bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and microhardness of pearlitic steel after laser shock processing and annealing
Authors: Xiong Y. , He T. T. , You L. , Li P. Y. , Chen L. F. , Ren F. Z. , Volinsky A. A.
Published: April 2015

The microstructure evolution of the high carbon pearlitic steel after laser shock processing (LSP) with different laser pulse energy and high temperature annealing was investigated. After LSP, the cementite lamella were bent, fractured and broken into granules. Fragmentation and dissolution of the cementite lamella were enhanced by increasing the laser pulse energy. Results show that the ferrite lattice parameter increased due to carbon atom dissolution in the ferrite matrix, and the corresponding ferrite X-ray diffraction peaks shifted significantly towards the smaller diffraction angles. After annealing at 650°C for 30 min, an ultrafine duplex microstructure (ferrite+cementite) was formed on the surface. After LSP with a high energy, equiaxed ferrite grains were refined to 400 nm and the cementite lamella were fully spheroidised with the particle diameter of ∼150 nm. The corresponding grain size of ferrite and cementite under low pulse energy was 500 and 300 nm respectively. After annealing, the ferrite peaks significantly shifted towards the higher diffraction angles, and the ferrite lattice parameter decreased. The microhardness initially increases after LSP and then slightly decreases after subsequent annealing but remained higher than without LSP.
Temperature dependence of impact deformation behavior of single crystal Ni based superalloy
Authors: Yang Y. H. , Yu J. J. , Sun X. F. , Jin T. , Guan H. R.
Published: April 2015

The impact test was carried out to investigate the intermediate temperature brittleness of single crystal Ni based superalloy. The samples were impacted at the velocity of ∼5 m s− 1. The results showed that the impact toughness also exhibited intermediate temperature brittleness, which is similar to the situation in tensile. The samples showed the highest impact toughness at 600°C but exhibited the lowest impact toughness at 760°C. Results showed that the variety of impact toughness was due to the deformation mechanism. At 600°C, a/2 < 110> dislocation slips on the {111} slip system were attributed to the high impact toughness; however, a/2 < 110> dislocation slips from octahedral {111} planes to cubic {100} planes resulted in significant work hardening, leading to the decrease of impact toughness.
Microstructural evolution and corresponding property changes after deep cryotreatment of tool steel
Authors: Li S. , Wu X.
Published: April 2015

The microstructural evolution and structure–property correlation subjected to deep cryotreatment of tool steel were studied. The results show that the retained austenite continues to transform into martensite almost but not complete at low temperature. The topography of retained austenite exhibits as a nanoscale thin film with a thickness range of 20–60 nm between the martensite laths. The changes of internal friction peaks have been explained well by the coupling model, which indicates that deep cryotreatment is not only removing retained austenite but also promoting the interstitial carbon atoms segregated to nearby dislocations under the shrinking strain energy. In addition, more carbides precipitated from the matrix during tempering in cryotreated samples and were verified by analyses of transmission electron microscopy.
Deformation speed and temperature effects on magnesium AZ91 during tubular channel angular pressing
Authors: Reshadi F. , Faraji G. , Aghdamifar S. , Yavari P. , Mashhadi M. M.
Published: April 2015

In the present paper, tubular channel angular pressing process is applied on as cast AZ91 magnesium alloy tubes at different punch speeds at two different temperatures of 150°C and 250°C. The results show that increases in the punch speed lead to higher strength and lower elongation. In addition, at a constant punch speed, an increase in the process temperature leads to a decrease in the strength, but the elongation is slightly increased. The grain size of the sample decreased to ∼1 μm from the initial value of ∼150 μm. The use of very low plunger speeds during the severe plastic deformation of hexagonal close packed (hcp) metals could be considered as a powerful method for increasing the elongation of ultrafine grained hcp metals while maintaining their high strengths.
Improvement of surface properties of 2316 stainless steel with ultrasonic electric surface modification
Authors: Liu D. , Li X. , Tang G. , Chen L. , Wang H. , Song G.
Published: April 2015

An ultrasonic electric surface modification treatment was employed to improve the surface properties of 2316 stainless steel. The surface properties of the specimens after conventional cutting, ultrasonic surface modification treatment and ultrasonic electric surface modification treatment were characterised respectively. A grain refinement layer was formed on the specimen's surface after ultrasonic electric surface modification treatment. The average grain size on the top surface was refined into the submicrometre or nanometre scale. This is caused mainly by two aspects: one is the accumulation of initial tiny particles during deformation, and the other is that the ferrite is smashed into pieces due to microfatigue damage. Moreover, it was found out that the specimen after ultrasonic electric surface modification treatment at four times had shown the optimal surface properties.
Granular bright fact crack propagating under very high cycle fatigue
Authors: Li Y.-D. , Xu N. , Ma H. , Li Y.-Z.
Published: April 2015

The different crack initiation modes from different internal defects of a high carbon chromium bearing steel are investigated in the present paper. The relative granular bright facet (GBF) size is approximately proportional to [Formula: see text] . The critical applied stress intensity factor range at the periphery of inclusion Δ Kinc,th, above which the GBF will no longer be formed, was obtained. For the present SUJ2 steel, Δ Kinc,th = 8 MPa m1/2. The crack growth process in GBF is further investigated by the low–high two-step variable amplitude loading tests. The crack growth process in GBF can be described by [Formula: see text] . The exponent m0 is a material constant independent of the applied stress amplitude and the inclusion size and increases with increasing of HV.
Sample conditions determine the ability of thrombin generation parameters to identify bleeding phenotype in FXI deficiency
Authors: Pike Gillian N. , Cumming Anthony M. , Hay Charles R. M. , Bolton-Maggs Paula H. B. , Burthem John
Published: April 2015

