bluuebunny/crossref_metadata_2025 huggingface dataset:
Destabilization of PVA-stabilized Ag NPs: color changes at low aqueous concentrations, induced by aggregation and coalescence
Authors: Hu Junqiang , Yang Longlai , Zhu Yan , Yang De-Quan , Sacher Edward
Published: January 2020

Aqueous concentrations of poly(vinyl alcohol) (PVA)-stabilized ∼10 nm silver nanoparticles (Ag NPs), in the 1000 ppm concentration range, have been shown to be highly stable at elevated temperatures. However, lower concentrations of these NPs undergo color changes, without precipitation, when heated or when held for extended periods of time at room temperature. We have studied their optical and morphological changes at 80 °C, using UV–vis spectra and TEM, and found that their color, at a concentration of 10 ppm, changes from yellow to claret-red to black without precipitation. Further, the plasmon resonance peak at ∼400 nm diminishes as a new peak develops at ∼550 nm. These changes occur as the previously well-dispersed NPs (yellow color) agglomerate to chains (claret-red color) and, finally, coalesce (black color). We discuss the cause of the instability.
Corrosion resistance mechanism of the passive films formed on as-cast FeCoCrNiMn high-entropy alloy
Authors: Jinlong Lv , Jin Huijin
Published: January 2020

The present work investigates the corrosion resistance of as-cast FeCoCrNiMn high-entropy alloy in borate buffer solution. Compared with 304 and 316L stainless steels steel, as-cast FeCoCrNiMn high-entropy alloy exhibited excellent passivation ability. This should be attributed to homogenization of alloying elements. Highly corrosion-resistant elements in as-cast FeCoCrNiMn alloys, for example, Cr, Co and Ni, could promote the formation of protective passive film in borate buffer solution. Moreover, combined effect of high mixing entropy and sluggish diffusion also could improve the corrosion resistance. The formation mechanism of the passive films on the surface of as-cast FeCoCrNiMn alloys satisfied the point defect model.
Improving the electrocatalytic activity for formic acid oxidation of bimetallic Ir–Zn nanoparticles decorated on graphene nanoplatelets
Authors: Ahmad Khairul Naim , Noor Azam Adam Mohd Izhan , Isahak Wan Nor Roslam Wan , Mohd Zainoodin Azran , Masdar Mohd Shahbudin
Published: January 2020

A graphene nanoplatelet (GNP)-supported Ir–Zn catalyst (Ir–Zn/GNP) was fabricated by H2 reduction to discover an alternative for non-platinum and non-palladium catalysts as an anode catalyst in direct formic acid fuel cell (DFAFC). The obtained Ir–Zn/GNP catalyst with ratio of Ir:Zn = 50:50 (Ir50Zn50/GNP) exhibited better electrocatalytic activity than GNP-supported iridium catalyst (Ir/GNP) for formic acid oxidation. Although the oxidation peak current density of Ir50Zn50/GNP was slightly lower than that of Ir/GNP, the oxidation peak potential shifted more negatively (193 mV) than Ir/GNP with higher value of the ratio of forward scan to reverse the scan peak current (If/Ib). The presence of Zn also enhanced the power density and current generation with increased performance stability in a passive DFAFC cell tests. The improvement of the electrochemical performance was ascribed to the ensemble effect where the addition of Zn could modify the Ir atom arrangement, thereby promoting the oxidation through dehydrogenation pathway. However, extremely high Zn content would inhibit oxidation capability because Zn atoms might reduce the Ir catalytic sites. A new alternative for non-Pt and non-Pd anode catalysts for DFAFC applications was successfully achieved.
Thermal properties of coatings based on full aluminosiloxane polymer
Authors: Peredriy Oksana , Pakholiuk Olena , Martirosyan Irina , Khvyshchun Nadiia
Published: January 2020

This article is devoted to the study of thermal properties, heat resistance, corrosion resistance and fire resistance of new protective coatings based on the filled aluminosiloxane polymer. The aim of the study is to determine the effect of the source composition on the physical properties of the finished coating. Thermal stability was determined by periodic heating in a thermal chamber to a temperature of 800 °C for 5 h and then cooled in water. Corrosion resistance was determined by the change in roughness. Profiles and profilometers were used to determine the roughness parameters. Fire resistance was determined by the time from the start of the test to the onset of one of the normalized boundary states. It is set, that to improve the heat resistance of steel structures it is expedient to use appropriate coatings based on full aluminosiloxane polymer which contain Al2O3, ZrO2, kaolin, kaolin fiber and modifier TiO2 as fillers. The heat resistance of protective coatings for steel decreases by 20%–30% when kaolin is added at a heating temperature higher than 753 K. The heat resistance is increased by 30%–40% when kaolin fiber is added. Depth of corrosion of materials with developed protective coatings decreases by 2.2–3.5 times. The results of the study confirm that the introduction of kaolin in the coatings increases the fire resistance of the studied materials. Thus, the performance properties of the protective coatings can be adjusted over a wide temperature range by changing the oxide and silicate fillers.
Characterization of micro-arc oxidation coatings on Ti6Al4V with addition of SiC particle
Authors: Lian Yong , Dai Xianyi , Zhang Jin
Published: January 2020

