bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation Markedly Reduces Bilirubin Interference in the Jaffé Creatinine Assay
Authors: Rajs G , Mayer M 
Published: January 2020

Abstract
Bilirubin causes underestimation of serum creatinine in the Jaffé alkaline picrate assay. We report an approach for preventing bilirubin interference by pretreating serum samples with peroxidase and H2O2. The dissociation of bilirubin from albumin and its subsequent oxidation markedly reduces the bilirubin interference and enables accurate determination of creatinine concentrations by the Jaffé reaction even in hyperbilirubinemic sera. Within-run CVs were 2.6%, 4.0%, and 3.8% at mean creatinine concentrations of 88, 165, and 349 mumol/L, respectively (n = 20). Day-to-day CVs were 4.0%, 6.3%, and 5.8% for mean creatinine concentrations of 87, 168, and 364 mumol/L, respectively (n = 12). Average recovery of creatinine added to serum in the presence of 600 mumol/L bilirubin was 97% (n = 15). This method requires only small serum volumes (70 microL) and is easily applicable to automated analyzers that can be programmed to add three reagents consecutively.
Interlaboratory Standardization of Measurements of Glycohemoglobins
Authors: Little R R , Wiedmeyer H M , England J D , Wilke A L , Rohlfing C L , Wians F H , Jacobson J M , Zellmer V , Goldstein D E 
Published: January 2020

Abstract
The diversity of methods used to measure glycohemoglobins (GHb) makes it difficult to compare patients' results among laboratories. We reported previously the feasibility of providing comparable results from different assays by use of common calibrators. We here compare results from seven different GHb methods calibrated by use of hemolysates assayed by a precise ion-exchange high-performance liquid-chromatographic (HPLC) method for hemoglobin A1c (HbA1c). Thus, regardless of the GHb species measured by the seven methods, results were referenced to the HbA1c content of the calibrators. Without this calibration, GHb values for single samples varied, e.g., from 4.0% to 8.1% and from 10% to 14.2% in the normal and high ranges, respectively. Calibration decreased between-method variability (single sample ranges of, e.g., 4.8% to 5.4% and 9.4% to 10.2% in the normal and high ranges, respectively) and improved interassay precision. We conclude that this approach to calibration of GHb measurements allows direct comparison of results obtained by different methods and improves precision.
Allelic Amino Acid Substitutions Affect the Conformation and Immunoreactivity of Germ-Cell Alkaline Phosphatase Phenotypes
Authors: Hoylaerts M F , Manes T , Millán J L 
Published: January 2020

Abstract
The gene encoding placental alkaline phosphatase (PLAP) displays a well-documented allelic polymorphism. Likewise, different phenotypes exist for the PLAP-related germ-cell alkaline phosphatase (GCAP). We investigated the extent to which various allelic GCAP positions are critical in determining the enzymatic, structural, and immunological properties of GCAP phenotypes. Three homozygous GCAP phenotypes [JEG3, BeWo, and wild-type (wt) GCAP] were analyzed and compared with a "core" GCAP mutant that contains the seven amino acid substitutions that are consistently different between PLAP and GCAP but are common to the three known allelic GCAP genotypes. Although some substitutions could influence the electrophoretic behavior of the phenotypes, the allelic differences did not affect the kinetic properties of GCAP. However, they did affect the immunoreactivity and conformation of the variants as detected with a panel of 18 epitope-mapped monoclonal antibodies (MAbs) to PLAP. The selective immunoreactivity of the PLAP/GCAP-discriminating MAb C2 was critically dependent on the nature of the allelic residues 133 and 361 in GCAP. Residue 133 was also important for the general stability of the molecule because BeWo and wt GCAP, which have Asn133 and Val133, respectively, instead of Met133, showed a consistently reduced heat stability compared to core GCAP and JEG3. Because the core GCAP mutant consistently shows the characteristics of wt GCAP, its use as an antigen should allow the generation of monoclonal antibodies to GCAP that will not cross-react with PLAP and whose immunoreactivity will only marginally be influenced by allelic GCAP variation.
Kinetic Colorimetric Assay of Lipase in Serum
Authors: Fossati Piero , Ponti Maurizio , Paris Paolo , Berti Giovanni , Tarenghi Giordano 
Published: January 2020

