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https://www.readbyqxmd.com/read/28718844/solvent-gradient-electrospray-for-laser-ablation-electrospray-ionization-mass-spectrometry
#1
Hang Li, Akos Vertes
Most electrospray based ambient ionization techniques, e.g., laser ablation electrospray ionization (LAESI), utilize a fixed spray solution composition. Complex samples often contain compounds of different polarity that exhibit a wide range of solubilities in the electrospray solvent. Thus, the fixed spray solution composition limits the molecular coverage of these approaches. Two-barrel theta glass capillaries have been used for the rapid mixing of two solutions for manipulating fast reactions including protein folding, unfolding, and charge state distributions...
July 18, 2017: Analyst
https://www.readbyqxmd.com/read/28714899/electrochemical-flow-elisa-for-rapid-and-sensitive-determination-of-microcystin-lr-using-automated-sequential-injection-system
#2
Lesedi Lebogang, Jongjit Jantra, Martin Hedström, Bo Mattiasson
An amperometric immunoanalysis system based on monoclonal antibodies immobilized on Sepharose beads and packed into a micro-immunocolumn was developed for the quantification of microcystin-LR. Microcystin-LR (MCLR) was used as a reference microcystin variant. Inside the immunocolumn, free microcystins and microcystin-horseradish peroxidase (tracer) were sequentially captured by the immobilized antibodies, and the detection was performed electrochemically using Super AquaBlue ELISA substrate 2,2'-azinobis(3-ethylbenzothiazoline-sulfonic acid) (ABTS)...
July 16, 2017: Sensors
https://www.readbyqxmd.com/read/28710792/biophysical-investigation-of-type-a-putas-reveals-a-conserved-core-oligomeric-structure
#3
David A Korasick, Harkewal Singh, Travis A Pemberton, Min Luo, Richa Dhatwalia, John J Tanner
Many enzymes form homooligomers, yet the functional significance of self-association is seldom obvious. Herein, we examine the connection between oligomerization and catalytic function for proline utilization A (PutA) enzymes. PutAs are bifunctional enzymes that catalyze both reactions of proline catabolism. Type A PutAs are the smallest members of the family, possessing a minimal domain architecture consisting of N-terminal proline dehydrogenase and C-terminal L-glutamate-γ-semialdehyde dehydrogenase modules...
July 15, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28709303/acoustic-multipole-sources-for-the-regularized-lattice-boltzmann-method-comparison-with-multiple-relaxation-time-models-in-the-inviscid-limit
#4
Congshan Zhuo, Pierre Sagaut
In this paper, a variant of the acoustic multipole source (AMS) method is proposed within the framework of the lattice Boltzmann method. A quadrupole term is directly included in the stress system (equilibrium momentum flux), and the dependency of the quadrupole source in the inviscid limit upon the fortuitous discretization error reported in the works of E. M. Viggen [Phys. Rev. E 87, 023306 (2013)PLEEE81539-375510.1103/PhysRevE.87.023306] is removed. The regularized lattice Boltzmann (RLB) method with this variant AMS method is presented for the 2D and 3D acoustic problems in the inviscid limit, and without loss of generality, the D3Q19 model is considered in this work...
June 2017: Physical Review. E
https://www.readbyqxmd.com/read/28700698/suppressors-of-selection
#5
Fernando Alcalde Cuesta, Pablo González Sequeiros, Álvaro Lozano Rojo
Inspired by recent works on evolutionary graph theory, an area of growing interest in mathematical and computational biology, we present examples of undirected structures acting as suppressors of selection for any fitness value r > 1. This means that the average fixation probability of an advantageous mutant or invader individual placed at some node is strictly less than that of this individual placed in a well-mixed population. This leads the way to study more robust structures less prone to invasion, contrary to what happens with the amplifiers of selection where the fixation probability is increased on average for advantageous invader individuals...