In the present work, particles of SiC were applied to the micro-arc oxidation (MAO) treatment of Ti6Al4V, characterization of MAO coatings with different SiC particle concentration were evaluated. X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) results show that the structure and morphology of MAO ceramic coatings could change with different amounts of SiC in the electrolyte. Both of the number and size of the pores on the ceramic coating surface were decreased, while the layer thickness increased with the increase in SiC particles in the electrolyte. A dense double-layer structure coating composed of a Ti-based layer and a SiC-based layer with a thickness of about 40 μm was prepared. It was shown that the addition of SiC particles participated in the process of micro-arc oxidation and changed the microstructure of MAO coating.
RETRACTED: Spinel zinc ferrite nanoparticles: an active nanocatalyst for microwave irradiated solvent free synthesis of chalcones
Authors: Borade Ravikumar M , Somvanshi Sandeep B , Kale Swati B , Pawar Rajendra P , Jadhav K M
Published: January 2020

A profoundly effective magnetically recoverable nano zinc ferrite nanocatalyst was fabricated by means of sol-gel auto ignition strategy. The synthesized nanocatalyst has been completely portrayed by standard techniques for structural, morphological, compositional, surface, magnetic, dielectric, optical and photoluminescence properties individually. The x-ray diffraction pattern affirmed the arrangement of cubic spinel structure with an average crystallite size of 21 nm. FE-SEM images uncovered the circular morphology with nanometric average grain measure (37 nm). The surface area, pore volume and pore radius was observed to be 39.812 m2 g−1, 3.41 cc g−1 and 1.34 nm individually from BET analysis. VSM investigation demonstrated the superparamgnetic nature of the prepared sample with moderate magnetization value and negligible coercivity. The optical band gap deduced from UV–vis spectra was observed to be 2.098 eV. Every one of these properties of zinc nanoferrite makes them brilliant contender for microwave radiation absorption. Further, a proficient and versatile microwave irradiated solvent free synthesis of chalcone derivatives has been developed using prepared zinc nanoferrite catalyst. The remarkable highlights of this new protocol are solvent free reaction, economical cheapness, eco-friendliness, high yields, reduced reaction times and easy recovery and reuse of zinc ferrite nanocatalyst.
Mechanical properties and wear behavior of fly ash particle reinforced Al matrix composites
Authors: Desai Akash Mayurbhai , Paul Tanay Rudra , Mallik Manab
Published: January 2020

In this study, aluminum-based metal matrix composites containing 5, 10, 15, 20, and 25% fly ash particles by weight have been fabricated using a stir casting route. Microstructural observations under an optical microscope suggest that fly ash particles in the cast composites are uniformly distributed throughout the matrix. The mechanical properties such as tensile strength and hardness of the aluminum alloy have enhanced significantly with the addition of fly ash. Wear behavior of base metal and its composite have been studied in dry sliding conditions using a pin-on-disc tribometer. Wear tests have been conducted at three different loads of 9.81, 19.62, and 29.43 N at a constant sliding velocity of 1.3 m s−1. Microstructural observations of worn surfaces and wear debris suggest that wear mechanism in base metal is controlled by adhesion, whereas that for composites is abrasive. The least wear rate has been obtained in Al-10% Fly ash composite. The Al-10% Fly ash is observed to possess an optimum level of mechanical properties and wear behavior.
Effect on corrosion behaviour of the surface of aluminium 4.5 Cu with bamboo leaf ash composites by laser treatment
Authors: Rao Gadudasu Babu , Bannaravuri Praveen Kumar , Birru Anil Kumar
Published: January 2020

Aluminium composites have various applications in engineering thanks to their greater strength with lightweight, formability and ductility. However, the properties of the Aluminium composites such as wear, corrosion, hardness, and fatigue resistance are critical at near-surface regions. In this present research work, the effect on the surface of Aluminium 4.5Cu with Bamboo Leaf Ash composite by laser surface melting was done, wherein the fabrication was done by stir-casting with bamboo leaf ash reinforced particles with 2 and 4 weight percentage. By using the laser machine, the composite’s surface was melted. Microstructure and corrosion behaviour of composites before surface melting and after laser surface melting was inspected and the outcomes were compared. It was perceived that, the diminishment of porosity in the grain refinement. The corrosion resistance of composites had improved remarkably by Laser Surface Melting. The Corrosion mechanism was analysed by observing the morphology of the corroded surface of composites. Henceforth the Laser Surface Melting will be applied appropriately to boost the surface properties of aluminium composites.
Synthesis and characterisation of magnesium matrix composite reinforced with titanium dioxide nanoparticulates
Authors: Elumalai P C , Ganesh R
Published: January 2020

In the present work, magnesium matrix composite reinforced with titanium dioxide (TiO2) nanoparticulates was synthesized using powder metallurgy (solid-state processing) technique followed by hybrid microwave heat treatment and hot extrusion. Commercially available magnesium particulates of average particle size 60–300 μm and titanium oxide nanoparticulates of average particle size ∼21 nm was used in this study. Extruded samples of pure magnesium and magnesium titanium dioxide (Mg-TiO2) nanocomposites were characterized for their physical, surface and internal microstructure (2D & 3D), elemental composition and mechanical behaviour. The experimental density and porosity of the composite specimens increases gradually with increase in addition of TiO2. Scanning electron micrographs (SEM) composite samples revealed that the nano TiO2 particulates distributed uniformly throughout the matrix with no significant agglomeration. The same was confirmed through 3D internal microstructure also. The elemental composition, crystalline structure was measured using x-ray diffractograms (XRD) which confirm that no foreign elements exists. Further, the microhardness and nanoindentation of composite samples showed an increasing trend with increase in addition of TiO2 nanoparticles.
Solution-processed flexible metal-oxide thin-film transistors operating beyond 20 MHz
Authors: Wei Xiaozhu , Kumagai Shohei , Tsuzuku Kotaro , Yamamura Akifumi , Makita Tatsuyuki , Sasaki Mari , Watanabe Shun , Takeya Jun
Published: January 2020

