bluuebunny/crossref_metadata_2025_split huggingface dataset:
Better laboratory evaluations of instruments and kits are required.
Authors: Fraser C G , Singer R 
Published: January 2020

Abstract
There are many published protocols for evaluating instruments and reagent-kit sets, and a plethora of papers describe the results of evaluations performed. It might be assumed, therefore, that this facet of clinical chemistry has no problems, but examination of evaluations of instruments published in the first half of 1984 shows flaws in some aspects of experimental design and execution, statistical analysis, and interpretation of data. We believe that clinical chemists, manufacturers and suppliers, and journal editors and referees can all contribute to improvement of this situation, and we suggest some guidelines for each of these groups.
Liquid chromatography of serotonin and adenine nucleotides in blood platelets, illustrated by evaluation of functional integrity of platelet preparations.
Authors: Ingebretsen O C , Bakken A M , Farstad M 
Published: January 2020

Abstract
In this relatively rapid liquid-chromatographic procedure the endogenous serotonin in blood platelets is quantified by fluorometry. We used this experimental procedure to estimate the platelet-release reaction as an indicator of the functional integrity of stored platelets. a decrease in the platelet-release reaction more sensitively indicates platelet changes during storage than do alterations in total ATP concentration or adenylate energy charge. The described method for quantifying serotonin is convenient enough for routine use in blood banks.
Urinary glycolate measured by use of (S)-2-hydroxy-acid oxidase.
Authors: Bais R , Nairn J M , Potezny N , Rofe A M , Conyers R A , Bär A 
Published: January 2020

Abstract
Glycolate can be determined in urine by using (S)-2-hydroxy-acid oxidase (EC 1.1.3.15; formerly called "glycolate oxidase"), either immobilized in a continuous-flow system or in a semiautomated procedure for the centrifugal analyzer. In the presence of peroxidase (EC 1.11.1.7), the hydrogen peroxide formed from glycolate is detected by use of a peroxide indicator reaction. Before the analysis, urine must be treated with charcoal to remove reducing substances such as ascorbic acid, which interfere with the assay by decreasing the color of the indicator reaction. Lactate also interferes with the determination of glycolate because it also is a substrate for this oxidase; thus a correction has to be made for the lactate content of urine. The system with (S)-2-hydroxy-acid oxidase immobilized to the inner surface of nylon tubing is accurate, precise, and sensitive but unsuitable for routine use because, even immobilized, the oxidase is unstable and can only be used for 12 days. We have used the semiautomated assay routinely: it has a mean analytical recovery of 96% (SD 4.2%), a within-batch CV less than 2%, and a between-batch CV less than 5%. The normal reference interval for urinary excretion of glycolate so measured is 0.13 to 1.31 mmol per day (n = 55).
Measurement of plasma fructosamine evaluated for monitoring diabetes.
Authors: Lim Y S , Staley M J 
Published: January 2020

Abstract
The mean fructosamine concentration in plasma of diabetics (n = 200) differed significantly (p less than 0.001) from those of a hospitalized nondiabetic population (n = 163)--the latter mean being essentially the same for ambulatory subjects (n = 145), expectant mothers (n = 58), and patients with renal failure (n = 31), regardless of sex. In the diabetic group, values for plasma fructosamine correlated with those for glycated hemoglobin (r = 0.767, p less than 0.01) and glycated protein (r = 0.817, p less than 0.01). Values for plasma fructosamine were stable from day to day in patients with controlled blood glucose, but fluctuated in certain patients receiving only parenteral nutrition, even when their concentrations of glucose were normal and stable. We conclude that measurement of plasma fructosamine is suitable for assessing intermediate-term control of blood glucose when the turnover of plasma proteins is normal.
Vitamin B12 assays compared by use of patients' sera with low vitamin B12 content.
Authors: Sheridan B L , Pearce L C 
Published: January 2020

Abstract
We compared four radioisotope dilution (RD) methods and a microbiological assay for measuring concentrations of vitamin B12 in a selected panel of serum samples from patients known to be deficient in the vitamin. Low (less than 100 ng/L) and borderline (100-180 ng/L) results were similar between methods, but use of the manufacturers' recommended ranges for borderline results would have changed the diagnostic classifications for 22 of 38 samples. Results of all the RD methods inter-correlated well, but less so with the microbiological assay. Borderline, nondiagnostic results were common to all methods, and no apparent advantage was gained from using the microbiological assay.
Enzyme immunoassay of free thyroxin in dried blood samples on filter paper.
Authors: Hata N , Miyai K , Ito M , Endo Y , Iijimi Y , Mizuta H , Amino N , Nose O , Harada T 
Published: January 2020

