bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid and Sensitive Method for Erythropoietin Determination in Serum
Authors: Tanebe M , Teshima S , Hanyu T , Hayashi Y 
Published: January 2020

Abstract
An enzyme-linked immunosorbent assay (ELISA) method for erythropoietin determination has been established by using two kinds of monoclonal antibodies with specific affinities to erythropoietin. Besides being rapid (2.5 h) and sensitive (detection limit 0.3 int. unit/L), the present method gives accurate results and is easy to perform. The method may be clinically applicable for discriminative diagnosis of polycythemia and analyses of various anemic conditions.
Immunonephelometric Assay of Vitamin D-Binding Protein
Authors: Haughton M A , Mason R S 
Published: January 2020

Abstract
An automated immunonephelometric assay was developed to measure vitamin D-binding protein (DBP) in serum. The assay is described for the Behring Nephelometer System, which uses rabbit anti-DBP antiserum and purified human DBP. The detection limit is 0.05 g/L (0.86 mumol/L), and the working range is less than or equal to 1.60 g/L (27.59 mumol/L). Intra- and interassay CVs of 2.0% and 2.8-3.8% compare favorably with alternative methods. When results were compared with those from a immunoradiometric assay, the correlation coefficient was 0.976 (P less than 0.001), and the regression equation [y = 0.866 +/- 0.085x + 0.05 (Syx = 0.042, n = 42)] identified a negative bias. Analysis indicated that both methods appeared to contribute equally to the bias. Although the assay was relatively free from analytical interference, falsely increased values were noted in severely lipemic specimens and in frozen specimens. Interference may be minimized by inclusion of Supplementary Precipitation reagent in a modified assay protocol. The range of concentrations expected in clinical samples was established from normal subjects [0.32-0.46 g/L (5.52-7.93 mumol/L), n = 28], pregnant subjects [0.51-0.70 g/L (8.79-12.07 mumol/L), n = 13], and subjects with liver diseases [0.12-0.33 g/L (2.07-5.69 mumol/L), n = 18].
Screening Cord Blood for Hemoglobinopathies and Thalassemia by HPLC
Authors: van der Dijs F P , van den Berg G A , Schermer J G , Muskiet F D , Landman H , Muskiet F A 
Published: January 2020

Abstract
We evaluated the use of an HPLC method for screening hemoglobins in cord blood. We studied the genotype frequencies of the structural hemoglobin variants HbS and HbC and the synthesis variants alpha- and beta(+)-thalassemia in babies born on Curaçao. During three months, 67.2% of all (748) newborns were screened: 122 (24.3%) had an abnormal hemoglobin pattern, of which 53 (43.4%) had a hemoglobinopathy (HbS or HbC), 64 (52.2%) had alpha-thalassemia (HbBarts greater than 0.5%, corresponding to heterozygous or homozygous alpha-thalassemia-2), and 5 (4.1%) had a hemoglobinopathy plus alpha-thalassemia. None of the newborns with heterozygous HbS and HbC had concomitant beta(+)-thalassemia. The population genotype frequency of heterozygous alpha-thalassemia-2 was calculated to be 30.7%. The data are in excellent agreement with those previously established for the adult population and those available from the black population in the United States and Jamaica. Based on the HPLC results, we estimate that 67.1% of newborns with heterozygous alpha-thalassemia-2 remain undetected. A coincidental finding was a relation between demonstrable alpha-thalassemia and short gestation. Because of its superior separating power and high sensitivity for quantifying relatively low percentages of hemoglobins in the presence of HbF0, the HPLC method was preeminently suitable for screening cord-blood samples.
Immunofixation to Quantify β2-Transferrin in Cerebrospinal Fluid to Detect Leakage of Cerebrospinal Fluid from Skull Injury
Authors: Zaret D L , Morrison N , Gulbranson R , Keren D F 
Published: January 2020

Abstract
beta 2-Transferrin, the desialated form of transferrin normally found only in cerebrospinal fluid (CSF) and aqueous and vitreous humor, is detected by high-resolution immunofixation (IFE). It is not normally found in nasal or aural fluids, saliva, tears, or serum. Detection in nasal fluid has been suggested to document CSF leakage into the nose after skull injury. We measured beta 2-transferrin in 48 samples of CSF. IFE of the CSF was performed on high-resolution agarose gels and stained with Coomassie Blue. beta 2-Transferrin was estimated by quantifying the total transferrin by rate nephelometry and then determining the percentage of transferrin in the beta 2 vs beta 1 region by densitometric scanning of the IFE pattern. We accurately quantified as little beta 2-transferrin as 2.5 mg/L in the CSF samples. The beta 2-transferrin fraction was clearly visible by IFE at concentrations less than 2.5 mg/L, but accurate quantification was difficult. In the samples assayed, the range of beta 2-transferrin was 4.6 +/- 1.9 mg/L. Use of this technique to examine rhinorrhea in a motor-vehicle-accident patient confirmed leakage of CSF into the nasal cavity through a vent in the left olfactory groove.
Recurrent Transient Hyperphosphatasemia of Infancy in an Adult
Authors: Onica D , Torssander J , Waldenlind L 
Published: January 2020

