material satisfied the homogeneity criteria for a reference material. We determined trace elements by inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry and investigated matrix interference effects. The material was certified by using the data obtained by various analytical techniques; certified values are provided for Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Sr, and Zn. The elemental composition of this reference material is considered similar to normal values for the male Japanese population.
Immunochemical methods for measurement of transferrin in serum: effects of analytical errors and inappropriate reference intervals on diagnostic utility.
Authors: Bandi Z L , Schoen I , Bee D E 
Published: January 2020

Abstract
We estimated analytical errors of the Calbiochem, Kallestad, Hyland, Meloy, Helena, and Beckman immunochemical methods for serum transferrin. Intermethod biases were determined by analysis of the "Reference Preparation for Serum Proteins" of the College of American Pathologists and by analysis of 106 patients' serum samples. We judged the acceptability of errors by comparing confidence limits for total errors with 1/4 of the normal reference intervals. The transferrin status of each patient's sample was interpreted by comparing the result of each method with the normal reference interval claimed by the corresponding manufacturer. We found that the combined effects of medically unacceptable analytical errors and inappropriate normal intervals caused results of the tested methods not to be interchangeable. The Calbiochem method identified 61 serum samples (57%) as having abnormally high transferrin concentrations. In contrast, for the same specimen, with the Meloy method we found abnormally high transferrin concentrations for only two samples (1.8%).
Solid-phase enzyme-receptor assay (SPERA): a competitive-binding assay for glycopeptide antibiotics of the vancomycin class.
Authors: Corti A , Rurali C , Borghi A , Cassani G 
Published: January 2020

Abstract
A solid-phase enzyme-receptor assay (SPERA) has been developed for glycopeptide antibiotics of the vancomycin class such as teicoplanin, vancomycin, ristocetin, avoparcin, actaplanin, A-47934, A-41030, and A-35512-B. The assay exploits the mechanism of most action of these antibiotics, which is based on their interaction with acyl-D-alanyl-D-alanine, a constituent of the walls of most growing bacterial cells. The antibiotics and enzyme-labeled teicoplanin compete for a synthetic analog of the biological receptor, albumin-epsilon-aminocaproyl-D-alanyl-D-alanine. The various antibiotics produced different competition curves, 50% displacement being obtained with antibiotic concentrations ranging from 0.04 to 4 mg/L, vancomycin and actaplanin being the weakest and strongest competitors, respectively. For teicoplanin in human serum the intra-assay CV was 7.2%, the interassay CV was 11.2%, and the analytical recovery 94%. Teicoplanin concentrations obtained by SPERA (chi) correlated well with those obtained by microbiological assay (y): y = 1.03 chi + 0.053 (r = 0.943; n = 60). We conclude that SPERA is a powerful tool for identification and quantitative detection of glycopeptide antibiotics, even in complex media.
Transcutaneous carbon dioxide and oxygen tension measured at different temperatures in healthy adults.
Authors: Wimberley P D , Grønlund Pedersen K , Olsson J , Siggaard-Andersen O 
Published: January 2020

Abstract
Transcutaneous carbon dioxide tension (tc-pco2) at 37, 39, 41, 43, and 45 degrees C, and transcutaneous oxygen tension (tc-po2) at 41, 43, and 45 degrees C were measured simultaneously in 10 healthy adults during hyperventilation and inhalation of O2/CO2 gas. Nine electrodes were applied to each subject: Five CO2 electrodes, one O2 electrode, and three combined O2/CO2 electrodes. The CO2 electrodes had negligible temperature coefficients in the calibration gases, but the O2 electrodes showed an increase in po2 of 4.5% per degree C. With skin application, tc-pco2 increased approximately 4% per degrees C between 37 and 45 degrees C, which is close to the anaerobic temperature coefficient of pco2 in blood. The tc-po2 increases on the skin with increasing temperature appeared to be more dependent on changes in blood flow in skin, but in the temperature range 43 to 45 degrees C, tc-po2 showed the expected decrease in the temperature coefficient with increasing po2. The correlation between transcutaneous and capillary pco2 was close at all transcutaneous electrode temperatures, even 37 degrees C, provided the skin was preheated (via the electrode) to 45 degrees C. For tc-po2, an electrode temperature of at least 43 degrees C was necessary to produce a reasonable correlation between tc-po2 and capillary po2. The combined O2/CO2 electrodes measured slightly higher pco2 values than the single CO2 electrodes, but there were no differences in po2 readings, stabilization time, imprecision, or electrode drift between the two electrode types. The imprecision (CV, %) of tc-pco2 and tc-po2 measurements was approximately twice that of the corresponding capillary blood-gas measurements.
Changes in the ratio of lactate dehydrogenase isoenzymes 1 and 2 during the first day after acute myocardial infarction.
Authors: Jablonsky G , Leung F Y , Henderson A R 
Published: January 2020