Abstract
We describe a double-antibody enzyme immunoassay for determination of free thyroxin (FT4) in dried blood samples on filter paper, with use of a T4-beta-D-galactosidase complex. The measurable range of FT4 concentration in two 3-mm blood discs, each of which contained about 2.7 microL of blood, was 1.9 to 93 ng/L, as determined by comparison with concentrations of FT4 in known serum standards. FT4 in blood samples dried on filter paper was stable for at least four weeks when kept dry at -20 degrees C, room temperature, or 37 degrees C. The mean coefficients of variation were 7.6% (within assay) and 6.4% (between assays). Results for FT4 by this method correlated well with those for serum determined by radioimmunoassay (r = 0.98). The proposed method can be used to differentiate persons with hyper- and hypothyroidism from normal subjects and those with abnormal concentrations of thyroxin-binding globulin. The procedure seems suited for screening studies.
Variations in total phospholipids and high-density lipoprotein phospholipids in plasma from a general population: reference intervals and influence of xenobiotics.
Authors: Cuvelier I , Steinmetz J , Mikstacki T , Siest G 
Published: January 2020

Abstract
The influence of different factors on variations in the concentrations of total phospholipids and high-density-lipoprotein (HDL) phospholipids in plasma was studied in a presumably healthy population of 2000 subjects, four to 70 years old. Age is the major factor associated with variation of total phospholipids. In females, this is due in part to age-related changes in hormonal status. The use of oral contraceptives affects only HDL phospholipid values. Use of tobacco does not influence plasma phospholipid values, but alcohol consumption increases values for both total and HDL phospholipids. We propose reference intervals for total plasma phospholipids and HDL phospholipids, adjusted for age and sex. Screening for lipid status can now include determinations of phospholipids as well as cholesterol and triglycerides.
Liquid-chromatographic determination of vanillylmandelic acid in urine.
Authors: Anderson G M , Feibel F C , Cohen D J 
Published: January 2020

Abstract
Urinary vanillylmandelic acid (VMA) was determined by "high-performance" liquid chromatography with fluorometric (LC-F) and amperometric (LC-EC) detection. Urine samples were first purified on a small, open-bed, reversed-phase preparatory column. VMA and the internal standard (iso-VMA) were then separated by reversed-phase ion-pair liquid chromatography. Analytical recovery of VMA was high (98.3%, SD 3.3%, n = 8), and concentrations measured by LC-F and LC-EC were in excellent agreement (r = 0.996). The LC-F chromatograms of urine samples had fewer late peaks; however, detection limits were lower (15 vs 120 micrograms/L) for the LC-EC method. Typical concentrations of 1-10 mg/L in urine can be measured easily with either method.
Liquid-chromatographic determination of total hydroxyproline in urine.
Authors: Turpeinen U , Pomoell U M 
Published: January 2020

Abstract
A reversed-phase "high-performance" liquid chromatographic assay for total hydroxyproline in urine is described. The urine samples are hydrolyzed overnight with acid, evaporated, solubilized, and derivatized with 4-dimethylaminoazobenzene-4'-sulfonyl chloride. The derivatives are chromatographed with a solvent gradient consisting of sodium acetate buffer and acetonitrile, the effluent being monitored at 436 nm. The useful lower limit of sensitivity for quantification is 13 pmol of hydroxyproline per 5-microL injection, corresponding to 33 mumol/L of urine. Either glutamine or cysteic acid is satisfactory as the internal standard. Peak heights and the amounts of hydroxyproline applied to the column are linearly related from 13.3 to 266 pmol. Mean analytical recovery was 83%. For four different concentrations the mean within-assay CV was 9.0% and the between-assay CV 12%. The normal reference interval found for 31 healthy adults was 31 to 177 mumol/24 h per square meter of body surface. We compared results for 10 samples from patients.
Increased serum sulfate in pregnancy: relationship to gestational age.
Authors: Cole D E , Baldwin L S , Stirk L J 
Published: January 2020