2017: PloS One
https://www.readbyqxmd.com/read/28694727/labile-glycated-haemoglobin-and-carbamylated-haemoglobin-are-still-critical-points-for-hba1c-measurement
#6
Aurore Desmons, Stéphane Jaisson, Nathalie Leroy, Philippe Gillery, Emmanuelle Guillard
INTRODUCTION: Haemoglobin A1c (HbA1c) is a key analyte for the monitoring of glycemic balance in diabetic patients and is used for diabetes diagnosis in many countries. The potential interference of carbamylated haemoglobin (cHb) and labile glycated haemoglobin (LA1c) on HbA1c assays must remain a matter of vigilance. Such a situation has occurred in our laboratory with a kit replacement on the Bio-Rad Variant™ II testing system, a cation-exchange high performance liquid chromatography (HPLC) system...
June 15, 2017: Biochemia Medica: časopis Hrvatskoga Društva Medicinskih Biokemičara
https://www.readbyqxmd.com/read/28686671/assessment-of-circulating-copy-number-variant-detection-for-cancer-screening
#7
Bhuvan Molparia, Eshaan Nichani, Ali Torkamani
Current high-sensitivity cancer screening methods, largely utilizing correlative biomarkers, suffer from false positive rates that lead to unnecessary medical procedures and debatable public health benefit overall. Detection of circulating tumor DNA (ctDNA), a causal biomarker, has the potential to revolutionize cancer screening. Thus far, the majority of ctDNA studies have focused on detection of tumor-specific point mutations after cancer diagnosis for the purpose of post-treatment surveillance. However, ctDNA point mutation detection methods developed to date likely lack either the scope or analytical sensitivity necessary to be useful for cancer screening, due to the low (<1%) ctDNA fraction derived from early stage tumors...
2017: PloS One
https://www.readbyqxmd.com/read/28679242/improvements-to-ultrasonic-beamformer-design-and-implementation-derived-from-the-task-based-analytical-framework
#8
Nghia Q Nguyen, Richard W Prager, Michael F Insana
The task-based framework, previously developed for beamformer comparison [Nguyen, Prager, and Insana, J. Acoust. Soc. Am. 140, 1048-1059 (2016)], is extended to design a new beamformer with potential applications in breast cancer diagnosis. The beamformer is based on a better approximation of the Bayesian strategy. It is a combination of the Wiener-filtered beamformer and an iterative process that adapts the generated image to specific features of the object. Through numerical studies, the new method is shown to outperform other beamformers drawn from the framework, but at an increase in computational cost...
June 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28669402/seqspark-a-complete-analysis-tool-for-large-scale-rare-variant-association-studies-using-whole-genome-and-exome-sequence-data
#9
Di Zhang, Linhai Zhao, Biao Li, Zongxiao He, Gao T Wang, Dajiang J Liu, Suzanne M Leal
Massively parallel sequencing technologies provide great opportunities for discovering rare susceptibility variants involved in complex disease etiology via large-scale imputation and exome and whole-genome sequence-based association studies. Due to modest effect sizes, large sample sizes of tens to hundreds of thousands of individuals are required for adequately powered studies. Current analytical tools are obsolete when it comes to handling these large datasets. To facilitate the analysis of large-scale sequence-based studies, we developed SEQSpark which implements parallel processing based on Spark to increase the speed and efficiency of performing data quality control, annotation, and association analysis...
July 6, 2017: American Journal of Human Genetics
https://www.readbyqxmd.com/read/28668563/production-of-a-bisdemethylated-microcystin-variant-by-planktothrix-rubescens
#10
Kristin Zoschke, Marta Schübel, Hilmar Börnick, Eckhard Worch
Reservoir samples from a bloom of Planktothrix rubescens were analyzed by ELISA and LC-MS/MS. The comparison of the results of both methods points to the presence of a microcystin variant not yet available as analytical standard and therefore, not detectable by LC-MS/MS analysis. It is proposed that the unknown cyanotoxin variant is a bisdemethylated microcystin variant, presumably [Asp(3),Dha(7)]-microcystin-RR. [Asp(3),Dha(7)]-MC-RR has not been described for a bloom of P. rubescens before.