Abstract
It is known that the ratio of isoenzyme 1 to total lactate dehydrogenase (LD, EC 1.1.1.27) in serum is increased in all patients with acute myocardial infarction within 24 h of the infarct. We now show that the LD-1/LD-2 ratio for serum more promptly indicates acute myocardial infarction, being for most patients equivalent to measurement of creatine kinase (EC 2.7.3.2) isoenzyme 2 (CK-2, CK-MB) in serum. Of 128 patients with a confirmed diagnosis of myocardial infarction, 66 had normal values for all "cardiac" enzymes at the time of admission, but greater than 75% of them showed a parallel increase in values for CK-2 and the LD-1/LD-2 ratio. Of the 26 patients who had one or more abnormal values for cardiac enzymes on admission, 95% showed a parallel increase in CK-2 and the LD-1/LD-2 ratio, the median time for the beginning of these changes being 9 h from the onset of chest pain. The remaining 36 patients were excluded from the study because CK-2 decreased after admission or because the time of onset of chest pain was uncertain.
Lack of specificity of current anti-digoxin antibodies, and preparation of a new, specific polyclonal antibody that recognizes the carbohydrate moiety of digoxin.
Authors: Thong B , Soldin S J , Lingwood C A 
Published: January 2020

Abstract
Current immunoassays for digoxin do not distinguish digoxin from its glycosidic metabolites. We have synthesized a novel digoxin/bovine serum albumin conjugate via reductive ozonolysis of the lactone ring such that the carbohydrate moiety of digoxin remains intact. Antibodies raised against this conjugate show minimal cross reactivity to digoxigenin, bisdigitoxide, monodigitoxide, digoxigenin, and digitoxin. With this antibody, digoxin can be measured in the presence of these metabolites.
Monoclonal antibodies can precipitate low-density lipoprotein. II. Radioimmunoassays with single and combined monoclonal antibodies for determining apolipoprotein B in serum of patients with coronary artery disease.
Authors: Marcovina S , Kottke B A , Mao S J 
Published: January 2020

Abstract
We have established four lines of monoclonal antibodies against human low-density lipoproteins (LDL) that, mixed in equal proportions, can precipitate LDL in gel and so can be used for apolipoprotein (apo) B determination in plasma. One monoclonal antibody (clone A), with a relatively low binding affinity to LDL (ka = 0.6 X 10(9) L/mol) and recognizing only two species of apo B, significantly underestimated the concentration of apo B in 74 patients with and 27 without coronary artery disease (CAD). High-affinity monoclonal antibody C (Ka = 3.8 X 10(9) L/mol), which recognized all four apo B species, gave the same value for apo B as determined with the mixture of monoclonal antibodies. The latter results (by radioimmunoassay, y) correlated well with those by radial immunodiffusion (chi): y = 0.994 chi + 0.003 (r = 0.987). The CAD patients showed an increased concentration of apo B as compared to the angiographically documented CAD-negative patients. Except for the values determined by clone B (p = 0.07), the increase was statistically significant (p = 0.002-0.018) for values determined by use of the other clones or their mixture.
Chemical nature of a synthetic bilirubin conjugate and its reactivities in the total and direct reactions by the Jendrassik-Gróf method.
Authors: Doumas B T , Wu T W , Poon K C , Jendrzejczak B 
Published: January 2020