Abstract
Controlled-flow ion chromatography has significantly improved the precision with which inorganic sulfate (SO4) can be measured in serum. In this study, we have shown that serum SO4 is increased in pregnancy. The increase appears to follow gestational age, resulting in a 39% higher value by the middle of the third trimester. We suggest that this increase is a natural physiological process, which enhances SO4 availability to the growing fetus and placenta.
Immunoturbidimetric assay for alpha 1-acid glycoprotein in serum with a centrifugal analyzer.
Authors: Marteau F , Biou D , Thérond P , Demelier J F 
Published: January 2020

Abstract
This is a simple immunoturbidimetric method for the rapid assessment of alpha 1-acid glycoprotein in serum with the "Flexigem" microcentrifugal analyzer. Results obtained for a pediatric population (n = 95) agree with those by radial immunodiffusion (x) and yield the regression equation: y = 1.4x + 0.017 (r = 0.98). Results are printed automatically after a procedure that takes only about 15 min. Within-run precision (CV) ranged from 2.2 to 2.5% for concentrations of 0.35 to 2.4 g/L. Day-to-day CV was 4.25% for an average concentration of 0.9 g/L.
Possible role of lysolecithins and nonesterified fatty acids in the pathogenesis of Reye's syndrome, sudden infant death syndrome, acute pancreatitis, and diabetic ketoacidosis.
Authors: Shaw W 
Published: January 2020

Abstract
In vitro denaturation and (or) alteration of protein function by detergents have been extensively documented. I suggest that similar biochemical and clinical features of Reye's syndrome, sudden infant death syndrome, acute pancreatitis, and diabetic ketoacidosis may be explained as sequelae of the toxic detergent effects of nonesterified fatty acids and lysolecithins. These diseases may be provoked by a drug-induced diminution of the detergent-buffering capacity of blood or tissue proteins; by excess detergents produced in vivo, consequent to lipase activity induced by viral infection or metabolic disease; or by some combination of these factors.
Interlaboratory evaluation of salicylate interference in colorimetric acetaminophen methods and its clinical significance.
Authors: Jenny R W 
Published: January 2020

Abstract
Serum specimens with concentrations simulating an overdose of salicylate and acetaminophen were submitted to laboratories participating in an external quality-control program, to evaluate both the magnitude of salicylate interference in colorimetric acetaminophen methods and the clinical significance of the interference. The apparent acetaminophen concentration determined by nitration methods was increased by about 0.70 mg/L per milligram of salicylate per deciliter. Of those laboratories using nitration procedures, 25% do not routinely correct for salicylate and 66% use the (incorrect) correction factor provided by a kit manufacturer. Laboratory data, as they would have been reported to physicians, were used to estimate the acetaminophen half-life and were also applied to a nomogram used to assess the probability of hepatotoxicity. Interference by salicylate in the simulated overdose of 10 g (total dose) of each drug falsely indicated impending hepatic necrosis unless the appropriate correction factor was used. Laboratories using nitration procedures should screen samples submitted for acetaminophen assay for the presence of salicylate and, if present, either use a method specific for acetaminophen or utilize a correction factor determined in-house.
"Total" acidic metabolites of catecholamines in urine as determined by hydrolysis with hydriodic acid and liquid chromatography: application to patients with neuroblastoma and melanoma.
Authors: Ito S , Kato T , Maruta K , Jimbow K , Fujita K 
Published: January 2020

Abstract
We describe a method for determining the "total" excretion of acidic metabolites of catecholamines by measuring 3,4-dihydroxyphenylacetic acid (DOPAC) formed by hydriodic acid hydrolysis of 4-hydroxy-3-methoxyphenylacetic acid (HVA), 4-hydroxy-3-methoxymandelic acid (VMA), and their conjugates. The DOPAC in the diluted hydrolysate is measured directly by liquid chromatography with electrochemical detection. Normal values, expressed in relation to excretion of creatinine, vary as a function of age. For healthy subjects, the mean DOPAC value after hydrolysis was 1.15 times that for unconjugated HVA, VMA, and DOPAC combined. Preliminary results for patients with neuroblastoma and melanoma indicate the potential usefulness of the method for diagnosis and prognosis of patients with neural crest tumors that produce dopa or catecholamines.
Determination of propranolol in plasma by radial compression liquid chromatography with fluorometric detection.
Authors: el-Yazigi A , Martin C R 
Published: January 2020