Abstract
We report a case of recurrent transient hyperphosphatasemia in a 29-year-old man with immune deficiency. He had serum alkaline phosphatase (ALP; EC 3.1.3.1) activity 16.9- and 4.8-fold greater than the upper reference limit on two occasions; the activity returned to normal within 2 months on the first and within 1 month on the second. On both occasions we observed the typical electrophoretic pattern for ALP isoenzymes seen in transient hyperphosphatasemia of infancy. We noted no evidence of liver or bone disease. Recognition of the occurrence of transient hyperphosphatasemia of infancy in adults, although rare (it is the fifth case reported), seems as important as in children so that unnecessary extensive investigations are avoided.
Evaluation of silyl-blocked p-nitrophenylmaltoheptaoside as a substrate for alpha-amylase reagents
Authors: Elbin C S , Becks S , Lepp C A 
Published: January 2020

Abstract
We describe a reagent for measuring alpha-amylase (EC 3.2.1.1) activity in serum with use of a thexyldimethylsilyl ether of p-nitrophenyl-alpha-D-maltoheptaoside (SB7) as substrate. This substrate differs from Genzyme's benzylidene-blocked p-nitrophenylmaltoheptaoside substrate (B-PNPG7). The reagent, optimized for the characteristics of the silyl-blocked substrate, contains 4-(2-hydroxyethyl)-1-piperazineethane sulfonate buffer at pH 7.3, alpha-glucosidase (maltase; EC 3.2.1.20), and glucoamylase (EC 3.2.1.3). Comparison with Ciba Corning Diagnostics Corp.'s, amylase reagent with B-PNPG7 as substrate (x) yielded a regression equation of y = 1.20x-2.7 (r = 0.9997). The linear range exceeded amylase concentrations &gt; 2500 U/L and total precision (CV) was 2.3% at an amylase concentration of 112 U/L with the Ciba Corning 550 Express analyzer. Reconstituted reagent is stable for 30 days at 5 degrees C and 7 days at ambient (18-25 degrees C) temperatures.
A robust strategy for screening and confirmation of familial defective apolipoprotein B-100
Authors: Mamotte C D , van Bockxmeer F M 
Published: January 2020

Abstract
The diagnosis of familial defective apolipoprotein B-100 (FDB) has been facilitated by the use of mutagenic polymerase chain reaction (PCR) primers to introduce restriction sites at the FDB gene locus. We describe a two-test strategy for diagnosing FDB that overcomes the potential for error in single-test methods based on such techniques. We introduce an Sau96I restriction site for PCR products of the normal apolipoprotein B allele. Incomplete digestion of the PCR product with Sau96I suggests an FDB heterozygote, although a false-positive result due to nonideal digestion conditions remains a possibility. In such cases we use a second test that introduces an ScaI restriction site in PCR products of the FDB allele. The diagnosis is confirmed if half of this product can be digested with ScaI. Both tests use 0.25 units of Taq polymerase and are robust with respect to annealing temperature (31-58 degrees C) and to Mg2+ concentration (1.0-3.2 mmol/L).
Cyclosporin G and metabolite binding to cyclophilin and a 50-kDa binding protein related to in vitro immunosuppression
Authors: Donnelly J G , Chen Y , Yatscoff R W , Copeland K R , Palaszynski E W , Soldin S J 
Published: January 2020

Abstract
Seven purified metabolites of cyclosporin G (CsG) were studied for binding to cyclophilin and a 50-kDa binding protein (50-kDa BP). The ratios of the metabolite dissociation constants with respect to CsG were compared with in vitro immunosuppression by using the primary mixed lymphocyte suppression assay. The immunosuppressive potency ratio of the parent compounds, both cyclosporin A (CsA) and CsG, compared favorably with the drug dissociation constants for cyclophilin and the 50-kDa BP. Three of the seven metabolites had comparable binding and potency ratios for the 50-kDa BP. In contrast, none of the seven metabolites appreciably bound to cyclophilin in the concentration range tested.
Proficiency test performance as a predictor of accuracy of routine patient testing for theophylline
Authors: Jenny R W , Jackson K Y 
Published: January 2020

