bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of DNA methylation in malignant MOLT F4 lymphoblasts by 6-mercaptopurine
Authors: Lambooy Lambert H J , Leegwater Peter A J , van den Heuvel Lambert P , Bökkerink Jos P , De Abreu Ronney A 
Published: January 2020

Abstract
Treatment of MOLT F4 lymphoblasts with 6-mercaptopurine (6-MP) resulted in a decrease of ATP and a depletion of S-adenosylmethionine (AdoMet). To investigate whether this might affect the methylation of DNA, we treated MOLT F4 lymphoblasts with increasing concentrations of 6-MP, followed by labeling with [methyl-14C]methionine and [methyl-3H]thymidine. After DNA isolation, we measured the incorporated radioactivity and determined the14C/3H ratio as a measure for the methylation of newly formed DNA. The 14C/3H ratio was decreased by 17% with 1 μmol/L 6-MP; treatment with increasing concentrations of 6-MP up to 10 μmol/L showed a further decrease to 70%, in comparison with untreated cells. To demonstrate that the methylation of deoxycytidine residues in DNA was reduced, we quantified hydrolyzed DNA by HPLC. The 14C/3H ratio showed a decrease with increasing 6-MP concentrations, indicating that treatment with 6-MP resulted in hypomethylation of DNA.
A new method to measure iron absorption from the enrichment of 57Fe and 58Fe in young erythroid cells
Authors: van den Heuvel Ellen G H M , Muys Theo , Pellegrom Hillie , Bruyntjes Joost P , van Dokkum Wim , Spanhaak Steven , Schaafsma Gertjan 
Published: January 2020

AbstractIron absorption can be measured by the incorporation of stable iron isotopes into erythrocytes, 14 days after isotope administration. The disadvantage of this method is the high dose of isotopes needed to obtain a sufficient enrichment. Therefore, in this study cell fractions rich in young erythroid cells were prepared by using a density separation method. From 10 women blood was taken 4, 5, and 7 days after oral and intravenous administration of 57Fe and58Fe. In these cell fractions and in whole blood taken 14 days after isotope administration, isotope enrichment was measured and absorption calculated. Absorption calculated from the isotope enrichment in the reticulocyte-rich cell fractions (12.2 ± SEM 3.7%) was not significantly different from absorption based on whole-blood values (13.0 ± 3.3%). Because a threefold higher isotope enrichment was found in the cell fractions, the required dose of stable isotopes can be reduced to one-third of the dose used in the traditional method without loss of sensitivity.
Detection and classification of paraproteins by capillary immunofixation/subtraction
Authors: Bossuyt Xavier , Bogaerts Ann , Schiettekatte Gilberte , Blanckaert Norbert 
Published: January 2020

AbstractA selection of 58 specimens with a monoclonal component identified by immunoelectrophoresis and/or immunofixation was analyzed with the immunosubtraction procedure on the Paragon 2000 capillary electrophoresis system. The capillary system detected 93% of the paraproteins and, using immunosubtraction, correctly identified 91% of the paraproteins. Paraproteins that were detected by immunofixation and/or immunoelectrophoresis but not by capillary electrophoresis were also missed by agarose electrophoresis and cellulose acetate electrophoresis. Cellulose acetate electrophoresis was the least sensitive method for detection of paraproteins. Only 74% of the monoclonal components were detected by this technique, whereas 86% were revealed by agarose electrophoresis. In addition to monoclonal paraproteins, we also studied biclonal paraproteins and oligoclonal banding. Capillary electrophoresis and immunosubtraction correctly detected and identified three specimens containing biclonal paraproteins. In one specimen, capillary zone electrophoresis detected only one band, whereas agarose gel electrophoresis detected two bands. The sensitivity for detection and identification of oligoclonal banding by capillary electrophoresis was inferior to immunofixation.
Zinc protoporphyrin as screening test in female blood donors
Authors: Harthoorn-Lasthuizen Else J , Lindemans Jan , Langenhuijsen Mart M A C 
Published: January 2020

