Electron tomography of (In,Ga)N insertions in GaN nanocolumns grown on semi-polar (112̄ 2) GaN templates

We present results of scanning transmission electron tomography on GaN/(In,Ga)N/GaN nanocolumns (NCs) that grew uniformly inclined towards the patterned, semi-polar GaN( 11 2 ̄ 2 ) substrate surface by molecular beam epitaxy. For the practical realization of the tomographic experiment, the nanocolumn axis has been aligned parallel to the rotation axis of the electron microscope goniometer. The tomographic reconstruction allows for the determination of the three-dimensional indium distribution inside the nanocolumns. This distribution is strongly interrelated with the nanocolumn morphology and faceting. The (In,Ga)N layer thickness and the indium concentration differ between crystallographically equivalent and non-equivalent facets. The largest thickness and the highest indium concentration are found at the nanocolumn apex parallel to the basal planes

Genotypic and phenotypic diversity in the noncapsulated Haemophilus infl uenzae: adaptation and pathogenesis in the human airways

The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus infl uenzae (NTHi) is a human-restricted member of the normal airway microbiota in healthy carriers and an opportunistic pathogen in immunocompromised individuals. The duality of NTHi as a colonizer and as a symptomatic infectious agent is closely related to its adaptation to the host, which in turn greatly relies on the genetic plasticity of the bacterium and is facilitated by its condition as a natural competent. The variable genotype of NTHi accounts for its heterogeneous gene expression and variable phenotype, leading to differential host-pathogen interplay among isolates. Here we review our current knowledge of NTHi diversity in terms of genotype, gene expression, antigenic variation, and the phenotypesassociated with colonization and pathogenesis. The potential benefi ts of NTHi diversity studies discussed herein include the unraveling of pathogenicity clues, the generation of tools to predict virulence from genomic data, and the exploitation of a unique natural system for the continuous monitoring of long-term bacterial evolution in human airways exposed to noxious agents. Finally, we highlight the challenge of monitoring both the pathogen and the host in longitudinal studies, and of applying comparative genomics to clarify the meaning of the vast NTHi genetic diversity and its translation to virulence phenotypes. [Int Microbiol 2012; 15(4): 157-170

Genotypic and phenotypic diversity in the noncapsulated Haemophilus infl uenzae: adaptation and pathogenesis in the human airways

The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus infl uenzae (NTHi) is a human-restricted member of the normal airway microbiota in healthy carriers and an opportunistic pathogen in immunocompromised individuals. The duality of NTHi as a colonizer and as a symptomatic infectious agent is closely related to its adaptation to the host, which in turn greatly relies on the genetic plasticity of the bacterium and is facilitated by its condition as a natural competent. The variable genotype of NTHi accounts for its heterogeneous gene expression and variable phenotype, leading to differential host-pathogen interplay among isolates. Here we review our current knowledge of NTHi diversity in terms of genotype, gene expression, antigenic variation, and the phenotypesassociated with colonization and pathogenesis. The potential benefi ts of NTHi diversity studies discussed herein include the unraveling of pathogenicity clues, the generation of tools to predict virulence from genomic data, and the exploitation of a unique natural system for the continuous monitoring of long-term bacterial evolution in human airways exposed to noxious agents. Finally, we highlight the challenge of monitoring both the pathogen and the host in longitudinal studies, and of applying comparative genomics to clarify the meaning of the vast NTHi genetic diversity and its translation to virulence phenotypes. [Int Microbiol 2012; 15(4): 157-170

Elucidation of the RamA Regulon in Klebsiella pneumoniae Reveals a Role in LPS Regulation

Klebsiella pneumoniae is a significant human pathogen, in part due to high rates of multidrug resistance. RamA is an intrinsic regulator in K. pneumoniae established to be important for the bacterial response to antimicrobial challenge; however, little is known about its possible wider regulatory role in this organism during infection. In this work, we demonstrate that RamA is a global transcriptional regulator that significantly perturbs the transcriptional landscape of K. pneumoniae, resulting in altered microbe-drug or microbe-host response. This is largely due to the direct regulation of 68 genes associated with a myriad of cellular functions. Importantly, RamA directly binds and activates the lpxC, lpxL-2 and lpxO genes associated with lipid A biosynthesis, thus resulting in modifications within the lipid A moiety of the lipopolysaccharide. RamA-mediated alterations decrease susceptibility to colistin E, polymyxin B and human cationic antimicrobial peptide LL-37. Increased RamA levels reduce K. pneumoniae adhesion and uptake into macrophages, which is supported by in vivo infection studies, that demonstrate increased systemic dissemination of ramA overexpressing K. pneumoniae. These data establish that RamA-mediated regulation directly perturbs microbial surface properties, including lipid A biosynthesis, which facilitate evasion from the innate host response. This highlights RamA as a global regulator that confers pathoadaptive phenotypes with implications for our understanding of the pathogenesis of Enterobacter, Salmonella and Citrobacter spp. that express orthologous RamA proteins

