bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromagnetic Properties of Composite Materials Based on ABS Plastic with Carbon Nanotubes Obtained by the Additive Technology in the SHF and EHF Bands
Authors: Kuleshov G E , Badin A V , Gering M O
Published: January 2020

The results of study of the electromagnetic characteristics of polymer composite materials containing multiwall carbon nanotubes are presented. New radio filaments for 3D printing with MWCNTs have been created. Experimental samples were obtained from composite filaments by 3D printing. Also investigated is the ABS plastic brand Conductive with carbon fibers. Studies of electromagnetic characteristics were carried out in the SHF and EHF ranges. The frequency dependences of the complex permittivity for these materials are shown. The results show that ABS Conductive plastic has the best absorbing properties on microwave frequency, and composite plastics with MWCNTs of 2% or more on EHF.
Improving the Mechanical Properties of SiC-ceramics by means of Vacuum Electron-ion-plasma Alloying with Titanium
Authors: Leonov A A , Ivanov Yu F , Kalashnikov M P , Abdulmenova E V , Shugurov V V , Teresov A D
Published: January 2020

The investigation results of elemental and phase composition, state of defective substructure and microhardness of the surface layer of «film (Ti)/substrate (SiC-ceramics)» system (Ti film 0.5 μm thick was deposited on the surface of SiC-ceramics) subjected to treatment with an intense pulsed low-energy electron beam (15 J/cm2, 200 μs, 0.3 s−1, 20 pulses) are presented. It is shown that irradiation of the «film (Ti)/substrate (SiC-ceramics)» system with an electron beam is accompanied by the formation of multielement multiphase (SiC; TiC; Ti5Si3) surface layer having submicro- and nanocrystalline structure. Microhardness of the irradiated surface layer reaches a value of 74 GPa, that is twice the value of microhardness of SiC-ceramics (36 GPa).
Electromagnetic Properties of Hexaferrite Polymer Composite Materials
Authors: Sbrodov A V
Published: January 2020

In this paper the results of studies of the electromagnetic characteristics of composite radio materials based on Z-, W-, M-type barium ferrites and epoxy resin are presented. The frequency dependences of the reflection, transmission, and absorption coefficients are shown. The obtained results of the electromagnetic response are in good agreement with the published data on the frequencies of natural ferromagnetic resonance for the types of ferrites considered. Based on the obtained data, the spectra of complex dielectric and magnetic permeabilities were calculated. It has been suggested that the above changes in the complex magnetic permeability are associated with the presence of domain wall resonance in the region of 1 GHz and natural ferromagnetic resonance at higher frequencies.
Cytotoxic Effects of Granulated Hydroxyapatite with Various Particle Size Distribution
Authors: Zakharova O , Gusev A , Chuprunov K , Yudin A , Kuznetsov D
Published: January 2020

Hydroxyapatite-based materials show promise in such applications as reconstructive surgery, stomatology and cosmetology, they can also be used as components of toothpaste, disinfectant products and dietary supplements (DS). However, cytotoxicity of hydroxyapatite powders synthesized via various methods towards a variety of biological cells requires a thorough study.

Cytotoxicity of hydroxyapatite powder samples with spherical particles in three size ranges: 5-25 μm, 25-45 μm and 40-125 μm, synthesized by hydrothermal synthesis with further ultrasonic and spray-drying treatment, was studied on human blood cells and on gram-negative bacteria E.coli.

The examined hydroxyapatite samples have no toxic effect on human blood leukocytes (in concentration 40 mg per 1 ml H2O or normal saline) and on gram-negative bacteria E.coli. (in concentration 40 mg per 1 ml H2O or normal saline) regardless of the contact time and particle size. The obtained data demonstrate safety of the examined materials and absence of toxic effects towards the test objects. This allows us to regard the studied hydroxyapatite samples as biocompatible.

The present study results could be used to develop products and medicinal drugs based on hydroxyapatite granules synthesized by means of hydrothermal synthesis technique with further sonication and spray drying.
Effect of Parameters of Ultrasonic Shot Peening on the Physicomechanical Properties of the Surface Layer of Flat Samples
Authors: Shiryaev A A , Trofimov V N , Karmanov V V , Vindokurov D V
Published: January 2020

The work is devoted to the study of the influence of the parameters of ultrasonic shot peening on the physicomechanical properties of the surface layer of flat samples of 08ps steel, AMg2 and M2 alloys. The results of determination of residual stresses, microhardness are given. As a result, it was established that the processing time makes the largest contribution in the selected modes.
Research on metallurgical bonding of selective laser melted AlSi10Mg alloy
Authors: Dong Sensen , Zhang Xiaoxun , Ma Fang , Jiang Juze , Yang Wei , Lin Zhixiong , chen Chuanbo
Published: January 2020

The densification behavior, surface morphology and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. Increasing the laser scanning speed or hatch spacing will deteriorate the metallurgical bonding between melt pools, resulting in the increase of irregular pores. Scanning speed and hatch spacing affect the liquid metallurgical bonding of melt pools in different ways. By manipulating scanning speed, the shape of the melt pool changes, resulting in different extents of metallurgical bonding. Whereas hatch spacing influences the resultant metallurgical bonding by controlling the overlapping rate between neighboring scan tracks simply. The formations of the hierarchical microstructures which discriminated by the Si phase are elucidated. Coarse zones are formed by the instantaneous existence of extremely high ratio of thermal gradient (G) and solidification rate (R) at the melt pool boundary, where solidification microstructure grows planar. Fine zones are formed by columnar-dendritic growth of microstructure. During the solidification process, the contraction forces that generated by the trapped gas in the pores and gravity are applied to the liquid around irregular pores and, forms the porous microstructures different from that in dense areas eventually. The tensile tests reveal that the tensile properties of SLM-processed samples are significantly affected by the formation of porosity.
Health and social care providers’ perspectives of older people’s drinking: a systematic review and thematic synthesis of qualitative studies
Authors: Bareham Bethany Kate , Kaner Eileen , Spencer Liam , Hanratty Barbara
Published: January 2020