Complementary metal-oxide-semiconductor, an elementary building block, allows for a high degree of implementation of logic circuits with relatively low power consumption and low manufacturing cost, which plays a vital role not only in current Si electronics, but also in printed flexible devices. To meet the looming challenges of the Internet of Things, p-channel thin-film transistors (TFTs) with an excellent mobility and processability have been increasingly developed using organic semiconductors. However, owing to the inherent electron-donating nature of organic compounds, the high performance of n-channel organic TFTs has yet to be demonstrated. Here, in this paper, we developed state-of-the-art solution-processed indium-zinc-oxide (IZO) TFTs with high electron mobility, sharp turn-on characteristics at 0 V, and excellent atmospheric stability and compatibility with wet patterning processes. With the damage-free lithography process in conjunction with the ultimate optimization of entire device processes, IZO-based TFT arrays were successfully fabricated via a solution process on flexible polyimide substrates. A cutoff frequency of 23 MHz in air was achieved, which is almost twice as fast as the frequency used in a near-field communication band. Furthermore, the as-fabricated IZO-based TFTs even function well under bending stress. Therefore, the current concept and technique is expected to open up opportunities to develop practical flexible devices with high-speed operation.
A quantum Mirković-Vybornov isomorphism
Authors: Webster Ben , Weekes Alex , Yacobi Oded
Published: January 2020

We present a quantization of an isomorphism of Mirković and Vybornov which relates the intersection of a Slodowy slice and a nilpotent orbit closure in

g
l

N

\mathfrak {gl}_N

to a slice between spherical Schubert varieties in the affine Grassmannian of

P
G

L
n

PGL_n

(with weights encoded by the Jordan types of the nilpotent orbits). A quantization of the former variety is provided by a parabolic W-algebra and of the latter by a truncated shifted Yangian. Building on earlier work of Brundan and Kleshchev, we define an explicit isomorphism between these non-commutative algebras and show that its classical limit is a variation of the original isomorphism of Mirković and Vybornov. As a corollary, we deduce that the W-algebra is free as a left (or right) module over its Gelfand-Tsetlin subalgebra, as conjectured by Futorny, Molev, and Ovsienko.
Lung Cancer Stigma: Does Smoking History Matter?
Authors: Williamson Timothy J , Kwon Diana M , Riley Kristen E , Shen Megan J , Hamann Heidi A , Ostroff Jamie S
Published: January 2020

Background

Lung cancer patients commonly report stigma, often attributing it to the well-established association of smoking as the leading preventable cause. Theory and research suggest that patients’ smoking history may differentiate patients’ experience of lung cancer stigma. However, there is inconsistent evidence whether lung cancer stigma varies by patients’ smoking history, owing to limitations in the literature.

Purpose

This study examined differences in lung cancer patients’ reported experience of lung cancer stigma by smoking history.

Method

Participants (N = 266, 63.9% female) were men and women with lung cancer who completed a validated, multidimensional questionnaire measuring lung cancer stigma. Multivariable regression models characterized relationships between smoking history (currently, formerly, and never smoked) and lung cancer stigma, controlling for psychological and sociodemographic covariates.

Results

Participants who currently smoked reported significantly higher total, internalized, and perceived lung cancer stigma compared to those who formerly or never smoked (all p < .05). Participants who formerly smoked reported significantly higher total and internalized stigma compared to those who never smoked (p < .001). Participants reported similar levels of constrained disclosure, regardless of smoking history (p = .630).

Conclusions

Total, internalized, and perceived stigma vary meaningfully by lung cancer patients’ smoking history. Patients who smoke at diagnosis are at risk for experiencing high levels of stigma and could benefit from psychosocial support. Regardless of smoking history, patients reported similar levels of discomfort in sharing information about their lung cancer diagnosis with others. Future studies should test relationships between health-related stigma and associated health behaviors in other stigmatized groups.
Differential network analysis of multiple human tissue interactomes highlights tissue-selective processes and genetic disorder genes
Authors: Basha Omer , Argov Chanan M , Artzy Raviv , Zoabi Yazeed , Hekselman Idan , Alfandari Liad , Chalifa-Caspi Vered , Yeger-Lotem Esti
Published: January 2020

Motivation

Differential network analysis, designed to highlight network changes between conditions, is an important paradigm in network biology. However, differential network analysis methods have been typically designed to compare between two conditions and were rarely applied to multiple protein interaction networks (interactomes). Importantly, large-scale benchmarks for their evaluation have been lacking.

Results

Here, we present a framework for assessing the ability of differential network analysis of multiple human tissue interactomes to highlight tissue-selective processes and disorders. For this, we created a benchmark of 6499 curated tissue-specific Gene Ontology biological processes. We applied five methods, including four differential network analysis methods, to construct weighted interactomes for 34 tissues. Rigorous assessment of this benchmark revealed that differential analysis methods perform well in revealing tissue-selective processes (AUCs of 0.82–0.9). Next, we applied differential network analysis to illuminate the genes underlying tissue-selective hereditary disorders. For this, we curated a dataset of 1305 tissue-specific hereditary disorders and their manifesting tissues. Focusing on subnetworks containing the top 1% differential interactions in disease-relevant tissue interactomes revealed significant enrichment for disorder-causing genes in 18.6% of the cases, with a significantly high success rate for blood, nerve, muscle and heart diseases.