AbstractErythrocyte zinc protoporphyrin (ZPP) was measured in 102 women blood donors to evaluate its usefulness in screening for evolving iron deficiency anemia, a reason for the deferral of donors. The results were compared with serum ferritin determinations. Five women were deferred before their first donation and eight women were deferred after one or two donations. Women with increased ZPP values all had low serum ferritin concentrations, indicating iron-deficient erythropoiesis that was caused by iron depletion. The positive predictive value of an increased ZPP in predicting deferral of the donor after one or two donations was 75%, whereas a serum ferritin concentration ≤12 μg/L predicted deferral in 26% of the donors. The results indicate that the ZPP test can be recommended as a feasible and inexpensive predonation test to determine a subset of donors with iron-deficient erythropoiesis at risk of developing iron deficiency anemia.
Evaluation of an acidic deproteinization for the measurement of ascorbate and dehydroascorbate in plasma samples
Authors: Koshiishi Ichiro , Mamura Yoshie , Liu Ji , Imanari Toshio 
Published: January 2020

AbstractThe most popular pretreatment method of plasma samples for the measurement of ascorbate (AsA) and dehydroascorbate (DHA) has been an acidic deproteinization via metaphosphoric acid or trichloroacetic acid. In general, DHA is absent in plasma samples prepared from human blood in a conventional manner. However, when these plasma samples were subjected to acidic deproteinization, DHA was detected in the acidified sample solutions. In the present study, we demonstrate that the oxidation of AsA to DHA in the solutions was promoted by at least two mechanisms, one involving catalysis by ferric ion released from transferrin, and the other involving catalysis by plasma hemoglobin. In the acidified transferrin solution by trichloroacetic acid, an oxidation of AsA to DHA proceeded with standing time, whereas the oxidation was not observed in that by metaphosphoric acid. This oxidation appeared to be catalyzed by ferric ion released from transferrin. In contrast, plasma hemoglobin functioned as a catalyst for AsA oxidation in both metaphosphoric acid and trichloroacetic acid solutions. Therefore, DHA content in the trichloroacetic acid-treated plasma sample was markedly higher than that in the metaphosphoric acid-treated one. These results suggest that DHA detected in acidified plasma samples is an artifact resulting from AsA oxidation.
Optimizing frequency and number of controls for automatic multichannel analyzers
Authors: Neubauer Aljoscha , Wolter Christian , Falkner Christine , Neumeier Dieter 
Published: January 2020

Abstract
Sampling strategy fundamentally influences the effectiveness of quality control with control charts. This study shows a simple approach for optimizing the control strategy for automatic multichannel analyzers that takes into account cost-efficiency considerations. Our main focus is on the frequency of controls necessary. The methods used are based on a field study (on a Hitachi/BM 747), the views of experts, and computer simulations of customary cost-models together with a survey of the literature. We found that industrial cost-models are applicable only with distinct limitations, but–unlike the test-yield model–they offer consistent solutions. On the basis of the field study and the opinions of experts, we adjusted the control strategy to account for inadequacies in the theoretical models. The combined result is that, for effective operation, the number of samples between controls may reach values up to 100 and should not require controls more often than every 30 samples on comparable multichannel analyzers. For adequate statistical performance, a simple 3-SD Shewhart chart usually requires not more than two controls of the same material at each time.
Accurate measurement of cholecystokinin in plasma
Authors: Rehfeld Jens F 
Published: January 2020

AbstractShortage of reliable plasma assays has hampered studies of cholecystokinin (CCK). The assay problems are low plasma concentrations, extensive molecular heterogeneity, and close homology of CCK to gastrin, which circulates in higher concentrations. To develop an accurate CCK RIA, antibodies were raised in rabbits, guinea pigs, and mice in titers from 200 to 4 000 000. The specificity of the antisera was tested with homologous peptides, and tissue and plasma extracts. Rabbit 92128 produced antibodies in high titer (≥500 000) with sufficient avidity (K \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(_{eff}^{{^\circ}}\) \end{document} ≥ 1012 mol−1) and the desired specificity. The antiserum binds the bioactive forms of CCK with equimolar potency and displays no reactivity with gastrin. CCK concentrations in plasma from healthy humans rose from 1.13 ± 0.10 pmol/L (mean ± SE, n = 26) to 4.92 ± 0.34 pmol/L after a mixed meal. Chromatography of human plasma revealed traces of CCK-58, a predominance of CCK-33 and CCK-22, and moderate amounts of CCK-8. The results show that it is possible to produce specific CCK-antisera using a sulfated CCK-12 analog.
Quantification of prostate-specific antigen mRNA by coamplification with a recombinant RNA internal standard and microtiterwell-based hybridization
Authors: Verhaegen Monique , Ioannou Pinelopi C , Christopoulos Theodore K 
Published: January 2020

