bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assay instrument-dependent matrix effects in standardization of cholesterol measurements
Authors: Waymack P P , Miller W G , Myers G L 
Published: January 2020

Abstract
Human serum-based frozen reference materials have been used by the Centers for Disease Control and Prevention (CDC)-National Heart, Lung and Blood Institute Lipid Standardization Program to improve the precision and accuracy of blood cholesterol measurements. Occasionally, laboratories in the program have had problems obtaining results for patients' fresh serum samples equivalent to those obtained with frozen CDC standardization pools. This incompatibility of sample, reagent, instrument, and assay characteristics has been labeled broadly as a "matrix effect," which usually is attributed to unknown characteristics of the processed pool material. In this study we showed that a large negative bias obtained with CDC pools was attributable to use of the sample blank mode on the Cobas-Bio analyzer. However, under the same conditions, fresh patients' serum samples were analyzed accurately. The use of a blank absorbance immediately after mixing sample and reagents (the "autoblank" mode) allowed the instrument to accurately analyze both fresh serum samples and CDC standardization pools and thus allowed the documentation of traceability of the cholesterol measurements to the National Reference System for Cholesterol.
Passive hemagglutination inhibition test for diagnosis of brown recluse spider bite envenomation
Authors: Barrett S M , Romine-Jenkins M , Blick K E 
Published: January 2020

Abstract
Our goal was to recreate a passive hemagglutination inhibition (PHAI) test to diagnose brown recluse spider (BRS; Loxosceles reclusa) bite envenomation for treatment trials. Guinea pigs received intradermal injections of concentrated spider venom from the following species: Loxosceles reclusa, Argiope aurantia, Argiope trifasciata, Phidippus audax, and Lycosa frondicola. Skin lesion exudate was collected and tested with the BRS venom PHAI assay. From 51 separate collections of exudate, test sensitivity was 90% as long as 3 days after venom injection. Specificity was 100% with venom from the other spider species listed above in vivo (7 test samples) and in vitro (5 test samples), as well as with random bacterial exudate with and without added serial dilutions of BRS venom (10 test samples). The test was reproducible over repetitive assays to within one 10-fold dilution. A positive PHAI test result could function as an entry criterion for BRS bite victims in human treatment trials.
Enzymatic rate assay of creatinine in serum and urine
Authors: Fujita T , Takata S , Sunahara Y 
Published: January 2020

Abstract
A two-step method for assaying creatinine in serum and urine samples, suitable with automated analyzers, is reported. Reagent 1, for the first step, contains a blanking system [creatine amidinohydrolase (CRTase), urease, glutamate dehydrogenase, NADPH, and 2-oxoglutarate] and a NADPH-regenerating system [Mg(2+)-dependent isocitrate dehydrogenase (ICD), MgCl2, and excess isocitrate]. Reagent 2, for the second step, contains the metal-chelating reagent trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CyDTA) and a trigger system [creatinine amidohydrolase (CRNase)]. When a specimen is mixed with reagent 1, all the creatine, urea, and NH3 present are removed by the blanking and NADPH systems. On adding reagent 2, CyDTA inactivates ICD to inhibit the NADPH system. Simultaneously, the creatinine (1 mol) in the specimen is hydrolyzed into creatine by CRNase, and then releases NADP+ (2 mol) through the blanking system. Our optimized method can determine creatinine linearly up to 500 mg/L, with within-day CVs &lt; 1.2% and day-to-day CVs &lt; 2.7%.
Quantification of the cross-link pentosidine in serum from normal and uremic subjects
Authors: Takahashi M , Kushida K , Kawana K , Ishihara C , Denda M , Inoue T , Horiuchi K 
Published: January 2020

Abstract
Pentosidine is a fluorescent cross-link compound that accumulates in human tissues from uremic and diabetic patients. Using SP-Sephadex C-25 pretreatment before reversed-phase HPLC, we developed a method for quantifying pentosidine in the acid hydrolysate of serum. We examined concentrations of pentosidine in serum from 98 patients with end-stage renal disease requiring hemodialysis and from 33 normal control subjects. The mean (+/- SD) concentration of pentosidine was significantly greater in serum from uremic patients than that from control subjects (1267 +/- 695 nmol/L vs 77 +/- 40 nmol/L, P = 0.0001). There was a significant correlation between serum pentosidine concentrations and age in control subjects (r = 0.453, P &lt; 0.01), but not in uremic patients. Serum pentosidine significantly increased with the duration of hemodialysis treatment (r = 0.272, P &lt; 0.05). The greater pentosidine concentrations in uremic patients may be caused by the increased synthesis of pentosidine (perhaps because of the retention of pentosidine precursors), by the retention of pentosidine molecule itself in end-stage renal failure, or both.
Homogeneous immunofluorometric assays of alpha-fetoprotein with macroporous, monosized particles and flow cytometry
Authors: Frengen J , Schmid R , Kierulf B , Nustad K , Paus E , Berge A , Lindmo T 
Published: January 2020

