bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation between lipoprotein(a) concentrations in patients with acute-phase response and risk analysis for coronary heart disease
Authors: Min Won-Ki , Lee Jae Ok , Huh Jung Won 
Published: January 2020

AbstractThis study investigated whether lipoprotein(a) [Lp(a)] is an acute-phase reactant that can cause important bias in risk factor analysis for coronary heart disease among patients with an acute-phase response (APR patients). To determine whether serum Lp(a) concentrations increase among APR patients, we compared the Lp(a) concentrations and apolipoprotein(a) [apo(a)] phenotypes of 100 controls with those of a random sampling of 100 APR patients. Serum Lp(a) concentration was measured by ELISA; Lp(a) phenotyping was performed by electrophoresis on sodium dodecyl sulfate–polyacrylamide gel. Lp(a) was significantly (P &lt;0.0001) higher among APR patients (mean ± SD 0.300 ± 0.284 g/L) than among controls (0.118 ± 0.193 g/L) even though the distribution of apo(a) phenotypes did not differ significantly. The 100 APR patients were grouped into 4 categories: 48 patients with infections, 25 postoperative patients, 17 patients with tumors, and 10 patients with other diseases, all of whom showed substantially higher Lp(a) values than did the controls. For the S5, S4S5, S5S5, and S4 phenotypes, the mean concentrations of serum Lp(a) were substantially higher among the APR patients.
Candidate reference methods for hemoglobin A1c based on peptide mapping
Authors: Kobold Uwe , Jeppsson Jan-Olof , Dülffer Thomas , Finke Andreas , Hoelzel Wieland , Miedema Kor 
Published: January 2020

AbstractA reference method that specifically measures hemoglobin (Hb) A1c is an essential part of the reference system for the international standardization of Hb A1c/glycohemoglobin. We have developed a new method for quantification, based on the specific N-terminal residue of the hemoglobin β-chains. Enzymatic cleavage of the intact hemoglobin molecule with endoproteinase Glu-C has been optimized to obtain the β-N-terminal hexapeptides of Hb A1c and Hb A0. These peptides have been separated by reversed-phase HPLC and quantitated by electrospray ionization-mass spectrometry (method A) or by capillary electrophoresis (method B). With these peptides and hyphenated separation techniques, it has been possible to overcome the insufficient resolution of currently used protein separation systems for Hb A1c.
Assessment of monoethylglycinexylidide as measure of liver function for patients with chronic viral hepatitis
Authors: Elin Ronald J , Fried Michael W , Sampson Maureen , Ruddel Mark , Kleiner David E , DiBisceglie Adrian M 
Published: January 2020

Abstract
The liver metabolizes lidocaine by oxidative deethylation to form monoethylglycinexylidide (MEGX), an analyte proposed as an index of liver function. We determined MEGX and lidocaine serum concentrations with the TDx (Abbott Laboratories) at baseline and 15, 30, 60, and 90 min after the intravenous administration of lidocaine (1 mg/kg), analyzing specimens from 12 apparently healthy volunteers and 40 patients with chronic viral hepatitis diagnosed by liver biopsy and serum tests. The patients were grouped on the basis of the histology activity index. The following laboratory tests were performed on serum specimens from all subjects: albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, total bilirubin, and prothrombin time. The results showed no significant difference among the four groups for the concentrations of MEGX, lidocaine, and lidocaine/MEGX at the four time points. However, the concentrations of ALB, ALT, AST, AST/ALT, and prothrombin time were substantially different among the four groups. Thus, we conclude that assay of MEGX in our patients with chronic viral hepatitis did not contribute to the assessment of liver function when compared with apparently healthy volunteers and traditional tests of liver function.
Graphical interpretation of analytical data from comparison of a field method with a Reference Method by use of difference plots
Authors: Petersen Per Hyltoft , Stöckl Dietmar , Blaabjerg Ole , Pedersen Bent , Birkemose Erling , Thienpont Linda , Lassen Jens Flensted , Kjeldsen Jens 
Published: January 2020