Abstract
This radial compression liquid-chromatographic assay for propranolol in plasma is rapid, reproducible, and suitable for use in routine monitoring. A 10-micron particle, 8 mm X 10 cm CN cartridge is used in conjunction with a radial compression separation system. The mobile phase is monobasic sodium phosphate (pH 3) solution/methanol/acetonitrile (760/84/156 by vol), the flow rate 6 mL/min. Propranolol was detected by use of a spectrofluorometer equipped with a 20-microL flow-through cell, at excitation and emission wavelengths of 250 and 336 nm. The retention times for propranolol and metoprolol (the internal standard) are 3.13 and 1.42 min, respectively. A one-step extraction with chloroform yields "clean" chromatograms, with greater than 90% of the drug being analytically accounted for. Under these conditions, results are precise and accurate. Currently we are using this method to monitor propranolol in hypertensive neonates. Data on changes in the concentrations of propranolol in plasma with time are presented for one such patient.
A cause of discrepancy between values for urinary protein as assayed by the Coomassie Brilliant Blue G-250 method and the sulfosalicylic acid method.
Authors: Shiba K S , Kanamori K , Harada T , Nakao M , Nakajima K , Kodaira T , Nakagawa H 
Published: January 2020

Abstract
In simultaneous assays of urinary proteins by the Coomassie Brilliant Blue G-250 (CBB) and the sulfosalicylic acid (SSA) methods, we noticed that about 18% of samples showed about twice higher protein values by the former method than by the latter. Some urinary proteins are soluble in SSA and react with CBB. Examinations with sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed that these proteins migrated in 13 protein bands having relative molecular masses ranging from 15 000 to 230 000. The protein corresponding to the most intensely stained band in urine samples from the patients studied (with malignant tumors, renal disorders, etc.) had an Mr of 45 000; that in the pattern for healthy subjects had an Mr of 94 000. The former was identified as alpha 1-acid glycoprotein, the latter as Tamm-Horsfall mucoprotein.
Guidelines for immunoassay data processing.
Authors: Dudley R A , Edwards P , Ekins R P , Finney D J , McKenzie I G , Raab G M , Rodbard D , Rodgers R P 
Published: January 2020

Abstract
These guidelines outline the minimum requirements for a data-processing package to be used in the immunoassay laboratory. They include recommendations on hardware, software, and program design. We outline the statistical analyses that should be performed to obtain the analyte concentrations of unknown specimens and to ensure adequate monitoring of within- and between-assay errors of measurement.
Assessment of corpus luteum function by direct radioimmunoassay for progesterone in blood spotted on filter paper.
Authors: Petsos P , Ratcliffe W A , Anderson D C 
Published: January 2020

Abstract
In this specific, direct RIA for progesterone in capillary blood dried on filter paper, progesterone is eluted, with phosphate buffer containing bovine serum albumin, from 5.9 microL of blood dried on 5.0-mm (diameter) discs of filter paper. The eluate is assayed, with 125I-labeled progesterone-11 alpha-glucuronyl-tyramine as tracer, with separation by a double-antibody solid-phase technique. The sensitivity of the assay is 4.7 pg per tube, corresponding to 2.5 nmol per liter of blood. Within- and between-batch CVs averaged 7.0 and 9.2%, respectively, over the working range of the assay (4.5-64 nmol/L). Concentrations of progesterone in blood spots (y) correlated well with those in serum (x) as measured by an established direct RIA (Clin Chem 28:1314, 1982): y = 0.430x - 2.44 (r = 0.972, n = 104). Progesterone is stable in the blood spots for at least 15 weeks at 25 degrees C. The convenience of multiple sampling of blood by finger prick and the simplicity of the assay make this approach useful in investigating serial progesterone concentrations in outpatients.
Epitope-selective, monoclonal-antibody-based immunoradiometric assays of predictable specificity for differential measurement of choriogonadotropin and its subunits.
Authors: Schwarz S , Berger P , Wick G 
Published: January 2020