Abstract
We describe a kinetic colorimetric method for assaying lipase (EC 3.1.1.3) activity in serum by using a natural long-chain fatty acid 1,2-diglyceride. In the presence of colipase, deoxycholate, and calcium ions, pancreatic lipase hydrolyzes the clear substrate solution to produce a 2-monoglyceride, which in turn releases glycerol by the action of a 2-monoglyceride lipase. Glycerol is then assayed by a sequence of enzymatic actions (glycerol kinase, glycerol phosphate oxidase, and peroxidase) that produce a violet quinone monoimine dye with peak absorption at 550 nm. The method features zero-order reaction kinetics, provides a simple and rapid assay with an extended dynamic range, is specific and precise, gives results that correlate well (r greater than or equal to 0.99) with those of methods in which emulsified triolein is the substrate, and lends itself readily to automation. For all these reasons, the method seems highly suitable for routine use in clinical laboratories.
α-Glucosidase and Ν-Acetyl-α-D-glucosaminidase Isoenzymes in Serum
Authors: Coma P , Gomez-Chacon L , Garcia-Serrano B , Fernandez E , Ortiz-Apodaca M A 
Published: January 2020

Abstract
Using different conditions for incubation and fluorometry with 4-methylumbelliferylglycosides as substrates, we demonstrated the presence of acid alpha-glucosidase, "renal" alpha-glucosidase, N-acetyl-beta-D-glucosaminidase A, and N-acetyl-beta-D-glucosaminidase B in freshly drawn normal human serum. The acid alpha-glucosidase enzymatic activity was determined at pH 4.0 in 0.1 mol/L Tris reagent, whereas the renal isoenzyme activity was determined at pH 5.6 in presence of 0.05 mol/L turanose reagent. N-Acetyl-beta-D-glucosaminidases A and B were determined by their different behaviors on heating. The corresponding reference intervals for each enzyme were calculated from results for 40 controls: acid alpha-glucosidase (0.024 +/- 0.010 U/L), renal alpha-glucosidase (0.035 +/- 0.012 U/L), N-acetyl-beta-D-glucosaminidase A (10.2 +/- 2.9 U/L), and N-acetyl-beta-D-glucosaminidase B (4.4 +/- 2.1 U/L).
Comparing the Power of Quality-Control Rules to Detect Persistent Increases In Random Error
Authors: Parvin C A 
Published: January 2020

Abstract
This paper continues an investigation into the merits of an alternative approach to the statistical evaluation of quality-control rules. In this report, computer simulation is used to evaluate and compare quality-control rules designed to detect increases in within-run or between-run imprecision. When out-of-control conditions are evaluated in terms of their impact on total analytical imprecision, the error detection ability of a rule depends on the relative magnitudes of the between-run and within-run error components under stable operating conditions. A recently proposed rule based on the F-test, designed to detect increases in between-run imprecision, is shown to have relatively poor performance characteristics. Additionally, several issues are examined that have been difficult to address with the traditional evaluation approach.
Total Urinary Hydroxyproline Determined with Rapid and Simple High-Performance Liquid Chromatography
Authors: Paroni R , De Vecchi E , Fermo I , Arcelloni C , Diomede L , Magni F , Bonini P A 
Published: January 2020

Abstract
A precolumn derivatization method was optimized for rapid and specific analysis of total urinary hydroxyproline by HPLC. After an overnight hydrolysis, urine samples dried and reconstituted with the internal standard cysteic acid (in sodium hydrogen carbonate, pH 9.3) were derivatized with N,N-diethyl-2,4-dinitro-5-fluoroaniline (FDNDEA) at 100 degrees C for 20 min. The DNDEA-hydroxyproline adduct was separated on an Ultrasphere ODS column with a mobile phase of acetate buffer (containing triethylamine, 6 mL/L, pH 4.3) and acetonitrile (80/20, by vol), and was detected at 360 nm. A single run took 18 min with a hydroxyproline retention time of 7.3 min. The assay showed a linear response to hydroxyproline concentrations from 5 to 100 mg/L with a detection limit of 0.8 ng injected, corresponding to 2 mg/L in urine. Mean (SD) analytical recovery was 94.2 (13)% and 104 (9)% at 10 and 50 mg/L, respectively. Within-run and between-run CVs (n = 10) were 3.74% and 4.33%, respectively, for 25 mg/L. Results for samples (n = 50) analyzed by HPLC (y) vs ion-exchange chromatography with postcolumn ninhydrin reaction (x) correlated well: y = 0.98x + 1.02 (r = 0.985, Sxy = 3.13). In another comparison, involving 173 samples, a colorimetric procedure (Hypronosticon, x) gave slightly higher values than the HPLC method (y): y = 0.83x + 2.21 (r = 0.937, Sxy = 4.6).
Low Bias in Assayed Values of Lipoprotein Antigens--Lipoprotein(a) and Apolipoproteins A-I and B--in Midday Postprandial Blood Specimens Compared with Morning Fasting Specimens
Authors: Emancipator K 
Published: January 2020

