bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly sensitive immunoradiometric assay for serum thyroglobulin with minimal interference from autoantibodies
Authors: Marquet P Y , Daver A , Sapin R , Bridgi B , Muratet J P , Hartmann D J , Paolucci F , Pau B 
Published: January 2020

Abstract
Five monoclonal antibodies (MAbs) directed against antigenic domains on thyroglobulin (Tg) not recognized by most anti-Tg human autoantibodies (aAbs) have been used to develop an improved IRMA for serum Tg with a limit of detection of 0.2 micrograms/L. Samples are incubated for 3 h in tubes coated with four anti-Tg MAbs. After washing, the tubes are incubated with the tracer MAb for 20 h at room temperature. Dilution and reproducibility tests demonstrated assay reliability. Tests performed on samples with (n = 361) or without (n = 283) aAbs showed that the TG IRMA Pasteur is largely independent of the marked interference generally caused by aAbs. These results were confirmed with an extended population of 2759 samples. For a cutoff of 1 micrograms/L, sensitivity and specificity were 0.97 and 1, respectively, in a follow-up of differentiated thyroid carcinoma in patients treated by total thyroidectomy.
DELISA: sensitive nonisotopic assay for GAD65 autoantibodies, a key risk-assessment marker for insulin-dependent diabetes mellitus
Authors: Mehta H B , Vold B S , Minkin S , Ullman E F 
Published: January 2020

Abstract
Nonisotopic assays for the measurement of autoantibodies to 65-kDa glutamic acid decarboxylase (GAD65) have not previously achieved performance equivalent to radiobinding assays (RBA). We have developed a modified ELISA protocol, DELISA, for measuring autoantibodies to GAD65 in serum. The method overcomes the problems of poor sensitivity and specificity associated with conventional ELISAs. Serum containing GAD65 autoantibodies is incubated with biotinylated GAD65 (bGAD65). Sufficient soluble Protein A-dextran conjugate is added to bind the immunoglobulins in the sample, including GAD65 autoantibodies to which GAD65 is bound. After incubation, the mixture is transferred to a streptavidin-p4ated microtiter well, which binds free bGAD65 but not bGAD65 bound to autoantibodies. Streptavidin-bound bGAD65 is detected by means of a peroxidase-GAS65MAb conjugate. The method appears to have comparable sensitivity and specificity to those of RBAs. Reaction of the antibodies with soluble antigen to increase the binding rate and the use of high serum concentrations and very low antigen concentrations to increase sensitivity are critical elements of the method.
Human placenta radioreceptor assay with digoxin and ouabain to detect endogenous digitalis-like factor(s) in human plasma and urine
Authors: Paci A , Ciarimboli G , Biver P 
Published: January 2020

Abstract
We describe the optimization and validation of a clinically feasible radioreceptor assay to detect endogenous digitalis-like factor(s) (EDLF) in human plasma and urine. The assay is based on the competitive replacement of 125I-labeled digoxin on human placenta membranes by ligands present in sample extracts. Digoxin and ouabain were used as calibrators. We also describe simple and effective methods for extraction and enrichment of EDLF from human plasma and urine. Assay sensitivity and precision were enhanced by using a sequential saturation technique with appropriate concentrations of tracer and receptors. Filtration was used to separate bound from free ligand. A two-step solid-state extraction with acetonitrile allowed the separation of two EDLFs with different polarity (EDLF-1 and EDLF-2) from the same plasma sample. A one-step solid-state extraction with methanol was suitable for urine. EDLF-1 and EDLF-2 in healthy adults were respectively 204 +/- 155 and 207 +/- 423 pmol/L ouabain equivalents, or 312 +/- 241 and 302 +/- 581 pmol/L digoxin equivalents. Plasma concentrations of EDLFs in newborns and pregnant women were higher than in healthy adults, and the concentrations in urine were higher than in plasma. Several cross-reactivity experiments showed that physiological concentrations of endogenous steroids and lipids did not inhibit binding, and supported the hypothesis that EDLFs are endogenous compounds other than the steroids and lipids also investigated.
Enzymatic measurement of creatine in erythrocytes
Authors: Beyer C , Alting I H 
Published: January 2020