Altogether, we offer a framework that includes expansive manually curated datasets of tissue-selective processes and disorders to be used as benchmarks or to illuminate tissue-selective processes and genes. Our results demonstrate that differential analysis of multiple human tissue interactomes is a powerful tool for highlighting processes and genes with tissue-selective functionality and clinical impact.

Availability and implementation

Datasets are available as part of the Supplementary data.

Supplementary information

Supplementary data are available at Bioinformatics online.
METADOCK 2: a high-throughput parallel metaheuristic scheme for molecular docking
Authors: Imbernón Baldomero , Serrano Antonio , Bueno-Crespo Andrés , Abellán José L , Pérez-Sánchez Horacio , Cecilia José M
Published: January 2020

Motivation

Molecular docking methods are extensively used to predict the interaction between protein–ligand systems in terms of structure and binding affinity, through the optimization of a physics-based scoring function. However, the computational requirements of these simulations grow exponentially with: (i) the global optimization procedure, (ii) the number and degrees of freedom of molecular conformations generated and (iii) the mathematical complexity of the scoring function.

Results

In this work, we introduce a novel molecular docking method named METADOCK 2, which incorporates several novel features, such as (i) a ligand-dependent blind docking approach that exhaustively scans the whole protein surface to detect novel allosteric sites, (ii) an optimization method to enable the use of a wide branch of metaheuristics and (iii) a heterogeneous implementation based on multicore CPUs and multiple graphics processing units. Two representative scoring functions implemented in METADOCK 2 are extensively evaluated in terms of computational performance and accuracy using several benchmarks (such as the well-known DUD) against AutoDock 4.2 and AutoDock Vina. Results place METADOCK 2 as an efficient and accurate docking methodology able to deal with complex systems where computational demands are staggering and which outperforms both AutoDock Vina and AutoDock 4.

Availability and implementation

https://Baldoimbernon@bitbucket.org/Baldoimbernon/metadock_2.git.

Supplementary information

Supplementary data are available at Bioinformatics online.
Improved 125I radioimmunoassay for cotinine by selective removal of bridge antibodies.
Authors: Knight G J , Wylie P , Holman M S , Haddow J E
Published: January 2020

We describe an 125I-based RIA for cotinine, the major metabolite of nicotine. The slope of the dose-response curve was quite shallow (6-8% change in binding per doubling dose), resulting in between-assay CVs of 15 to 20%. This effect occurred because the radioligand formed by linking a cotinine derivative to tyramine manifested greater affinity for the anti-cotinine antibodies than did cotinine itself. We absorbed the serum with a derivative of nicotine coupled to the carrier protein via a chemical bridge similar to that used to form the cotinine/carrier protein immunogen. An RIA in which we used such absorbed serum showed a significantly increased slope of the dose-response curve (11-13% change in binding per doubling dose), and between-assay CVS were only 6 to 8%. We suggest that this improvement results because absorption removes anti-bridge antibodies directed against the chemical-bond common to the cotinine/carrier-protein immunogen and to the cotinine/tyramine radioligand.
Improved determination of estriol-16 alpha-glucuronide in pregnancy urine by direct liquid chromatography with fluorescence detection.
Authors: Andreolini F , Borra C , Di Corcia A , Samperi R , Raponi G
Published: January 2020

In this relatively simple, rapid assay of estriol-16 alpha-glucuronide in pregnancy urine, the urine sample is diluted 20-fold with phosphate buffer (pH 5.2) containing 360 mL of acetonitrile and 2 g of cetyltrimethylammonium bromide per liter, then directly injected into the chromatograph. A sample can be assayed within 14 min. Day-to-day CVs ranged from 2.3% at 45 mg/L to 2.9% at 4.8 mg/L. The limit of sensitivity is 0.4 mg/L. Results by the present method (y) correlated and compared very well with those by a method involving fractionation of estrogen conjugates and gas chromatography (x) for 24 samples of pregnancy urine (y = 1.09x + 0.303; r = 0.947). This assay is inexpensive and suitable for complete automation.
Assay of total and free propranolol in plasma by liquid chromatography with fluorometric detection.
Authors: Ray K , Trawick W G , Mullins R E
Published: January 2020

We report a liquid-chromatographic method for assay of total and free propranolol and its metabolite, propranolol glycol, in plasma. An ultrafiltration device is used to separate the free drugs from the protein-bound drugs. The total and free drugs are isolated from plasma or ultrafiltrate by liquid-solid extraction on a Waters C18 SEP-PAK and the drugs are quantified on a C18 mu-Bondpak radial-compression column. The mobile phase consists of equal parts of methanol and a solution of potassium 50 mmol/L phosphate and 2.5 mmol/L 1-pentane-sulfonic acid, pH 5.0. Detection was by fluorescence, with excitation at 296 nm and emission at 338 nm. Time required for sample preparation for total-propranolol assay is 40 min per eight samples. Sample preparation for free-propranolol assay requires an additional 1 h per eight samples. Chromatography requires 15 min per sample. The extraction recovery is approximately 75% and the assay curve is linear from 5 to 400 micrograms/L. The run-to-run CV is 4% for total propranolol, 15% for free propranolol.
Determination of serum aspartate aminotransferase with pyridoxal 5'-phosphate in the Technicon SMAC and Du Pont aca compared and correlated with the IFCC recommended method.
Authors: Neeley W E , O'Classen K , Gruber M
Published: January 2020