Abstract
We report a quantitative analytical methodology for prostate-specific antigen (PSA) mRNA, which is based on the coamplification of the target with a recombinant RNA internal standard (IS) using reverse transcriptase-polymerase chain reaction. PSA mRNA and the RNA IS contain the same primer recognition sites and generate amplification products that have identical sizes but differ in a 24-bp sequence located in the center of the molecule. Amplified sequences are labeled with biotin using a biotinylated upstream primer. The products are captured on streptavidin-coated microtiter wells and hybridized to specific probes labeled with the hapten digoxigenin. The hybrids are determined using alkaline phosphatase-labeled anti-digoxigenin antibody and time-resolved fluorometry. The ratio of the fluorescence values obtained for the PSA mRNA and the RNA IS is a linear function of the amount of PSA mRNA present in the sample. Samples containing total RNA from PSA-expressing cells (LNCaP cells) in addition to 1 μg of RNA from healthy cells give fluorescence ratios related linearly to the number of cells in the range of 4 to 3000 cells.
Urokinase plasminogen activator: a prognostic marker in breast cancer including patients with axillary node-negative disease
Authors: Duffy Michael J , Duggan Catherine , Mulcahy Hugh E , McDermott Enda W , O’Higgins Niall J 
Published: January 2020

Abstract
Urokinase plasminogen activator (uPA) is a serine protease causally involved in cancer invasion and metastasis. In this study, high concentrations of uPA in primary breast cancers were independently associated with both a shortened disease-free interval and overall survival. For the disease-free interval as endpoint, uPA was a stronger indicator of outcome than lymph node status, whereas for overall survival, nodal status was stronger than uPA. In patients without metastasis to axillary nodes, uPA was also an independent prognostic marker, using both the disease-free interval and overall survival as end points. In contrast to uPA, neither tumor size nor estrogen receptor status was prognostic in the node-negative patients. Measurement of uPA concentrations might thus be of value in selecting the more aggressive subpopulation of node-negative breast cancer patients that could benefit from adjuvant therapy.
Detection and identification of monoclonal gammopathies by capillary electrophoresis
Authors: Henskens Yvonne , de Winter John , Pekelharing Maurits , Ponjee Gabrielle 
Published: January 2020

Abstract
Capillary electrophoresis (CE) and immunosubtraction capillary electrophoresis (IS-CE) were compared with the conventional methods agarose gel electrophoresis (AGE) and immunofixation electrophoresis (IFE) for detection and identification of paraproteins. In total, 74 paraproteins out of 468 serum samples were detected by both methods. Seventy-three monoclonal bands with concentrations ranging from 0.6 to 50.9 g/L were detected by the routine method. With CE, 70 paraproteins were detected and quantified on the electropherogram. Four paraproteins were not detected by CE; three of these were IgG (0.6, 1.1, and 2.2 g/L, respectively), and one was a IgM paraprotein (20.3 g/L) that could be visualized by minor changes in the running conditions. In comparison with IFE, 69 paraproteins were typed identically using IS-CE; only one paraprotein (IgMκ, 14.9 g/L) could not be identified. On the other hand, a monoclonal IgA band that had not been detected by AGE was identified by CE and IS-CE. We conclude that, in general, CE could be a useful method for detection of paraproteins and that IS-CE is a good alternative to IFE. Additional studies are required to investigate the ionic strength and pH of the running buffer, because these prove to be the most crucial factors for routine CE separation of paraproteins.
Comparison of the Axis %CDT TIA and the CDTect method as laboratory tests of alcohol abuse
Authors: Viitala Katja , Lähdesmäki Kaija , Niemelä Onni 
Published: January 2020

