bluuebunny/crossref_metadata_2025_split huggingface dataset:
An improved ultrafiltration method for free thyroxine and triiodothyronine in serum.
Authors: Sophianopoulos J , Jerkunica I , Lee C N , Sgoutas D 
Published: February 2020

Abstract
We describe an ultrafiltration technique for rapidly and directly determining free triiodothyronine or free thyroxine, or both. After equilibrating serum at 37 degrees C with purified tracer of high specific activity, we placed 0.15 mL of serum in 2.8 mL of phosphate buffer (0.1 mol/L, pH 7.4) in the ultrafiltration cell and obtained successive 0.2- and 0.6-mL fractions of protein-free ultrafiltrate. Under our conditions free ligand concentration was independent of flow rate. After purifying the second fraction with protein-coated charcoal, we could determine the proportion of free triiodothyronine or free thyroxine. Samples from normal adult men and women, including women who were taking oral contraceptives or were pregnant, and from hypo- and hyperthyroid patients gave results that agreed with those obtained by equilibrium dialysis. Speed is the main advantage of the method: one technologist can complete the procedure in 2 h and, using a multi-micro-ultrafiltration system, can process many samples in one day. For laboratories where index-type reactions are performed routinely and direct free triiodothyronine or free thyroxine is determined only on selected specimens, this method is superior to dialysis. It is also very convenient for rapidly purifying tracers, to at least 97% radiochemical purity, with 94% recovery and no dilution.
Biochemical individuality and the recognition of personal profiles with a computer.
Authors: Robertson E A , Van Steirteghem A C , Byrkit J E , Young D S 
Published: February 2020

Abstract
Multitest analysis of an individual's blood provides a biochemical profile that reflects his identity and pathophysiological state. During a six-week period we repeatedly profiled 10 volunteers for 22 different analytes, using continuous-flow and discrete analyzers (SMAC, KA 150 enzyme analyzer, ABA-100, AutoAnalyzers) and manual procedures. Two years later, we obtained multiple follow-up profiles. Using linear discriminant functions derived from the first five (or first 10) specimens from each subject, we were able correctly to identify 96% (or 100%) of the specimens collected during the remainder of the six-week testing period. Ninety percent of the two-year follow-up specimens were correctly identified when we used all the original profiles to calculate the discriminant functions. Deliberately mislabeled specimens were also correctly identified by discriminant analysis. Profiles of individual samples (and average profiles for each subject) were graphically displayed as computer-drawn faces and non-linear maps. Covariances between pairs of tests on repeated profiles differed significantly for different subjects. Inter-test relationships were graphically displayed by nonlinear mapping.
Lipid interference in steroid radioimmunoassay.
Authors: Rash J M , Jerkunica I , Sgoutas D S 
Published: February 2020

Abstract
To study lipid interference in steroid radioimmunoassays in which dextran-coated charcoal is used as the separating agent, we tested triolein and phosphatidylcholine as model hydrophobic and amphipathic lipids, respectively. Addition of either caused distortion of the standard curve to an extent that was inversely related to the polarity of the steroid molecule. Both lipids form a dispersion that entraps steroid molecules. When we increased the charcoal concentration, the effect of phosphatidylcholine addition was eliminated for assays of both polar and nonpolar steroids. In contrast, the effect from triacylglycerol was not corrected, particularly in assays of nonpolar steroids. We also studied mixtures of lipids mimicking the mixture of lipids extracted from plasma of normolipemic and hyperlipemic indviduals. The degree of lipemia that can be tolerated differs from assay to assay, and primarily varies directly with the polarity of the steroid being assayed.
Effects of centrifugation, storage, and contamination of amniotic fluid on its total phospholipid content.
Authors: van Voorst tot Voorst E J 
Published: February 2020

Abstract
The total phospholipid content of the supernatant fluid decreases rapidly with increasing relative centrifugal force when amniotic fluid is centrifuged. Possible explanations for this are discussed. The effect of storage on the total phospholipid content of amniotic fluid at different temperatures and the influence of contamination with blood and meconium are also described.
Simultaneous liquid-chromatographic analysis for 4-hydroxy-3-methoxymandelic acid and 4-hydroxy-3-methoxyphenylacetic acid in urine.
Authors: Soldin S J , Hill J G 
Published: February 2020