Key Points

When contact activation is inhibited, Factor XI:C levels only correlate with thrombin generation if platelets are present. Thrombin generation measured in platelet-rich plasma with contact activation inhibition identifies bleeding phenotype in FXI deficiency.
Pex11mediates peroxisomal proliferation by promoting deformation of the lipid membrane
Authors: Yoshida Yumi , Niwa Hajime , Honsho Masanori , Itoyama Akinori , Fujiki Yukio
Published: April 2015

Pex11p family proteins are key players in peroxisomal fission, but their molecular mechanisms remains mostly unknown. In the present study, overexpression of Pex11pβ caused substantial vesiculation of peroxisomes in mammalian cells. This vesicle formation was dependent on dynamin-like protein 1 (DLP1) and mitochondrial fission factor (Mff), as knockdown of these proteins diminished peroxisomal fission after Pex11pβ overexpression. The fission-deficient peroxisomes exhibited an elongated morphology, and peroxisomal marker proteins, such as Pex14p or matrix proteins harboring peroxisomal targeting signal 1, were discernible in a segmented staining pattern, like beads on a string. Endogenous Pex11pβ was also distributed a striped pattern, but which was not coincide with Pex14p and PTS1 matrix proteins. Altered morphology of the lipid membrane was observed when recombinant Pex11p proteins were introduced into proteo-liposomes. Constriction of proteo-liposomes was observed under confocal microscopy and electron microscopy, and the reconstituted Pex11pβ protein localized to the membrane constriction site. Introducing point mutations into the N-terminal amphiphathic helix of Pex11pβ strongly reduced peroxisomal fission, and decreased the oligomer formation. These results suggest that Pex11p contributes to the morphogenesis of the peroxisomal membrane, which is required for subsequent fission by DLP1.
VEGF-A isoform-specific regulation of calcium ion flux, transcriptional activation and endothelial cell migration
Authors: Fearnley Gareth W. , Bruns Alexander F. , Wheatcroft Stephen B. , Ponnambalam Sreenivasan
Published: April 2015

Vascular endothelial growth factor A (VEGF-A) regulates many aspects of vascular physiology such as cell migration, proliferation, tubulogenesis and cell-cell interactions. Numerous isoforms of VEGF-A exist but their physiological significance is unclear. Here we evaluated two different VEGF-A isoforms and discovered differential regulation of cytosolic calcium ion flux, transcription factor localisation and endothelial cell response. Analysis of VEGF-A isoform-specific stimulation of VEGFR2-dependent signal transduction revealed differential capabilities for isoform activation of multiple signal transduction pathways. VEGF-A165 treatment promoted increased phospholipase Cγ1 phosphorylation, which was proportional to the subsequent rise in cytosolic calcium ions, in comparison to cells treated with VEGF-A121. A major consequence of this VEGF-A isoform-specific calcium ion flux in endothelial cells is differential dephosphorylation and subsequent nuclear translocation of the transcription factor NFATc2. Using reverse genetics, we discovered that NFATc2 is functionally required for VEGF-A-stimulated endothelial cell migration but not tubulogenesis. This work presents a new mechanism for understanding how VEGF-A isoforms program complex cellular outputs by converting signal transduction pathways into transcription factor redistribution to the nucleus, as well as defining a novel role for NFATc2 in regulating the endothelial cell response.
Trade-offs between performance and variability in the escape responses of bluegill sunfish (Lepomis macrochirus)
Authors: Hitchcock Amanda C. , Chen Tiffany , Connolly Erin , Darakananda Karin , Jeong Janet , Quist Arbor , Robbins Allison , Ellerby David J.
Published: April 2015

Successful predator evasion is essential to the fitness of many animals. Variation in escape behaviour may be adaptive as it reduces predictability, enhancing escape success. High escape velocities and accelerations also increase escape success, but biomechanical factors likely constrain the behavioural range over which performance can be maximized. There may therefore be a trade-off between variation and performance during escape responses. We have used bluegill sunfish (Lepomis macrochirus) escape responses to examine this potential trade-off, determining the full repertoire of escape behaviour for individual bluegill sunfish and linking this to performance as indicated by escape velocity and acceleration. Fish escapes involve an initial C-bend of the body axis, followed by variable steering movements. These generate thrust and establish the escape direction. Directional changes during the initial C-bend were less variable than the final escape angle, and the most frequent directions were associated with high escape velocity. Significant inter-individual differences in escape angles magnified the overall variation, maintaining unpredictability from a predator perspective. Steering in the latter stages of the escape to establish the final escape trajectory also affected performance, with turns away from the stimulus associated with reduced velocity. This suggests that modulation of escape behaviour by steering may also have an associated performance cost. This has important implications for understanding the scope and control of intra- and inter-individual variation in escape behaviour and the associated costs and benefits.
Planar polarization of Vangl2 in the vertebrate neural plate is controlled by Wnt and Myosin II signaling
Authors: Ossipova Olga , Kim Kyeongmi , Sokol Sergei Y.
Published: April 2015

