bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical performance and clinical usefulness of a commercially available IRMA kit for measuring atrial natriuretic peptide in patients with heart failure
Authors: Clerico A , Iervasi G , Del Chicca M G , Maffei S , Berti S , Sabatino L , Turchi S , Cazzuola F , Manfredi C , Biagini A 
Published: January 2020

Abstract
We evaluated the analytical characteristics and clinical usefulness of a commercially available IRMA kit for measuring plasma concentrations of atrial natriuretic peptide (ANP) in healthy subjects and in patients with heart failure. The method uses two monoclonal antibodies prepared against sterically remote epitopes of the ANP molecule; the first antibody is coated on the solid-phase beads, and the second is radiolabeled with 125I. Fifty-nine healthy subjects and 77 patients with heart failure were studied. After subjects had rested 20 min in a recumbent position, blood samples were collected from a brachial vein into ice-chilled disposable polypropylene tubes containing aprotinin and EDTA. Plasma samples were immediately separated by centrifugation and stored at -20 degrees C until assay. The working range (CV &lt;15%) was 10-2000 ng/L. The detection limit (2.13 +/- 0.91 ng/L) was similar to those reported for other IRMAs but was much better than those of RIAs. For healthy subjects, the results of this method (18.0 +/- 10.6 ng/L, range 4.7-63 ng/L, median 16.7 ng/L, n = 59) were similar to those generally reported for the most accurate methods, i.e., those using preliminary extraction and chromatographic purification of plasma samples. Measured plasma ANP was significantly associated with the severity of clinical symptoms, i.e., NYHA class (ANOVA, P &lt;0.0001), and with the left ventricular ejection fraction (n = 62, r = 0.618, P &lt;0.0001). Patients with severe heart failure showed greatly increased values (NYHA III-IV: 257.4 +/- 196.6 ng/L, n = 23).
Standardization of assay for cytokeratin-related tumor marker CYFRA21.1 in urine samples
Authors: Dittadi R , Barioli P , Gion M , Mione R , Barichello M , Capitanio G , Cocco G , Cazzolato G , De Biasi F , Praturlon S , Antinozzi R , Gianneo E 
Published: January 2020

Abstract
The determination of tumor markers in urine samples has been proposed as an effective diagnostic tool in bladder cancer. The aim of the present investigation was to validate in urine samples the assay of the CYFRA21.1 cytokeratin-related marker, the serum concentrations of which showed promising diagnostic utility in patients with bladder cancer. First-voided urine samples were collected from patients with different malignancies. CYFRA21.1 was assayed with a commercially available enzyme immunoassay (Boehringer Mannheim). Different centrifugation patterns, the use of different buffers and nonionic detergents, and pH variations were evaluated. We demonstrated that: (a) cells and cell debris contain a large amount of CYFRA21.1 and must be eliminated by centrifugation; (b) storage at -20 degrees C causes amorphous precipitate, which may aspecifically bind CYFRA21.1; (c) the latter behavior may be prevented by diluting fresh urine samples with phosphate buffer with nonionic detergent added; (d) pH variations within the range 4.9-8.2 do not significantly affect CYFRA21.1 assay results. Provided that samples are diluted with buffer containing nonionic detergent, the CYFRA21.1 assay showed good precision and accuracy characteristic in urine samples. We therefore propose a standard protocol for the collection of urine samples for CYFRA21.1 assay. In a preliminary clinical evaluation, CYFRA21.1 concentrations in 16 patients with primary bladder cancer were higher than in healthy subjects. In the urine collected in the follow-up of patients treated for bladder cancer, CYFRA21.1 tended to be higher in relapsed patients than in those without evidence of disease. These preliminary data induced us to extend the clinical trial to establish the actual role of this assay in routine use.
Coated-tube radioimmunoassay for C-telopeptides of type I collagen to assess bone resorption
Authors: Bonde M , Fledelius C , Qvist P , Christiansen C 
Published: January 2020