Abstract
Various viewpoints have been offered regarding the appropriate use of scatter plots or difference plots (bias plots or residual plots) in comparing analytical methods. In many of these discussions it seems the basic concepts of identity (within inherent imprecision) and acceptability based on analytical goals (analytical quality specifications) have been forgotten. With the increasing number of Reference Methods in laboratory medicine, these basic concepts are becoming more important in validation of field methods. Here we describe a simple and effective graphical test of these hypotheses (identity and acceptability) by use of difference plots. These plots display the underlying hypothesis before the measured differences are plotted and allow interpretation of the results according to specific criteria. We further describe simple but effective interpretations of the data, when the hypothesis is not fulfilled, by using two data sets drawn from comparisons of field methods for S-creatinine with a Reference Method for this analyte. The difference plot is a graphical tool with related simple statistics for comparison of a field method with a Reference Method, focusing on (a) identity within the inherent analytical imprecision or (b) acceptability within analytical quality specifications. Calculation of the standard deviation of the differences is an indispensable tool for evaluation of aberrant-sample bias (matrix effects).
Evidence that serum NTx (collagen-type I N-telopeptides) can act as an immunochemical marker of bone resorption
Authors: Clemens J Daniel , Herrick Michael V , Singer Frederick R , Eyre David R 
Published: January 2020

AbstractPrevious studies have shown that immunoassay of urinary NTx (cross-linked N-telopeptides of type I collagen) provides a responsive index of human bone resorption. Here we report by a sensitive immunoassay that NTx is present in serum and is suppressed appropriately in patients with Paget disease of bone by bisphosphonate antiresorptive therapy. The monoclonal antibody (1H11) developed against urinary NTx was applied in a sensitive chemiluminescence format. Results for human serum and urine showed parallel inhibition curves. The NTx concentrations in paired serum and urine samples from individual patients correlated well when urinary concentrations were normalized to creatinine concentrations (in premenopausal and postmenopausal women and Paget disease patients, r = 0.90, n = 60). The percentage of NTx suppression from baseline values for Paget disease patients on bisphosphonate therapy was similar for serum and urine. Blood samples drawn from bone marrow at the site of Pagetic lesions in three patients with active disease had as much as 10-fold higher concentrations of NTx than did peripheral blood samples drawn at the same time. The latter finding is consistent with other evidence showing that immunoreactive NTx originates directly during the proteolytic cleavage of bone collagen by osteoclasts rather than, e.g., by degradative processes occurring later in the liver and kidney.
Rapid detection of 21-hydroxylase deficiency mutations by allele-specific in vitro amplification and capillary zone electrophoresis
Authors: Carrera Paola , Barbieri Anna Maria , Ferrari Maurizio , Righetti Pier Giorgio , Perego Marilena , Gelfi Cecilia 
Published: January 2020

Abstract
A quick diagnosis of the classic form of 21-hydroxylase deficiency (simple virilizing and salt wasting) is of great importance, especially for prenatal diagnosis and treatment in pregnancies at risk. A method for simultaneous detection of common point mutations in the P450c21 B gene is here proposed by combining a nested PCR amplification refractory mutation system (ARMS) with capillary zone electrophoresis (CZE) in sieving liquid polymers. In the first PCR, B genes are selectively amplified. In the nested reaction, ARMS-detected wild-type and mutated alleles are separately pooled and resolved by CZE. CZE is performed in coated capillaries in the presence of 30 g/L hydroxyethyl cellulose in the background electrolyte for size separation of the DNA analytes. For high-sensitivity detection the electrophoresis buffer contains the fluorescent dye SYBR Green I. Laser-induced fluorescence detection is obtained by excitation at 488 nm and signal collection at 520 nm. Specificity and reproducibility of the protocols were established by using samples from 75 Italian families with 21-hydroxylase deficiency already genotyped by allele-specific oligonucleotide hybridization or direct sequencing. Whereas dot-blot is time consuming because of the high number of hybridizations with radioactive probes, this present protocol is more rapid, giving sufficient separation on CZE after PCR reactions without preconcentration or desalting of samples.
Capillary isoelectric focusing and high-performance cation-exchange chromatography compared for qualitative and quantitative analysis of hemoglobin variants
Authors: Mario Nathalie , Baudin Bruno , Aussel Christian , Giboudeau Jacqueline 
Published: January 2020