The vertebrate neural tube forms as a result of complex morphogenetic movements, which require the functions of several core planar cell polarity (PCP) proteins, including Vangl2 and Prickle. Despite the importance of these proteins for neurulation, their subcellular localization and the mode of action have remained largely unknown. Here we describe the anteroposterior planar cell polarity (AP-PCP) of the cells in the Xenopus neural plate. At the neural midline, the Vangl2 protein is enriched at anterior cell edges and that this localization is directed by Prickle, a Vangl2-interacting protein. Our further analysis is consistent with the model, in which Vangl2 AP-PCP is established in the neural plate as a consequence of Wnt-dependent phosphorylation. Additionally, we uncover feedback regulation of Vangl2 polarity by Myosin II, reiterating a role for mechanical forces in PCP. These observations indicate that both Wnt signaling and Myosin II activity regulate cell polarity and cell behaviors during vertebrate neurulation.
Evaluation of a knowledge translation and exchange platform to advance non-communicable disease prevention
Authors: Pettman Tahna Lee , Armstrong Rebecca , Waters Elizabeth , Allender Steven , Love Penelope , Gill Tim , Coveney John , Boylan Sinead , Booth Sue , Bolton Kristy , Swinburn Boyd
Published: April 2015

Coordinated systems are required to ensure evidence-informed practice and evaluation of community-based interventions (CBIs). Knowledge translation and exchange (KTE) strategies show promise, but these require evaluation. This paper describes implementation and evaluation of COOPS, a national KTE platform to support best practice in obesity prevention CBIs. A logic model guides KTE activities including knowledge brokering, networking, tailored communications, training, and needs assessments. A mixed-methods evaluation includes communications data, knowledge brokering database, annual survey of CBIs, pre- and post-event questionnaires, interviews, social network analysis, and case studies. This evaluation will contribute to understanding the process of implementing a KTE platform with CBIs and its reach, quality and effectiveness.
Wnt Signaling Cascades and the Roles of Syndecan Proteoglycans
Authors: Pataki Csilla A. , Couchman John R. , Brábek Jan
Published: April 2015

Wnt signaling comprises a group of pathways emanating from the extracellular environment through cell-surface receptors into the intracellular milieu. Wnt signaling cascades can be divided into two main branches, the canonical/β-catenin pathway and the non-canonical pathways containing the Wnt/planar cell polarity and Wnt/calcium signaling. Syndecans are type I transmembrane proteoglycans with a long evolutionary history, being expressed in all Bilateria and in almost all cell types. Both Wnt pathways have been extensively studied over the past 30 years and shown to have roles during development and in a multitude of diseases. Although the first evidence for interactions between syndecans and Wnts dates back to 1997, the number of studies connecting these pathways is low, and many open questions remained unanswered. In this review, syndecan’s involvement in Wnt signaling pathways as well as some of the pathologies resulting from dysregulation of the components of these pathways are summarized.
Forensic accounting and fraud: A review of literature and policy implications
Authors: Ozili Peterson
Published: April 2015

This review present some evidence on fraud, forensic accounting, the skills and education of the forensic investigator. Also, some explanation for the diverging views among academics and regulators in relation to detecting fraud are provided. To regulators, I address the question on why academic research in forensic accounting have little significance to inform policy. Further, I present some rich set of questions and identify a number of important directions for future research in forensic accounting. This paper is intended to stimulate debates and future research of the issues identified.
Adaptation, Clonal Interference, and Frequency-Dependent Interactions in a Long-Term Evolution Experiment withEscherichia coli
Authors: Maddamsetti Rohan , Lenski Richard E , Barrick Jeffrey E
Published: April 2015

Twelve replicate populations of Escherichia coli have been evolving in the laboratory for >25 years and 60,000 generations. We analyzed bacteria from whole-population samples frozen every 500 generations through 20,000 generations for one well-studied population, called Ara−1. By tracking 42 known mutations in these samples, we reconstructed the history of this population’s genotypic evolution over this period. The evolutionary dynamics of Ara−1 show strong evidence of selective sweeps as well as clonal interference between competing lineages bearing different beneficial mutations. In some cases, sets of several mutations approached fixation simultaneously, often conveying no information about their order of origination; we present several possible explanations for the existence of these mutational cohorts. Against a backdrop of rapid selective sweeps both earlier and later, two genetically diverged clades coexisted for >6000 generations before one went extinct. In that time, many additional mutations arose in the clade that eventually prevailed. We show that the clades evolved a frequency-dependent interaction, which prevented the immediate competitive exclusion of either clade, but which collapsed as beneficial mutations accumulated in the clade that prevailed. Clonal interference and frequency dependence can occur even in the simplest microbial populations. Furthermore, frequency dependence may generate dynamics that extend the period of coexistence that would otherwise be sustained by clonal interference alone.
Resistencia a Phytophthora infestans linaje clonal EC-1 en Solanum tuberosum mediante la introducción del gen RB
Authors: Román María Lupe , Rivera Cristina , Orbegozo Jeanette , Serna Fernando , Gamboa Soledad , Perez Willmer , Suarez Victor , Forbes Greg , Kreuze Jan , Ghislain Marc
Published: April 2015

Una de las opciones para el control de la enfermedad del tizón tardío de la papa es el desarrollo de variedades resistentes a Phytophthora infestans mediante la transferencia directa de genes de resistencia (R) por ingeniería genética. En el siguiente trabajo de investigación, se usó el gen RB de Solanum bulbocastanum, el cual otorga un amplio espectro de resistencia a razas de P. infestans. Para dicho fin, se transformó genéticamente vía Agrobacterium la variedad susceptible de papa Desiree (Solanum tuberosum) con el vector binario pCIP68 que contiene el gen RB. Como resultado, se obtuvieron 19 plantas transformadas con el gen RB, confirmadas por la prueba de resistencia a kanamicina y por la prueba de reacción en cadena de la polimerasa (PCR). Las 19 plantas transgénicas fueron sometidas a infección en invernadero bajo condiciones de bioseguridad con el aislamiento POX067 de P. infestans perteneciente al linaje clonal EC-1 que es dominante en el Perú. Tres de las 19 plantas ([RB]54, [RB]56 y [RB]70) presentaron un alto nivel de resistencia al aislamiento POX067 de P. infestans.
Crecimiento por ramificación basal en dos especies de palmeras huicungo, Astrocaryum carnosum y A. huicungo
Authors: Machahua Miguel , Kahn Francis , Millán Betty
Published: April 2015