Abstract
Two-hour postprandial specimens have a -14% proportional bias for lipoprotein(a) [Lp(a)], a -0.035 g/L systematic bias for apolipoprotein (apo) A-I, and a -9% proportional bias for apo B, compared with values in 12-h fasting specimens. Although a physiological hemodilution appears to account for a portion of these biases, other major factors must be implicated for Lp(a) and apo B. Even after dilutional effects are controlled for, assayed values of Lp(a) are 11-13% lower, and assayed values of apo B are 8-9% lower, in postprandial specimens than in fasting specimens. Therefore, the time of collection of a blood sample relative to the last meal can significantly affect assayed values of lipoprotein antigens. Further studies are needed to determine whether these observations result from a physiological sequestering of lipoproteins in the postprandial state or from negative interferences affecting the assays of lipoprotein antigens.
Aspartate Aminotransferase, Alanine Aminotransferase, and Glutathione Transferase in Plasma During and after Sedation by Low-Dose Isoflurane or Midazolam
Authors: Howie A F , Spencer E , Beckett G J 
Published: January 2020

Abstract
To assess the effect of prolonged administration of midazolam or isoflurane on hepatocellular integrity, we measured the concentrations of glutathione transferase (EC 2.5.1.18) B1 subunit and the activities of alanine aminotransferase (ALT; EC 2.6.1.2) and aspartate aminotransferase (AST; EC 2.6.1.1) in 40 patients who required long-term sedation with low-dose midazolam or isoflurane. Blood samples were collected before and 24 h after the start of the sedation and 0, 24, 72, 120, and 172 h after the last dose. ALT and AST activities did not change appreciably, but the glutathione transferase B1 concentration decreased significantly (P less than 0.03) at all times studied. The patients who received isoflurane and those who received midazolam showed no significant differences in any of the enzyme tests. We conclude that long-term sedation with midazolam or isoflurane is unlikely to affect hepatocellular integrity.
Prevalence and Properties of the Intestinal Alkaline Phosphatase Identified in Serum by Cellulose Acetate Electrophoresis
Authors: Griffiths W C , Camara P D , Rosner M , Lev R , Brooks E M 
Published: January 2020

Abstract
We investigated the prevalence and characteristics of intestinal alkaline phosphatase (ALP; EC 3.1.3.1) identified in human serum by cellulose acetate electrophoresis in 8% of fasting serum samples from hospital patients (n = 500) and in 35% of fasting serum samples from patients with diabetes mellitus (n = 106; not differentiated between types 1 and 2). The intestinal ALP electrophoretic band was usually heterogeneous and contained two major subtypes of ALP. Isoelectric focusing of intestinal-ALP-positive serum treated with levamisole and neuraminidase (EC 3.2.1.18) revealed two distinct regions of enzymatic activity that comigrated with ALP extracted from small intestinal and colonic mucosa. Anodic intestinal ALP was resistant to treatment with levamisole and neuraminidase and comigrated with ALP from small intestinal mucosa. The more-cathodic intestinal ALP, which comigrated with ALP from colonic mucosa, was completely inhibited by levamisole and converted by neuraminidase to a species with a more basic pI than that of neuraminidase-digested tissue-nonspecific form. This component of intestinal ALP may be of vascular origin.
Reference Values for Apolipoproteins A-I and B in Healthy Subjects, by Age
Authors: Zunić G , Jelić-Ivanović Z , Spasić S , Stojiljković A , Majkić-Singh N 
Published: January 2020

Abstract
We determined reference values of apolipoproteins A-I (apo A-I) and B (apo B) in serum from a population of 448 healthy subjects (265 men and 183 women, ages 18 to 61 years) by a kinetic immunonephelometric procedure. Frequency distributions of apo A-I were normal, whereas those of apo B were not and yielded asymmetrical curves. Thus, reference intervals for apo A-I were determined as mean +/- 2SD (1.08-1.89 g/L), but a nonparametric method was used for determining reference intervals for apo B (0.60-1.94 g/L). Apo B concentrations were significantly higher (P less than 0.001) in men than in women (0.63-2.01 g/L, mean 1.21 g/L; and 0.54-1.91 g/L, mean 1.08 g/L, respectively). No significant differences for apo A-I between men and women were observed. Concentrations of both proteins increased with age, but apo B increased more than apo A-I. We conclude that not only sex but also the age of the subjects must be considered in interpreting laboratory results for apolipoproteins.
Increased Alpha-Hydroxybutyrate Dehydrogenase in Serum from Children with Measles
Authors: Kano K , Ichimura T 
Published: January 2020