Background

alcohol may increase risks to late-life health, due to its impact on conditions or medication. Older adults must weigh up the potential risks of drinking against perceived benefits associated with positive roles of alcohol in their social lives. Health and social care workers are in a key position to support older people’s decisions about their alcohol use.

Objective

to systematically review and synthesise qualitative studies exploring health and social care providers’ views and experiences of older people’s drinking and its management in care services.

Method

a pre-specified search strategy was applied to five electronic databases from inception to June 2018. Grey literature, relevant journals, references and citations of included articles were searched. Two independent reviewers sifted and quality-appraised articles. Included study findings were analysed through thematic synthesis.

Results

18 unique studies were included. Four themes explained findings: uncertainty about drinking as a legitimate concern in care provision for older people; the impact of preconceptions on work with older adults; sensitivity surrounding alcohol use in later life; and negotiating responsibility for older adults’ alcohol use. Discipline- and country-specific patterns are highlighted.

Conclusions

reservations about addressing alcohol could mean that service providers do not intervene with older adults. Judgements of whether older care recipients’ drinking warrants intervention are complex. Providers will need support and training to recognise and provide appropriate intervention for drinking amongst older care recipients.
GCdiscrimination: identification of gastric cancer based on a milliliter of blood
Authors: Wu Jiangpeng , Yang Yifan , Cheng Long , Wu Jing , Xi Lili , Ma Ying , Zhang Pengyi , Xu Xiaoying , Zhang Dekui , Li Shuyan
Published: January 2020

Gastric cancer (GC) continues to be one of the major causes of cancer deaths worldwide. Meanwhile, liquid biopsies have received extensive attention in the screening and detection of cancer along with better understanding and clinical practice of biomarkers. In this work, 58 routine blood biochemical indices were tentatively used as integrated markers, which further expanded the scope of liquid biopsies and a discrimination system for GC consisting of 17 top-ranked indices, elaborated by random forest method was constructed to assist in preliminary assessment prior to histological and gastroscopic diagnosis based on the test data of a total of 2951 samples. The selected indices are composed of eight routine blood indices (MO%, IG#, IG%, EO%, P-LCR, RDW-SD, HCT and RDW-CV) and nine blood biochemical indices (TP, AMY, GLO, CK, CHO, CK-MB, TG, ALB and γ-GGT). The system presented a robust classification performance, which can quickly distinguish GC from other stomach diseases, different cancers and healthy people with sensitivity, specificity, total accuracy and area under the curve of 0.9067, 0.9216, 0.9138 and 0.9720 for the cross-validation set, respectively. Besides, this system can not only provide an innovative strategy to facilitate rapid and real-time GC identification, but also reveal the remote correlation between GC and these routine blood biochemical parameters, which helped to unravel the hidden association of these parameters with GC and serve as the basis for subsequent studies of the clinical value in prevention program and surveillance management for GC. The identification system, called GC discrimination, is now available online at http://lishuyan.lzu.edu.cn/GC/.
Consensus features nested cross-validation
Authors: Parvandeh Saeid , Yeh Hung-Wen , Paulus Martin P , McKinney Brett A
Published: January 2020

Feature selection can improve the accuracy of machine-learning models, but appropriate steps must be taken to avoid overfitting. Nested cross-validation (nCV) is a common approach that chooses the classification model and features to represent a given outer fold based on features that give the maximum inner-fold accuracy. Differential privacy is a related technique to avoid overfitting that uses a privacy-preserving noise mechanism to identify features that are stable between training and holdout sets.

We develop consensus nested cross-validation (cnCV) that combines the idea of feature stability from differential privacy with nCV. Feature selection is applied in each inner fold and the consensus of top features across folds is used as a measure of feature stability or reliability instead of classification accuracy, which is used in standard nCV. We use simulated data with main effects, correlation and interactions to compare the classification accuracy and feature selection performance of the new cnCV with standard nCV, Elastic Net optimized by cross-validation, differential privacy and private evaporative cooling (pEC). We also compare these methods using real RNA-seq data from a study of major depressive disorder.

The cnCV method has similar training and validation accuracy to nCV, but cnCV has much shorter run times because it does not construct classifiers in the inner folds. The cnCV method chooses a more parsimonious set of features with fewer false positives than nCV. The cnCV method has similar accuracy to pEC and cnCV selects stable features between folds without the need to specify a privacy threshold. We show that cnCV is an effective and efficient approach for combining feature selection with classification.

Availability and implementation

Code available at https://github.com/insilico/cncv.