Abstract
Proficiency testing (PT) is pivotal in assessing laboratory qualifications for certification and licensure. PT is expected to typify routine assay performance and determine whether the laboratory is producing clinically useful test results. Conventional schemes use mail-distributed test specimens and are often criticized as measuring the best possible laboratory performance, principally because of special practices associated with processing PT specimens. We used on-site proficiency tests and split samples to evaluate the ability of conventional PT schemes to accurately characterize routine laboratory performance. Using 412 assays of theophylline, performed routinely by 200 laboratories and subsequently in a reference laboratory, we found that the predictive value of PT performance in assessing quality of routine testing was high (100% for predicting substandard reliability of routine patient testing and 94% for excluding substandard reliability of patient testing). The imprecision of interlaboratory PT results was equivalent whether testing was observed (hand-carried specimens) or unobserved (mail-distributed specimens). Many methods used for determining theophylline concentration in serum were highly automated, closed, and precise analytical systems. The performance characteristics of these analytical systems are not easily manipulated by the analyst for purposes of improving PT outcome, and PT by use of mail-distributed test specimens is effective for assessing intralaboratory performance.
Breath acetone analyzer: diagnostic tool to monitor dietary fat loss
Authors: Kundu S K , Bruzek J A , Nair R , Judilla A M 
Published: January 2020

Abstract
Acetone, a metabolite of fat catabolism, is produced in excessive amounts in subjects on restricted-calorie weight-loss programs. Breath acetone measurements are useful as a motivational tool during dieting and for monitoring the effectiveness of weight-loss programs. We have developed a simple, easy-to-read method that quantifies the amount of acetone in a defined volume of exhaled breath after trapping the sample in a gas-analyzer column. The concentration of acetone, as measured by the length of a blue color zone in the analyzer column, correlates with results obtained by gas chromatography. Using the breath acetone analyzer to quantify breath acetone concentrations of dieting subjects, we established a correlation between breath acetone concentration and rate of fat loss (slope 52.2 nmol/L per gram per day, intercept 15.3 nmol/L, n = 78, r = 0.81). We also discussed the possibility of using breath acetone in diabetes management.
Double-label time-resolved immunofluorometric assay of prostate-specific antigen and of its complex with alpha 1-antichymotrypsin
Authors: Leinonen J , Lövgren T , Vornanen T , Stenman U H 
Published: January 2020

Abstract
We have developed a procedure for simultaneous immunofluorometric assay (IFMA) of prostate-specific antigen (PSA) and its complex with alpha 1-antichymotrypsin (ACT). A PSA-specific monoclonal antibody, which captures both free PSA and the PSA-ACT complex, was used as solid-phase antibody. Total PSA immunoreactivity was measured with a Eu(3+)-labeled PSA antibody that reacted with both free PSA and PSA-ACT. PSA-ACT was assayed simultaneously with a Sm(3+)-labeled polyclonal ACT antibody as a tracer. As standard we used pooled serum in which most of the PSA occurred as the PSA-ACT complex. The assay range was 0.03-500 micrograms/L for total PSA and 0.16-450 micrograms/L for PSA-ACT. In comparison with the assay for total PSA, assay of the PSA-ACT/PSA ratio improved the clinical specificity for cancer by reducing the number of false-positive results in prostatic hyperplasia.
Enzyme immunoassay, kinetic microparticle immunoassay, radioimmunoassay, and fluorescence polarization immunoassay compared for drugs-of-abuse screening
Authors: Armbruster D A , Schwarzhoff R H , Hubster E C , Liserio M K 
Published: January 2020