Abstract
We have developed two assays for complete analysis of hemoglobins (Hbs) in the field of hemoglobinopathies: a high-performance cation-exchange liquid chromatography (HPLC) assay on the weak cation-exchanger Poly Cat A and a two-step capillary isoelectric focusing (CIEF) assay on the neutral-coated capillary from Beckman in a narrow pH gradient. The resolution was satisfactory for both HPLC and CIEF and allowed separation of normal and common abnormal Hbs, i.e., Hb A, Hb F, Hb A2, Hb S, Hb C, and Hb E; slight differences were shown for the resolution of unusual variants such as Hb C-Harlem and Hb D-Punjab. The reproducibility of retention times was satisfactory as well for HPLC (CV 3.3%) and CIEF (CV 4.9%). The imprecision of quantification of Hb A2, evaluated at two concentrations, and of Hb F and Hb S was &lt;5%, except for low concentrations of Hb A2quantified by CIEF. Quantitative data obtained for these three Hb forms were highly correlated between the two assays. These results suggest that the new CIEF assay can be competitive with HPLC for complete routine analysis of Hb variants.
Biological variation of International Normalized Ratio for prothrombin times, and consequences in monitoring oral anticoagulant therapy: computer simulation of serial measurements with goal-setting for analytical quality
Authors: Kjeldsen Jens , Lassen Jens Flensted , Petersen Per Hyltoft , Brandslund Ivan 
Published: January 2020

Abstract
Oral anticoagulant therapy (OAT) has a well-established efficacy in prophylaxis and treatment of thromboembolic disorders. Because complications are related to intensity of OAT, optimal control of treatment is mandatory. In studies of OAT, as many as 30% of International Normalized Ratio (INR) measurements for prothrombin times fall outside the therapeutic interval. Preanalytical, analytical, and biological variation all contribute to this. Computer simulations of serial INR measurements were performed for various assumed in-treatment setpoints within the therapeutic interval INR 2.0–3.0 and for an “in-treatment within-subject variation” (CV) of 10.1%. Results are presented in difference plots with therapeutic intervals and critical differences. If the in-treatment setpoint is mid-interval (INR = 2.5), only 5% of simulated INR values fall outside the therapeutic interval. Setpoints deviating from the mid-interval and increases in the in-treatment within-subject variation considerably increase the number of observations outside the therapeutic interval and the critical differences. In conclusion, random variation, biological or analytical, and setpoints (targets) deviating from mid-interval explain a substantial number of the INR values outside therapeutic intervals observed in clinical studies. Analytical imprecision should be kept &lt;5% and analytical bias &lt;±0.2 INR.
Sensitive and specific cytokeratin 18 reverse transcription-polymerase chain reaction that excludes amplification of processed pseudogenes from contaminating genomic DNA
Authors: Tschentscher Peter , Wagener Christoph , Neumaier Michael 
Published: January 2020

Abstract
Processed pseudogenes of residual contaminating genomic DNA interfere with a sensitive detection of cytokeratin 18 (CK18) mRNA by reverse transcription and polymerase chain reaction (RT-PCR). This may cause false-positive results when CK18 mRNA is used as a marker for ectopic tumor cells in specimens from cancer patients. To establish a sensitive CK18 RT-PCR by excluding the amplification of processed pseudogenes, the following strategy was chosen: (a) CK18 pseudogene sequences were cloned from genomic DNA by PCR; (b) cDNA-specific primers were designed on the basis of mismatches between pseudogenes and cDNA; (c) PCR conditions were adjusted to reach maximum sensitivity and specificity. Epithelial cells (1–10) could be detected in 1 mL of blood. Among the numerous CK18 genes homologous to the transcribed gene, at least two different processed pseudogenes exist that are highly homologous to each other and to the exons of the transcribed CK18 gene.
Single-strand conformation polymorphism analysis to detect p53 mutations: characterization and development of controls
Authors: Welsh Judith A , Castrén Katariina , Vähäkangas Kirsi H 
Published: January 2020

Abstract
Single-strand conformation polymorphism (SSCP) analysis is widely used to prescreen mutations in p53 gene. However, standardization of SSCP to detect p53 mutations has rarely been pursued so far. We have developed complete conditions for a temperature-controlled nonradioactive SSCP for mutation detection in amplified p53 exons 4-8, where mutations frequently occur in human tumors. Easily obtainable and clearly distinguishable positive controls were developed by replacing the regular 5′ primers in amplification with primers that include one to three mutated sites. Careful purification of the amplified products by gel electrophoresis appeared to be essential. The efficiency of the method was studied by using previously sequenced samples with p53 mutations and the various positive controls. The use of two temperatures (exon 4: 4 °C and 15 °C; other exons: 4 °C and 20 °C) in combination with other optimized conditions resulted in 98% efficiency in mutation detection, which was considered sufficient for routine screening.
Double-monoclonal immunofluorometric assays for pregnancy-associated plasma protein A/proeosinophil major basic protein (PAPP-A/proMBP) complex in first-trimester maternal serum screening for Down syndrome
Authors: Qin Qiu-Ping , Christiansen Michael , Oxvig Claus , Pettersson Kim , Sottrup-Jensen Lars , Koch Claus , Nørgaard-Pedersen Bent 
Published: January 2020