Supplementary information

Supplementary data are available at Bioinformatics online.
Pirfenidone inhibits epithelial–mesenchymal transition in keloid keratinocytes
Authors: Satish Latha , Evdokiou Alexander , Geletu Eleni , Hahn Jennifer M , Supp Dorothy M
Published: January 2020

Background

Keloids are benign fibroproliferative skin lesions that are difficult to treat and become a lifetime predicament for patients. Several treatment modalities have been put forth, but as yet no satisfactory approach to the prevention or treatment of keloids has been identified. The process of epithelial-to-mesenchymal transition (EMT) has been implicated in keloid scarring, as keloid keratinocytes display an EMT-like phenotype. This study investigated the potential of pirfenidone, an antifibrotic agent, to counteract EMT-like alterations in keloid keratinocytes, including gene expression, cell migratory and proliferative functions.

Methods

Normal and keloid keratinocytes were isolated from discarded normal skin tissues and from resected keloid tissues, respectively. Cells were quiesced for 24 h without epidermal growth factor DS-Qi1MCDigital and were exposed to transforming growth factor-beta1 (TGF-β1; 10 ng/mL), with or without pirfenidone (400 μg/mL), for an additional 24 h. The effects of pirfenidone on cytotoxicity, cell migration, cell proliferation, and on expression of genes and proteins involved in EMT were assayed. Statistical significance was determined by two-way ANOVA using Sigma Plot.

Results

We found that pirfenidone did not elicit any cytotoxic effect at concentrations up to 1000 μg/mL. A statistically significant dose-dependent decrease in basal cell proliferation rate was noted in both normal and keloid keratinocytes when exposed to pirfenidone at concentrations ranging from 200 to 1000 μg/mL. Pirfenidone significantly decreased basal cell migration in both normal and keloid keratinocytes, but a significant decrease in TGF-β1-induced cell migration was seen only in keloid keratinocytes. Significant inhibition of the expression of TGF-β1-induced core EMT genes, namely hyaluronan synthase 2, vimentin, cadherin-11, and wingless-type MMTV integration site family, member 5A along with fibronectin-1, was observed in both normal and keloid keratinocytes treated with pirfenidone. In addition, the protein levels of vimentin and fibronectin were significantly reduced by pirfenidone (400 μg/mL) in both normal and keloid keratinocytes.

Conclusions

For the first time, this study shows the efficacy of pirfenidone in inhibiting the EMT-like phenotype in keratinocytes derived from keloids, suggesting that pirfenidone may counteract a critical contributor of keloid progression and recurrence.
Action-Perception Coupling and Near Transfer: Listening to Melodies after Piano Practice Triggers Sequence-Specific Representations in the Auditory-Motor Network
Authors: de Manzano Örjan , Kuckelkorn Karen L , Ström Karin , Ullén Fredrik
Published: January 2020

Understanding how perception and action are coupled in the brain has important implications for training, rehabilitation, and brain–machine interfaces. Ideomotor theory postulates that willed actions are represented through previously experienced effects and initiated by the anticipation of those effects. Previous research has accordingly found that sensory events, if previously associated with action outcomes, can induce activity in motor regions. However, it remains unclear whether the motor-related activity induced during perception of more naturalistic sequences of actions actually represents “sequence-specific” information. In the present study, nonmusicians were firstly trained to play two melodies on the piano; secondly, they performed an fMRI experiment while listening to these melodies as well as novel, untrained melodies; thirdly, multivariate pattern analysis was used to test if voxel-wise patterns of brain activity could identify trained, but not novel melodies. The results importantly show that after associative learning, a series of sensory events can trigger sequence-specific representations in both sensory and motor networks. Interestingly, also novel melodies could be classified in multiple regions, including default mode regions. A control experiment confirmed these outcomes to be training-dependent. We discuss how action-perception coupling may enable spontaneous near transfer and action simulation during action observation.
Chronology of Practice: Chinese Practice in Public International Law in 2018*
Authors: Wu Xiaohui
Published: January 2020

This Survey covers materials reflecting Chinese practice in 2018 relating to: treaties, agreements and other documents signed or ratified by the People’s Republic of China; national legislation; statements made by Chinese representatives at the meetings of the UN and other international organizations, international conferences, and those made by the Foreign Ministry spokespersons, with respect to various branches of international law; and judicial decisions, in particular on the applicability and application of international conventions, by Chinese courts.
Trachoma, Anti-Pgp3 Serology, and Ocular Chlamydia trachomatis Infection in Papua New Guinea
Authors: Macleod Colin K , Butcher Robert , Javati Sarah , Gwyn Sarah , Jonduo Marinjho , Abdad Mohammad Yazid , Roberts Chrissy H , Keys Drew , Koim Samuel Peter , Ko Robert , Garap Jambi , Pahau David , Houinei Wendy , Martin Diana L , Pomat William S , Solomon Anthony W
Published: January 2020

Background

In Melanesia, the prevalence of trachomatous inflammation–follicular (TF) suggests that public health–level interventions against active trachoma are needed. However, the prevalence of trachomatous trichiasis is below the threshold for elimination as a public health problem and evidence of conjunctival infection with trachoma’s causative organism (Chlamydia trachomatis [CT]) is rare. Here, we examine the prevalence of ocular infection with CT and previous exposure to CT in three evaluation units (EUs) of Papua New Guinea.

Methods

All individuals aged 1–9 years who were examined for clinical signs of trachoma in 3 Global Trachoma Mapping Project EUs were eligible to take part in this study (N = 3181). Conjunctival swabs were collected from 349 children with TF and tested by polymerase chain reaction to assess for ocular CT infection. Dried blood spots were collected from 2572 children and tested for anti-Pgp3 antibodies using a multiplex assay.

