Nano-terracing on polycrystalline palladium induced via simple heat treatment

This paper concerns formation of terraces on polycrystalline Pd, via heat treatments followed by quenching with gas jets. The driving force for terrace formation is the crystallographic anisotropy of the surface energy. Information is presented regarding the surface topography of the terraces and of the grain boundary regions. Typically, the step heights are about 50 nm and the widths of the faces between them are around 1 μm. It is shown that a measure of control can be exercised over the structures produced, although they are determined by a complex interplay of related effects.This research was supported by the EPSRC (EP/E025862/1) and the European Research Council (grant no. 240446)

An accelerated buoyancy adhesion assay combined with 3-D morphometric analysis for assessing osteoblast adhesion on microgrooved substrata.

An accelerated negative buoyancy method has been developed to assess cell adhesion strength. This method has been used in conjunction with 3-D morphometric analysis to understand the effects of surface topology on cell response. Aligned micro-grooved surface topographies (with a range of groove depths) were produced on stainless steel 316L substrates by laser ablation. An investigation was carried out on the effect of the micro-grooved surface topography on cell adhesion strength, cell and nucleus volumes, cell phenotypic expression and attachment patterns. Increased hydrophobicity and anisotropic wettability was observed on surfaces with deeper grooves. A reduction was noted in cell volume, projected areas and adhesion sites for deeper grooves, linked to lower cell proliferation and differentiation rates and also to reduced adhesion strength. The results suggest that the centrifugation assay combined with three-dimensional cell morphometric analysis has considerable potential for obtaining improved understanding of the cell/substrate interface.Financial support for this work has been provided by the EPSRC (grant GR/R95364/01) and by the ERC (grant No. 240446). The authors are grateful to Dr. Tim Nunney, of Thermo-Fisher Scientific, for carrying out the XPS measurements.This is the final version of the article. It first appeared from Elsevier via https://doi.org/ /10.1016/j.jmbbm.2015.12.03

Control over fine scale terrace structures induced on polycrystalline Pd by simple heat treatments in air

This paper presents information about the formation of terraces (often composed of relatively wide faces and relatively narrow steps between them) on samples of polycrystalline palladium. These have been formed via simple heat treatments, involving holding at 1200˚C for periods ranging from a few minutes to several hours, followed by quenching by jets of inert gas. These treatments are such that the terraces are created, and survive the cooling, without significant formation of surface oxide. The crystallographic anisotropy of the surface energy is the driving force for terrace formation, with low surface energy planes tending to be preferentially exposed. Information is presented regarding the surface topography of the terraces and of the grain boundary regions, which have mainly been explored using AFM. Typically, the step heights are of the order of 50 nm and the widths of the faces between them are around 1 µm, although there are quite substantial local variations in these figures. It is shown that a degree of control is possible via the grain structure and texture of the sample, as well as via the processing conditions during the terracing treatment.This research was supported by the EPSRC (EP/E025862/1) and the European Research Council (Grant No. 240446). Financial support for RR was provided by the Nabaa El Mahabaa, Egypt (ID 5898)

Kalirin: a novel genetic risk factor for ischemic stroke

Cerebrovascular and cardiovascular diseases are the leading causes of death and disability worldwide. They are complex disorders resulting from the interplay of genetic and environmental factors, and may share several susceptibility genes. Several recent studies have implicated variants of the Kalirin (KALRN) gene with susceptibility to cardiovascular and metabolic phenotypes, but no studies have yet been performed in stroke patients. KALRN is involved, among others, in the inhibition of inducible nitric oxide synthase, in the regulation of ischemic signal transduction, and in neuronal morphogenesis, plasticity, and stability. The goal of the present study was to determine whether SNPs in the KALRN region on 3q13, which includes the Ropporin gene (ROPN1), predispose to ischemic stroke (IS) in a cohort of Portuguese patients and controls. We genotyped 34 tagging SNPs in the KALRN and ROPN1 chromosomal region on 565 IS patients and 517 unrelated controls, and performed genotype imputation for 405 markers on chromosome 3. We tested the single-marker association of these SNPs with IS. One SNP (rs4499545) in the ROPN1-KALRN intergenic region and two SNPs in KALRN (rs17286604 and rs11712619) showed significant (P < 0.05) allelic and genotypic (unadjusted and adjusted for hypertension, diabetes, and ever smoking) association with IS risk. Thirty-two imputed SNPs also showed an association at P < 0.05, and actual genotyping of three of these polymorphisms (rs7620580, rs6438833, and rs11712039) validated their association. Furthermore, rs11712039 was associated with IS (0.001 < P < 0.01) in a recent well-powered genomewide association study (Ikram et al. 2009). These studies suggest that variants in the KALRN gene region constitute risk factors for stroke and that KALRN may represent a common risk factor for vascular diseases

Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

An appraisal of students' awareness of "self-reflection" in a first-year pathology course of undergraduate medical/dental education

<p>Abstract</p> <p>Background</p> <p>Self-reflection and reflective practice are increasingly considered as essential attributes of competent professionals functioning in complex and ever-changing healthcare systems of the 21^stcentury. The aim of this study was to determine the extent of students' awareness and understanding of the reflective process and the meaning of 'self-reflection' within the contextual framework of their learning environment in the first-year of their medical/dental education. We endorse that the introduction of such explicit educational tasks at this early stage enhances and promotes students' awareness, understanding, and proficiency of this skill in their continuing life-long health professional learning.</p> <p>Methods</p> <p>Over two years, students registered in first-year pathology at the University of Saskatchewan were introduced to a self-reflection assignment which comprised in the submission of a one-page reflective document to a template of reflective questions provided in the given context of their learning environment. This was a mandatory but ungraded component at the midterm and final examinations. These documents were individually analyzed and thematically categorized to a "5 levels-of-reflection-awareness" scale using a specially-designed rubric based on the accepted major theories of reflection that included students' identification of: 1) personal abilities, 2) personal learning styles 3) relationships between course material and student history 4) emotional responses and 5) future applications.</p> <p>Results</p> <p>410 self-reflection documents were analyzed. The student self-awareness on personal learning style (72.7% level 3+) and course content (55.2% level 3+) were well-reflected. Reflections at a level 1 awareness included identification of a) specific teaching strategies utilized to enhance learning (58.4%), b) personal strengths/weaknesses (53%), and c) emotional responses, values, and beliefs (71.5%). Students' abilities to connect information to life experiences and to future events with understanding were more evenly distributed across all 5 levels of reflection-awareness.</p> <p>Conclusions</p> <p>Exposure to self-reflection assignments in the early years of undergraduate medical education increases student awareness and promotes the creation of personal meaning of one's reactions, values, and premises in the context of student learning environments. Early introduction with repetition to such cognitive processes as practice tools increases engagement in reflection that may facilitate proficiency in mastering this competency leading to the creation of future reflective health professionals.</p

Genome Sequence of Brucella abortus Vaccine Strain S19 Compared to Virulent Strains Yields Candidate Virulence Genes

The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study is to identify candidate virulence genes by systematic comparative analysis of the attenuated strain with the published genome sequences of two virulent and closely related strains of B. abortus, 9–941 and 2308. The two S19 chromosomes are 2,122,487 and 1,161,449 bp in length. A total of 3062 genes were identified and annotated. Pairwise and reciprocal genome comparisons resulted in a total of 263 genes that were non-identical between the S19 genome and any of the two virulent strains. Amongst these, 45 genes were consistently different between the attenuated strain and the two virulent strains but were identical amongst the virulent strains, which included only two of the 236 genes that have been implicated as virulence factors in literature. The functional analyses of the differences have revealed a total of 24 genes that may be associated with the loss of virulence in S19. Of particular relevance are four genes with more than 60bp consistent difference in S19 compared to both the virulent strains, which, in the virulent strains, encode an outer membrane protein and three proteins involved in erythritol uptake or metabolism

Study of Bc+B_c^+ decays to the K+K−π+K^+K^-\pi^+ final state and evidence for the decay Bc+→χc0π+B_c^+\to\chi_{c0}\pi^+

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2$, with a significance of 2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html, link to supplemental material inserted in the reference

Temporal Controls of the Asymmetric Cell Division Cycle in Caulobacter crescentus

The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella)

Modulation of hepatic PPAR expression during Ft LVS LPS-induced protection from Francisella tularensis LVS infection

<p>Abstract</p> <p>Background</p> <p>It has been shown previously that administration of <it>Francisella tularensis </it>(<it>Ft</it>) Live Vaccine Strain (LVS) lipopolysaccharide (LPS) protects mice against subsequent challenge with <it>Ft </it>LVS and blunts the pro-inflammatory cytokine response.</p> <p>Methods</p> <p>To further investigate the molecular mechanisms that underlie <it>Ft </it>LVS LPS-mediated protection, we profiled global hepatic gene expression following <it>Ft </it>LVS LPS or saline pre-treatment and subsequent <it>Ft </it>LVS challenge using Affymetrix arrays.</p> <p>Results</p> <p>A large number of genes (> 3,000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by pre-treatment with <it>Ft </it>LVS LPS in the surviving mice. However, <it>Ft </it>LVS LPS alone had a subtle effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of the fatty acid metabolism pathway, which is regulated by peroxisome proliferator activated receptors (PPARs).</p> <p>Conclusions</p> <p>We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (α and γ).</p