June 28, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28666229/structural-characterization-and-identification-of-cyclic-lipopeptides-produced-by-bacillus-methylotrophicus-dcs1-strain
#11
Nawel Jemil, Angeles Manresa, Francesc Rabanal, Hanen Ben Ayed, Noomen Hmidet, Moncef Nasri
Bacillus methylotrophicus DCS1 strain was isolated from diesel contaminated soil and screened for its ability to produce biosurfactants; it was found effective for the production of surface active molecules. The structural characterization of the isolated lipopeptides was studied by a variety of analytical techniques. The organic extract of DCS1 lipopeptides was fractionated by silica gel column chromatography (60Mesh). Fractions containing lipopeptides were collected and identified by tandem mass spectrometry MALDI-TOF-MS and MALDI-TOF MS(2)...
June 8, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28665992/gene-expression-allelic-imbalance-in-ovine-brown-adipose-tissue-impacts-energy-homeostasis
#12
Shila Ghazanfar, Tony Vuocolo, Janna L Morrison, Lisa M Nicholas, Isabella C McMillen, Jean Y H Yang, Michael J Buckley, Ross L Tellam
Heritable trait variation within a population of organisms is largely governed by DNA variations that impact gene transcription and protein function. Identifying genetic variants that affect complex functional traits is a primary aim of population genetics studies, especially in the context of human disease and agricultural production traits. The identification of alleles directly altering mRNA expression and thereby biological function is challenging due to difficulty in isolating direct effects of cis-acting genetic variations from indirect trans-acting genetic effects...
2017: PloS One
https://www.readbyqxmd.com/read/28656904/mapping-quorum-sensing-onto-neural-networks-to-understand-collective-decision-making-in-heterogeneous-microbial-communities
#13
Tahir Yusufaly, James Boedicker
Microbial communities frequently communicate via quorum sensing (QS), where cells produce, secrete, and respond to a threshold level of an autoinducer (AI) molecule, thereby modulating gene expression. However, the biology of QS remains incompletely understood in heterogeneous communities, where variant bacterial strains possess distinct QS systems that produce chemically unique AIs. AI molecules bind to 'cognate' receptors, but also to 'non-cognate' receptors found in other strains, resulting in inter-strain crosstalk...
June 28, 2017: Physical Biology
https://www.readbyqxmd.com/read/28653391/multiple-phenotype-association-tests-using-summary-statistics-in-genome-wide-association-studies
#14
Zhonghua Liu, Xihong Lin
We study in this article jointly testing the associations of a genetic variant with correlated multiple phenotypes using the summary statistics of individual phenotype analysis from Genome-Wide Association Studies (GWASs). We estimated the between-phenotype correlation matrix using the summary statistics of individual phenotype GWAS analyses, and developed genetic association tests for multiple phenotypes by accounting for between-phenotype correlation without the need to access individual-level data. Since genetic variants often affect multiple phenotypes differently across the genome and the between-phenotype correlation can be arbitrary, we proposed robust and powerful multiple phenotype testing procedures by jointly testing a common mean and a variance component in linear mixed models for summary statistics...
June 26, 2017: Biometrics
https://www.readbyqxmd.com/read/28649937/the-genetics-of-platelet-count-and-volume-in-humans
#15
John D Eicher, Guillaume Lettre, Andrew D Johnson
The last decade has witnessed an explosion in the depth, variety, and amount of human genetic data that can be generated. This revolution in technical and analytical capacities has enabled the genetic investigation of human traits and disease in thousands to now millions of participants. Investigators have taken advantage of these advancements to gain insight into platelet biology and the platelet's role in human disease. To do so, large human genetics studies have examined the association of genetic variation with two quantitative traits measured in many population and patient based cohorts: platelet count (PLT) and mean platelet volume (MPV)...