Results

The proportion of children with TF who had CT infection was low across all 3 EUs (overall 2%). Anti-Pgp3 seroprevalence was 5.2% overall and there was no association between anti-Pgp3 antibody level and presence of TF. In 2 EUs, age-specific seroprevalence did not increase significantly with increasing age in the 1- to 9-year-old population. In the third EU, there was a statistically significant change with age but the overall seroprevalence and peak age-specific seroprevalence was very low.

Conclusions

Based on these results, together with similar findings from the Solomon Islands and Vanuatu, the use of TF to guide antibiotic mass drug administration decisions in Melanesia should be reviewed.
Bronchial Infection and Temporal Evolution of Bronchiectasis in Patients With Chronic Obstructive Pulmonary Disease
Authors: Martínez-García Miguel Ángel , de la Rosa-Carrillo David , Soler-Cataluña Juan Jose , Catalan-Serra Pablo , Ballester Marta , Roca Vanaclocha Yolanda , Agramunt Marcos , Ballestin Javier , Garcia-Ortega Alberto , Oscullo Grace , Navarro-Soriano Cristina , Agusti Alvar
Published: January 2020

Background

Bronchiectasis (BE) impact the clinical course and prognosis of patients with chronic obstructive pulmonary disease (COPD). Yet, the temporal evolution of BE in these patients is unknown. This study seeks to assess the temporal evolution of BE in persons with COPD.

Methods

201 moderate-to-severe patients were recruited between 2004 and 2007 and followed up at least every 6 monts (median of 102 months). To investigate the temporal evolution of BE, in 2015 a second high-resolution computed tomography scan (HRCT) was obtained in survivors and compared with the one obtained at recruitment.

Results

99 (49.3%) died during follow-up. The second HRCT could be obtained in 77 patients and showed that (1) in 27.3% of patients BE never developed, in 36.4% they remained stable, in 16.9% they increased in size and/or extension, and in 19.5% new BE emerged; and that (2) the presence of chronic purulent sputum (hazard ratio [HR], 2.8 [95% confidence interval {CI}, 1.3–5.8]), number of hospitalizations due to exacerbatons (HR, 1.2 [95% CI, 1.1–1.5]), and number of pathogenic microorganism (PPM) isolations (HR, 1.1 [95% CI, 1.02–1.3]) were independent risk factors for the progression or development of BE.

Conclusions

The presence of chronic purulent sputum production, number of PPMs isolated in sputum, and number of hospitalizations due to exacerbations of COPD are independent risk factors of BE progression in patients with COPD.
Chemical Basis and Specificity of Chemical Screening Tests for Urinary Vanilmandelic Acid
Authors: Knight Joseph A , Fronk S , Haymond R E
Published: January 2020

The most common metabolite of neural crest tumors is vanilmandelic acid. There have recently been several screening tests for this substance in urine, in which diazotized aromatic amines couple with it to produce colored azo dyes. The general opinion has been that these tests are very nonspecific, yet little has been written concerning the exact chemical basis of the reaction with respect to biological compounds. We have examined this reaction in some detail, using p-nitroaniline as the diazotized amine, and found it to be surprisingly selective with respect to the chemical configuration of the compounds with which it couples to produce the characteristic violet color interpreted as a positive result. The important structural feature of most of these compounds is that they contain a hydroxymethyl group attached to the guaiacol nucleus, as seen in 3-methoxy-4-hydroxybenzyl alcohol.
Preliminary Evaluation of a Latex Agglutination-Inhibition Tube Test for Morphine
Authors: Ross Robert , Horwitz Charles A , Hager Hans , Usategui Magdalena , Burke M Desmond , Ward Patrick C J
Published: January 2020

We evaluated a new 2-hour latex agglutination-inhibition tube test, designed to detect a minimum of 200 ng of morphine (or structurally related compounds) per milliliter of either serum or urine. It was compared with a more sensitive radioimmunoassay procedure, by use of 159 addict urines (radioimmunoassay-positive) and 506 selected (radioimmunoassay-negative) urines. Our results were negative for 99.6% of the radioimmunoassay-negative specimens, including many from addicts taking several drugs other than opiates, and for 94.3% (33 of 35) of radioimmunoassay-positive specimens from addicts, containing only 40-99 ng (morphine equivalents) per milliliter. Positive test results were recorded for 108 of 110 specimens containing 200 or more nanograms (morphine equivalents) per milliliter. The test is technically and instrumentally simple and has a clearcut negative endpoint. Because glucuronide-conjugated morphine is readily detected, this test can be used before chromatography to eliminate those specimens that have no significant concentrations of narcotics (i.e., give a negative latex tube test) and thus obviate timeconsuming hydrolysis before chromatography.
Azide as a Preservative in Assays of Aspartate Aminotransferase Activity
Authors: Rej Robert , Vanderlinde Raymond E
Published: January 2020

Azide at an effective antimicrobial concentration, 7.7 mmol/liter, inhibits neither the cytoplasmic or the mitochondrial isoenzymes of human aspartate aminotransferase (EC 2.6.1.1) or porcine malate dehydrogenase (EC 1.1.1.37). It markedly prolongs the usefulness of substrates in assays for estimating aspartate aminotransferase activity (aspartate substrate without azide deteriorates in less than 24 h at 25 °C) and does not affect results obtained in assays in which activity is continuously monitored. It also has no effect on chromophore development or absorption spectra in 2,4-dinitrophenylhydrazine-coupled assays, but it eliminates oxalacetate-diazonium salt chromophore formation, thus making it unsuitable for use in this assay. At concentrations greater than 100 mmol/liter it inhibits activities of both enzymes. Azide also catalyzes the ketoenol tautomerization of oxalacetate.
Enzymatic Determination of Serum Urea on the Surface of Silicone-Rubber Pads
Authors: Kuan Jui-chang W , Lau Herbert K Y , Guilbault George G
Published: January 2020