Abstract
Four double-monoclonal time-resolved immunofluorometric assays (TrIFMAs) have been developed for the specific determination of pregnancy-associated plasma protein A/proeosinophil major basic protein (PAPP-A/proMBP) complex in first-trimester maternal serum samples. The assays have a functional sensitivity of &lt;4 mIU/L and a working range from 4 to 1000 mIU/L. These 4 assays, together with a polyclonal sandwich TrIFMA, were compared for their ability to discriminate between normal pregnancies (n = 149) and pregnancies carrying a Down syndrome fetus (n = 36) in maternal serum screening samples from gestational weeks 4–13. In 26 Down syndrome pregnancies from gestational weeks 7–12, the median PAPP-A multiples of the median concentration in controls (MoMs) determined by monoclonal antibody combinations 234–3/234–2*, 234–4/234–2*, 234–4/234–5*, and 234–5/234–6* were 0.35, 0.37, 0.42, and 0.44, respectively, whereas the median MoM determined by the polyclonal assay was 0.56. ROC curve analysis also showed that better overall diagnostic accuracy and detection rates were achieved by the monoclonal TrIFMAs than by the polyclonal TrIFMA. This report is the first to describe assays that specifically measure PAPP-A/proMBP complex without possible interference from other proMBP-containing complexes.
Differential reactivity of cardiac and skeletal muscle from various species in a cardiac troponin I immunoassay
Authors: O’Brien Peter J , Landt Yvonne , Ladenson Jack H 
Published: January 2020

AbstractTo identify a blood test that can differentiate cardiac from skeletal muscle injury in animals, we compared tissue reactivities for various species with the use of an immunoassay for human cardiac troponin I (cTnI). Tissue reactivity varied as a function of the homology of tissue troponin with human cTnI. Cardiac reactivity in large mammals was equivalent to cTnI, 9.8 ± 0.6 mg/g, and was 2-fold, 10-fold, and 100-fold greater than in small mammals, birds, and fish, respectively. Skeletal muscle reactivity was equivalent to cTnI, 5.1 ± 0.6 μg/g, in all species except fish, in which it was 50% lower. The ratio of reactivities of cardiac and skeletal muscle was: 1800 in large mammals, 1100 in small mammals, 230 in birds, and 43 in fish. We conclude that cTnI is a powerful candidate in mammals, a possible candidate in birds, but unlikely to be of use in fish as a sensitive and tissue-selective diagnostic test for cardiac injury.
Apolipoprotein B and AI distributions in the United States, 1988–1991: results of the National Health and Nutrition Examination Survey III (NHANES III)
Authors: Bachorik Paul S , Lovejoy Kathleen L , Carroll Margaret D , Johnson Clifford L 
Published: January 2020

AbstractSerum apolipoproteins (apo) B and AI were measured in a probability sample of the noninstitutionalized US civilian population, ages ≥4 years, which included non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. Apo B concentrations were the same in males and females, lower in black males than in other males, low in childhood (∼0.80 g/L) and increasing to ∼1.2 g/L in adults, and higher in younger women on hormones. Apo AI was higher in females than males, higher in blacks than in others, remained constant from childhood to adulthood (∼1.35 g/L) in males, but increased with age (∼1.30 g/L to ∼1.55 g/L) in females, and was higher in women taking hormones. These are the first national probability estimates of apo B and apo AI in the US and are referable to the WHO-IFCC First International Reference Materials for apo AI and B.
Low plasma vitamin A concentrations in familial combined hyperlipidemia
Authors: Ribalta Josep , LaVille Agnes E , Girona Josefa , Vallvé Joan C , Masana Lluís 
Published: January 2020