Abstract
For treatment and prognostic evaluation of patients with measles, it is important to determine the source of the increase in serum alpha-hydroxybutyrate dehydrogenase (HBD; EC 1.1.99.6). Here we measured HBD and L-lactate dehydrogenase (LD; 1.1.1.27) activities in the serum of 18 children with measles and in 18 age-matched control patients with bronchopneumonia. HBD and LD activities in the measles patients were significantly higher than those in control subjects (P less than 0.001). The HBD/LD ratio in the measles patients two to three days after the onset of rash was significantly lower than that in control subjects (P less than 0.001). The low HBD/LD ratio was similar to the ratio found in lymphocytes. The number of peripheral lymphocytes decreased markedly after the onset of rash. Our results suggest that increased serum HBD and LD activity is common in measles infection and that the increase originates from the destruction of infected lymphocytes rather than from myocardiac injury.
Certification of Cholesterol Measurements by the National Reference Method Laboratory Network with Routine Clinical Specimens: Effects of Network Laboratory Bias and Imprecision
Authors: Bennett S T , Eckfeldt J H , Belcher J D , Connelly D P 
Published: January 2020

Abstract
The National Reference Method Laboratory Network has initiated a program to certify clinical laboratory cholesterol measurement performance by using routine clinical specimens. Clinical laboratory and reference laboratory measurements of split samples are used to assess whether the clinical laboratory is meeting the Laboratory Standardization Panel's goals for accuracy and precision. We used a computer-based Monte Carlo simulation model of split-sample proficiency testing to evaluate the certification program and, in particular, to analyze the effects of reference laboratory bias and imprecision. Results of our simulations indicate that the accuracy of the certification program is strongly influenced by reference laboratory bias and less influenced by reference laboratory imprecision. The certification program is potentially highly accurate, but unless reference laboratory bias is tightly controlled, the number of classification errors may limit its utility. Moreover, the decision limit of the certification program needs to be higher than the Laboratory Standardization Panel's goal (3.5% instead of 3.0%) to ensure that an acceptably high proportion of well-performing clinical laboratories can become certified.
Patterns of Serological Markers for Cellular Immune Activation in Patients with Dilated Cardiomyopathy and Chronic Myocarditis
Authors: Samsonov M , Fuchs D , Reibnegger G , Belenkov J N , Nassonov E L , Wachter H 
Published: January 2020

Abstract
We determined serum concentrations of neopterin and beta 2-microglobulin, soluble markers of cellular immune activation, in 27 patients with either dilated cardiomyopathy (DCM) or chronic myocarditis. Neopterin and beta 2-microglobulin concentrations were respectively increased in 2 and 5 of 11 patients with DCM and in 11 and 9 of 16 patients with chronic myocarditis. A higher cardiac functional class (according to the New York Heart Association) was associated with greater neopterin and beta 2-microglobulin concentrations. During follow-up of patients, both neopterin and beta 2-microglobulin concentrations in serum correlated with the course of disease. Additionally, correlations were significant between left ventricular functional tests (end-diastolic volume, end-systolic volume, and ejection fraction) and neopterin and beta 2-microglobulin concentrations. We conclude that measurement of neopterin and beta 2-microglobulin are useful to monitor disease development in patients with myocardial inflammation.
High-Performance Liquid Chromatography of 125I-Labeled Mouse Epidermal Growth Factor Radioiodinated by Six Different Methods
Authors: Kienhuis C B , Heuvel J J , Ross H A , Foekens J A , Benraad T J 
Published: January 2020

Abstract
Six different procedures for radioiodination of mouse epidermal growth factor (EGF) all resulted in a heterogeneous 125I-labeled EGF preparation, as analyzed by reversed-phase HPLC. EGF preparations that had been iodinated with Chloramine T, lodogen, or lodo-beads were found mainly to consist of oxidized 125I-labeled EGF moieties. In contrast, the heterogeneous 125I-labeled EGF preparations obtained by using iodine monochloride, Protag-125, or lactoperoxidase-glucose oxidase-coupled beads (Enzymobeads) contained insignificant amounts of oxidized EGF entities. Ligand equivalence analysis (LEA) of distinct HPLC column fractions, obtained after preparative separation of Chloramine T-125I-labeled EGF, showed that the receptor-binding affinity of the tracer in all subfractions was less than the affinity of unlabeled EGF. This implies that HPLC purification of these 125I-labeled EGF preparations does not yield 125I-labeled EGF preparations with ligand equivalence. However, all but one HPLC column fraction of Enzymobeads-125I-labeled EGF showed ligand equivalence. Despite the small amount of the nonequivalent component in the Enzymobeads-labeled tracer, the nonchromatographed 125I-labeled EGF preparation showed ligand equivalence. No significant differences were observed in the maximal binding capacity of the different 125I-labeled EGF preparations.
Enzyme Immunoassay with Synthetic Peptides to Detect Anti-HTLV-I Antibodies
Authors: Yamada K , Kuroda N , Washitani Y , Shiraki H , Maeda Y 
Published: January 2020