Abstract
We describe a rapid, reliable “high-performance" liquid-chromatographic method of simultaneously analyzing for 4-hydroxy-3-methoxymandelic acid (I) and 4-hydroxy-3-methoxyphenylacetic acid (II) in urine. Paired-ion chromatography and amperometric detection are used in the method. A 5-mL aliquot of urine is adjusted to pH 6.1 and subjected to anion-exchange chromatography (Dowex AG 1-X4, 1.8 X 0.7 cm column). The two analytes are eluted from the column with 10 mL of 3 mol/L sodium chloride, and 2 microL of the eluate, injected directly into the liquid chromatograph, is chromatographed at 40 degrees C. This column contains mu Bondapak C18, and the mobile phase is 100 mmol/L potassium phosphate buffer, pH 6.7, containing 0.5 mmol of tetrabutylammonium phosphate per liter. Detector sensitivity is 50 nA full scale. Analytical recoveries of I and II are 80--84% and 48--49%, respectively; the coefficients of variation for various concentrations in urine are about 10%.
A lyophilized hemoglobin control prepared from stroma-free hemolysates.
Authors: Bonderman D P , Proksch G J , Haskins S 
Published: February 2020

Abstract
We prepared a stable lyophilized hemoglobin control from human erythrocytes by removing stroma with calcium and Ficoll. Addition of polyhydroxy compounds enhanced reconstitution and stability. The lyophilized product was stable during one year of use in a service laboratory. Accelerated aging studies demonstrated the potential of up to two years of stability, with methemoglobin increasing at a projected rate of approximately 6% per year. Reconstituted, the control gave reproducible values for at least five days when refrigerated.
Evaluation of an immobilized-enzyme analyzer for measuring galactose in serum.
Authors: Buffone G J , Johnson J M , Lewis S A , Sparks J W 
Published: February 2020

Abstract
Reportedly, galactose provides an alternative carbohydrate source and improved homeostatic regulation of glucose in the premature infant. Because of its potentially toxic effects, sensitive methods are needed for monitoring its concentration during therapy. We evaluated an immobilized galactose oxidase/hydrogen peroxide electrode system and a modified homogeneous enzymic method. Both methods are suitable for measuring galactose in a small sample and are comparably precise. The latter method gives superior analytical recoveries below 100 mg/L, but is linear in absorbance response to only 300 mg/L. We find the immobilized-enzyme method superior for monitoring treatment of neonates with galactose, because it requires only a few minutes and 25 microL of serum, and the analytical procedure is simpler.
Taurine transport in epilepsy.
Authors: Goodman H O , Connolly B M , McLean W , Resnick M 
Published: February 2020

Abstract
Previous studies of plasma taurine concentrations in epileptics have yielded equivocal results. We measured plasma and urinary taurine in 41 epileptic and 68 control subjects and found plasma concentrations among epileptics to be comparable in general to those of controls, but that two or three classes of plasma taurine concentrations, possibly genetically regulated, occur in both epileptic and control subjects. Our previous studies and data from the present study on taurine excretion revealed three excretion classes under genetic control. The principal finding is that epileptics include disproportionate numbers of low excretors (high reabsorbers), who are presumptive homozygotes for the allele effecting higher reabsorption. If confirmed, these findings suggest that the transport of taurine, rather than absolute taurine concentration, may explain the efficacy of taurine administration in some epileptics but not in others. The locus involved may be one component in the polygenic diathesis to the idiopathic epilepsies.
A simplified assay for dihydroxylated vitamin D metabolites in human serum: application to hyper- and hypovitaminosis D.
Authors: Mason R S , Lissner D , Grunstein H S , Posen S 
Published: February 2020

Abstract
We describe a simplified assay for 24,25-and 1.25-dihydroxyvitamin D in human serum. It involves two preparative steps, and normal chick intestine is used in preparing cytosol-binding protein. Our results for 24,25-dihydroxyvitamin D include a reference interval of 2.9—16 nmol/L (1.2—6.7 microgram/L), a mean of 6.7 nmol/L (2.8 microgram/L), an intra-assay CV of 11%, and an interassay CV of 22%. For 1,25-dihydroxyvitamin D, these data were 29—168 pmol/L (12—70 ng/L), 86 pmol/L (36 ng/L), 12%, and 22%, respectively. In hypoparathyroid patients with vitamin D intoxication, mean concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum were significantly above normal; the 1,25-dihydroxyvitamin D concentrations were significantly below normal. Patients with malabsorption and/or post-gastrectomy states had significantly subnormal values for both 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum, and there was a significantly negative correlation between each of these biochemical values and the severity of osteomalacia. We also discuss cost effectiveness of assaying vitamin D metabolites in human serum.
Kinetic serum creatinine assays I. The role of various factors in determining specificity.
Authors: Bowers L D 
Published: February 2020