An enzymatic, fluorometric method is described for determination of serum urea on silicone-rubber pads. In this method, the reagents are lyophilized on the surface of the pads, NADH on one side and a mixture of urease, glutamate dehydrogenase, and α-ketoglutarate on the other. The rate of disappearance of NADH fluorescence at 460 nm (excitation wavelength, 340 nm) is monitored and related to serum urea concentration. The calibration curve is linear to 250 mg of urea per liter. The method affords a rapid, simple, and inexpensive means for urea assay, the results of which correlate well with automatic diacetyl monoxime method (correlation coefficient, 0.998).
Thin-Layer Chromatographic Detection and Identification of Methaqualone Metabolites in Urine
Authors: Sleeman H Kenneth , Cella James A , Harvey Johnnie L , Beach Douglas J
Published: January 2020

A procedure for detecting methaqualone and identifying methaqualone metabolites in urine by thin-layer chromatography is described and evaluated. Urine is hydrolyzed with HCl or NalO4, adjusted to pH 9.5, and extracted with chloroform. The chloroform extract is evaporated, reconstituted in methanol, applied to fluorescent silica-gel plates, and developed with ethyl acetate:methanol:ammonium hydroxide (28%) (85:10:5 by vol). Methaqualone use is detected by a pattern of four metabolites, which can be seen under ultraviolet light or are made visible by acidified iodoplatinate reagent. Synthetic methaqualone metabolites are used for identification and to compensate for procedural variables. More than 250 positive urine specimens were correctly identified by this method. Hydrolyzed natural and synthetic metabolites were identical by several criteria.
Simultaneous Detection of Morphine and Barbiturates in Urine by Radioimmunoassay
Authors: Usategui-Gomez M , Heveran J E , Cleeland R , McGhee B , Telischak Z , Awdziej T , Grunberg E
Published: January 2020

This report describes a radioimmunoassay for the simultaneous detection of morphine and barbiturates. Morphine and barbiturate antibodies, obtained from goats, were mixed with 125I-labeled antigens. By adjusting concentrations of the morphine and barbiturate antibodies and radiolabeled antigens, closely superimposed standard curves for the two drugs would be obtained. As a consequence, similar response curves were obtained for urine specimens containing morphine or barbiturates. Although concentrations as low as 25 µg/liter could be measured, to ensure against false positive reactions the test should be performed at the 100 µg/liter concentration. Unknown samples positive by the dual assay were confirmed by separately testing the specimens with the individual radioimmunoassay specific for morphine or barbiturate. Equivalency tests of urines positive for morphine, positive for barbiturates, or negative for both demonstrated complete correlation between the single and dual assays. The mixed reagent retained its sensitivity and specificity for at least three months when stored at 4 or 25 °C. The dual radioimmunoassay is a rapid, simple procedure that can be adapted to automated processes and that is suitable for largeand small-scale screening.
Optimum Kinetic Enzymatic Procedures for Glucose and Triglycerides in Plasma and Serum
Authors: DiCesare Joseph L
Published: January 2020

I describe optimum kinetic procedures for measuring glucose and triglycerides in plasma and serum by enzymatic techniques. Glucose was measured by the hexokinase method at a 1000-fold sample dilution. Absorbance and concentration are linearly related for concentrations up to 4 g/liter. Results are reproducible to about 25 mg/liter (standard error). Comparisons between the kinetic glucose method described here and an automated o-toluidine and a manual end-point method showed no apparent bias between the methods; correlation coefficients were 0.998 and 0.991, respectively. Triglycerides (triacylglycerols) were measured in a fully enzymatic system by measuring free glycerol after hydrolysis with lipase. Absorbance and concentration are linearly related to >2.5 g/liter at a 300-fold sample dilution. Repeatability was about 30 mg/liter (standard error). Compared with a manual method, the correlation coefficient was 0.978, with a slope of 0.93.
Rapid, Specific Assay for Plasma Cortisol by Competitive Protein Binding
Authors: Keane Paul M , Stuart Judith , Mendez Jean , Barbadoro Sandra , Walker William H C
Published: January 2020

We describe a modified competitive protein-binding method for assay of plasma cortisol. Plasma samples are deproteinized by dilution with an ethanol/phosphate buffer, followed by heating at 100 °C for 2 min. Horse serum is used as the source of transcortin. Free radioactivity is separated from the protein-bound component by partition into liquid scintillation counting fluid. A batch of 30 tubes can be ready for counting within 60 min. The assay has better specificity and precision than a competitive protein-binding assay in which ethanol extraction and Florisil adsorbent are used, and results correlate well with those of a specific radioimmunoassay method.
Fluorometric Serum Lipase Assay: Evaluation of Monodecanoyl Fluorescein as Substrate
Authors: Klein Bernard , Standaert Fontaine
Published: January 2020