Abstract
We present a coated-tube RIA that is useful for assessment of bone resorption. The assay uses a monoclonal antibody raised against a linear 8-amino-acid sequence (EKAHDGGR) derived from the C-telopeptides of type I collagen. Within-run and total CVs were 4.4% and 5.3-6.2%, respectively, at concentrations of 1-7 mg/L (n = 4-20). Analytical recovery was 98% +/- 8% and dilution 97% +/- 7%. Values obtained in a group of 36 premenopausal women were 227 +/- 89.6 mg/mol creatinine. In a group of 141 postmenopausal women, the values obtained were 429 +/- 225 mg/mol creatinine, a highly significant increase of 89% (P &lt;0.001) over the premenopausal value. In a double-blind placebo-controlled clinical study of these postmenopausal women receiving five different doses of a bisphosphonate, a significant decrease of RIA-measured C-telopeptide values was seen in all bisphosphonate-treated groups, after just 3 months. Values in urine samples from postmenopausal women assayed with the RIA (gamma) and the CrossLaps(TM) ELISA (x) agreed well: slope = 0.98 (95% confidence interval, 0.94-1.01), intercept = 0.34 (0.25-0.43) mg/L, and Sylx = 0.93 mg/L (n = 678). We conclude that this RIA represents a valuable tool for assessing bone resorption.
Metabolite and matrix interference in phenytoin immunoassays
Authors: Rainey P M , Rogers K E , Roberts W L 
Published: January 2020

Abstract
The major phenytoin metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin glucuronide (HPPG), was primarily responsible for the positive bias noted when uremic specimens were assayed with the Abbott TDx Free Phenytoin fluorescence polarization immunoassay. The amount of bias depended on both HPPG and phenytoin concentration, increasing with increases in either concentration. The new Abbott TDx II assays for phenytoin and free phenytoin exhibited no significant cross-reactivity with HPPG and no bias in clinical specimens from uremic patients. Both assays correlated well with Emit-based assays (r &gt;0.98), had CVs of &lt;3.5%, and had minimum detection limits of &lt;0.1 mg/L. Calibration curves were stable for at least 6 weeks. All of the TDx assays cross-reacted with another metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH), but expected HPPH concentrations are too low to cause a clinically significant bias. The Emit-based phenytoin assay exhibited a significant matrix effect when calibrators were prepared in defibrinated plasma processed to resemble serum.
Isotope dilution--mass spectrometric quantification of specific proteins: model application with apolipoprotein A-I
Authors: Barr J R , Maggio V L , Patterson D G , Cooper G R , Henderson L O , Turner W E , Smith S J , Hannon W H , Needham L L , Sampson E J 
Published: January 2020

Abstract
An enzymatic hydrolysis isotope dilution-mass spectrometric method was developed for reference quantification of specific proteins. The analytical procedure involved measuring a reproducibly hydrolyzed peptide (serving as the primary standard) unique to a specific protein. This new mass spectrometric method was evaluated by assessing the concentration of apolipoprotein (apo) A-I in the European Community Bureau of Reference (BCR) lyophilized Certified Reference Material (CRM 393). We used the method to make 96 measurements (4 replicate analyses of 4 enzymatic digests of 6 vials of BCR-CRM 393), which gave an average total protein mass of 1.048 mg (+/- 1.0% at 99% confidence limits). The total overall analytical CV was 3.95%. The results of this evaluation of our model approach to determine the concentration of a specific protein in a purified preparation demonstrated that our new mass spectrometric method can be used to measure apolipoproteins and other specific proteins without the use of epitopic immunoassay methods.
Results of an international round robin for serum and whole-blood folate
Authors: Gunter E W , Bowman B A , Caudill S P , Twite D B , Adams M J , Sampson E J 
Published: January 2020

Abstract
Because of the increasing significance of folate nutriture to public health, a "round robin" interlaboratory comparison study was conducted to assess differences among methods. Twenty research laboratories participated in a 3-day analysis of six serum and six whole-blood pools. Overall means, SDs, and CVs derived from these results were compared within and across method types. Results reported for serum and whole-blood folate demonstrated overall CVs of 27.6% and 35.7%, respectively, across pools and two- to ninefold differences in concentrations between methods, with the greatest variation occurring at critical low folate concentrations. Although results for serum pools were less variable than those for whole-blood pools, substantial intermethod variation still occurred. The overall results underscore the urgent need for developing and validating reference methods for serum and whole-blood folate and for properly characterized reference materials. For evaluating study or clinical data, method-specific reference ranges (established with clinical confirmation of values for truly folate-deficient individuals) must be used.
Comparative sensitivity of cardiac troponin I and lactate dehydrogenase isoenzymes for diagnosing acute myocardial infarction
Authors: Jaffe A S , Landt Y , Parvin C A , Abendschein D R , Geltman E M , Ladenson J H 
Published: January 2020