El proceso de ramificación basal de Astrocaryum carnosum y A. huicungo es descrito y su frecuencia y expresión estructural es analizado en el nivel poblacional. Dos poblaciones de palmeras fueron utilizadas en este estudio, A. carnosum del valle del Alto Huallaga y A. huicungo del valle del Alto Mayo. Los sistemas de ramificación subterráneos fueron examinados y dibujados. Para ambas especies, se establecieron 25 cuadrantes de 20x20 m, en los cuales se contó el número de individuos solitarios y cespitosos, y para estos últimos se registró el número de ejes que conformaban el individuo. Los ejes tanto de los individuos solitarios como de los cespitosos se repartieron por estadio de desarrollo (plántula/juvenil-1/juvenil-2/adulto). El proceso de ramificación basal comienza en individuos al estadio juvenil-2, no se observó en juvenil-1, ni en plántula. A. huicungo presentó mayor densidad de ejes producido por ramificación basal que A. carnosum. Este proceso de ramificación en las dos especies por formaciones de clones a partir de rizomas cortos permite una explotación óptima del espacio y asegura la continuidad de la población en el tiempo. Sin embargo su papel en la propagación espacial de la población es muy reducido, siendo los rizomas de muy poca extensión.
New mammalian records in the Parque Nacional Cerros de Amotape, northwestern Peru
Authors: Hurtado Cindy M. , Pacheco Víctor
Published: April 2015

The Pacific Tropical Rainforest and Equatorial Dry Forest are found only in southern Ecuador and northern Peru, and are among the most poorly known ecosystems of South America. Even though these forests are protected in Parque Nacional Cerros de Amotape (PNCA), they are threatened by fragmentation because of farming and agriculture. The aim of this study was to determine the medium and large mammalian species richness, using transect census, camera trapping, and specimen bone collection. Nine transects were established and 21 camera trap stations were placed along 16 km2 in three localities of PNCA, from August 2012 to April 2013. Total sampling effort was 215 km of transects and 4077 camera-days. We documented 22 species; including 17 with camera trapping, 11 with transect census, and 10 with specimen collection.  Camera traps were the most effective method, and four species (Dasyprocta punctata, Cuniculus paca, Leopardus wiedii and Puma concolor) were documented only with this method. This comprised the first Peruvian record for Dasyprocta punctata, and the first record for the western slope of the Peruvian Andes for Cuniculus paca. Also, both specimen collections and sightings confirm the presence of Potos flavus, first record in the western slope of the Peruvian Andes. Panthera onca, Tremarctos ornatus and Saimiri sciureus are considered locally extinct, while several species are in need of further research. We highlight the importance of the high diversity of this rainforests and encourage local authorities to give the area the highest priority in conservation.
Vegetación de un bosque de Polylepis incarum (Rosaceae) en el distrito de Lampa, Puno, Perú
Authors: Montesinos-Tubée Daniel B. , Pinto Ángel C. , Beltrán Diana F. , Galiano Washington
Published: April 2015

Se estudió la vegetación de los bosques de Polylepis incarum (Bitter) M. Kessler & Schmidt-Lebuhn en el anexo de Lamparaquen, en la provincia de Lampa, departamento de Puno en los años 2009 y 2014. Se determinaron 83 especies vasculares pertenecientes a 35 familias. En cuanto a las formas de vida, dominan las herbáceas, gramíneas, arbustos y árboles, siendo en su mayoría, nativas e endémicas, algunas introducidas. Se identificó el ecosistema queñoal representado por la nueva unidad fitosociológica Lupino chlorolepis-Polylepidetum incari con cuatro subasociaciones respectivamente. La composición florística demuestra una riqueza moderada-alta de especies, siendo las familias con mayor representatividad, Asteraceae, Poaceae, Caryophyllaceae, Fabaceae y Pteridaceae. Se aplicó el método fitosociológico de Braun-Blanquet para el análisis de unidades vegetativas. Se presenta la clasificación de comunidades mediante el software TWINSPAN, el análisis de ordinación DCA con el software CANOCO 4.5 y un dendrograma basado en correlación de especies para cada cuadrante efectuado con el software PC-ORD. Mayores estudios son aún necesarios para tener una visión más amplia de las comunidades de plantas en otras zonas geográficas, y evaluar como la vegetación puede verse afectadas con el cambio climático y acciones antrópicas.
Composición química y actividad antibacteriana del aceite esencial de Hyptis suaveolens (L.) Poit. (Lamiaceae) de los Llanos venezolanos
Authors: Ríos Tesch Nurby , Márquez Yánez Ramón , Mendoza Rojas Xiogelis , Rojas-Fermín Luis , Velasco Carrillo Judith , Díaz Tulia , Mora Vivas Flor , Yánez Colmenares Carlos , Meléndez González Pablo
Published: April 2015