Abstract
We evaluated two homogeneous immunofluorometric assays (IFMAs) of alpha-fetoprotein (AFP) based on new macroporous acrylate particles combined with flow cytometry. The standard IFMA, requiring 1 h of incubation, provided a working range from 1.8 to &gt; 900 kIU/L (CV &lt; 10%) and a detection limit of 0.6 kIU/L. Use of overnight incubation and a lower particle concentration extended the working range by 1 decade in the lower end. Analytical recoveries for the standard IFMA varied between 97% and 108%. The slope and y-intercept of the regression line correlating measurements by the standard IFMA and a routine immunoradiometric assay were not significantly different from 1 and 0, respectively (P &gt; 0.5), and the correlation coefficient was 0.996. High precision and warning of spuriously high measurements were obtained by including in each sample separate particle types for detecting instrument instability and measuring nonspecific binding only.
Relation between serum and whole-blood ethanol concentrations
Authors: Rainey P M 
Published: January 2020

Abstract
An algorithm is suggested for interpretation of serum ethanol concentrations under legal statutes that specify whole-blood alcohol concentrations. The algorithm uses the distribution of individual serum:whole-blood alcohol concentration ratios to allow calculations at various levels of confidence that can be related to legal standards of evidence. Serum:whole-blood alcohol concentration ratios were determined for 211 patients. The ratios ranged from 0.88 to 1.59 (median 1.15). The distribution of ratios was positively skewed, but the logarithms of the ratios were normally distributed. This allowed the parametric calculation of a range of ratios of 0.90-1.49 for the central 99% of the population and a range of 0.95-1.40 for the central 95%. The serum:whole-blood alcohol concentration ratio was independent of both the serum alcohol concentration (R2 = 0.005) and the hematocrit (R2 = 0.03).
Solid-phase extraction protocol for isolating retinol-d4 and retinol from plasma for parallel processing for epidemiological studies
Authors: Dueker S R , Lunetta J M , Jones A D , Clifford A J 
Published: January 2020

Abstract
Solid-phase extraction permits the parallel processing of samples in large numbers. We have applied this technique to the isolation of retinol isotopomers from plasma of humans participating in a study of vitamin A stable isotope dilution. The isotopomers were analyzed by gas chromatography/mass spectrometry. The extraction involves the separation of retinol from its aqueous matrix with a C18 silica-based sorbent followed by removal of lipid contaminants with an aminopropyl silica-based sorbent. Overall recovery of retinol from plasma was 47.2% +/- 1.8%. Purity of the retinol isolated from plasma is comparable with that obtained with a single HPLC method. This method permits the preparation of 32 samples per day by one analyst. Elimination of the need for HPLC permits sample preparation in the field with a minimum of equipment and technical skill.
Improved quantitative Apt test for detecting fetal hemoglobin in bloody stools of newborns
Authors: Liu N , Wu A H , Wong S S 
Published: January 2020

Abstract
We devised an improved spectrophotometric method, based on the differential susceptibility of various hemoglobins to alkaline denaturation, to measure the percentage of fetal hemoglobin (HbF) in bloody meconium so as to determine the source of the blood. The oxyhemoglobin of a sample was spectrophotometrically scanned from 450 to 650 nm before and after the addition of sodium hydroxide. With Allen baseline correction, the ratio of absorbance at 576 nm was linearly proportional to the percentage of HbF in the specimen as described by the equation: ratio = 0.01 (%HbF) + 0.0045 (r = 0.9971, Sy/x = 0.047). Preliminary studies on samples containing 10% or 80% HbF revealed that the method was fairly precise. The accuracy of this test was verified by comparing the results (y) with those obtained by radial immunodiffusion (x): y = 0.997x + 2.93 (r = 0.91). This preliminary study demonstrates that the modified test is simple, fast, and free from bilirubin interference. It should be useful for the diagnosis of gastrointestinal bleeding of the newborn on a stat basis.
Automated enzymatic analysis of inulin
Authors: Summerfield A L , Hortin G L , Smith C H , Wilhite T R , Landt M 
Published: January 2020