Abstract
Criteria for the retrospective diagnosis of acute myocardial infarction rely heavily on increases in lactate dehydrogenase (LD) isoenzymes. However, increases of LD isoenzyme activities are not specific for myocardial injury. Recently, increased concentrations of cardiac troponin I (cTnI) have been shown to be highly specific for myocardial damage and to have sensitivity comparable with that of creatine kinase MB isoenzyme for detecting cardiac injury. Furthermore, increases of cTnI persist in plasma for at least several days. The present study was designed to determine the relative sensitivities of cTnI and LD isoenzymes over time for the diagnosis of infarction. The results indicate that cTnI values are at least as sensitive as LD isoenzymes: 90% of patients with myocardial infarction had above-normal concentrations of cTnI on the 4th day after admission to the coronary care unit. Criteria based on cTnI should improve the accuracy of retrospective diagnoses of acute myocardial infarction.
Use of a rapid HPLC assay for determination of pharmacokinetic parameters of ibuprofen in patients with cystic fibrosis
Authors: Rifai N , Sakamoto M , Law T , Galpchian V , Harris N , Colin A A 
Published: January 2020

Abstract
High doses of ibuprofen have been shown to delay the progression of lung disease without serious adverse effects in patients with cystic fibrosis. To be effective, peak ibuprofen concentration of 50 to 100 mg/L has to be achieved. We developed an HPLC assay to rapidly determine plasma ibuprofen concentration. We used this assay to determine the pharmacokinetics of ibuprofen in patients with cystic fibrosis. The assay possessed linearity up to 500 mg/L, sensitivity to 1 mg/L, average recovery of 98%, and run-to-run precision (n = 23) of 3%. Furthermore, the assay proved to be free of interference from 51 medications. Observed time to peak concentration varied significantly between those receiving ibuprofen tablets (mean + SD, 94 +/- 29 min, n = 16) and syrup (30 +/- 0 min, n = 4) (P &lt; 0.0001). We conclude that the method described here is ideal for therapeutic monitoring of ibuprofen.
Frequency of phenotype-genotype discrepancies at the apolipoprotein E locus in a large population study
Authors: Lahoz C , Osgood D , Wilson P W , Schaefer E J , Ordovas J M 
Published: January 2020

Abstract
Apolipoprotein E (apoE) genotypes were determined in a random subset of 1041 subjects enrolled in the Framingham Offspring Study by using DNA amplification followed by restriction isotyping. The results were compared with the apoE phenotypes previously assessed by isoelectric focusing. Discrepancies in apoE allele assignment were found in 98 subjects (9.4%). Both genotype and phenotype were reassessed in these subjects. Genotype misclassification was observed in 20 subjects, whereas the initial phenotype assignment was modified in 46 subjects. No concordance between apoE phenotype and genotype remained in 32 subjects (3.07%). Both methods resulted in similar apoE allele frequencies. Furthermore, no differences were observed regarding the average allelic effect on total cholesterol, LDL cholesterol, or HDL cholesterol concentrations; however, a significant difference was noted on triglyceride concentrations. Our results indicate that most discrepancies between genotype and phenotype assessment of apoE polymorphism were due to sample mishandling, data entry, and technical difficulties rather than true discordances.
Biological variability in serum vitamin E concentrations: relation to serum lipids
Authors: Maes M , Weeckx S , Wauters A , Neels H , Scharpé S , Verkerk R , Demedts P , Desnyder R 
Published: January 2020

Abstract
The components of biological variation in serum vitamin E in relation to serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), apolipoprotein A-I (apo A-I), and apo B were examined in 26 healthy volunteers who had monthly blood samplings during one calendar year. The estimated CVs for vitamin E were: interindividual, 19.9%, and intraindividual, 11.9%; the index of individuality (I-index) was 0.59. The I-indices for all lipid variables were &lt; 0.51. Serum concentrations of vitamin E, cholesterol, triglycerides, HDL-C, LDL-C, and apo B were lower in spring than in the other seasons. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were for vitamin E 14.5%, cholesterol 16.2%, triglycerides 14.5%, and LDL-C 24.3%. A significant common annual rhythm was expressed in vitamin E or lipid variables and in the changes in ambient temperature the weeks before blood sampling (inverse relations). There were highly significant positive time relations between serum vitamin E and cholesterol, triglycerides, and apo B. Subjects with higher homeostatic setpoints of cholesterol showed higher homeostatic setpoints of vitamin E, triglycerides, LDL-C, and apo B.
Problems and practical considerations in assessing accuracy with NIST SRM 909a: report of defective vials
Authors: De B K , Karr B A , Ghosn S , Copeland B E 
Published: January 2020