Abstract
We developed an enzyme immunoassay (EIA) system to detect antibodies to human T-lymphotropic virus type I (HTLV-I). This system uses chemically synthesized oligopeptides to capture anti-HTLV-I antibodies in serum. The two epitopes of HTLV-I proteins exhibiting the most specific antigen-antibody reaction reside within amino acids 100-130 of p19, a core protein encoded by gag, and amino acids 175-199 of gp46, an envelope glycoprotein encoded by env. This new assay uses synthetic peptides corresponding to these two regions modified by adding two lysine residues at the amino terminal of each peptide to facilitate the binding to the surface of the microtiter plate wells. We compared the performance of our EIA with gelatin-particle-agglutination (PA) and indirect-immunofluorescence (IF) assays, both of which use viral proteins purified from virus-carrying cell cultures. Mass screening by EIA with various synthetic peptides was more accurate than the current confirmatory IF assay.
Apolipoprotein A-Containing Lipoprotein Particles: Physiological Role, Quantification, and Clinical Significance
Authors: Fruchart J C , Ailhaud G 
Published: January 2020

Abstract
High-density lipoprotein (HDL) particles are made up of two major populations of particles, differing in composition and metabolism. Both contain apolipoprotein (apo) A-I but only one contains apo A-II. Lipoprotein particles that contain only apo A-I (LpA-I particles) can increase cellular cholesterol efflux from cultured cells in vitro. LpA-I:A-II particles, however, do not increase cholesterol efflux. LpA-I:A-II can be determined directly with an enzyme-linked differential antibody immunosorbent assay. LpA-I is determined by differential electroimmunoassay: in the presence of a large excess of anti-apo A-II, LpA-I:A-II particles are retained in one peak, whereas LpA-I migrates grates as a second peak. Both lipoprotein forms of apo A-I-containing particles are present mainly in HDL, but the relative proportion of LpA-I is greater in HDL2 than in HDL3. Concentrations of LpA-I in plasma samples from normolipemic subjects average approximately 10% higher in women than in men. The lower apo A-I concentrations in patients with significant coronary artery disease reflect a decrease in the LpA-I particles. Data obtained in octogenarians also support the possibility that LpA-I might represent the anti-atherogenic fraction of HDL. Moreover, the concentration of LpA-I in children of parents with premature coronary heart disease was lower than that of a control group without any family history of this disease. Nutrients and hypolipidemic drugs seem to affect the two kinds of particles differently.
Immunoassays for Quantifying Choriogonadotropin Compared for Assay Performance and Clinical Application
Authors: Witherspoon L R , Shuler S E , Joseph G F , Baird E F , Neely H R , Sonnemaker R E 
Published: January 2020

Abstract
We examined calibration and accuracy, precision, sensitivity, specificity, and "hook" effects for recently revised automated choriogonadotropin (hCG) immunoassay systems (Baxter-Dade Stratus II, Abbott IMx intact hCG and total beta hCG) and compared them with a widely used immunoradiometric assay (Hybritech). We estimated hCG in pregnant women, women with trophoblastic disease, nonpregnant young and menopausal women, normal men, and men with testicular tumors. We found clinically unimportant differences in calibration (all calibrated to the 3rd International Standard). Detection of hCG by all four assays was limited by their responses in serum from nonpregnant women and men. Precision within-run was best for the automated instruments, but all four assays had similar between-run precision. The Hybritech, Stratus, and IMx intact assays are specific for intact hCG. The IMx total beta assay quantifies both free beta subunit and beta subunit present in intact hCG. There is a clinically important hook effect in the Hybritech assay but not the Stratus or IMx assays (to 1.2 x 10(6) int. units/L). Results for pregnant women were similar by all four assays. We measured "hCG" to 8 int. units/L in menopausal women, which weakly correlated with concentrations of lutropin and follitropin and was, in part, explained by crossreactivity. There was no sample-probe carryover in either instrument. We found the IMx diluting module as well as results at the extremes of the IMx calibration curves (less than 10, 800-1200 int. units/L) unreliable but encountered no such problems with the Stratus system. Both automated systems involve batch analyzers with limited throughput but provide hCG concentration estimates much more quickly than the Hybritech assay can.