Abstract
We studied the specificity of kinetic methods of analysis, with emphasis on creatinine determination. The error contributed by an interferent that reacts with the analytical reagent and absorbs at the wavelength of analysis is shown to be related to the ratio of the equilibrium absorbances of the analyte and interferent, the ratio of the rate constants, the extent of the analytical reaction, and the duration of the measurement. To assess the potential diminution of the interference with kinetic methods, we determined the rate constants of several alpha-keto acids in the Jaffé reaction. Evaluation of the advantages of various measuring techniques with respect to specificity showed the main factors to be the extent of the analytical reaction and the relative value of the rate constants. Total specificity for creatine appears to be unattainable with currently used kinetic techniques.
Effects of sample aging on total cholesterol values determined by the automated ferric chloride-sulfuric acid and Liebermann-Burchard procedures.
Authors: Wood P D , Bachorik P S , Albers J J , Stewart C C , Winn C , Lippel K 
Published: February 2020

Abstract
To investigate the comparability of three commonly used methods for determination of total cholesterol in plasma in several studies, we used fresh plasma samples as well as plasmas and reference sera that had been stored frozen at −15 degrees C for as long as several years. Duplicate determinations by the manual method of Abell et al. (J. Biol. Chem. 195: 357, 1952) were compared with estimates from one to five continuous-flow analyzers by the ferric chloride-sulfuric acid procedure and also with estimates from five to 13 continuous-flow analyzers by the Liebermann-Burchard procedure with calibrator, as part of the laboratory standardization activities of the Lipid Research Clinics. The agreement among all three procedures was generally within acceptable limits (within 5% of the manual method) when plasmas or sera were fresh or had been frozen for less than one month. Results by the manual method of Abell et al. agreed well with those by the automated Liebermann-Burchard method for samples that had been stored at −15 degrees C for as long as two years. However, the automated ferric chloride-sulfuric acid procedure often showed unacceptably high values (as compared with those from the manual method) for samples that had been stored frozen for a year or more. With the ferric chloride-sulfuric acid method, measured cholesterol concentration increased about 2.5% per year of storage for at least two years. We conclude that reference sera of plasmas that have been kept in long-term frozen storage (−15 degrees C) are not suitable for ongoing standardization of the automated ferric chloride-sulfuric acid assay for cholesterol.
Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.
Authors: Winartasaputra H , Mallet V N , Kuan S S , Guilbault G G 
Published: February 2020

Abstract
We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.
Evaluation of standard curves in the graded hemagglutination-inhibition method applied to quantitation of human immunoglobulins.
Authors: Wolk M 
Published: February 2020

Abstract
For accurate quantitation of human immunoglobulins A and B by graded hemagglutination inhibition, I have established standard curves. For IgA, plotting the inner diameter of the ring formed by sedimented erythrocytes vs the log of the antigen concentrations gives a straight line. Plotting the same parameters for IgG gives a hyperbolic line. These ratios between antigen concentration and ring diameter were constant for at least one year. Both undiluted and 10,000-fold diluted human serum may be quantitated by this method, depending only on immunoglobulin concentrations. Precision (CV) of the system, assessed in 35 patients’ sera over the period of one year, ranged from 0.5 to 15.2% (mean 10%) for IgA and from 1.4 to 14.9% (mean 7.3%) for IgG.
Method for determination of hydrogen peroxide, with its application illustrated by glucose assay.
Authors: Graf E , Penniston J T 
Published: February 2020

Abstract
We describe a simple colorimetric method for determining micromolar quantities of hydrogen peroxide, based on the oxidation of iodide in the presence of ammonium molybdate and photometry of the resulting blue starch-iodine complex. Color development is linearly dependent on analyte concentration, but only slightly time dependent, and the color of the complex formed is stable for several hours. In the range of wavelengths that may be used (570 to 630 nm), lack of interference from other biological compounds makes this method seem suitable for routine analyses. As one illustrative application of the method we quantitated glucose by measuring hydrogen peroxide produced from it by glucose oxidase catalysis. This method of quantitating glucose is more than five times as sensitive as the commonly used dianisidine method. With the appropriate hydrogen peroxide-producing oxidases, this method may be used to directly measure amino acids, purines, uric acid, xanthine, and hypoxanthine.
The contribution of assays for lymphocyte capping and creatine kinase to detection of the Becker-type dystrophy trait.
Authors: Goldsmith B M , Gruemer H D , Hawley R J , Pickard N A , Verrill H L , Nance W E , Miller G , Crawford R G 
Published: February 2020

Abstract
Members of three unrelated families with the mild Becker type of muscular dystrophy were subjected to lymphocyte capping tests and measurements of serum creatine kinase activity. Both tests correctly identified all nine affected males, but only the capping test was abnormal in seven of eight obligate carriers. The number of capped cells in carriers and affected persons with the Becker-type dystrophy was generally intermediate between those observed for individuals with the Duchenne trait and normal controls, thus potentially aiding in the differential diagnosis between the two myopathies. The lack of sensitivity of measurements of serum creatine kinase activity in identifying carriers is further complicated by the difficulty of establishing reliable reference intervals for this enzyme in 204 healthy controls. Detailed directions for the performance of the capping test are presented.
The coefficient of analysis, a new figure of merit for laboratory performance.
Authors: Louderback A L , Szatkowski P R 
Published: February 2020