June 26, 2017: Platelets
https://www.readbyqxmd.com/read/28646708/piezoelectric-parametric-effects-on-wave-vibration-and-contact-mechanics-of-traveling-wave-ultrasonic-motor
#16
Dongsheng Zhang, Shiyu Wang, Jie Xiu
Elastic wave quality determines the operating performance of traveling wave ultrasonic motor (TWUM). The time-variant circumferential force from the shrink of piezoelectric ceramic is one of the factors that distort the elastic wave. The distorted waveshape deviates from the ideal standard sinusoidal fashion and affects the contact mechanics and driving performance. An analytical dynamic model of ring ultrasonic motor is developed. Based on this model, the piezoelectric parametric effects on the wave distortion and contact mechanics are examined...
May 25, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28644841/low-dimensional-spike-rate-models-derived-from-networks-of-adaptive-integrate-and-fire-neurons-comparison-and-implementation
#17
Moritz Augustin, Josef Ladenbauer, Fabian Baumann, Klaus Obermayer
The spiking activity of single neurons can be well described by a nonlinear integrate-and-fire model that includes somatic adaptation. When exposed to fluctuating inputs sparsely coupled populations of these model neurons exhibit stochastic collective dynamics that can be effectively characterized using the Fokker-Planck equation. This approach, however, leads to a model with an infinite-dimensional state space and non-standard boundary conditions. Here we derive from that description four simple models for the spike rate dynamics in terms of low-dimensional ordinary differential equations using two different reduction techniques: one uses the spectral decomposition of the Fokker-Planck operator, the other is based on a cascade of two linear filters and a nonlinearity, which are determined from the Fokker-Planck equation and semi-analytically approximated...
June 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28644050/hba1c-analysis-by-capillary-electrophoresis-comparison-with-chromatography-and-an-immunological-method
#18
Olav Klingenberg, Torill Furuset, Camilla R Hestbråten, Marit H Hallberg, Astrid Steiro, Iren R Orset, Jens P Berg
BACKGROUND: Haemoglobin A1c (HbA1c) has become an even more important analyte for clinical laboratories during recent years with the introduction of its diagnostic use for diabetes mellitus. Several different analytical principles can be used, each with their advantages and disadvantages. AIM: We wanted to compare Sebia Capillarys 2 Flex Piercing (Capillarys) with our routine HbA1c methods, which were an HPLC method (Tosoh G7) and an immunoassay (Tina-Quant on Roche Modular P) by analysing a large clinical material...
June 23, 2017: Scandinavian Journal of Clinical and Laboratory Investigation
https://www.readbyqxmd.com/read/28642271/powerful-genetic-association-analysis-for-common-or-rare-variants-with-high-dimensional-structured-traits
#19
Xiang Zhan, Ni Zhao, Anna Plantinga, Timothy A Thornton, Karen N Conneely, Michael P Epstein, Michael C Wu
Many genetic association studies collect a wide range of complex traits. As these traits may be correlated and share a common genetic mechanism, joint analysis can be statistically more powerful and biologically more meaningful. However, most existing tests for multiple traits cannot be used for high-dimensional and possibly structured traits, such as network-structured transcriptomic pathway expressions. To overcome potential limitations, in this paper we propose the dual kernel-based association test (DKAT) for testing the association between multiple traits and multiple genetic variants, both common and rare...
June 22, 2017: Genetics
https://www.readbyqxmd.com/read/28641388/recognition-of-the-component-odors-in-mixtures
#20
Marion E Frank, Dane B Fletcher, Thomas P Hettinger
Natural olfactory stimuli are volatile-chemical mixtures in which relative perceptual saliencies determine which odor-components are identified. Odor identification also depends on rapid selective adaptation, as shown for 4 odor stimuli in an earlier experimental simulation of natural conditions. Adapt-test pairs of mixtures of water-soluble, distinct odor stimuli with chemical features in common were studied. Identification decreased for adapted components but increased for unadapted mixture-suppressed components, showing compound identities were retained, not degraded to individual molecular features...
June 21, 2017: Chemical Senses
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