Abstract
Using liquid chromatography, nuclear magnetic resonance spectroscopy, and elemental analyses, we verified that a commercially available synthetic bilirubin conjugate is predominantly a ditaurobilirubin (DTB) disodium salt. The Jendrassik-Gróf total bilirubin (TBIL) method quantitatively measures unconjugated bilirubin (Bu) and the Bu-equivalent content in DTB, from which we infer that the azopigments of Bu and DTB have identical molar absorptivities, which do not change in the presence of either serum or serum albumin of human or bovine origin. However, based on the ratio of direct bilirubin (DBIL) to TBIL, the DBIL reaction in dilute HCI is incomplete (even up to 20 min), with lower yields in a matrix of bovine serum albumin than in human serum. By contrast, the DBIL reaction in acetate buffer (pH 4.75) is quantitative for DTB in human serum (or its albumin), but less so in bovine serum (or its albumin). DTB is water soluble, is relatively stable when lyophilized with human serum, and is determined with such high precision in the above-mentioned endpoint assays that it may be a suitable surrogate calibrator for conjugated bilirubin.
Improved assay of antithrombin-III. Effects of certain additives on thrombin and on chromogenic peptide substrates.
Authors: Gram J , Jespersen J 
Published: January 2020

Abstract
When manual assays of antithrombin-III with use of different synthetic chromogenic peptide substrates are modified for a centrifugal analyzer, the downward deflection of the reference curve at the zero point raises a serious problem, because the position of the zero value is included in the calculation of the reference curve. Complete linearity was obtained by addition of polyethylene glycol 6000 to the thrombin solution and Tween 80 to the substrate solution in final concentrations of 1 g/L and 100 mg/L, respectively. The additives increased the concentration of active thrombin in the solutions by preventing its adsorption and aggregation, and the solubility of the substrates in aqueous media is increased. The precision of the optimized method, tested in routine assays during three months, yielded an estimated day-to-day CV of 3.4%.
Estriol and its conjugates in late pregnancy determined by extraction with Carbopack B and liquid chromatography with fluorometric detection.
Authors: Andreolini F , Borra C , Caccamo F , Di Corcia A , Nicoletti I , Samperi R , Improta F 
Published: January 2020

Abstract
We report a method for measuring estriol and its intact conjugates in urine, serum, and amniotic fluid. A single assay can be done within about 50 min, eight samples assayed in less than 5 h. A 70-microL urine sample is diluted and the estriol conjugates are adsorbed from it onto graphitized carbon black (Carbopack B, Supelco). After two washings, the analytes are desorbed with chloroform/methanol (60/40, by vol) containing tetrapropylammonium bromide. After solvent evaporation, the residue is redissolved in 100 microL of water/acetonitrile and 20 microL is injected into the chromatograph. Or 1 mL of serum or 0.5 mL of amniotic fluid is deproteinized with cold methanol, then passed through the Carbopack column. After three washings, the estriol and its conjugates are desorbed and treated as for urine. Mean analytical recoveries of the analytes in any of these body fluids were within about 92-98%, except for estriol-3-sulfate-16 alpha-glucuronide in serum (mean recovery 88.3%). The limit of sensitivity is well below the concentrations of clinical interest, and the method is not susceptible to substantial interferences.
Solid-phase extraction and liquid chromatography for improved assay of cyclosporine in whole blood or plasma.
Authors: Kabra P M , Wall J H , Blanckaert N 
Published: January 2020

Abstract
In this simple, precise, accurate, and specific isocratic liquid chromatographic procedure for determining cyclosporine, the cyclosporine is extracted from 1 mL of whole blood or from plasma, with 500 micrograms of cyclosporin D added per liter as internal standard, by elution from a Bond-ElutTM C18 extraction column with 300 microL of a mixture of ethanol and tetrahydrofuran. A 100-microL aliquot of the eluate, injected onto a cyano-phase analytical column, is eluted with a mixture of acetonitrile and pH 7.0 phosphate buffer at a flow rate of 1.0 mL/min and at 50 degrees C. Detection is at 210 nm. The chromatography is complete in less than 14.0 min. The method can measure less than 10.0 micrograms/L. Analytical recovery of cyclosporine added to whole blood ranged from 99 to 109% for concentrations up to 2000 micrograms/L. Between-run CVs ranged from 6.4 to 6.6%. None of numerous drugs and steroids tested interfered. Results by radioimmunoassay exceeded by 20 to 350% those measured by the present method.
Studies directed toward labeling analysis of angiotensin II in plasma.
Authors: Emanuel R L , Joppich-Kuhn R , Williams G H , Giese R W 
Published: January 2020