Abstract
The newest formulation of the Syva EMIT assay for drugs of abuse, EMIT II, and a new immunoassay, OnLine (Roche), utilizing the kinetic interaction of microparticles in solution (KIMS) methodology, RIA tests, and TDx fluorescence polarization immunoassay (FPIA) procedures were compared for marijuana, cocaine, opiates, and barbiturates. Both EMIT II and OnLine immunoassays were performed with a Hitachi 717 analyzer. Calibration curves, the degree of separation between negative and cutoff calibrators, precision, likelihood of carryover from positive to negative samples, and overall ease and speed of analysis were evaluated. RIA and OnLine detected 99% of gas chromatography/mass spectrometry (GC/MS)-confirmed marijuana samples; TDx, 95%; and EMIT II, 88%. All four immunoassays detected approximately 99% of confirmed cocaine-positive urines. RIA, OnLine, and TDx all detected 100% of opiate-confirmed samples; EMIT II, 97%. Barbiturate assays exhibited the greatest disparity, with OnLine and TDx detecting 100% of confirmed positives; EMIT II, 88%; and RIA, 78%. For a variety of reasons, we prefer the fully automated EMIT II and OnLine assays for high-volume urine testing, in comparison with our laboratory's semiautomated RIA tests and the limited-throughput TDx system. The four immunoassays investigated delivered comparable performance in terms of detection rates for GC/MS-confirmed positives for some drugs but not for others.
Modified assay of prostate-specific antigen with a detection limit &lt; 0.01 microgram/L
Authors: Liedtke R J , Kroon G , Batjer J D 
Published: January 2020

Abstract
We modified the Hybritech Tandem-E prostate-specific antigen (PSA) assay by increasing the sample volume, increasing enzyme-substrate incubation time, and using diethanolamine buffer. Our modified method has a detection limit of 0.009 microgram/L (P &lt; 0.01). The assay curve is linear from 0.01 to 1.0 micrograms/L and has an overall assay time of about 4 h. Linear plots are obtained when the 1.0 micrograms/L standard is diluted with either matrix buffer or serum from men containing PSA &lt; 0.01 microgram/L. Recovery of PSA (0.10 microgram/L) added to serum from men averaged 94%. Interassay CVs were 13%, 7%, and 4% at PSA concentrations of 0.04, 0.07, and 0.30 micrograms/L, respectively (n = 33). This assay should be useful in the detection of early recurrence of prostate cancer after radical prostatectomy.
Chemiluminescent third-generation assay (Amerlite TSH-30) of thyroid-stimulating hormone in serum or plasma assessed
Authors: Wilkinson E , Rae P W , Thomson K J , Toft A D , Spencer C A , Beckett G J 
Published: January 2020

Abstract
We assessed the laboratory performance and clinical utility of a new commercial third-generation assay of thyroid-stimulating hormone (TSH), Amerlite TSH-30. The interassay CV was 6% at TSH concentrations of approximately 0.08 mIU/L, and the analytical and functional detection limits of the assay were 0.005 and 0.0125 mIU/L, respectively. Although the assay recovered approximately 96% of TSH International Reference Preparation (TSH-IRP) 80/558 added to serum samples, the endogenous TSH concentrations in basal samples were significantly lower than those found by using two other TSH assays; bias data obtained from thyroliberin stimulation tests suggested that the negative bias found with TSH-30 may be due to the heterogeneity of TSH in basal samples. TSH-30 completely discriminated hyperthyroid and hypothyroid patients from euthyroid ambulatory patients but also detected TSH (&gt; 0.0125 mIU/L) in 3 of 46 untreated hyperthyroid patients. Compared with two second-generation assays, TSH-30 better discriminated between patients with subnormal TSH due to hyperthyroidism, thyroxine overreplacement, and nonthyroidal illness but there was still significant overlap between results for these groups.
Iron-deficiency anemia and thalassemia trait differentiated by simple hematological tests and serum iron concentrations
Authors: Jiménez C V 
Published: January 2020

Abstract
The diagnostic value of common hematology tests in differentiating between thalassemia trait and iron-deficiency anemia (IDA) was assessed. Serum iron concentration was included in a second stage of the diagnostic model and its predictive contribution was determined. After applying discriminant analysis to the data, minimization of Wilks's lambda (lambda) criterion was used to select the best predictive variables. A training sample of 754 subjects previously classified as either IDA (428) or thalassemia trait (326) was used to determine the classification rule. When serum iron concentrations were included, the model showed a higher predictive capacity than that constructed from hematological variables only (D = 2.342 RBC - 0.079 Hb + 3.627 log[Fe] - 6.459, where D = discriminant score). The sensitivity, specificity, and diagnostic efficiency associated with this model, as assessed on a control sample of 256 patients (137 thalassemia and 119 IDA), were 94.2%, 91.6%, and 93.0%, respectively. This model, when compared with those of other authors, has the highest diagnostic efficiency.
Colorimetric solid-phase minisequencing assay illustrated by detection of alpha 1-antitrypsin Z mutation
Authors: Harju L , Weber T , Alexandrova L , Lukin M , Ranki M , Jalanko A 
Published: January 2020