Abstract
We describe an automated enzymatic procedure for quantifying creatine in erythrocytes. In this assay, after sample clean-up, creatine kinase (CK; EC 2.7.3.2) and pyruvate kinase (EC 2.1.7.40) are used as auxiliary enzymes; lactate dehydrogenase (EC 1.1.1.27) is used in the indicator reaction. CK is also used as the starting reagent. Data obtained with the present method (y) correlated as follows with those from the comparison method (x) for creatine measurement in erythrocytes (colorimetric, diacetyl-alpha-naphthol): y = 1.017x - 27.5 (S(y/x) = 11.9, r = 0.997). Precision data were obtained by analyzing three different samples of erythrocytes nine times per day for 25 days with both methods. The total CVs determined by our method and the comparison method were respectively 3.0-4.8% (measured creatine range, 171-463 micromol/L) and 5.1-7.1% (creatine, 185-485 micromol/L). We established the reference interval (mean +/- 2SD) for creatine in erythrocytes from healthy individuals as 194-538 micromol/L for men (n = 71) and 241-677 micromol/L for women (n = 100). Using erythrocytes from patients with various hematological abnormalities and chronic renal failure, who were being treated with continuous ambulatory peritoneal dialysis or hemodialysis, we performed a clinical evaluation and obtained results in agreement with existing data on biochemical markers for the mean age of erythrocytes.
Detection of prostate-specific antigen mRNA and protein in breast tumors
Authors: Zarghami N , Diamandis E P 
Published: January 2020

Abstract
We have developed reverse transcription-polymerase chain reaction (RT- PCR) methods for detecting prostate-specific antigen (PSA) mRNA. Using these methods, and a highly sensitive immunofluorometric assay for measuring PSA protein, we have assessed the concentrations of PSA mRNA and PSA protein in 30 primary breast tumors and a few other control tissues. We found good agreement between presence of PSA protein and PSA mRNA in breast tumors. We thus propose that, in women, detection of PSA protein or PSA mRNA in tissues and tumors offers equivalent information. Because PSA protein is present in male blood and thus could contaminate extracts from tumors and tissues from men, we propose that the RT-PCR methods we describe be used to assess nonprostatic expression of the PSA gene in men.
Matrix effects and the performance and selection of quality-control procedures to monitor PO2 measurements
Authors: Olafsdottir E , Westgard J O , Ehrmeyer S S , Fallon K D 
Published: January 2020

Abstract
We have assessed how variation in the matrix of control materials would affect error detection and false-rejection characteristics of quality-control (QC) procedures used to monitor PO2 in blood gas measurements. To determine the expected QC performance, we generated power curves for S(mat)/S(meas) ratios of 0.0-4.0. These curves were used to estimate the probabilities of rejecting analytical runs having medically important errors, calculated from the quality required by the CLIA '88 proficiency testing criterion and the precision and accuracy expected for a typical analytical system. When S(mat)/S(meas) ratios are low, the effects of matrix on QC performance are not serious, permitting selections of QC procedures based on simple power curves for a single component of variation. As S(mat)/S(meas) ratios increase, single-rule procedures generally show a loss in error detection, whereas multirule procedures, including the 3(1)s control rule, show an increase in false rejections. An optimized QC design is presented.
Clinical trials of a novel centrifugation method: axial separation
Authors: Estey C A , Felder R A 
Published: January 2020

Abstract
Specimen centrifugation is one of the most time-consuming tasks associated with preanalytical specimen processing. We report the first clinical use and impact study of the novel centrifugation method, axial separation, using the Axial Separation Module (ASM). The ASM centrifuges medical specimens one at a time (in 1 min 9 s) in proprietary Axial Process Containers (APC). Here we report tests of the ASM in an outpatient clinical laboratory. Use of the ASM in the outpatient clinic laboratory led to an average total improvement (decrease in total bench time) of 8 min 9 s per specimen compared with conventional centrifugation. Laboratory analysis revealed no statistical difference between plasma obtained from the APC vs that from a Becton Dickinson Vacutainer Tube. We conclude the ASM offers a cost-effective alternative to conventional centrifugation. Further, the use of axial separation may allow specimen separation to become an integral part of the phlebotomy process.
Homogeneous assay for direct determination of high-density lipoprotein cholesterol evaluated
Authors: Nauck M , März W , Haas B , Wieland H 
Published: January 2020