Abstract
We assay a 1-mL plasma sample containing angiotensin II (103 pg by radioimmunoassay) for the hormone by the following sequence of steps: add 125I-labeled val5-angiotensin II as an internal standard, extract on a C18 Sep Pak column, extract on an antibody affinity column, label the extract with an 125I Bolton-Hunter reagent, separate on a Bio Gel P2 column, and repetitively separate on a reversed-phase "high-performance" liquid-chromatographic column, detecting the eluting compounds by counting radioactivity. The fact that we measured 46 pg of angiotensin II-like substance per milliliter in a sample of pooled plasma is encouraging for the further development of this methodology. In particular, replacing the radioisotope with a more suitable chemical label such as an electrophoric (electron-capturing) release tag should be useful.
Five methods for measuring low-density lipoprotein cholesterol concentration in serum compared.
Authors: Hoffmann G E , Hiefinger R , Weiss L , Poppe W 
Published: January 2020

Abstract
Five methods for the quantification of low-density-lipoprotein cholesterol were compared: ultracentrifugation, electrophoresis, precipitation with polyvinyl sulfate or heparin, and an indirect calculation procedure (Friedewald formula). Excellent agreement of results was obtained with all procedures for 49 of 51 sera. Discrepancies were as much as 1.69 g/L for the remaining two cases, which contained appreciable amounts of "floating" beta-cholesterol as detected with a combination of ultracentrifugation and electrophoresis.
Estimation of the response-error relationship in immunoassay.
Authors: Sadler W A , Smith M H 
Published: January 2020

Abstract
Estimation of the response-error relationship in immunoassay provides a weighting function for the main analysis, and may in general be essential to ensure statistically valid data reduction. In this study we generated 50,000 sets of simulated radioimmunoassay response data with a computer, using five response-error functional forms that are commonly assumed. Parameters were estimated by three least-squares regression methods and three that are modifications of a maximum-likelihood method. Two likelihood estimators that require significantly different computing times were shown to be virtually indistinguishable, statistically more efficient than least-squares estimators, and-in contrast to least-squares estimators-to guarantee positive predicted variances in the range of the data.
Particle-counting immunoassay of a fetuin-like antigen in serum and cerebrospinal fluid.
Authors: Fagnart O C , Cambiaso C L , Sindic C J , Masson P L 
Published: January 2020

Abstract
A fetuin-like antigen was detected (smallest concentration detectable: 5 micrograms/L) by particle-counting immunoassay in 2% (13/641) of consecutive patients' sera but not in sera from 80 healthy blood donors, 40 neonates, or 40 pregnant women. The relation of the presence of detectable antigen to patients' diagnosis is not yet clear. However, in the group with cancer (154), it was found only in two of four patients with nephroblastoma and in three of five with tumors of tissue derived from the neurological crest: retinoblastoma (1/1), neuroblastoma (1/3), and medulloblastoma (1/1). Serum specimens from 422 patients with neurological disorders showed the antigen at a concentration greater than 5 micrograms/L in cases of neurosyphilis (5/11), peripheral neuropathy (12/38), Guillain-Barré syndrome (7/27), and multiple sclerosis (74/184). When we assayed 232 specimens of cerebrospinal fluid from the same neurological patients, we found the antigen in two cases of multiple sclerosis (6 and 15 micrograms/L) and in one case of Guillain-Barré syndrome (54 micrograms/L).
Free thyroxin measured in dried blood spots: results for 10 000 euthyroid and 29 hypothyroid newborns.
Authors: Travert G , Lemonnier F , Fernandez Y 
Published: January 2020

Abstract
We measured free thyroxin (FT4) in dried blood samples from 10 000 euthyroid and 29 hypothyroid newborns (three with transient hypothyroidism and 26 permanent). In euthyroids, the mean FT4 concentration was 16.9 (SD 4.5) pmol/L. Preterm babies had low concentrations of FT4, and values were closely related to birth weight when less than 2500 g. Assay of blood-spot FT4 appears to be specific as a test for hypothyroidism screening, yielding 0.42% false positives when a mean minus 2 SD cutoff value (8 pmol/L) was used. Correcting FT4 for birth weight further decreased the false-positive rate, to 0.07%. In all three newborns with transient hypothyroidism, FT4 was less than 8 pmol/L. In 25 of 26 permanent hypothyroids, FT4 ranged from undetectable to 5 pmol/L; in the 26th infant, who had a large ectopic gland, it was 8.2 pmol/L. We believe that FT4 assay offers an attractive improvement over total T4, whether performed as the first screening test or as a confirmatory test in thyrotropin screening programs.
Radioenzymatic microassay for simultaneous estimations of dopamine, norepinephrine, and epinephrine in plasma, urine, and tissues.
Authors: Hussain M N , Benedict C R 
Published: January 2020