Abstract
We have developed an automated enzymatic assay for quantitation of inulin in plasma and urine that can be performed on the Cobas FARA II. In the assay, inulinase hydrolyzes inulin to fructose, and sorbitol dehydrogenase converts fructose to sorbitol with consumption of NADH, which is detected by spectrophotometry. The method incorporates a sample blank (inactivated inulinase) for each specimen to subtract contributions of endogenous fructose. Recovery of fructose or inulin was near 100%, with linearity to 300 mg/L. The enzymatic assay (y) agreed well with an anthrone comparison method (x) for analysis of inulin in both urine specimens (y = 1.00x - 138; Sy/x = 714) and plasma specimens (y = 1.00x - 3.5; Sy/x = 5.5). Glucose at 300 mg/L yielded an apparent inulin value of 1.3 mg/L in the enzymatic assay, but reacted at nearly 10% equivalency in the anthrone assay. Interferences from sorbitol, mannitol, and xylitol were negligible. CVs for day-to-day precision studies were 1-4%. The automated enzymatic assay of inulin is faster and avoids the use of caustic reagents required by the classical anthrone method.
Modified Method for Determining Carcinoembryonic Antigen in the Presence of Human Anti-Murine Antibodies
Authors: Morrissey Nancy E , Quadri Syed Farhat , Kinders Robert , Brigham Christine , Rose Steve , Blend Michael J 
Published: January 2020

Abstract
Vol. 39:
p. 527. In the article by N. E. Morrissey, S. F. Quadri, R. Kinders, C. Brigham, S. Rose, and M. J. Blend entitled "Modified method for determining carcinoembryonic antigen in the presence of anti-murine antibodies," 1993;39:522-9, the graphs A and B in the left-hand column of page 527 should be exchanged with graphs A and B in the right-hand column, so that the legend for Figure 2 refers to graphs for two HAMA-negative patients and the legend for Figure 3 refers to three HAMA-positive patients.
p. 1401. In the article by J. M. Queraltó, J. C. Boyd, and E. K. Harris entitled "On the calculation of reference change values, with examples from a long-term study," 1993;39:1398-403, the last two columns of Table 4 are incorrect: in the next-to-last column, a misprint occurred in the line for sodium; in the last column, a number was omitted, causing other numbers to be misplaced. The columns should have read as follows:
See table in the PDF file
p. 1901. In the Scientific Note by R. G. Parsons, R. Kowal, D. LeBlond, V. T. Yue, L. Neargarder, L. Bond, D. Garcia, D. Slater, and P. Rogers, entitled "Multianalyte assay system developed for drugs of abuse," 1993;39:1899-903, the word "trihexylphenidyl" in line 1 of the text in column 2, page 1901, should read "trihexyphenidyl."
p. 1942. In Oak Ridge Conference paper by R. Devlin, R. M. Studholme, W. D. Dandliker, K. Blumeyer, and S. S. Ghosh, entitled "Homogeneous detection of nucleic acids by transientstate polarized fluorescence," 1993;39:1939-43, the x-axis for Figure 5 should read: "Volume of 3SR product solution (1O-4 x µL)," not (10-3 x µL).
p. 1982. In the Oak Ridge Conference Poster Session, the paper by D. Crisan, M. J. Anstett, N. Matta, and D. H. Farkas entitled "Detection of bcl-2 oncogene rearrangement in follicular lymphoma: nucleic acid hybridization and polymerase chain reaction compared," 1993;39:1980-2, the word "bone" in the first line at the top of page 1982 should have read "bone marrow."
Effect of thyroid function on concentrations of lipoprotein(a)
Authors: Engler H , Riesen W F 
Published: January 2020