El aceite esencial (AE) obtenido de las hojas y flores de Hyptis suaveolens (L.) Poit. recolectado en Guasdualito, Estado Apure, Venezuela, fue obtenido por hidrodestilación empleando una trampa de Clevenger. El aceite se analizó mediante cromatografía de gases acoplada a espectrometría de masas (GC/MS), se identificaron treinta y cinco compuestos en las hojas (91.9% de la muestra) y treinta compuestos en las flores (97.0% de la muestra), con los siguientes compuestos principales: 1,8-cineol (19.1% hojas, 13.3% flores), fenchona (18.5% hojas, 16.1% flores), biciclogermacreno (12.7% hojas, 18.8% flores), D-Germacreno (6.3% hojas, 10.0% flores). La actividad antibacteriana se evaluó por el método de difusión en agar con discos contra Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 23357, Salmonella typhi CDC 57, Pseudomonas aeruginosa ATCC 27853. Ambos AE inhibieron el desarrollo de E. coli, K. pneumoniae y S. typhi, con una concentración inhibitoria mínima (CIM) que osciló entre 300 μL/mL y 450 μL/mL. Estos resultados representan un aporte al estudio del AE de H. suaveolens, siendo el primer reporte sobre la actividad antibacteriana del AE de las flores de esta especie.
Primer registro de Lophodinium polylophum (Daday) Lemmermann 1910 (Dinophyceae: Lophodiniaceae) en el Perú
Authors: Samanez Iris
Published: April 2015

Se presenta el primer registro para el Perú de Lophodinium polylophum, dinoflagelado de agua dulce, identificado en muestras de plancton procedentes de la laguna Picoplancha en el Santuario Nacional de Pampas del Heath (Madre de Dios) y de una quebrada en la cuenca del rio Puinahua (Loreto).
Primer reporte del dinoflagelado potencialmente tóxico Alexandrium minutum Halim 1960 en el litoral peruano
Authors: Baylón Maribel , Sánchez Sonia , Bárcena Víctor , López Juan , Mamani Enrique
Published: April 2015

En el presente trabajo se registra por primera vez al dinoflagelado potencialmente tóxico Alexandrium minutum Halim 1960 causante de las floraciones algales de marzo del 2006 y febrero del 2009, en el en el litoral del Callao, Perú. La identificación de A. minutum se realizó mediante un examen morfo-taxonómico detallando sus placas con microscopía de luz y epifluorescencia. Para su cuantificación se utilizaron cámaras de sedimentación. Nuestros resultados reportan por primera vez la presencia de A. minutum en el lado sudamericano del Pacífico, frente al Callao. Las características en tamaño, forma y morfología tecal que exhibieron los especímenes fueron muy similares a las descripciones clásicas de esta especie.
Reptiles terrestres de la isla San Lorenzo, Lima, Perú
Authors: Pérez Z. José , Lleellish Miguel
Published: April 2015

Se reportan cuatro especies de reptiles terrestres, un gecónido (Phyllodactlus cf. microphyllus), dos lagartijas (Microlophus peruvianus y M. tigris) y una culebra (Pseudalsophis elegans) para la isla San Lorenzo, departamento de Lima, Perú. La lagartija de las Lomas M. tigris y la culebra P. elegans son reportadas por primera vez para las islas del mar peruano. La presencia de lomas de herbáceas y la considerable extensión de la Isla San Lorenzo explicarían la considerablemente alta riqueza de especies de reptiles terrestres en esta isla.
Reframing graduate student writing strategies from an Activity Theory perspective
Authors: Park Ji-Hyun , De Costa Peter
Published: April 2015

This study adopts a sociocultural approach, more specifically, an Activity Theory (Leont’ev, 1978, 1981; Engestr?m, 1987, 1999) framework, to explore an international graduate student’s use of writing strategies. Using a case study design, we investigate how an MA student from Nepal learns to write academic papers that meet the academic norms of a US graduate school. Through the analysis of course materials, the participant’s written work, stimulated recall, and interview, we examine what strategies the participant used, and how she developed them over her first semester in graduate school. Findings indicate that the participant used various tool-mediated, rule-mediated, and community-mediated strategies. Her mediated actions were driven by her goals and motives that were understood within her social and cultural environments, and interacted with each other in a dynamic and constructive manner. In addition, contradictions between the strategies used by the participant and between the participant and the contextual factors were found; these contradictions, in turn, acted as sources of the development and the change of her writing activity.
Classic and Revisionist Sociocultural Theory, and their analyses of expressive language
Authors: Ratner Carl
Published: April 2015

This article articulates two approaches to sociocultural theory, Vygotsky’s classic approach and a contemporary revisionist approach. We examine: (1) their principle tenets for understanding psychology in relation to culture; (2) how they characterize and explain language in particular; and (3) how they characterize and explain a sample linguistic specimen of two dialogues from a middle-class child and a lower-class child. I utilize a critical discourse analysis of the dialogues to empirically determine: (1) which of the two approaches better accounts for the discursive differences; (2) which is a more adequate linguistic theory; (3) which is a more adequate approach to SCT; and (4) which is a more viable and progressive social and political philosophy. We find Vygotsky’s classic formulation superior on all counts. This article concerns the politics of language, linguistics, and social theory.
Formation and participation of nano-amyloids in pathogenesis of Alzheimer's disease and other amyloidogenic diseases
Authors: Maltsev A.V. , Galzitskaya O.V.
Published: April 2015