Inexpensive improvements in continuous-flow analytical apparatus can eliminate some perplexing inconsistencies and limitations in the use of the Technicon SMAC instrument for measuring the activity in serum of aspartate aminotransferase (EC 2.6.1.1) in the presence of pyridoxal 5'-phosphate. In addition, a calibration procedure based on values for this enzyme obtained by a modified IFCC method can be used to calibrate both the Technicon SMAC and the Du Pont aca instruments to produce excellent correlation between the two.
Ultrafiltration studies in vitro of serum aluminum in dialysis patients after deferoxamine chelation therapy.
Authors: Leung F Y , Hodsman A B , Muirhead N , Henderson A R
Published: January 2020

Using gel filtration chromatography, we evaluated aluminum bound to albumin, transferrin, and other plasma proteins in the serum of patients on maintenance hemodialysis. The proportion of dialyzable aluminum, as determined by selective membrane ultrafiltration and flameless atomic absorption spectrometry, increased by more than fourfold on treatment with the metal chelator, deferoxamine. This ultrafiltration technique may prove useful for monitoring the proportion of aluminum mobilized during such therapy.
Measurement of aluminum in serum, blood, urine, and tissues of chronic hemodialyzed patients by use of electrothermal atomic absorption spectrometry.
Authors: D'Haese P C , Van de Vyver F L , de Wolff F A , De Broe M E
Published: January 2020

We describe different methods of electrothermal atomic absorption spectrometry with automatic sampling for determining aluminum in human serum, blood, urine, and tissues. Contamination with Al originating from receptacles and reagents was minimized. Whole-blood Al concentrations were measured after hemolysis of EDTA-anticoagulated blood samples with Triton X-100. A straightforward method for tissue destruction was developed. Instrument settings of the graphite furnace and of the atomic absorption spectrometer were adjusted so as to obtain close agreement between direct and standard-additions methodologies. The result is a reliable direct method appropriate for use with multiple samples. Tissue Al measurements showed low detection limits and approximately 100% analytical recoveries. Al concentration in serum of 10 healthy volunteers and of 100 chronic hemodialysis patients were 2.0 (SD 0.4) and 77 (SD 70) micrograms/L, respectively. Blood Al concentrations of 10 controls and of 100 dialysis patients were 12.1 (SD 1.5) and 79 (SD 70) micrograms/L, respectively. Al concentrations in serum and blood of 47 chronic hemodialysis patients were not significantly different. Bone Al concentrations were 8.2 (SD 5.8) micrograms/g of fresh tissue for 10 chronic hemodialysis patients without osteomalacia, as compared with 51 (SD 20) micrograms/g for 10 chronic-dialysis patients with Al-induced osteomalacia.
Pregnanediol-3 alpha-glucuronide measured in diluted urine by mass spectrometry with fast atom bombardment/negative-ion ionization.
Authors: Moneti G , Agati G , Giovannini M G , Pazzagli M , Salerno R , Messeri G , Serio M
Published: January 2020

We describe a mass-spectrometric method based on the fast atom bombardment ionization technique in the negative-ion mode for measuring pregnanediol-3 alpha-glucuronide in diluted urine from women. The procedure requires addition of testosterone-17 beta-D-glucuronide (2.5 micrograms/25 microL) to the urine sample as internal standard, and the sample is added directly to the fast atom bombardment target with no further manipulation. We have assessed and evaluated the method by the traditional criteria of reliability.
Effect of arylsulfatase A and sialidase on the biochemical and immunological properties of creatine kinase isoenzyme BB.
Authors: McBride J H , Rodgerson D O
Published: January 2020

This work describes the action of the lysosomal enzymes arylsulfatase A (EC 3.1.6.1) and sialidase (EC 3.2.1.18) on human creatine kinase (CK, EC 2.7.3.2) isoenzyme BB. The isoenzyme, which gives a positive reaction with the periodic acid-Schiff reagent, contains 12 molecules of sulfate and two molecules of sialic acid per molecule. On treatment with arylsulfatase, CK-BB lost enzyme activity but retained immunoreactivity, its isoelectric point was altered, and it was partly bound to a "Glyco-gel" affinity column. On treatment with sialidase, the isoenzyme lost activity, its immunoreactivity was decreased by 70%, and the inactivated CK-BB would not bind to either "Glyco-gel" or concanavalin A. We propose that the sulfate groups are involved in maintaining the integrity of the active site of the enzyme but are not involved in antigenic recognition sites on the molecule. Sialic acid plays an important role in both the structural pattern of the antigenic determinant and the active site of CK-BB.
Quantification of apolipoprotein C-III in serum by a noncompetitive immunoenzymometric assay.
Authors: Parsy D , Clavey V , Fievet C , Kora I , Duriez P , Fruchart J C
Published: January 2020