Abstract
In solid-phase minisequencing, a defined point mutation is detected in microtiter plate-immobilized DNA by a single nucleotide primer extension reaction. We have here developed the method into a colorimetric assay and applied it to the detection of the Z mutation of the alpha 1-antitrypsin gene. We used novel nucleoside triphosphates modified with dinitrophenyl (DNP) hapten, permitting detection by anti-DNP-alkaline phosphatase conjugate, with p-nitrophenyl phosphate as substrate. The Z mutation is detected in two reactions: DNP-labeled dCTP is incorporated when the template is normal, DNP-dUTP when the Z mutation is present. Both modified nucleotides were incorporated with high specificity and with an efficiency similar to that of unmodified nucleotides. The test results are measured by spectrophotometry, yielding quantitative absorbance values. Calculation of the ratio of C to U signal permitted unambiguous distinction of normal homozygous, ZZ homozygous, and ZM heterozygous genotypes. The colorimetric minisequencing assay is rapid, standardized, and automatable, and thus provides an accurate and simple alternative for the analysis of known point mutations.
Kinetic parameters for the cleaved substrate, and enzyme and substrate stability, vary with the phosphoacceptor in alkaline phosphatase catalysis
Authors: Stinson R A 
Published: January 2020

Abstract
Nine different isoenzymes and (or) isoforms of alkaline phosphatase (ALP; EC 3.1.3.1) from human tissue were studied with respect to Km and Vmax values for p-nitrophenyl phosphate (p-NPP) in seven different potential phosphoacceptors/buffers. Generally, the phosphoacceptors/buffers with the lowest affinity for p-NPP (highest Km values) gave the highest Vmax values; for the nine enzyme forms in this study, the mean Km and Vmax values were greatest in 2-(ethylamino) (EAE). The two amino-propanol buffers gave the lowest Km and Vmax values. The phosphoacceptors/buffers N-methyl-D-glucamine (MEG), diethanolamine, and Tris had intermediate Km and Vmax values. Hydrophilic liver ALP retained &gt; 90% of its activity after 24 h at 30 degrees C in both 1.0 and 0.3 mol/L Tris and 2-amino-2-methyl-1,3-propanediol and in 0.3 mol/L MEG. This isoenzyme showed greatest inactivation upon prolonged exposure to 1.0 and 0.3 mol/L EAE, the activity at 24 h being approximately 50-66% of that at zero time. p-NPP underwent the greatest spontaneous degradation, approximately 2.5 times that of baseline levels, in 1 mol/L MEG. There was little degradation in all of the buffers tested at 0.3 mol/L or in Tris, EAE, and 2-amino-2-methyl-1-propanol at 1.0 mol/L.
Intraindividual variation of glycohemoglobin: implications for interpretation and analytical goals
Authors: Phillipou G , Phillips P J 
Published: January 2020

Abstract
Intraindividual variation (CVi) for glycohemoglobin (GHb) was estimated from serial measurements in patients with diabetes in either stable or variable clinical control. GHb determinations were performed by an affinity column procedure with an analytical imprecision of 4.9% (weighted average; GHb 8.2-14.7%). Within the groups of patients, both a short- (28-32 days) and long-term (approximately 85 days) sampling protocol was used. The derived CVi for each category was 4.2% (n = 16, stable, short-term), 7.1% (n = 23, stable, long-term), 5.1% (n = 13, variable, short-term), and 9.8% (n = 21, variable, long-term). The mean GHb within each category was similar (approximately 11%), and there was no statistically significant difference in GHb values between categories. The results establish that the CVi for GHb is affected by both clinical control and the sampling time interval. These findings have important implications for the estimation of significant differences between serial GHb measurements and the setting of appropriate analytical precision goals.
Competitive solid-phase enzyme immunoassay for melatonin in human and rat serum and rat pineal gland
Authors: Yie S M , Johansson E , Brown G M 
Published: January 2020

Abstract
We describe a solid-phase competitive enzyme immunoassay for determination of melatonin in serum. The detection limit of the assay is 1.0 fmol/well. Low cross-reactivity of the antiserum with other indoles, parallel serum extract dilution and melatonin standard curves, good analytical recovery, and within- and between-assay CVs of 6.4-14.4% provide validation of the assay. Linear regression analysis of melatonin concentrations measured with this assay (y) and with a commercial 3H RIA (x) in 88 sera yielded the relation y = 0.62 x - 0.76, Sy/x = 0.03. Values for melatonin in serum samples from healthy subjects are lower during the day than during the night. Melatonin response in rat serum and pineal gland to isoproterenol injection is similar to published RIA data. The analytical procedure is also simple. Thus, the assay should have practical applications in investigation of pineal function in both clinical and basic studies.