Studies of neurodegenetrative disorders have become particularly actual attracting the attention of researchers from over the world because of the dissemination of Alzheimer's disease. The reason for such pathogenesis is the transition of a "healthy" molecule or peptide from the native conformation into a very stable "pathological" isoform. During this, molecules in the "pathological" conformation aggregate, forming amyloid fibrils that can increase without any control. Novel knowledge is required on sporadic isoforms of Alzheimer's disease, on the nature of triggering mechanisms of conformational transitions of beta-amyloid fragments from normally functioning proteins into new formations - nano-beta-amyloids - that spiral out of control of neurons and organism which leads to the loss of neurons. Herein we review studies devoted to the formation of amyloid fibrils and their role in pathogenesis of amyloid diseases.
Molecular recognition elements - DNA/RNA-aptamers to proteins
Authors: Spiridonova V.A.
Published: April 2015

In this review summarizes data on DNA/RNA aptamers - a novel class of molecular recognition elements. Special attention is paid to the aptamers to proteins involved into pathogenesis of wide spread human diseases. These include aptamers to serine protease, to cytokines/growth factors, to influenza viral protein, nucleic acid binding proteins. Strong and specific binding for a given protein target of aptamers make them an attractive class of direct protein inhibitors. They can inhibit pathogenic proteins and it is becoming clear that aptamers have the potential to be a new and effective class of therapeutic molecules.
Nuclear glutathione and its functions
Authors: Kulinsky V.I. , Kolesnichenko L.S.
Published: April 2015

During recent years the nuclear localization of glutathione has been confirmed and this fraction has been quantitatively determined. The nuclear GSH and the enzymes of its metabolism realize independent and important functions. They considerably differ from functions of hyaloplasmic and mitochondrial GSH. Glutathione interacts with regulatory pathways, involved into signal transmission into the nucleus.
Microencapsulated multicellular tumor spheroids:preparation and use as a novel in vitro model for drug screening
Authors: Tsoy A.M. , Zaytseva-Zotova D.S. , Edelweiss E.F. , Bartkowiak A. , Goergen J-L. , Vodovozova E.L. , Markvicheva E.A.
Published: April 2015

In the current study a technique for microencapsulation of human breast adenocarcinoma cells MCF-7 in alginate-chitosan microcapsules is used. Microencapsulation is proposed to generate multicellular tumor spheroids (MTS) based on these cells and to test them further as an in vitro model for anti-tumor drug screening. Cytotoxicity of methotrexate (MTX) was studied on the obtained MTS. A set of MTS with mean size of 150, 200 and 300 m was prepared in function of a cultivation time. After incubation of MTS in cultivation medium containing MTX at concentrations of 1, 2, 10, 50 and 100 nM for 48 hs cell viability was evaluated. MTS were shown to be more resistant to MTX than the monolayer culture, and the resistance to MTX was increased with enhancing a spheroid size. At MTX concentration of 100 nM a number of viable cells in MTS with the size of 300 m was 2.5-fold bigger than that one in monolayer culture. It is suggested that the cells in microencapsulated MTS can better mimic cell behavior in a small size solid tumor than the cells in a monolayer culture. In future microencapsulated MTS can be proposed as a novel in vitro model for anticancer drug screening.
Delayed appearance of hypertension in spontaneously hypertensive rat (SHR) injected with CpG-rich DNA early in ontogenesis
Authors: Veiko N.N. , Konorova I.L. , Neverova M.E. , Fidelina O.V. , Mkrtumova N.A. , Ershova E.S. , Postnov A.Iu. , Kon'kova M.S.
Published: April 2015

In this study we have investigated properties of blood serum extracellular DNA (cell-free DNA) from patients with essential arterial hypertension (AH). Cell-free DNA concentration was not changed in the control AH group compared to norma (healthy donors) but fragments of CpG-rich cell-free DNA marker content were increased at transcribed area of ribosomal repeat (TArDNA, CpG-DNA). To evaluate effect of CpG-DNA on AH development in 2-day SHR line and in control normotensive line (WKY), 700 ng of human TArDNA single subcutaneous injection were inoculated to obtain anti-CpG-DNA polyclonal antibodies. These antibodies could change CpG-DNA contents in total cell-free DNA. Blood pressure (BP) in 9-week SHR line rats immunized with CpG-DNA was equal to BP of WKY rats. Then BP of immunized SHR steadily increased with age and reached high value 8 weeks later compared to control SHR rats. Cell-free DNA analysis in 17-week SHR line rats showed significantly reduced concentrations of cell-free DNA and also showed decrease in small DNA fragments content, but increased content of CpG-DNA (rat TArDNA). These changes were accompanied with 3.5-fold blood endonuclease activity increase and decrease of free (unbound to cell-free DNA) anti-CpG-DNA antibodies quantity. Total anti-CpG-DNA antibodies quantity in immunized rats wasn't changed compared to control animals. Thus, observed effect of increase in stable BP elevation age in immunized SHR line rats doesn't relate to increase of anti-CpG-DNA antibody production. Possible reason of this effect is further discussed.
Hepatotoxic efects of acetaminophen. Protective properties of tryptophan-derivatives
Authors: Dremza I.K. , Cheshchevik V.T. , Zabrodskaya S.V. , Maksimchik Y.Z. , Sudnikovich E.Ju. , Lapshina E.A. , Zavodnik I.B.
Published: April 2015