The elements of the mechanized fluorometric lipase (EC 3.1.1.3) assay of Fleisher and Schwartz [Clin. Chem. 17, 417 (1971)] were made optimum; a manual adaptation was also developed. Hydrolysis of the monodecanoyl fluorescein substrate by hog pancreatic lipase is a zero-order reaction. The hydrolytic activity of normal human serum, serum from hospitalized patients without pancreatitis, and serum from patients with acute pancreatitis showed considerable overlap. Bile salts, considered activators in titrimetric or turbidimetric lipase assays, inhibited hydrolysis of the substrate by human serum. We conclude that monodecanoyl fluorescein is not a specific substrate for the serum lipase measured in acute pancreatitis.
Gas Chromatographic/Thin-Layer Chromatographic Analysis of Acetylated Codeine and Morphine in Urine
Authors: Jain Naresh C , Sneath Thomas C , Budd Robert D , Leung Wai J
Published: January 2020

This procedure positively identifies codeine and morphine in urine. Urine samples are hydrolyzed and extracted with organic solvent, and the extracts are evaporated and acetylated. The presence of codeine and morphine is ascertained by gas chromatography (3% OV-25 and 3% Poly-A 103 columns) and confirmed by thin-layer chromatography (system: ethyl acetate/acetone/concd ammonium hydroxide, 100/10/4.5 by vol; reagent: iodoplatinate). As little as 0.5 mg each of codeine and morphine per liter, in free and conjugated forms, is detectable by this method.
Centrifugal Analyzer Determination of Ascorbate in Serum or Urine with Fe3+/Ferrozine
Authors: Butts William C , Mulvihill Harold J
Published: January 2020

Measurement of serum ascorbate may be useful in long-term population studies because of the possible influence of ascorbate on numerous physiological factors. We describe an automated method for determining ascorbate in serum and urine by using the reduction of ferric iron by ascorbate and the formation of a color between the resulting ferrous iron and Ferrozine [3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine]. A centrifugal analyzer is used to rapidly and simultaneously measure ascorbate in the samples and standards and minimize interference from slower reacting substances in the sample. The method is highly precise and specific. Data are also presented on the stability of ascorbate in serum, urine, and aqueous solutions.
Evaluation of an Automated Glucose-Oxidase Procedure
Authors: Rodriguez-Castellon Jose A , Robinson C Andrew , Smith Mary S , Frye Joyce H
Published: January 2020

We evaluated a slight modification of the automated oxidase/peroxidase method for glucose determination in blood with use of 4-aminophenazone [J. Clin. Pathol. 22, 246 (1969)]. Nonsugar reducing substances did not interfere, except for ascorbic acid in very high concentrations. Lipemic sera gave slightly lower values. Values for reproducibility, specificity, and sensitivity were closer to such values for the hexokinase method than was the case for some other commonly used methods.
Determination of Na+ and K+ in Urine with Ion-Selective Electrodes in an Automated Analyzer
Authors: Pelleg Amir , Levy Gabor B
Published: January 2020

We applied an automatic potentiometric electrolyte analyzer (STAT/ION) to the routine determination of Na+ and K+ in urine samples, and found a high correlation with results obtained by flame photometry. The electrodes were selective and no obvious interferences were encountered in the limited number of samples available in this study
Manual and Semi-Automated Procedures for Measurement of Triglycerides in Serum
Authors: Giegel Joseph L , Ham Anna Bell , Clema William
Published: January 2020

We describe manual and semi-automated procedures for serum triglyceride determinations, in which lipids are partitioned between a water/isopropanol phase and a nonane phase. More than 99% of the triglyceride is extracted into the nonane phase, as determined by recovery of 3H-labeled triolein. Studies with 14C-labeled lecithin demonstrate that less than 1.3% is extracted into the nonane phase at concentrations up to 2.5 g/liter. A novel feature of the method is that glycerol can be liberated from triglyceride by sodium hydroxide at room temperature in less than 5 min. Glycerol is oxidized by periodate in 1-2 min at 25 °C; the formaldehyde produced is reacted with 2,4-pentanedione to yield 3,5-diacetyl-1,3-dihydrolutidine. The manual procedure requires less than 20 min; the semi-automated method requires 7 min from sampling to readout. The procedure may be run at 30-40 samples/h, with stable baseline and less than 2.0% carryover. Both methods are linear to 0.50 g (5.6 mol) of triolein per liter. Analytical recoveries at several concentrations ranged from 97-101% (mean, 100%)
Measurement of Spectral Bandwidth, as Exemplified with the Beckman "Enzyme Analyzer System TR Spectrophotometer"
Authors: Passey Richard B , Gillum Ronald L , Fuller John B
Published: January 2020

This paper describes simple methods for determining spectral bandwidth by measurement and by calculation. We measured the spectral bandwidth of the monochromator from the Beckman Enzyme Analyzer TR, and found it to be 3.5-4.0 nm (av 3.8) by two different methods. We visually estimated it to be 4 nm. Using the specifications for the diffraction grating, focal length, and fixed slit width, we calculated the theoretical spectral bandwidth to be 3.6 nm.
Effects of Buffers on Aspartate Aminotransferase Activity and Association of the Enzyme with Pyridoxal Phosphate
Authors: Rej Robert , Vanderlinde Raymond E
Published: January 2020