Abstract
We evaluated a new homogeneous assay for quantifying high-density lipoprotein cholesterol (HDL-C). The assay included four reagents: polyethylene glycol for "wrapping" chylomicrons, very-low-density lipoproteins (VLDL), and low-density lipoproteins (LDL); antibodies specific for apolipoprotein (apo) B and apo C-III to produce aggregates of chylomicrons, VLDL, and LDL; enzymes for the enzymatic cholesterol determination of the noncomplexed lipoproteins with 4-aminoantipyrine as the color reagent; and guanidine salt to stop the enzymatic reaction and to solubilize the complexes of apo B-containing lipoproteins, which would otherwise interfere with the reading of absorbance. The total CVs of the new method ranged between 2.4% and 8.4%. The HDL-C values (y) were in good agreement with those by a comparison phosphotungstic acid/MgCl2 method (x): y= 0.987x + 17.2 mg/L (68th percentile of the residuals on the regression line= 21.49, r= 0.970). At triglyceride concentrations of 20 g/L (Intralipid) the homogeneous HDL-C concentrations increased by 2%. Hemoglobin markedly increased the results, whereas bilirubin reduced them. The homogeneous HDL-C assay was easy to handle and allows full automation. This test should considerably facilitate the screening of individuals at an increased risk of cardiovascular disease.
Interference in glucose and other clinical chemistry assays by thiocyanate and cyanide in a patient treated with nitroprusside
Authors: Randell E W , St Louis P 
Published: January 2020

Abstract
A 3-year-old patient treated with nitroprusside for congestive heart failure had 6.5 mmol/L thiocyanate (toxic, &gt;1.5 mmol/L) and 110 micromol/L cyanide (toxic, &gt;5 micromol/L) present in her blood. At this time a whole-blood glucose concentration assayed on the Nova Stat Profile 5 Plus (Stat Profile) was 25.1 mmol/L. Plasma from that specimen analyzed on a Kodak Ektachem 700 analyzer (E700) indicated 5.2 mmol/L glucose. We investigated the potential interference of dissolved thiocyanate or cyanide on glucose and other routine assays. Toxic concentrations of thiocyanate increased Stat Profile glucose values and E700 total calcium, chloride, and creatinine values. Stat Profile ionized calcium values were decreased by toxic concentrations of thiocyanate. Cyanide (100 micromol/L) decreased alanine aminotransferase activity measured on the E700. Interference with the Stat Profile glucose assay may have been caused by thiocyanate oxidation at the glucose electrode.
Reference intervals for plasma apolipoprotein B determined with a standardized commercial immunoturbidimetric assay: results from the Framingham Offspring Study
Authors: Contois J H , McNamara J R , Lammi-Keefe C J , Wilson P W , Massov T , Schaefer E J 
Published: January 2020

Abstract
We evaluated a commercially available, standardized immunoturbidimetric assay for apolipoprotein (apo) B, the protein constituent of low-density lipoprotein (LDL), to establish reference ranges for men and women, and to determine the concentrations associated with increased risk of coronary heart disease (CHD). The between-run CV for assay of a normal-concentration control for this assay was 6.60%. The mean (+/-SD) apo B concentration was 1.03 +/- 0.24 g/L in 1880 men, significantly higher than the mean for 1944 women (0.96 +/- 0.26 g/L) participating in cycle 4 of the Framingham Offspring Study (P&lt;0.001). An apo B value of 1.20 g/L corresponded roughly to the 75th percentile in men, similar to an LDL cholesterol concentration of 1.60 g/L, and subjects with concentrations greater than this were significantly more likely to have CHD than subjects with apo B concentrations less than 1.00 g/L, the approximate 50th percentile (P&lt;0.05 in men and P&lt;0.001 in women).
Four frequently used test systems for serum cholesterol evaluated by isotope dilution gas chromatography-mass spectrometry candidate reference method
Authors: Thienpont L M , Van Landuyt K G , Stöckl D , De Leenheer A P 
Published: January 2020

Abstract
We evaluated the performance of four frequently used cholesterol test systems, using split-sample measurements with a panel of 79 patients' specimens and isotope dilution gas chromatography-mass spectrometry (ID GS-MS) as a comparison method. The test systems were from Beckman, a Boehringer Mannheim, Merck, and Johnson & Johnson Clinical Diagnostics, performed on the Synchron CX7, Hitachi 717, Mega, and Ektachem 250 analyzers, respectively. The liner regression data for the method comparison [ID GS-MS as independent variable (x)] were for Beckman: slope = 1.012, intercept = 0.0243 mmol/L, dispersion (S(y/x)) = 0.1303 mmol/l, and correlation coefficient (r) = 0.9867; for Boehringer Mannheim: slope = 1.002, intercept = 0.114 mmol/L, Sy/x = 0.0759 mmol/L, r = 0.9954; for Merck: slope = 1.034, intercept = -0.0613 mmol/L, Sy/x = 0.0886 mmol/L, r = 0.9941; and for Johnson & Johnson Clinical Diagnostics: slope = 1.007, intercept = 0.01 mmol/L, Sy/x = 0.15 mmol/L, and r = 0.9811. These data demonstrate excellent state-of-the-art cholesterol measurement for some of the most widely used test systems.
Nephelometric determination of carbohydrate deficient transferrin
Authors: Schellenberg F , Martin M , Cacès E , Bénard J Y , Weill J 
Published: January 2020