Rat intoxication with acetaminophen (APAP) (500-1500 mg/kg body weight intragastrically) caused a considerable dose-dependent decrease in reduced glutathione (GSH) level in both liver cellular cytoplasm and mitochondria (at the dose 1500 mg/kg body weight by 60% and 33%, respectively). The cytoplasmic GSH level decreased more pronounced by comparison with that in mitochondria. At the same time, we did not observe any inactivation of the mitochondrial enzymes: succinate dehydrogenase, α-ketoglutarate dehydrogenase, glutathione peroxidase despite of mitochondrial GSH consumption; also we did not observe any decrease in the respiratory activity of liver mitochondria isolated from APAP-intoxicated rats. A tryptophan derivative, melatonin (10 mg/kg body weight), did not prevent intramitochondrial GSH oxidation, but decreased the hepatoxity of APAP, diminishing the activities of AlT and AsT as well as bilirubin level in blood plasma of intoxicated rats. N-acetyl-nitrosotryptophan (a nitric oxide donor) did not exhibit any hepatoprotective effects.
Assessment of caspase-3 activity in rabbit myocardial tissue during experimental hemodynamic overload of the left ventricle of the heart
Authors: Blagonravov M.L. , Onufriev M.V. , Demurov E.A. , Guliaeva N.V. , Frolov V.A.
Published: April 2015

It's well known that chronic overload of the cardiac left ventricle is accompanied by an increase in the cardiomyocyte apoptosis rate. However direction and extent of programmed cell death changes under an acute overload of the left ventricle still requires detailed investigation. Caspase-3 activity has been investigated in myocardium of rabbits on the 1, 3 and 5 days after modeling of left ventricle hemodynamic overload caused by surgical narrrowing of the ascending aorta. Control group included intact animals. It was found that caspase-3 activity significantly increased in both ventricles on day 1; it increased more than twofold above controls on day 3; it began to decrease by day 5. On the basis of the obtained data it was concluded that: an acute hemodynamic overload of the left ventricle is a cause of apoptosis acceleration in the myocardial tissue of both cardiac ventricles during first days of the investigated process.
An approach to the identification of the phospholipid molecular species in human erythrocytes using HPLC with mass-spectrometric detection
Authors: Korzhenevskiy D.A. , Selischeva A.A. , Saveliev S.V.
Published: April 2015

A modified RP-HPLC-MS approach has been proposed for a single run separation and identification of the molecular species of different phospholipid classes in a complex extract. This approach has been applied to the analysis of glycero- and sphingolipid composition of human erythrocytes and a number of ceramide fractions have been identified; these fractions was missed in previous studies employing similar methods. The fine experimental design leads to the decrease in the number of procedures needed for a complete phospholipid profiling of the sample.
Electrochemical immunoanalysis of cardiac myoglobin
Authors: Shumyantseva V.V. , Bulko T.V. , Vagin M.Yu. , Suprun E.V. , Archakov A.I.
Published: April 2015

Method targeting the direct monitoring of myoglobin based on analysis of electrochemical parameters of modified electrodes were proposed. Method of direct detection is based on interaction of myoglobin with anti-myoglobin with subsequent electrochemical registration of hemeprotien. Myocardial infarction biomarker myoglobin was quantified at biological level using screen printed electrodes modified with gold nanoparticles stabilized with didodecyldimethylammonium bromide (DDAB) and antibodies. Proposed method did not require signal enhancement and amplification and also labeled secondary antibodies. Electro analysis has high specificity and sensitivity. Myoglobin -antibodies interaction was studied also with electrochemical impedance spectroscopy. Sensor has low detection limit and broad diapason of working concentrations (17.8 ng/ml - 1780 ng/ml; 1 nM - 10 nM). Method based on gold nanoparticles detection on the surface of electrodes was treated for myoglobin identification. AuNP worked as an electrochemical sensing platform: the oxidation of gold surface (resulted in gold oxide formation) upon polarization served as a basis for analytical response. The difference of cathodic peak area and peak high of gold oxide reduction in the case of electrodes with antibodies and electrodes with antibodies - myoglobin complex, was registered.
The dissolution test in biorelevant media as a prognostic tool for modeling of drug behavior in vivo
Authors: Ramenskaya G.V. , Shohin I.E. , Savchenko A.Y. , Volkova E.A.
Published: April 2015

The review deals with the modern tool for modeling of drug behavior in vivo, - the dissolution test in biorelevant media, imitating gastrointestinal fluids. The formulations and preparation methods of fasted state simulation intestinal fluid, FaSSIF and fed state simulation intestinal fluid, FeSSIF, are defined. In addition, the dissolution characteristics of APIs from different BCS classes in biorelevant media are described. Possible applications of biorelevant media in regulatory practice and science are also shown.
The influence of mildronate on peripheral neuropathy and some characteristics of glucose and lipid metabolism in rat streptozotocin-induced diabetes mellitus model
Authors: Sokolovska J. , Rumaks J. , Karajeva N. , Grinvalde D. , Sharipova J. , Klusha V. , Kalvinsh I. , Sjakste N.
Published: April 2015

Streptozotocin (STZ) was used to induce the diabetic rat model. STZ rats were treated with mildronate (100 mg/kg daily, per os or intraperitoneally for 6 weeks). Body weight, blood glucose, triglyceride, ketone body concentrations, glycated hemoglobin percent (HbA1c%), glucose tolerance, and the development of neuropathic pain were monitored throughout the experiment. In the STZ + mildronate group, mildronate treatment caused a significant decrease in mean blood glucose (on week 4) and triglyceride concentrations (on weeks 3-6), significantly slowed the increase in HbA1c% (on week 6) and improved glucose tolerance 120 minutes after glucose ingestion during oral glucose tolerance test versus the STZ group. Mildronate completely protected development of STZ-induced neuropathic pain from the first administration week up to end of the experiment. The obtained data indicate clinical usefulness of the drug for the treatment of diabetes mellitus and its complications.
The influence of compound itel1296 on telomerase activity and the growth of cancer cells
Authors: Kovalenko N.A. , Zhdanov D.D. , Bibikova M.V. , Gotovtseva V.Y.
Published: April 2015