We used a noncompetitive immunoenzymometric assay to measure the concentration of total apolipoprotein C-III in human sera. Affinity-purified antibodies to apolipoprotein C-III were adsorbed to the surface of microtiter plates. After washing, this solid-phase antibody was incubated with antigen (serum from fasting subjects), washed, and then incubated with peroxidase-labeled purified antibodies to apolipoprotein C-III. After a last washing, the bound label was assayed, providing a direct measurement of the antigen. Optimized technical conditions for the assay yielded assay CVs of 3.5 and 5.6% for within- and between-run precision, respectively. Analytical recovery of apolipoprotein C-III added to a serum was quantitative (97%). This noncompetitive assay can be used to measure apolipoprotein C-III in different lipoprotein fractions (very-low or high-density fractions) and yields values that compare favorably with those obtained by electroimmunoassay (r = 0.94). The assay offers several advantages over existing techniques--sensitivity, specificity, simplicity, and no use of radioisotopes--and hyperlipemic samples can be used.
Identification by nuclear magnetic resonance and mass spectrometry of a glucuronic acid conjugate of o-hydroxybenzoic acid in normal urine and uremic plasma.
Authors: Monti J P , Gallice P , Crevat A , Murisasco A
Published: January 2020

An endogenous compound (included in the fraction of uremic toxins often called the "uremic middle molecules") was separated from plasma of uremic patients and urine from normal persons. As elucidated by mass spectrometry, enzymatic hydrolysis, and 1H, 13C nuclear magnetic resonance, it appears to be a conjugate of o-hydroxybenzoic acid with glucuronic acid. Its presence in urine of healthy subjects indicates its physiological character.
Adenylate kinase: an oncodevelopmental marker in an animal model for human prostatic cancer.
Authors: Hall M , Mickey D D , Wenger A S , Silverman L M
Published: January 2020

Data are presented demonstrating that adenylate kinase (AK; EC 2.7.4.3) is an oncodevelopmental enzyme in the prostate of Copenhagen rats. We selected the Dunning tumor (dorsal rat prostate) as a model system because it most nearly approximates the human pathology. Four sublines of the tumor (R3327-H, R3327-AT, MAT Lu, and MAT LyLu) were studied. The tumor sublines were maintained as solid tumors in syngeneic rats and as monolayers in tissue culture. AK activity appeared in conjunction with malignant transformation of the dorsal prostate. We also determined the normal developmental enzyme pattern: AK was present in prostates of newborns, but was undetectable in prostates of adults. However, AK increased after castration. Therefore, we propose AK as a potential oncofetal tumor marker in prostatic cancer.
In-vitro stability of human alpha-fetoprotein.
Authors: Wu J T , Knight J A
Published: January 2020

We assessed the stability of alpha-fetoprotein (AFP) in clinical specimens in the presence and absence of serum and albumin, at different temperatures and concentrations. We find it depends on both AFP concentration and incubation temperature. Dilution of most specimens with either phosphate buffer or phosphate-buffered saline or by immunoelectrodiffusion resulted in some loss of AFP. Attempts to stabilize AFP during either sample dilution or incubation by use of albumin in concentrations up to 1 g/L did not protect it from inactivation unless normal human serum was also included. Frozen AFP solutions were less stable than solutions stored at 4 degrees C. AFP was most stable when lyophilized and stored desiccated. The AFP-inactivation curves were usually nonlinear. Apparently both polymerization and degradation occur simultaneously as AFP loses its activity. Proteolytic enzyme inhibitor and sulfhydryl reagent not only failed to protect it from inactivation, they appeared to speed it.
Stability of ascorbate in urine: relevance to analyses for ascorbate and oxalate.
Authors: Chalmers A H , Cowley D M , McWhinney B C
Published: January 2020

Ascorbate is unstable in urine at room temperature at pH values ranging from 1 to 12. At pH 7 and above, oxalate is generated in amounts directly proportional to the ascorbate concentration. In 12 different urines, adjusted to pH 12 and incubated for 20 h at room temperature, there was a significant correlation between the amount of oxalate formed and the initial ascorbate concentration (r = 0.97, p less than 0.01). The mean (+/- SD) concentration of oxalate (1.32 +/- 0.70 mmol/L) formed during this period approximated the initial ascorbate concentration (1.57 +/- 1.09 mmol/L). Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period. We therefore propose that urine specimens for ascorbate and oxalate analyses be collected with disodium EDTA present such as to give about this final concentration.
Direct solid-phase time-resolved immunofluorometric assay of cortisol in serum.
Authors: Eskola J U , Näntö V , Meurling L , Lövgren T N
Published: January 2020

A dissociation-enhanced lanthanide fluoroimmunoassay of serum cortisol based on time-resolved fluorescence is described. The assay is a direct assay, where cortisol immobilized on the wall of a microtiter-strip well competes with cortisol in the sample for the europium-labeled polyclonal antibody. The amount of bound europium-labeled antibody is inversely proportional to the amount of cortisol in the sample. Separation is accomplished by washing the strip well. The assay is carried out in 2 h, at room temperature; it is easy to perform and gives accurate and reliable results. A chaotropic agent, trichloracetic acid, was very effective in releasing cortisol from binding proteins. This finding will have practical importance in the immunoassay field.
Estimation of highly increased concentrations of fetal hemoglobin in Fanconi's anemia.
Authors: Krauss J S , Hahn D A , Jonah M H , Trinh M
Published: January 2020