Abstract
During an experimental period of 12 months in 1992-1993, while we were comparing the effectiveness of monthly vs quarterly use of the National Institute for Standards and Technology Standard Reference Material (NIST SRM) 909a as an accuracy material for the projected 30-year Fernald Medical Monitoring Program, we encountered three random defective vials with a glucose recovery of less than 30% of the NIST-assigned value. Analysis with five different multichannel instruments confirmed the original finding. Concomitant glucose recovery from adjacent vials was 97%-104%, as determined by using the same instruments, reagents, calibrators, and quality-control criteria on the same days. Recoveries of uric acid and cholesterol were also low (53-75% and 75-80%, respectively) in the three defective vials. Other analytes were unaffected. Studies to identify the cause of the defective vials were carried out with microbiological, electron microscopic, and biochemical techniques. When used for accuracy studies, each vial of NIST SRM 909a should have a concomitant check for glucose recovery to detect whether the vial is defective.
Diagnostic value of various serum antibodies detected by diverse methods in childhood celiac disease
Authors: Sacchetti L , Ferrajolo A , Salerno G , Esposito P , Lofrano M M , Oriani G , Micillo M , Paparo F , Troncone R , Auricchio S , Salvatore F 
Published: January 2020

Abstract
The diagnostic performances of antiendomysium IgA detected on monkey esophagus and human umbilical cord smooth muscle, of antireticulin IgA, and of antigliadin IgA and IgG were calculated in 74 children with celiac disease (CD) or other gastrointestinal disorders. We also compared four methods for gliadin antibody detection. With a diagnostic specificity of 100%, diagnostic sensitivity was 94% for antireticulin IgA, 93% for antiendomysium IgA when detected on human umbilical cord smooth muscle, and 97% when detected on monkey esophagus. The diagnostic sensitivity for gliadin antibody was highest with an ELISA procedure, followed by fluorogenic detection (94% for IgG, 91% for IgA, 97% with IgA and IgG combined). Because of its high diagnostic sensitivity and ease and speed of use, the combined antigliadin IgG and IgA antibody assay is suitable for screening large groups of patients. In IgG- or IgA-positive cases, the more demanding and more specific antiendomysium IgA evaluation is required to confirm suspected CD.
Enzymatic deconjugation of erythrocyte polyglutamyl folates during preparation for folate assay: investigation with reversed-phase liquid chromatography
Authors: Pfeiffer C M , Gregory J F 
Published: January 2020

Abstract
Erythrocyte (RBC) folates occur mainly as 5-methyltetrahydrofolate polyglutamates. Determination of RBC folate concentration requires an initial deconjugation of these polyglutamates. In this study, existing HPLC methods were adapted to investigate the rate and extent of this deconjugation process. The action of endogenous plasma pteroyl-polyglutamate hydrolase activity was strongly affected by the conditions of sample preparation, with pH of the incubation mixture more critical to effective deconjugation than incubation time. Dilution of whole blood with 10 g/L ascorbic acid yielded fast hydrolysis of long-chain polyglutamates, and total conversion to 5-methyltetrahydrofolate monoglutamate occurred after 90 min of incubation at 37 degrees C. In contrast, dilution of whole blood with 10 g/L sodium ascorbate, with up to 90 min of incubation at 37 degrees C, yielded a mixture of polyglutamates of 5-methyltetrahydrofolate (glun = 1-8). As documented by direct HPLC analysis and in concurrent assays with Lactobacillus casei, acidification provided by ascorbic acid can have dramatic effects on the measurement of RBC folates.
Development of human renal function: reference intervals for 10 biochemical markers in fetal urine
Authors: Muller F , Dommergues M , Bussières L , Lortat-Jacob S , Loirat C , Oury J F , Aigrain Y , Niaudet P , Aegerter P , Dumez Y 
Published: January 2020