Abstract
The effect of thyroid hormones on concentrations of lipoprotein(a) [Lp(a)] was analyzed in 60 patients with active thyroid dysfunction (hyperthyroidism 30 cases, hypothyroidism 32 cases, and 2 cases with opposite changes) and after normalization of the thyroid state. Treatment of hyperthyroidism increased the mean Lp(a) concentrations by 60% (from 73 to 102 mg/L, P &lt; 0.002); at the same time, low-density lipoprotein cholesterol (LDL-C) increased by 53% (from 2.6 to 3.7 mmol/L, P &lt; 0.0001) and apolipoprotein B (apo B) by 35% (from 0.91 to 1.17 g/L, P &lt; 0.0005). In hypothyroidism, the opposite changes were observed: mean Lp(a) decreased from 136 to 114 mg/L (10%, P &lt; 0.02), LDL-C from 4.6 to 3.9 mmol/L (13%, P &lt; 0.01), and apo B from 1.51 to 1.20 g/L (14%, P &lt; 0.01). Although the changes in Lp(a) concentrations did correlate with changes of LDL-C during treatment of hyperthyroidism (r = 0.43, P &lt; 0.05), and with changes in apo B during thyroxine-substitution therapy for hypothyroidism (r = 0.46, P &lt; 0.05), we observed no associations between Lp(a) and LDL-C or apo B in the euthyroid state. These data cannot rule out the possibility that the thyroid hormone-induced increase in LDL-C receptor activity was responsible for the decreased concentrations of Lp(a) in hyperthyroidism. Given that LDL-C is approximately 30% of the Lp(a) molecule but the changes in Lp(a) concentrations are comparable with those in LDL-C (60% vs 53%), and given that Lp(a) is metabolized by an LDL-C-receptor-independent pathway, the present data suggest a direct effect of thyroid hormones on Lp(a) synthesis.
Combined serum amylase and lipase determinations for diagnosis of suspected acute pancreatitis
Authors: Corsetti J P , Cox C , Schulz T J , Arvan D A 
Published: January 2020

Abstract
Serum amylase and lipase measurements are often used to diagnose acute pancreatitis. This study addresses the question of whether it is advantageous to order serum amylase and lipase tests simultaneously. We evaluated performance of the two tests separately and in combination through a retrospective study of patients for whom both amylase and lipase determinations were ordered. Initial analysis of test performance was conducted with a uniformly applied criterion based on determination of optimal sensitivity-specificity pairs. Individual tests and combinations of tests, including the "AND" and "OR" rules and discriminant functions, were examined. Only the discriminant approach demonstrated better performance than the lipase test alone. This finding was subsequently confirmed by logistic regression analysis. We conclude that ordering both tests simultaneously can be advantageous in diagnosing acute pancreatitis when a bivariate approach is used; however, this must be weighed against the difficulties associated with clinical implementation of such approaches.
Densitometric determination of urinary 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid)
Authors: Agbaba D , Stojanov M , Rajacic S , Zivanov-Stakic D , Majkic-Singh N 
Published: January 2020

Abstract
We propose a simple and precise densitometric method for measuring vanillylmandelic acid (VMA). The method comprises direct urine application, thin-layer chromatographic (TLC) separation, postchromatographic derivatization, and in situ reading of the formed derivative at 560 nm. Quantitation was done by measuring peak area with a computer-controlled TLC Scanner and applying a five-point calibration function. The calibration function was 7.57-49.23 mumol/L. This method was used to determine urinary concentrations of excreted VMA; concentrations ranged from 4.84 to 56.06 mumol/day.
Free cortisol in serum assayed by temperature-controlled ultrafiltration before fluorescence polarization immunoassay
Authors: Lentjes E G , Romijn F , Maassen R J , de Graaf L , Gautier P , Moolenaar A J 
Published: January 2020

Abstract
A method is described for a temperature-controlled ultrafiltration procedure to measure free cortisol in serum. A special thermometer with a sensor was developed, measuring the temperature directly in the ultrafiltration device. The sensor is screwed on the axis of the centrifuge rotor, and the centrifuge is placed in a temperature-controlled box so that the temperature of the sample is kept at 37 degrees C +/- 0.1 degrees C. The overall CV of the free cortisol assay ranges from 2.2% to 11.4%, of which the ultrafiltration contributes only 2.2-3.6%. Increasing amounts of cortisol-binding protein, as found in women using estrogen-containing oral contraceptives, have minor but significant effects on the free cortisol concentrations in serum. Serum free cortisol concentrations in a reference population (n = 114; central 95 percentiles) were 12-43 nmol/L (4-9.5% of total cortisol); in the group of the oral-contraceptive users (n = 27), the reference interval was 11-53 nmol/L (1.5-4.5%).
Urinary Oligosaccharides In Pregnant or Lactating Women: Pitfall in Screening
Authors: Kuczynski Thaddeus W , Kendzierski Kevin S , Sewell Adrian C 
Published: January 2020

Abstract
Vol. 39
p. 2347: In the letter by Thaddeus W. Kurczynski, Kevin S. Kendzierski, and Adrian C. Sewell entitled "Urinary oligosaccharides in pregnant or lactating women: pitfall in screening," 1993;39:2346-7, the name of the first author was misspelled.
Modifying an enzyme immunoassay of immunoreactive trypsinogen to use time-resolved fluorescence
Authors: Ryall R G , Gjerde E M , Gerace R L , Ranieri E 
Published: January 2020