Abstract
Knowing the epitope specificities of our monoclonal antibodies (MCA) to human choriogonadotropin (hCG), we could design three classes of two-site immunoradiometric assays (IRMA): a combination of two MCA recognizing two separate alpha-epitopes (alpha-MCA) provides a system (i.e., an alpha-IRMA) that measures holo-hCG plus free alpha-subunits plus follitropin, lutropin, and thyrotropin, whereas a beta-IRMA, consisting of two beta-MCA, quantifies holo-hCG plus free beta-subunits. The amount of either of the two subunits can be calculated by subtracting the amount of holo-hCG determined in parallel in a holo-hCG-IRMA. In the latter, one of the alpha- or beta-MCA may be either cross-combined or, preferably, paired with an MCA specific for a conformational epitope. These analytical specificities, predicted from our previously established epitope map of hCG, could be experimentally verified. With these IRMAS we could demonstrate that in certain choriocarcinoma cell lines the earliest and quantitatively predominant tumor marker is the free alpha-subunit. Similar results showing an unbalanced secretion of hCG and its subunits were obtained for patients with related tumors. These findings challenge the present diagnostic practice of relying solely on "beta-hCG" radioimmunoassays and at the same time offer a novel analytical strategy.
An evaluation of a fluorescence polarization immunoassay of thyroxin and thyroxin-uptake.
Authors: Symons R G , Vining R F 
Published: January 2020

Abstract
We evaluated the fluorescence polarization immunoassay for total thyroxin (T4) and thyroxin-uptake (T-U) in the Abbott "TDx" Analyzer. Between-assay precision was good when we did once-fortnightly calibration and assayed samples in singleton. Measured T4 concentration was decreased in hemolyzed samples with obvious red coloration and undetectable in severely hemolyzed samples. The T-U assay was unaffected by hemolysis. Unlike the triiodothyronine-uptake methods, the T-U assay utilizes labeled T4 and measures a variable related to serum thyroxin-binding capacity rather than the concentration of unoccupied binding sites in serum. The T4 and T-U values of 422 samples correlated highly with a T4 (in-house) radioimmunoassay and a commercial assay for thyroxin-binding globulin, respectively. The free thyroxin ratio (ratio of T4 to T-U, FTI) correlated highly with free T4 concentration as measured by T4-analog-tracer radioimmunoassay (fT4 analog RIA). FTI and fT4 values were discordant in late pregnancy (normal FTI and low fT4) and euthyroid sick patients (above-normal or normal FTI and low fT4), suggesting that the FTI gives fewer misleading results in these patients.
Preparation and use of serum-based material as control and calibrator in evaluating ion-selective electrodes for calcium.
Authors: Toffaletti J , Lee K M 
Published: January 2020

Abstract
We analyzed 93 sera and 81 whole-blood samples, plus several aqueous materials and one serum-based material as controls, with two analyzers for ionized calcium (Radiometer ICA 1 and AVL 980). On 16 days, comparisons of results for patients' samples were good, with nearly all between-instrument differences (delta Ca2+) of samples being within 0.04 mmol/L. On 12 days, comparisons were mediocre, with the delta Ca2+ of samples usually 0.04 to 0.10 mmol/L. The control material that most consistently indicated the direction and magnitude of the delta Ca2+ of patients' samples was the serum-based control. Adjustment of results for samples from patients, based on the delta Ca2+ of the serum control on the same day, substantially improved comparisons between instruments. Our findings suggest that the use of a serum-based calibrator provides the most valid comparison between different calcium-ion analyzers and reliably indicates when electrode replacement is needed.
Adequacy of interlaboratory precision criteria in measuring intralaboratory performance.
Authors: Ehrmeyer S S , Laessig R H 
Published: January 2020

Abstract
We compared the predictive value of the various criteria used for grading pH and blood-gas measurements in interlaboratory proficiency testing programs with performance as determined from actual intralaboratory quality-assurance data. The evaluation criteria were the two-standard-deviation interval (2 SDI) proposed by the College of American Pathologists (CAP); CAP's proposed fixed criteria; and the fixed criteria of the American Thoracic Society (ATS). These were compared with 95% confidence limits derived from the individual laboratories' actual intralaboratory data. We found that the CAP's most-stringent criterion (2 SDI) overestimated the number of outliers (unacceptable results) for PCO2 and PO2, whereas the proposed fixed limits underestimated them. For pH and PCO2 the ATS's limits, which are more stringent, more closely match the individual laboratory's actual performance as measured by conventional (mean +/- 2 SD) intralaboratory quality-assurance practices.