Abstract
We describe a technique for measuring carbohydrate-deficient transferrin (CDT) in serum. Serum transferrin fractions are separated by anion-exchange chromatography on microcolumns. Sialic acid-deficient transferrin fractions are collected in the eluate, and transferrin is then quantified by a rate-nephelometric technique. Imprecision (CV) was 4-5% within-run and 7-9% between runs (n = 15). Comparison with an isoelectric focusing-immunofixation method for transferrin index (x) yielded y = 761x + 7, Sy/x = 39 mg/L. Assay of sera from 90 abstainers or moderate consumers of alcohol showed that 81 (90%) had CDT concentrations between 30 and 70 mg/L. Among 74 alcoholics admitted to an alcohol treatment center, 54 (73%) had CDT &gt; 70 mg/L, i.e., the diagnostic sensitivity was 73% at a specificity of 90% (area under receiver-operator characteristic curve = 0.891).
Quantification of circulating 1,25-dihydroxyvitamin D by radioimmunoassay with 125I-labeled tracer
Authors: Hollis B W , Kamerud J Q , Kurkowski A , Beaulieu J , Napoli J L 
Published: January 2020

Abstract
We report here the first RIA for 1,25-dihydroxyvitamin D utilizing a radioiodinated (125I) tracer. This is also the first validated RIA for 1,25-dihydroxyvitamin D [1,25(OH)2D] that does not require sample prepurification by HPLC before the binding assay. The assay involves acetonitrile extraction, treatment of the crude extract supernate with sodium periodate, extraction and purification of endogenous 1,25(OH)2D by solid-phase chromatography, and finally, quantification by RIA. Calibrators were prepared in stripped human serum and processed exactly the same as samples, eliminating the need for internal control for procedural losses of endogenous 1,25(OH)2D. The assay consists of a 2-h room temperature incubation with the primary antibody, a 20-min incubation with a second antibody, and separation of bound from free by centrifugation. Assay results can be in hand with 5 h. The detection limit of the assay is 2.4 ng/L 1,25-dihydroxyvitamin D3. Results compare well with those from an accepted radioreceptor assay. Sample pretreatment with sodium periodate is absolutely essential before quantification by RIA; otherwise, concentrations of endogenous 1,25(OH)2D may be greatly overestimated.
Influence of specimen carryover on sensitive thyrotropin (TSH) assays: is there a problem?
Authors: Sadler W A , Murray L M , Turner J G 
Published: January 2020

Abstract
A relatively slow transition has occurred from so-called 1st-generation thyrotropin (TSH) assays (e.g., RIAs) through 2nd-generation assays (e.g., IRMAs) to 3rd-generation assays (e.g., immunochemiluminometric assays). Analysis of data from a modified internal quality-control design, followed up by a computer simulation, showed that specimen carryover has minimal effect on 2nd-generation TSH assays. However, extension of the simulation to a 3rd-generation assay showed the possibility of substantial effects in the subnormal region. Carryover of 1:1250 (0.08%), for example, may reduce the theoretical 10-fold precision improvement claimed for 3rd-generation assays to nearer fourfold. Simulation results suggest maximum allowable specimen carryover of approximately 1:10,000 (approximately 0.01%) for 3rd-generation TSH assays. We suggest that when automated specimen handling is used in a TSH assay, a well-designed carryover experiment should become a routine part of reports that claim 3rd-generation (or better) performance characteristics.
Denaturing gradient gel electrophoresis to diagnose multiple endocrine neoplasia type 2
Authors: Blank R D , Sklar C A , Martin M L 
Published: January 2020

Abstract
Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant cancer syndrome caused by mutations in the RET protooncogene. Others have already demonstrated the value of genetic testing in known MEN 2 kindreds. Previously described approaches to DNA-level diagnosis, particularly of index cases, are tedious. We developed appropriate denaturing gradient gel electrophoresis (DGGE) conditions for analysis of exons 10, 11, and 16 of this gene, where many of the pathogenic mutations map. We screened 16 members of a three-generation MEN 2 kindred by DGGE and found five affected but still asymptomatic patients, ranging in age from 5 to 67 years. We used DGGE to localize the pathogenic mutations and screen at-risk individuals in several other kindreds. DGGE--which requires no radioactive, fluorescent, or chemiluminescent labeling--is ideally suited to the diagnosis of MEN 2 because of the syndrome's dominant genetics and the rarity of clinically silent variants in the RET gene.
Use of neural networks to diagnose acute myocardial infarction. I. Methodology
Authors: Jørgensen J S , Pedersen J B , Pedersen S M 
Published: January 2020