Using purified enzymes of human origin and patients’ sera, we examined factors influencing the in vitro association of pyridoxal phosphate with aspartate aminotransferase (EC 2.6.1.1). The rate of association was markedly retarded by phosphate buffer in comparison with tris(hydroxymethyl)aminomethane or six other buffers. Pyridoxal phosphate at an incubation concentration of 130 µmol/liter reactivated the entire apoenzyme portion of an apoenzyme/holoenzyme mixture within 5 min in tris(hydroxymethyl)aminomethane; in contrast, less than 20% was associated during 15 min in phosphate. Activity measured in tris(hydroxymethyl)aminomethane-buffer without exogenous pyridoxal phosphate was 4% greater than that in phosphate and was slightly increased by increasing the pH of the assay mixture from 7.5 to 8.0. Aspartate in the incubation medium did not retard the stimulation in tris(hydroxymethyl)aminomethane buffer. While the magnitude of stimulation varied greatly among sera, a consistent mean stimulation of 30% for groups of sera with normal activities was found when asparate at 125 mmol/liter, 2-oxoglutarate at 6.7 mmol/liter and tris(hydroxymethyl)aminomethane at 90 mmol/liter were used, an increase over the 16% with phosphate buffer [Clin. Chem. 19, 92 (1973)]. Absorbance spectra suggest pyridoxal phosphate exists as the Schiff base of tris(hydroxymethyl)aminomethane or aspartate, or both, under conditions of assay incubation (without addition of 2-oxoglutarate). Nonenzymatic catalysis of the reaction by pyridoxal phosphate alone or a formation of a protein/pyridoxal phosphate adduct was discounted with use of D-asparate substrates
Parallel Radioimmunoassay for Plasma Cortisol and 11-Deoxycortisol
Authors: Kao Michael , Voina Sandra , Nichols Albert , Horton Richard
Published: January 2020

We describe a direct, rapid, and specific procedure for the parallel radioimmunoassay for cortisol and 11-deoxycortisol in plasma. The plasma sample is used directly, after heat inactivation of the natural cortisol-binding protein. The radioimmunoassay utilizes antibodies generated in rabbits by steroids conjugated at their 3-oxo position to thyroglobulin. Ammonium sulfate is used to separate bound and free steroids. Our cortisol antibody and an 11-deoxycortisol antibody obtained elsewhere cross reacted negligibly with each other or with other steroids that might be present in plasma. Radioimmunoassays were therefore developed for both steroids in only 1.25 µl of plasma. The intra-and interassay coefficients of variation for both steroids were less than 10%, with a sensitivity of 4 µg/liter. Steroid values obtained by a competitive protein binding method were consistently higher than those of the present method, suggesting that the former is measuring total corticosteroids. This simple approach requires only 4 h for the specific measurement of both cortisol and 11-deoxycortisol in 20 samples of plasma
Fluorometric Determination of δ-Aminolaevulinate Dehydratase Activity in Human Erythrocytes as an Index to Lead Exposure
Authors: Chakrabarti Saroj K , Brodeur Jules , Tardif Robert
Published: January 2020

We describe a fluorometric method for determining δ-aminolaevulinate dehydratase (EC 4.2.1.24) activity in human erythrocytes and compare it with the existing colorimetric method. Incubation conditions are identical. In the proposed method, the porphobilinogen formed during incubation is converted to a stable and highly fluorescent uroporphyrin by heating for 20 min at 93 °C in an acidic medium in the presence of air. The correlation between results by the two methods was good (r = 0.89). We found a good negative correlation between the activity of the enzyme and the concentration of circulating lead with both methods (r = -0.61 for present method and -0.59 for colorimetric method) for groups of persons subjected to various degrees of lead exposure. Our method is more sensitive and accurate, requires less sample, and the fluorescence is more stable than is the color in the colorimetric method.
Semi-Solid Surface Fluorometric Analysis of Glucose
Authors: Kiang Shiow-ling W , Kuan Jui-chang W , Guilbault George G
Published: January 2020

We describe an enzymatic fluorometric method for determining glucose concentrations in blood samples by analysis on a semi-solid surface (silicone-rubber pads). The method is an adaptation of existing spectrophotometric procedures based on the sequential coupling reactions with glucose-6-phosphate dehydrogenase and NADP+. The rate of appearance of NADPH fluorescence at 460 nm (excitation wavelength, 340 nm) is monitored and related to the glucose concentration in plasma or serum. The calibration curve is linear to 2.50 g/liter. The chief advantages of this method over the spectrophotometric procedure are low cost and rapid response. The results obtained correlate well with those of the o-toluidine method (correlation coefficient, 0.986).
Current Concepts of "Normal Values," "Reference Values," and "Discrimination Values" in Clinical Chemistry
Authors: Sunderman F William
Published: January 2020

The term "normal values" is seriously afflicted by sylleptic ambiguities and conceptual problems, and it is gradually being discarded from the lexicon of clinical chemistry. The neutral term "reference values" is preferable on semantic and scientific grounds, and its use in clinical chemistry is rapidly gaining acceptance. The term "discrimination value" has been added to the lexicon of clinical chemistry. Use of the "discrimination value" for the results of a laboratory test in a specified clinical situation provides the optimal discrimination between the "healthy" and the "diseased," or between "those who need not be investigated further" and "those who do."
Factors Influencing Evaporation from Sample Cups, and Assessment of Their Effect on Analytical Error
Authors: Burtis C A , Begovich J M , Watson J S
Published: January 2020

We studied sample evaporation and its effect on analytical error. Several factors influencing evaporative loss have been identified and measured: environmental, instrumental, and operational factors, and the chemical and physical properties of the sample and its container. Such losses from several different types of sample cups have been measured, either chemically or gravimetrically, and compared with those calculated by using a model that allows evaporative loss from a cup of known geometry to be predicted under various environmental conditions. We discuss some steps that may be taken to minimize evaporative loss and give an example to demonstrate that analytical error from this source can be decreased to a routine 1-2% or less by selecting a particular cup design.
Identification of Human Hemoglobins by Use of Isoelectric Focusing in Gel
Authors: Koepke John A , Thoma James F , Schmidt Robert M
Published: January 2020