Abstract
Carbohydrate-deficient transferrin (CDT) has been suggested as a specific marker of alcohol abuse. We designed this study to compare the conventional CDTect method (Pharmacia & Upjohn) and the new semiautomated Axis %CDT turbidimetric immunoassay (%CDT TIA) for their diagnostic performance to identify problem drinking. The sensitivities of the %CDT TIA and CDTect for correctly classifying heavy drinkers (n = 90) were 29% and 59% with the thresholds currently recommended by the manufacturers, respectively. In the control group (n = 114), which included hospitalized patients with abnormal serum transferrin concentrations, the CDTect assay gave 21 false-positive values (18%), whereas the %CDT TIA showed 100% specificity. With the cutoff limits based on the present healthy control group (mean + 2 SD), the sensitivities of the %CDT TIA and CDTect were 61% and 86%, respectively. For men, the ROC plot area of the CDTect results in comparisons of alcohol abusers and healthy controls was significantly (P &lt;0.05) higher than that of the %CDT TIA results, whereas for women, there was no significant difference in this respect. The slope and intercept (with 95% confidence intervals) for linear regression between CDTect and %CDT TIA were 0.13 (0.12–0.15) and 1.16 (0.73–1.59), respectively (Sy‖x = 1.51, r = 0.744). CDTect results correlated positively with serum transferrin (r = 0.224, P &lt;0.001), whereas the %CDT TIA results showed a slight inverse correlation with serum transferrin (r = −0.132, P = 0.07). The data suggest that CDTect is more sensitive than %CDT TIA in detecting drinking problems. However, the %CDT TIA method yields more specificity when analyzing samples from patients with high serum transferrin concentrations.
Novel immunoassay for the measurement of complexed prostate-specific antigen in serum
Authors: Allard W Jeffrey , Zhou Zeqi , Yeung Kwok K 
Published: January 2020

Abstract
Serum prostate-specific antigen (PSA) is an effective diagnostic tool for detection of prostate cancer (CaP) at an early and potentially curable stage, but specificity is low. Studies have shown that the proportion of serum PSA complexed with α-1-antichymotrypsin (ACT) is higher in men with CaP than in men with benign prostate disease. We developed a novel immunoassay for complexed PSA based on the unique binding properties of a monoclonal antibody that fails to bind free PSA in the presence of antibodies specific for free PSA. The assay measured mixtures of free and complexed PSA accurately, and the measured values of free + complexed PSA in artificial mixtures and in patient sera were equivalent to the measured value of total PSA. Both the serum concentration and the proportion of complexed PSA was substantially higher in patients with CaP compared with patients with benign prostate disease. The cPSA assay may have utility in improving specificity in screening for prostate cancer.
Determination of monoethylglycinexylidide by fluorescence polarization immunoassay in highly icteric serum samples: modified precipitation procedure and HPLC compared
Authors: Schütz Ekkehard , Shipkova Maria , Niedmann Paul Dieter , Wieland Eberhard , Armstrong Victor William , Oellerich Michael 
Published: January 2020

AbstractHyperbilirubinemia, which frequently occurs in severe liver disease, interferes with the fluorescence polarization immunoassay (FPIA) monoethylglycinexylidide (MEGX) assay manufactured by Abbott Diagnostics. Because the MEGX test is particularly helpful in this clinical situation, strategies have been developed to overcome this problem. Precipitation of serum with the Abbott Digoxin II precipitation reagent eliminates bilirubin. Therefore, we compared FPIA results after precipitation of 81 icteric samples from 27 MEGX tests to results obtained using a validated HPLC method. The precipitation did not substantially alter the performance characteristics of FPIA: detection limit, 8 μg/L; between-days imprecision, 5.3–6.2%; recovery, 102–104% (50–200μg/L). This pretreatment of serum did not eliminate all interference, and only a poor correlation was observed between serum MEGX concentrations measured with HPLC or modified FPIA (r2 = 0.46; Sy‖x = 20.0 μg/L). In contrast, MEGX formation values calculated by subtraction of the prelidocaine MEGX concentration were in close agreement (r2 = 0.98; Sy‖x = 2.3 μg/L). Because only MEGX formation is clinically relevant, this modified FPIA procedure offers a simple and rapid alternative to HPLC.
Validation of the Point-EXACCT method in non-small cell lung carcinomas
Authors: Somers Veerle A M C , Leimbach Darcy A , Theunissen Paul H M H , Murtagh James J , Holloway Brian , Ambergen Anton W , Thunnissen Frederik B J M 
Published: January 2020

Abstract
K-ras point mutations are often detected in part of the lung carcinomas. For the validation of a highly sensitive and rapid assay for known point mutations, Point-EXACCT (Biochim Biophys Acta 1998; 1379:42–52), we analyzed 89 non-small cell lung carcinomas and compared the results with two sequencing methods. No point mutations were found with double-stranded sequencing. Single-stranded sequencing detected six patients positive for K-ras codon 12. When Point-EXACCT was used, K-ras codon 12 mutations were detected in 8 of 52 patients with squamous cell carcinomas, 10 of 29 patients with adenocarcinomas, and 3 of 8 patients with large cell carcinomas. The finding of K-ras mutations in squamous cell carcinomas is explained by the high sensitivity of the method. Therefore, Point-EXACCT may be applicable to detection of those alterations occurring at a low frequency among an excess of cells with wild-type DNA.
Comparison of seven immunoassays for the quantification of CA 125 antigen in serum
Authors: Davelaar Elvira M , van Kamp Gerard J , Verstraeten Rob A , Kenemans Peter 
Published: January 2020