Abstract
We investigated several aspects of using neural networks as a diagnostic tool: the design of an optimal network, the amount of patients' data needed to train the network, the question of training the network optimally while avoiding overfitting, and the influence of redundant variables. The specific clinical problem chosen for illustration was the diagnosis of acute myocardial infarction, given only the electrocardiogram and the concentration of potassium in serum at the time of admission. We found that, in contrast to usual practice, the termination of the training process should be based on the generalization performance and not on the training performance. We also found that a principal component analysis can be used to eliminate redundant variables, thereby reducing the data space. The diagnostic performance of the neural network we used was 78%--superior to that of linear discriminant function analysis but similar to that of quadratic discriminant function analysis.
Laboratory testing for recent alcohol consumption: comparison of ethanol, methanol, and 5-hydroxytryptophol
Authors: Helander A , Beck O , Jones A W 
Published: January 2020

Abstract
The ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid (5HTOL/5HIAA) in urine was compared with concentrations of ethanol and methanol as a way to monitor recent alcohol consumption. During detoxification of alcohol-dependent subjects, ethanol persisted longer in urine than in breath or plasma. Blood and urinary methanol remained increased for 2-6 h after blood ethanol had returned to background concentrations, whereas 5HTOL/5HIAA remained increased for 6-15 h. In healthy volunteers who had ingested alcohol (range 3-98 g) the previous afternoon or evening, 87% (for men) and 59% (for women) of all drinking occasions exceeding 7 g of alcohol were identified by an increased 5HTOL/5HIAA in the first morning urine void. This compared with 32% and 12%, respectively, identified by analysis of ethanol (&gt;200 micromol/L). No gender difference in the excretion pattern of 5HTOL/5HIAA was seen. The results demonstrate that 5HTOL/5HIAA provides a specific and more sensitive method to detect recent alcohol consumption than does ethanol or methanol.
Circulating total and ionized magnesium after ethanol ingestion
Authors: Wu C , Kenny M A 
Published: January 2020

Abstract
Hypomagnesemia is associated with alcoholism (Lim P, Jacob E. Metabolism 1972;21:1045-51). Here we assess two measurements of blood magnesium in emergency care patients with confirmed ethanol ingestion. Serum total and ionized magnesium (tMg, iMg) were measured in 88 patients with ethanol concentrations of 6-128 mmol/L and in sera of 97 hospitalized patients (control group). iMg was measured by an ion-selective electrode method; tMg was measured spectrophotometrically. iMg was significantly lower for the ethanol-containing specimens (0.35 +/- 0.12 mmol/L, mean +/- SD) than for the control group (0.46 +/- 0.15 mmol/L), with P &lt;0.0001. The tMg for the test group (0.87 +/- 0.20 mmol/L) was not significantly different from the controls (0.88 +/- 0.33 mmol/L), with P = 0.5987. tMg was not well-correlated with iMg in the ethanol-positive specimens. Most ethanol-positive patients had abnormally low serum iMg (87 of 88 had iMg &lt;0.53 mmol/L).
Automated HPLC screening of newborns for sickle cell anemia and other hemoglobinopathies
Authors: Eastman J W , Wong R , Liao C L , Morales D R 
Published: January 2020

Abstract
Automated HPLC is used to test dried blood-spot specimens from newborns for hemoglobins (Hb) F, A, S, C, E, and D. We present the method and report on its performance determined during &gt;4 years of testing 2.5 x 10(6) newborns. The method features automated derivation of presumptive phenotypes; quantitative quality control and proficiency testing; throughput of one specimen per minute; small sample volume; hemoglobin concentrations quantified with an interlaboratory CV of 14-18%; retention times with interlaboratory CV of &lt;2% and matching, within +/- 0.03 min, of laboratories and reagent lots; control of peak resolution; 0.5% detection limit for Hb S and C, and 1.0% for Hb F, A, E, and D; few interferences; and negligible background and carryover. Shortcomings of the method are the absence of microplate barcode identification and the need for manually pipetting the sample eluate into the microplate.