We report a case of Fanconi's anemia with an extremely high proportion of fetal hemoglobin (Hb F). A three-year-old girl with multiple birth defects, mental retardation, and aplastic anemia consistent with Fanconi's anemia showed Hb AF by electrophoresis; the Kleihauer smear showed Hb F in 70% of her erythrocytes. Total Hb concentration was 34 g/L, mean corpuscular volume 119 fL. The proportion of Hb F was 45% by densitometry, 36% by radial immunodiffusion, and 30% by cation-exchange microchromatography. The Hb A2 was 0.5%; glycated Hb was 7.8% by affinity chromatography. Sample volume was insufficient for alkali denaturation. As exemplified with this patient, we recommend microchromatographic cation-exchange assay when Hb F exceeds 30% by densitometry. Here the effect of contamination by Hb A1 was lessened by the high proportion of Hb F. Cation-exchange microchromatography provides clinically relevant Hb F values more quickly than radial immunodiffusion and more conveniently than alkali denaturation.
Increased activity of creatine kinase isoenzyme MB in a theophylline-intoxicated patient.
Authors: Ng R H , Roe C , Funt D , Statland B E
Published: January 2020

A 78-year-old woman had increased activities of creatine kinase (CK; EC 2.7.3.2) and CK-MB isoenzyme in her serum, associated with severe theophylline intoxication. The time course for CK-MB activity was similar to that from an acute myocardial infarction. Clinical findings, however, including electrocardiograms, did not support the diagnosis of myocardial infarction. We suggest caution in interpreting CK-MB results in severe theophylline intoxication.
Competitive idiotype--anti-idiotype immunoassay for adenosine deaminase binding protein in urine.
Authors: Thompson R E , Hewitt C R , Piper D J , Hansen W P , Rubin R H , Tolkoff-Rubin N E , Barrett M C , Nelles M J
Published: January 2020

This competitive immunoassay, based on inhibition by antigen of the idiotype-anti-idiotype interaction, detects adenosine deaminase binding protein (ABP), and involves use of monoclonal anti-idiotype antibodies prepared to a monoclonal antibody specific for ABP. The conditions for this new type of competitive immunoassay are investigated. This competitive immunoassay is as sensitive and reproducible as an earlier described "sandwich"-type immunoassay for ABP (Clin Chem 31: 679-683, 1985). Evaluation of urine samples from normal subjects and from patients showed increased concentrations of ABP in patients with renal disease.
Analytical considerations for quantitative determination of serotonin and its metabolically related products in biological matrices.
Authors: Mailman R B , Kilts C D
Published: January 2020

We discuss the use of "high-performance" liquid chromatography with electrochemical detection for the quantification fo serotonin (5-hydroxytryptamine) and metabolically related products (i. e., 5-hydroxyindoleacetic acid and 5-hydroxytryptophan) in biological matrices. Two methods are described: one for routine quantification of nanogram amounts or more; the other a two-column purification-separation ("trace enrichment") technique for determining subnanogram amounts of these compounds. Various factors affecting the liquid-chromatographic separation and quantification of 5-hydroxy-indoles are detailed, including selection of appropriate internal standard, sample purification, and effects of changes in mobile phase composition, e.g., ion-pair reagent, organic modifier content, and pH. We describe in detail the trace-enrichment method for determinations in the range of 25 pg to 25 ng, and discuss the general factors to consider when developing or modifying an assay for specific applications.
Thyrotropin as measured by a sensitive immunoradiometric assay.
Authors: McBride J H , Thibeault R V , Rodgerson D O
Published: January 2020

An immunoradiometric assay (Boots-Celltech's "Sucrosep"; IRMA) for thyrotropin (TSH) was evaluated and results were compared with those of our in-house RIA procedure. The IRMA had a sensitivity of 0.02 milli-int. unit/L. In addition it displayed excellent intra- and inter-batch precision, cross-reacted negligibly with other pituitary hormones, and appeared to be relatively free of matrix effects (although deionized water did give an apparent TSH concentration of 0.13 milli-int. unit/L). Over the range 1.2 to 64 milli-int. units/L, correlation between the IRMA (y) and RIA (x) was excellent: y = 1.16x - 1.69 (r = 0.98). The normal reference interval for the IRMA was 0.4 to 4.2 milli-int. units/L. For patients suspected of hyperthyroidism who had been subjected to the thyroliberin test, the IRMA more effectively differentiated between euthyroidism and hyperthyroidism. During testing with thyroliberin, all nonresponding hyperthyroid patients had initial baseline TSH concentrations of less than 0.02 milli-int. unit/L by IRMA. This sensitive assay represents an important advance in the ability to differentiate between euthyroidism and hyperthyroidism.
Polyacrylamide gel electrophoresis in quantification of high-density lipoprotein cholesterol.
Authors: Roche D , Atger V , Le Quang N T , Girard A , Ekindjian O G
Published: January 2020

We evaluated a method for quantifying high-density lipoprotein cholesterol in plasma, based on electrophoretic migration of the prestained (with Sudan Black III) sample through a discontinuous polyacrylamide++ gel and densitometric integration of the stain associated with each class of lipoprotein. With this method, operations can be carried out on all types of lipoproteins over a broad range of concentrations. Overloading with very-low and low-density lipoproteins did not affect reliability within a wide range of HDL concentrations (0.45 to 16.60 mmol/L). Results for 22 individual plasma samples from normal and dyslipemic subjects correlated well with those by ultracentrifugal analysis (r=0.96; Student's t= 0.90, p > 0.30). We conclude that this method is reliable, sensitive, and accurate, It may be used for simultaneously typing dyslipoproteinemias and assaying HDL cholesterol.
A case of proteinuria with analbuminuria.
Authors: Sun T , Lien Y , Mailloux L
Published: January 2020