AbstractAs many as 20% of the survivors of acute myocardial infarction present with the heritable form of hyperlipidemia, termed familial combined hyperlipidemia (FCHL). Some of the genes reported to be involved in this disorder, such as those for lipoprotein lipase (LPL) and apolipoprotein (apo) C-III, are controlled by a peroxisome proliferator-activated receptor (PPAR)/retinoic acid receptor X (RXR) regulatory system, which is retinoic acid dependent. If, as we hypothesized, the availability of retinoic acid or its precursor retinol (vitamin A) could be altered in FCHL, this could help explain some aspects of the phenotypic expression of the disease. We therefore measured plasma retinol concentrations in 30 FCHL subjects and 56 controls. Plasma retinol concentrations in FCHL subjects were significantly lower than that of control subjects (1.96 ± 0.83 μmol/L vs 2.91 ± 1.23 μmol/L, respectively; P &lt;0.0001). This novel finding of significantly decreased concentrations of plasma retinol in FCHL relative to control subjects gives support to the hypothesis that vitamin A might be involved in the expression of this disorder.
Plasma and erythrocyte vitamin E content in asymptomatic hypercholesterolemic subjects
Authors: Simon Emmanuelle , Paul Jean-Louis , Soni Théophile , Simon Alain , Moatti Nicole 
Published: January 2020

AbstractThe present study was designed to assess plasma and erythrocyte vitamin E concentrations in 57 asymptomatic hypercholesterolemic (HC) men compared with 56 normocholesterolemic (NC) men. Vitamin E concentrations were determined by using a reversed-phase HPLC method. Compared with NC subjects, HC men had a significantly lower red blood cell (RBC) vitamin E content in spite of their normal plasma vitamin E concentration. This study demonstrates that total plasma vitamin E concentration is not a suitable predictor of cell vitamin E status and suggests an abnormal transfer of tocopherol between plasma and RBCs in HC men. Moreover, the RBCs of HC men were more susceptible to a peroxidative stress. The strong correlation between RBC susceptibility to oxidation and RBC vitamin E content suggests that the low RBC vitamin E content found in HC men has physiological consequences on the RBC oxidation.
Medians for second-trimester maternal serum α-fetoprotein, human chorionic gonadotropin, and unconjugated estriol; differences between races or ethnic groups
Authors: Benn Peter A , Clive Jonathan M , Collins Roxanne 
Published: January 2020

Abstract
Second-trimester maternal serum α-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are routinely measured in screening fetuses at high risk for Down syndrome or open neural tube defects (ONTD). For test interpretation, individual patient values of these three analytes are related to population-derived median values. We evaluated data from &gt;21 000 pregnancies to determine the extent of race-specific differences in median concentrations. For samples at most gestational ages, median AFP, hCG, and uE3 values for white, black, Hispanic, and other patients were all significantly different. Differences remained significant even when data were corrected for patient weights. For each analyte, the extent of the variation was not the same at different gestational ages. Differences in median values across race/ethnicity groups appear to have only a small impact in Down syndrome screening but it may be appropriate to use alternative sets of AFP medians or adjustment factors to AFP medians for some Asian populations receiving ONTD screening.
Critical difference between serial measurements of CK-MB mass to detect myocardial damage
Authors: de Winter Robbert J , Koster Rudolph W , van Straalen Jan P , Gorgels Jozef P M C , Hoek Frans J , Sanders Gerard T 
Published: January 2020

Abstract
To assess the critical difference in serial measurements of CK-MBmass and the ability of this critical difference to detect myocardial damage, we studied 110 patients in whom an acute myocardial infarction (AMI) had been ruled out. Blood samples were drawn at 3, 4, 5, 6, 7, 8, 12, 16, 20, and 24 h after onset of symptoms. With a critical difference of 72.6%, an increase of &gt;2.0 μg/L between two CK-MBmass measurements was determined to be significant. Twenty-three of the non-AMI patients had an increase in CK-MBmass &gt;2.0 μg/L, but five of these did not have an abnormal concentration of troponin T (i.e., not &gt;0.1 μg/L). Also among the 110 non-AMI patients, 22 did have an abnormal troponin T value, 18 of whom (82%) also had CK-MBmassincreased by &gt;2.0 μg/L. In 20 of the 23 patients with an increase in CK-MBmass &gt;2.0 μg/L, this increase was detected from the values for two samples collected at 5 and 12 h after onset of symptoms. In conclusion, using the critical difference for CK-MBmassdefined as an increase &gt;2.0 μg/L detected myocardial damage in patients without AMI.