Abstract
Evaluation of fetal renal function by analysis of fetal urine sampled in utero may improve perinatal care after a prenatal diagnosis of bilateral obstructive uropathy. We provide reference intervals for 10 fetal urinary compounds and examine their variation with gestational age. Forty-one fetuses with bilateral obstructive uropathy (urine sampled between 20 and 38 weeks of gestational age) had normal, healthy values for serum creatinine (&lt; or = 50 mumol/L) at ages 1-2 years. These cases were thus assumed to represent a reasonable approximation to healthy values. Sodium and beta 2-microglobulin concentrations significantly decreased with gestational age; calcium, ammonia, and creatinine significantly increased; glucose, phosphorus, chloride, urea, and total protein concentrations did not vary. Our results provide reference values for prenatal evaluation of fetal renal function and suggest that glomerular filtration of macromolecules and tubular reabsorption of glucose and phosphorus are mature by 20 weeks of gestation, whereas tubular reabsorption of sodium and beta 2-microglobulin increases progressively during the second half of gestation.
Highly sensitive ELISA for soluble Fas in serum: increased soluble Fas in the elderly
Authors: Seishima M , Takemura M , Saito K , Sano H , Minatoguchi S , Fujiwara H , Hachiya T , Noma A 
Published: January 2020

Abstract
We have developed and characterized a highly sensitive ELISA for soluble Fas (sFas) in the serum. The linearity of calibrator range was 0.06-2.00 micrograms/L and the detection limit was 0.01 microgram/L. The average within- and between-run CVs were 3.9% and 3.8%, respectively. The recovery of added sFas to serum was 93-118%. The effects of possible interferences (tryglyceride, hemoglobin, bilirubin) were negligible. We determined serum sFas in 155 healthy subjects, ages 20-69. The mean value of sFas in men (2.50 +/- 0.63 micrograms/L, n = 78) was significantly higher than that in women (2.01 +/- 0.53 micrograms/L, n = 77) (P &lt; 0.001). Furthermore, there was a significant correlation between serum sFas concentration and age (men, r = 0.397, P &lt; 0.001; women, r = 0.569, P &lt; 0.001). Although the concentrations of sFas tended to increase with aging, it remains to be clarified how Fas-mediated apoptosis relates to aging.
Importance of standardization of lipase assays by using appropriate calibrators
Authors: Lessinger J M , Dourson J L , Férard G 
Published: January 2020

Abstract
Comparability of lipase catalytic activities was poor when lipase was determined in 50 patients' specimens by a turbidimetric (Boehringer) and a colorimetric (Sigma) assay. Mean values of results differed by a ratio of 2.39. Optimal common conditions were defined for the titration of lipase activity in two commercial calibrators and in a home-purified preparation of human pancreatic lipase (HPL). When using these titers for each calibrator, comparability was greatly improved (ratio = 1.25). This result indicates that a significant part of between-method discrepancy is due to the lack of a reference method for the titration of lipase calibrators. Intermethod behavior of each material was compared with that of patients' specimens. By using HPL as calibrator, comparability was still dramatically improved (ratio = 1.01). This study shows the importance of the validation of a material for defined routine measurement procedures, before its use as calibrator.
Immunofluorometric assay of prostaglandin D synthase in human tissue extracts and fluids
Authors: Melegos D N , Diamandis E P , Oda H , Urade Y , Hayaishi O 
Published: January 2020

Abstract
A two-site sandwich-type assay for human prostaglandin D (PGD) synthase (beta-trace) was developed with two monoclonal antibodies and using time-resolved fluorometry as the detection technique. The assay is precise (CVs &lt; 10%), accurate, and highly specific for PGD synthase and has a detection limit of 0.05 microgram/L. Using this assay, we measured PGD synthase concentrations in serum, urine, amniotic fluid, cerebrospinal fluid (CSF), seminal plasma, breast cyst fluid, breast discharge fluid, breast milk, and breast tumor extracts. The highest concentrations were found in CSF. We identified proteolytic degradation of PGD synthase in amniotic fluid. Fetal tissues contained various amounts of the enzyme, with the highest values being found in brain and heart. In placental extracts, PGD synthase content was greatest at 11-28 weeks of gestation-in accordance with the concentrations measured in amniotic fluids for this gestational period. We conclude that PGD synthase is ubiquitous and is present in many fluids and tissues of adults and fetuses. This first quantitative and sensitive assay of PGD synthase should facilitate expansion of knowledge on this enzyme and possibly will have applications for diagnosis and monitoring of human diseases.