Abstract
A coated microtiter-well, enzyme-linked immunometric assay for quantifying immunoreactive trypsinogen in dried blood spots was modified to use time-resolved fluorescence of europium in place of end-point enzymatic color development as the quantification step. The streptavidin-horseradish peroxidase and color development solutions supplied as packaged reagents were replaced by europium-labeled avidin, and the signal was developed with commercially available enhancement solution and read by time-resolved fluorescence. The change of label from enzyme to europium increased the dynamic range of the assay by about 5-fold, reduced the detection limit 10-fold, and halved the intra- and interassay imprecision. The improved analytical precision and stability of the modified assay resulted in a more precise description of the population distribution of immunoreactive trypsinogen values in newborns, showing less variance in the upper centiles. This effect is of paramount importance when using this assay for neonatal screening for cystic fibrosis.
Multiwavelength photometry of thermochromic indicator solutions for temperature determination in multicuvettes
Authors: Schilling K , Cumme G A , Hoffmann-Blume E , Hoppe H , Horn A 
Published: January 2020

Abstract
If buffer/indicator systems are used as optical thermometers in multicuvettes, the temperature resolution is limited by errors of optical measurements produced mainly by variations of pathlength and blank transmittance of the wells. Theoretical and practical approaches show that, in multicuvettes, a between-well temperature resolution of &lt; 0.05 degrees C can be achieved by multiwavelength photometry with use of the Tris/cresol red indicator system. Using up to three absorbances (A0, A1, A2) measured in the same well at different wavelengths for calculation of differences, quotients, and quotients of differences, we found the optimum temperature signal to be In(A1/A2), with equal-ranking absorbances changing with temperature in opposite directions. We have used the method successfully to measure the temperature profiles and temporal dynamics of temperatures at all positions in two types of multicuvettes under controlled conditions, or not controlled thermostatically.
Monitoring both serum amyloid protein A and C-reactive protein as inflammatory markers in infectious diseases
Authors: Nakayama T , Sonoda S , Urano T , Yamada T , Okada M 
Published: January 2020

Abstract
We examined serum amyloid protein A (SAA) and C-reactive protein (CRP) as inflammatory markers of viral and bacterial infections. Both acute-phase reactants increased in the acute stage and thereafter decreased in the convalescent stage. In viral infections, the mean serum concentrations of SAA during the acute stage were 141 mg/L in infections with adenovirus, 77 mg/L with measles virus, 63 mg/L with influenza virus, 55 mg/L with parainfluenza virus, 31 mg/L with respiratory syncytial virus, and 31 mg/L in aseptic meningitis. The mean serum concentration of CRP was 19 mg/L for adenovirus infection and &lt; 7 mg/L in all other viral infections. The SAA concentrations were 5- to 11-fold greater than the CRP concentrations. Both the SAA and the CRP concentrations were higher in bacterial infections than in viral infections. Changes in the concentrations of serum SAA paralleled those in serum CRP in bacterial infection; during the course of viral infection, however, serum SAA tended to disappear more quickly than CRP did. SAA appears to be a clinically useful marker of inflammation in acute viral infections, with or without significant changes in the CRP concentration.
Total error assessment of five methods for cholesterol screening
Authors: Miller W G , McKenney J M , Conner M R , Chinchilli V M 
Published: January 2020

Abstract
We report the accuracy, imprecision, total analytical errors, and patient misclassification errors for cholesterol measured from capillary whole blood, venous whole blood, and venous plasma samples by five devices used in public cholesterol screening environments: Reflotron, Vision, Ektachem DT-60, QuickRead, and Liposcan. None of the methods met the National Cholesterol Education Program (NCEP) performance recommendations of 3% CV with 3% bias. The Vision and Reflotron methods used with venous samples gave individual results with total errors consistent with a combined CV and bias in the 4-5% range; capillary blood samples had total errors &gt; 5% (combined CV and bias criteria). The DT-60 performance was near the 5% total error criterion for capillary samples and was &gt; 5% for venous samples. Misclassification of individuals into desirable or referral groups for venous samples was as great as 5.1% for the DT-60, 5.7% for the Vision, and 7.1% for the Reflotron. Misclassifications for capillary blood samples were as great as 6.7%, 18.3%, and 14.1% for DT-60, Vision, and Reflotron, respectively. The QuickRead and Liposcan results were substantially poorer than those obtained by the other methods.