A 46-year-old black man with diabetes mellitus and hypertension was hospitalized because of myocardial ischemia and chronic renal failure. The electrophoretogram for protein in urine revealed proteins only in the alpha 1, alpha 2, and beta regions. These protein fractions were identified as small molecules by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. No albumin was detected in the urine. The molecular mass of albumin, the protein present in highest concentration in serum, is near the glomerular filtration threshold, and this protein is not reabsorbed by renal tubules; therefore, albumin is consistently present in proteinuric specimens. Thus this analbuminuric pattern is highly unusual. Although the mechanism of the analbuminuria in this case is not fully understood, we wished to document this extremely rare electrophoretic pattern to alert clinical chemists and pathologists of its existence.
Assay of carboxypeptidase N activity in serum by liquid-chromatographic determination of hippuric acid.
Authors: Hendriks D , Scharpé S , van Sande M
Published: January 2020

We describe conditions for determining carboxypeptidase N (EC 3.4.17.3) activity by liquid chromatography. Serum (10 microL) is mixed with the artificial substrates hippuryl-L-arginine (30 mmol/L) and hippuryl-L-lysine (100 mmol/L) in 50 mmol/L 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution at pH 8.2 and 7.8, respectively. The hippuric acid product is separated from the substrate in less than 2 min by reversed-phase "high-performance" liquid chromatography and measured spectrophotometrically. o-Methyl hippuric acid is used as internal standard. By this method, optimized for activity and sensitivity of detection, carboxypeptidase N activities are 60-fold greater than those by another procedure (J Chromatogr 266:173-177, 1983). The mean value for 80 normal control subjects was 74.8 (SD 10.3) nmol of hippuric acid released per milliliter of serum per minute for hippuryl-L-arginine substrate, 378 (SD 55) for hippuryl-L-lysine substrate. The sensitivity and precision of the method make it suitable both for routine clinical determinations and as a reference procedure.
Ektachem multilayer dry-film assay for ammonia evaluated.
Authors: Iosefsohn M , Hicks J M
Published: January 2020

We evaluated the Kodak Ektachem multilayer dry-film method for ammonia. Within-day precision (CV) was 5.9% and 2.7% at ammonia concentrations of 53 and 654 mumol/L, respectively. Between-run precision (CV) was 7.8% and 7.3% at 51 and 109 mumol/L, respectively. Correlation with a manual ion-exchange chromatography-Berthelot reaction-based method (x) was good (y = 0.96x - 1.37; r = 0.984; SEE = 9.16). The response of the method varies linearly with ammonia concentration up to 900 mumol/L. Bilirubin less than or equal to 270 mg/L, triglycerides less than or equal to 6.0 g/L, and slight hemolysis did not interfere. The concentration of ammonia in plasma of 120 healthy adults was 16-53 mumol/L (nonparametric central 95 percentiles).
Effects of temperature on measurement of alkaline phosphatase activity.
Authors: Copeland W H , Nealon D A , Rej R
Published: January 2020

We examined the effects of temperature on the activity and steady-state kinetic properties of alkaline phosphatase (EC 3.1.3.1). Purified isoenzymes from human liver, intestine, and placenta were used, as was human serum, and the enzyme from porcine kidney. Phosphatase activity was estimated by two different assay techniques. For all isoenzymes, apparent Michaelis constants for the substrate 4-nitrophenyl phosphate decreased with increased temperature; Km at 37 degrees C was typically half that determined at 25 degrees C. All enzymes of human origin exhibited similar linear Arrhenius relationships over the range examined, 20-37 degrees C (Ea of 30-36 kJ X mol-1). The porcine kidney enzyme obeyed an Arrhenius relationship that was slightly, but significantly, different from the isoenzymes of human origin. Temperature relationships based upon Arrhenius behavior and individual activity measurements are presented. For human alkaline phosphatases, they differed by no more than 10%.
A more specific, simpler radioimmunoassay for carcinoembryonic antigen, with use of monoclonal antibodies.
Authors: Liu Y S , Tobias R J , Zurawski V R
Published: January 2020

A solid-phase, two-site monoclonal antibody radioimmunoassay for carcinoembryonic antigen in serum or plasma has been developed. Two monoclonal antibodies are used: 3d6, which is immobilized on polystyrene beads, reacts with high-molecular-mass CEA; the other, C4, with apparently restricted reactivity toward gastrointestinal tract and mammary carcinomas, is labeled with 125I. The assay consists of incubating 0.2 mL of serum both with 3d6-coated beads and 125I-labeled C4 at room temperature for 18 h. The CEA standard is calibrated against WHO international standard (73/601). Advantages of this assay include: (a) no heat or acid pre-treatment of samples; (b) linear response over a wider functional range, 0 to 150 micrograms/L, requiring fewer calibration points; and (c) no interference by glycosaminoglycans. Average inter- and intra-assay reproducibilities (CVs) are less than 10%; analytical recovery of CEA was 94 to 107%. CEA of less than 0.5 micrograms/L can be detected. The mean concentration of CEA in serum from healthy individuals is 0.97 (SD 1.18) micrograms/L; only 3% of the sera tested had concentrations greater than 3.0 micrograms/L. On comparing this assay with a polyclonal RIA, we found similar assay sensitivity for colorectal carcinoma but fewer false-positive results for sera from patients with benign liver and bowel diseases.