Newly-developed gel isoelectric focusing techniques provide for rapid and correct identification of human hemoglobins. With this technique, we examined samples previously identified by the National Hemoglobinopathy Standardization Laboratory of the Center for Disease Control. A wide variety of both normal and abnormal hemoglobins was included in the 134 different specimens examined. The isoelectric points (pl's) were precisely determined; no discrepancies with results by standard techniques of identification were found. The method is accurate and precise. It is proposed as a powerful adjunct to other laboratory methods suitable for use in a hemoglobinopathy reference laboratory or specialized hematology service laboratory.
5-Decynedioic Acid, an Acetylenic Compound in Human Urine
Authors: Lindstedt Sven , Steen Göran
Published: January 2020

An acetylenic dicarboxylic acid, 5-decynedioic acid, has been isolated from human urine. The structure was determined by mass spectrometry of several derivatives, and by infrared spectroscopy. On osmium tetroxide oxidation, a vic-diketone was formed, the mass spectrum of which established the position of the triple bond between carbon atoms 5 and 6. Mass spectrometric evidence for the presence of a small amount of the isomeric 4-decynedioic acid was also obtained. The 24-h excretion of these acids is 0.01-0.1 mmol for healthy adults on a regular diet.
Faster Enzymatic Procedure for Serum Triglycerides
Authors: Sampson Eric J , Demers Laurence M , Krieg Arthur F
Published: January 2020

We describe a single-reagent, enzymatic procedure for triglycerides in serum, which may be performed in 5 min per sample with use of an Abbott ABA-100 analyzer system. This procedure is compared to the semi-automated enzymatic procedure with the ABA-100, which requires 30 min per sample.
Rapid, Simplified Diagnosis of Cystinosis in Conjunctival Biopsies
Authors: Potter Joseph L , Nicely Alfred , Burnstine Robert A
Published: January 2020

Assessment of the markedly elevated concentration of free cystine in conjunctival tissue from patients with cystinosis permits a rapid, simple, and unequivocal diagnosis of this disorder of amino acid metabolism.
The Double Pelican (A Cautionary Tale)
Authors: Grannis George F
Published: January 2020

Gather Dew in the Month of May, when the Sun is in Aries and the Moon is in Taurus, with a clean white Linen Cloth spread upon the Grass [Figure 1]. Filter the Dew into a clean white Porcelain Pan, and deliver it into the Great Egg. Combine this Dew with Virgin's Milk and Infant's Blood, digest for fourteen Days in Horse Dung, and distill to one quarter its Bulk four times running. This Procedure will yield a potent Spirit of Dew which, if you are truly an Artist, may be used to prepare an Elixir of Wonderful Virtue that will Transmute all Metals, and will cause Old Men to rejoice in their restored Youth and Vigor.
Drug Screening by Enzymatic Immunoassay with the Centrifugal Analyzer
Authors: Broughton Alan , Ross Doris L
Published: January 2020

We describe a method for determination of barbiturates, amphetamines, opiates, and methadone by the "enzyme multiplied immunoassay technique" (EMIT) applied to the centrifugal analyzer. This method gives results that agree well (92% for barbiturates, 97% for opiates, 94% for methadone, and 96% for amphetamines) with those obtained by the same technique with the SyvaGilford EMIT instrumentation. Its advantages include use of half as much of the expensive reagents; capability of batch operation, which removes the need for continual attention; and more nearly complete automation. For individual samples it is as fast as the manual method; for large numbers of specimens it is faster.
Immunochemical Determination of Serum Albumin with a Centrifugal Analyzer
Authors: Blom Mogens , Hjørne Niels
Published: January 2020

The turbidity resulting from the reaction between albumin and specific anti-human serum was measured with a good precision by using a GEMSAEC centrifugal analyzer. The reaction was enhanced by polyethylene glycol to shorten the reaction time (5 min) and to displace the point of equivalence between antigen and antibody to an albumin concentration unlikely to occur in human sera (about 100 g/liter). An additional program for the computer was necessary to fit the absorbance readings of individual sera to the nonlinear standard curve. Serum albumin values obtained by the described method correlated well with values obtained by the electroimmuno-technique. About 100 samples could be analyzed per hour, 500 µl of 100-fold diluted antiserum being used per specimen.
Routine Radioimmunoassay of Plasma Testosterone, and Results for Various Endocrine Disorders
Authors: Wong Pui-Yuen , Wood Donald E , Johnson Thomas
Published: January 2020

We describe a modification of published methods for radioimmunoassay of plasma testosterone. This simpler method involves no chromatographic steps, and the necessary reagents, including tritiated testosterone and testosterone anti-serum, are commercially available. A digital computer is used for the calculation. Without difficulty, a technician can complete 100 assays in three working days. Mean testosterone concentrations (± 2 SD) in the plasmas of 21 normal men and 26 women with a normal menstrual cycle were 684 ± 300 and 45 ± 2O ng/dl, respectively. Within- and between-assay precision (coefficient of variation) were 5.2% (n = 29) and 6.7% (n = 26), respectively. We have assayed more than 1000 samples during the past year. We give data on the concentrations of testosterone in plasma of patients with various endocrine disorders.