Telomerase is a ribonucleoprotein that synthesizes telomeric repeats and identified as a promising target for anticancer therapy. Here we describe a new compound aITEL1296 as a potent telomerase inhibitor. Its inhibitory activity was a bit higher (IC50 = 0,19±0,02 ng/ml) than that of BIBR1532, one of the most potent telomerase inhibitors known to date. Besides telomerase inhibition aITEL1296 activated apoptotic mechanisms and effectively suppressed proliferation of tumor cell lines (GI50 = 5,0±0,2 ng/ml for most sensitive cell line LnCap) but not normal fibroblast cell line.
Lysozyme activity of the salivary gland secretion of the medicinal leech h. verbana, h. medicinalis and h. orientalis
Authors: Baskova I.P. , Kharitonova O.V. , Zavalova L.L.
Published: April 2015

Salivary gland secretions of three species of the medicinal leech differ in the level of lysozyme peptidoglycan-lysing activity. Using the synthetic fluorogenic substrate, 4-methyl-umbelliferyl tetra N-acetyl-β-chitotetraosid, the glycosidase activity (as one of peptidoglycan-lysing activities) of salivary gland secretion of three species of the medicinal leech was quantitatively evaluated in comparison with egg lysozyme. It is supposed, that lysozyme activity of the leech secretions is determined not only by 5 isoforms of destabilase-lysozyme, but by some other enzymes which can utilize this substrate. These may be lysozymes other than i- (invertebrate) lysozymes (such as destabilase-lysozyme, or related enzymes).
The influence of n-[imino(1-piperidinyl)methyl]guanidine and n-[imino(4-morpholinyl)methyl]guanidine on citrate content,aconitase and citrate synthase activities at ischemia-reperfusionof rats brain
Authors: Sukhoveeva O.V. , Popova T.N. , Makeeva A.V. , Iskusnykh I.Yu.
Published: April 2015

The influence of some guanidine derivatives on the level of brain citrate, brain activities of aconitase and citrate synthase has been investigated in rats subjected to ischemia-reperfusion. Administration of N-[imino(1-piperidinyl)methyl]guanidine and N-[imino(4-morpholinyl)methyl]guanidine resulted in changes of specific activities of aconitase and citrate synthase towards control values. Under these conditions the citrate level considerably decreased versus rats with untreated ishemia-reperfusion. Treatment with these compounds also decreased the degree of DNA fragmentation markedly increased in rats with ischemia-reperfusion.
Some inhibitors of purine nucleoside phosphorylase
Authors: Pogosian L.H. , Nersesova L.S. , Gazariants M.G. , Mkrtchian Z.S. , Akopian J.I.
Published: April 2015

Purine nucleoside phosphorylase (PNP) catalyzes reversible phosphorolysis of purine deoxy- and ribonucleosides with formation (d)Rib-1-P and corresponding bases. PNP plays a leading role in the cell metabolism of nucleosides and nucleotides, as well as in maintaining the immune status of an organism. The major aim of the majority of studies on the PNP is the detection of highly effective inhibitors of this enzyme, derivatives of purine nucleosides used in medicine as immunosuppressors, which are essential for creating selective T-cell immunodeficiency in a human body for organ and tissue transplantation.The present work is devoted to the study of the effects of some synthetic derivatives of purine nucleosides on activity of highly purified PNP from rabbit spleen and also from human healthy and tumor tissues of lung and kidneys. Purine nucleoside analogues modified at various positions of both the heterocyclic base and carbohydrate residues have been investigated. Several compounds, including 8-mercapto-acyclovir, 8-bromo-9-(3,4-hydroxy-butyl)guanine, which demonstrated potent PNP inhibition, could be offered for subsequent study as immunosuppressors during organ and tissue transplantation.
The cultivation of bone marrow cells and cell lines on polymeric films
Authors: Dolgikh M.S. , Livak D.N. , Krasheninnikov M.E. , Onishchenko N.A.
Published: April 2015

The cultivation of multipotent mesenchymal stromal bone marrow cells and cells of A-431, MDCK, Vero, 3T3 and Hep-G2 was performed on polymeric films (PVA) with different hydrophobic fatty acid residues. The cells of different types grew on these films with different intensity, but in the most cases comparable with the cultivation control on usual plastic. The examined films were nontoxic to cells and sufficiently adhesive. They did not changed pH of cultural media, were optically transparent under microscope and comfortable in the experimental work. These films can be used as a model for the artificial organ construction. The covalent binding of different fatty acids to PVA shows possibility of the adaptable changes of films properties (hydrophobity and adhesiveness), and therefore possibility of the creation of optimal conditions for different cell types attachement and growth.
Enzyme-linked immunosorbent assay for determination of cyclosporin a in whole blood
Authors: Andreeva I.P. , Vorobyeva N.T. , Vinnitsky L.I. , Bogush S.S. , Gavrilova E.M. , Egorov A.M.
Published: April 2015

A test-system based on enzyme-linked immunosorbent assay (ELISA) for quantitative determination of cyclosporin A (CSA) in human whole blood has been developed. The detection limit of the method was 25 ng/ml, the linearity of the method in the concentration range 60-1400 ng/ml varied from 94 to 105%, the variation coefficient did not exceed 8%. The novel method exhibited good correlation with radio-immunoassay and polarization fluoroimmunoassay methods; the linear regression coefficients were 0.965 and 0.983, respectively. The developed test system is stable for at least 9 months when stored at 4°C and can be used in clinical practice.