Abstract
Seven CA 125 immunoassays were compared for their clinical performance. CA 125 concentrations were determined in 289 serum samples obtained from women with benign pelvic tumors (samples from 98 patients) and patients with various cancers (samples from 111 patients). In the range of 0–1000 kilounits/L, all assays tested were linearly correlated, with correlation coefficients ranging from 0.89 to 0.99. In relation to the original Centocor CA 125 assay, there was an overall tendency to measure higher absolute values in the lower CA 125 value range. This was not seen in relation to the Centocor CA 125 II assay. ROC curves (benign vs pretreatment ovarian cancer patients) were nearly identical for all assays, and the areas under the ROC curves were not markedly different. We conclude that the CA 125 assays tested are strongly related to each other and are clinically reliable for the quantification of serum CA 125 and that none of the assays offers higher diagnostic accuracy or better discrimination between patient groups, especially not in the lower ranges.
Human cholesteryl ester transfer protein measured by enzyme-linked immunosorbent assay with two monoclonal antibodies against rabbit cholesteryl ester transfer protein: plasma cholesteryl ester transfer protein and lipoproteins among Japanese hypercholesterolemic patients
Authors: Sasai Kanna , Okumura-Noji Kuniko , Hibino Takeshi , Ikeuchi Reiko , Sakuma Nagahiko , Fujinami Takao , Yokoyama Shinji 
Published: January 2020

AbstractPlasma cholesteryl ester transfer protein (CETP) concentrations were measured in Japanese subjects by an ELISA with two different monoclonal antibodies that were raised against rabbit CETP and cross-reacted against human CETP. Among 63 patients who consecutively underwent coronary angiography, the plasma CETP of 37 patients with luminal stenosis ≥50% in their coronary arteries was not significantly different from that of the 26 patients with luminal stenosis &lt;50%. No other lipoprotein-related measurement except HDL-cholesterol differentiated the two groups. Among 40 hypercholesterolemic patients, no lipoprotein-related measurement other than LDL-cholesterol was found to positive correlate with the CETP. Before and after the treatment of 23 patients with simvastatin 5 mg a day for 4 weeks, plasma CETP markedly decreased in those whose pretreatment CETP was ≥3 mg/L; no change was observed for those with lower pretreatment CETP. In the former group, negative correlation between CETP and HDL-cholesterol was demonstrated only in the posttreatment plasma.
Radioreceptor assay of an endothelin A receptor antagonist in plasma and urine
Authors: Cernacek Peter , Franchi Luigi , Dupuis Jocelyn , Rouleau Jean-Lucien , Levy Mortimer 
Published: January 2020

Abstract
Orally active nonpeptide antagonists of endothelin (ET) receptors may prove beneficial in the treatment of cardiovascular and renal disease. The pharmacodynamics and pharmacokinetics of these drugs are not sufficiently known, and practical methods for their analysis have not been developed. We describe a simple, sensitive, and reproducible radioreceptor assay (RRA) for LU135252, a selective antagonist of the ETA receptor, using porcine aortic smooth muscle membranes as the acceptor and 125I-endothelin-1 as the ligand. With methanol extraction of plasma and urine samples, recovery of LU135252 ranged from 79% to 91% at 60–1000 nmol/L. The logit-log transformed calibration curves constructed with LU135252 added to plasma or to urine were linear (r = 0.993 ± 0.005, n = 11) in the range from 18.7 to 2400 nmol/L. The detection limit with plasma- and urine-based calibration curves was 19 nmol/L. The interassay coefficient of variation was 12.6% at 70 nmol/L (n = 9) and 6.5% at 590 nmol/L (n = 9). Endothelin-1 did not interfere in the RRA at pathophysiologically and clinically relevant concentrations [up to 15 pmol/L (40 pg/mL)]. When LU135252 was added to plasma, the signal was completely stable after storage for 1 week at 4 °C, although there was a modest loss of the signal after 24 h at room temperature. The practical performance of this RRA was then tested in plasma samples obtained from (a) rats after a single oral administration of LU135252, (b) from coronary-ligated rats chronically treated with LU135252, and (c) in plasma and urine samples obtained from dogs during intrarenal infusion of LU135252.