Abstract
With this sensitive and specific radioenzymatic assay picogram quantities of norepinephrine, epinephrine, and dopamine can be simultaneously determined directly in plasma, urine, and tissue. We discuss in detail the steps that are critical for success of the assay, as well as the rationale behind the use of specific reagents. The assay is appropriate for use in any routine clinical chemistry laboratory. This assay is sensitive to approximately 1 pg of catecholamine. As compared with a commercially available method, this assay is significantly more economical and less time consuming.
Evaluation of a commercial immunoenzymometric assay for alpha-fetoprotein.
Authors: Hullin D A , Woodhead J S 
Published: January 2020

Abstract
A two-site immunoenzymometric assay (Abbott Diagnostics) for alpha-fetoprotein (AFP) in maternal serum and amniotic fluid has been evaluated for its suitability as a screening test for open neural tube defects. In a retrospective study based on 190 pregnancies of known outcome, performance of the kit in measuring both serum and amniotic fluid AFP correlated well with that of an in-house radioimmunoassay. Of 39 pregnancies associated with open neural tube defects, only four would not have been detected by the use of sequential measurement of serum and amniotic fluid AFP (also essentially in agreement with results obtained by the RIA). We conclude that this immunoassay could form the basis for a screening program for antenatal detection of open neural tube defects.
An automated liquid-chromatographic system for convenient determination of glycated hemoglobin A1c.
Authors: Saleh A K , Moussa M A 
Published: January 2020

Abstract
For quantification of glycated hemoglobin (HbA1c), we compared an automated system (Pharmacia Fast Protein Liquid Chromatography), which separates and determines HbA1c, with a commercial disposable-minicolumn kit (Boehringer-Mannheim), which separates total HbA1. We studied 41 diabetic women and 79 apparently normal women on their first postparturition day. The automated method was more precise (within-run CV 0.98-4.16%) than the kit method (within-run CV 3.67-7.77%). Results by the two methods correlated well for both control (p less than 0.001) and diabetic (p less than 0.05) groups. Values for HbA1c correlated significantly with fasting blood-glucose concentrations in controls and diabetics (intraclass correlation coefficient rI = 0.822 and 0.851, respectively, p less than 0.001) as well as with 1- and 2-h values for glucose after a 75-g glucose load in the control group (rI = 0.649 and 0.846, respectively, p less than 0.001). For HbA1 no such significant correlation was found except with values for fasting blood glucose in diabetics (rI = 0.745, p less than 0.001). Evaluation of HbA1c was a more sensitive index of glycemic status. The automated system is convenient, reliable, and easily operated.
Rapid measurement of free anticonvulsant drugs by direct liquid chromatography of serum ultrafiltrates.
Authors: Bock J L , Ben-Ezra J 
Published: January 2020

Abstract
In this simultaneous assay of unbound phenobarbital, phenytoin, primidone, and carbamazepine, serum ultrafiltrate is prepared by centrifugation in disposable filter units (Centrifree Micropartition System, Amicon Corp.) and injected directly onto a reversed-phase liquid-chromatography column. Drugs in the effluent are detected by absorbance at 210 nm. The measured concentrations were not critically dependent on the exact conditions of ultrafiltration (rotor angle, speed or time of centrifugation, amount of sample filtered). Pooled serum containing all four drugs gave reproducible results in repeated analyses during several days. For comparison we assayed 113 clinical specimens for one or more of these drugs by this method, and for the total (bound plus unbound) concentration of each drug by immunoassay. For each drug there was a nearly linear relationship between the two types of measurements, except for six specimens that had unusually high fractions of unbound drug. This assay appears highly suitable for routine determination of the free, biologically active fraction of anticonvulsant drugs, possibly as an alternative to measurements of total drug concentrations.