Abstract
A simple statistic has been developed to determine a figure of merit for overall laboratory performance. This simple statistic, the coefficient of analysis, relates for the first time both the imprecision and the inaccuracy of a laboratory analysis to a single value that clinical chemists will easily understand. In the derivation of the coefficient of analysis, we also define two secondary statistics: the coefficient of bias, which is mathematically similar to the CV and represents the inaccuracy of an analysis, and the coefficient of accuracy, which is mathematically represented as 100 minus the coefficient of bias and is a measure of the accuracy of the analysis.
Continuous-flow enzymatic determination of total serum cholesterol and method standardization with CDC-calibrated pooled sera.
Authors: MacAulay M A , Jacklyn C L , Mathers J M , Storm V A 
Published: February 2020

Abstract
We compared Boehringer Mannheim's enzymatic kit for the continuous-flow (AutoAnalyzer II) determination of serum cholesterol with Technicon's N-24a extraction method. Results for patients' samples analyzed by the enzymatic method were higher than those by the comparison method. To evaluate accuracy in the cholesterol determinations, we enrolled the enzymatic method into the Center for Disease Control's (CDC) Lipid Standardization program. We calibrated the method by use of a pooled sera for which cholesterol content was assigned by CDC after analysis by their reference Abell-Kendall procedure. We discuss the difficulties with available calibration material and limitations in the application of some commercial control materials to the enzymatic cholesterol method. The continuous-flow variables, Michaelis-Menton constants, percent ester-hydrolase activity, and other factors affecting the performance of the enzyme-linked cholesterol method are evaluated. We believe pooled sera with an assigned value for cholesterol content is the best calibrator material.
Liquid-chromatographic separation of urinary 5-hydroxy-3-indoleacetic acid, with measurement at 254 nm.
Authors: Draganac P S , Steindel S J , Trawick W G 
Published: February 2020

Abstract
A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.
A Method for Reconstructing the Past Soil Temperature Based on Tree-Ring Widths
Authors: Yuan Shuai , Zheng Yonghong , Qi Yongdong , Kong Fanxi , Wang Dan , Zhang Fangfang 
Published: February 2020

Abstract
Soil temperature can affect tree growth and is one of the most important types of basic data for forest cultivation and management. To obtain a long-term time series of soil temperatures, we explored the utility of dendroclimatology in a subtropical area of China. In this study, the relations between tree-ring-width chronologies and climate factors were explored by correlation analysis. The results indicated that the limiting climatic factors for the radial growth of Huangshan pine were elevation-specific. Further investigation found that chronology at high elevations was significantly correlated with soil temperature. Then, we described a reconstruction of the soil temperatures of the Dabie Mountains area using the tree-ring width chronology from 1869 to 2015 and showed that the reconstruction explained 42.9 percent of the instrumental soil temperature variation in the common years. We found that the 1970s and 2000s were the coldest and warmest decades since 1884, respectively. The results of the reconstruction method for describing past soil temperatures can provide a reference for other subtropical forests. Furthermore, the results of our research also have a certain significance for guiding policymaking related to forest cultivation and management.
Darwin’s Fancy Revised: An Updated Understanding of the Genomic Constitution of Pigeon Breeds
Authors: Pacheco George , van Grouw Hein , Shapiro Michael D , Gilbert Marcus Thomas P , Vieira Filipe Garrett 
Published: February 2020

AbstractThrough its long history of artificial selection, the rock pigeon (Columba livia Gmelin 1789) was forged into a large number of domestic breeds. The incredible amount of phenotypic diversity exhibited in these breeds has long held the fascination of scholars, particularly those interested in biological inheritance and evolution. However, exploiting them as a model system is challenging, as unlike with many other domestic species, few reliable records exist about the origins of, and relationships between, each of the breeds. Therefore, in order to broaden our understanding of the complex evolutionary relationships among pigeon breeds, we generated genome-wide data by performing the genotyping-by-sequencing (GBS) method on close to 200 domestic individuals representing over 60 breeds. We analyzed these GBS data alongside previously published whole-genome sequencing data, and this combined analysis allowed us to conduct the most extensive phylogenetic analysis of the group, including two feral pigeons and one outgroup. We improve previous phylogenies, find considerable population structure across the different breeds, and identify unreported interbreed admixture events. Despite the reduced number of loci relative to whole-genome sequencing, we demonstrate that GBS data provide sufficient analytical power to investigate intertwined evolutionary relationships, such as those that are characteristic of animal domestic breeds. Thus, we argue that future studies should consider sequencing methods akin to the GBS approach as an optimal cost-effective approach for addressing complex phylogenies.