Alteraciones fisarias tras radiación láser

Ante el auge actual de la radiación láser y al no encontrar bibliografía referente al posible efecto sobre el cartílago de crecimiento, hemos decidido hacer una valoración del mismo en un modelo experimental. Se utilizaron 50 ratas, estableciéndose cinco grupos de estudio de 10 animales cada uno, dependiendo de la dosis de radiación aplicada percutáneamente sobre la fisis femoral distal. Tras el estudio ultraestructural, histoquímico y morfométrico, hemos observado una serie de alteraciones indicadoras de un daño celular directo. Los hallazgos permiten concluir que este tipo de radiación está contraindicado absolutamente durante la fase de crecimiento óseo o en el esqueleto inmaduro.In view of the present importance of Laser Radiation, and due to the lack of references about its effects on the growth cartilage, we designed an experimental model in order to asses it. A total of 50 rats were used, establishing five groups of study at 10 animals each, depending on the dosis of radiation applied percutaneously on the distal femoral phisys. After the structural, histochemical and morphometric study, we observed a series of alterations indicating a direct celular damage at the physion. From the results, it is concluded that laser radiation should be on absolute contraindication during the phase of bone growth or in the inmature skeleton

Significance of tagl and mfd genes in the virulence of non-typeable Haemophilus infl uenzae

Non-typeable Haemophilus infl uenzae (NTHi) is an opportunist pathogen well adapted to the human upper respiratory tract and responsible for many respiratory diseases. In the human airway, NTHi is exposed to pollutants, such as alkylating agents, that damage its DNA. In this study, we examined the signifi cance of genes involved in the repair of DNA alkylation damage in NTHi virulence. Two knockout mutants, tagI and mfd, encoding N3methyladenine-DNA glycosylase I and the key protein involved in transcription-coupled repair, respectively, were constructed and their virulence in a BALB/c mice model was examined. This work shows that N3-methyladenine-DNA glycosylase I is constitutively expressed in NTHi and that it is relevant for its virulence. [Int Microbiol 2014; 17(3):159-164]Keywords: Haemophilus infl uenzae · alkylating agents · virulence · genes tagI and mf

Twitter, partisan use and institutional use: Comparative analysis between the profiles of Moncloa, Madrid City Council and their ruling parties

This paper seeks to compare and analyse the differences in the use of Twitter that, Partido Popular, as a traditional political party, and Ahora Madrid, as a new political party, make of the institutional channels for the public institutions that they administer. In addition, the present study analyses three different periods in the electoral process: the pre-campaign, campaign and post-campaign during the Spanish general elections of December 20th, 2015 in order to see if the election periods caused changes in their communications on Twitter. The sample consists of four cases divided into two groups for content analysis. On one hand, the Government’s Twitter profile (@desdelamoncloa) and of its ruling party, Partido Popular (@ppopular), comprise the old political group, while the Madrid City Council (@Madrid) and its ruling party, Ahora Madrid (@AhoraMadrid), are integrated into the new political group. Additionally, word clouds provide a visual representation of the main terms used by each group. The study results show which group uses and better leverages Twitter’s potential, in that Partido Popular and Moncloa have clearer differences between party and institutional channels, while Ahora Madrid and the Madrid City Council do not seem to be as clear about the difference between the two concepts and use the party channel as the city council channel. However, the results demonstrate that the new political profile leverages Twitter’s potential more.El presente trabajo analiza las diferencias de uso de Twitter por parte de dos partidos políticos españoles, Partido Popular, como partido tradicional, y Ahora Madrid, como nuevo partido, así como la utilización de los canales institucionales de los entes públicos que estos partidos presiden a nivel nacional y local, respectivamente. Los resultados muestran usos y aprovechamientos diferentes de las potencialidades de Twitter. El estudio se realizó en tres periodos electorales diferenciados: precampaña, campaña y post-campaña de las elecciones generales del 20 de diciembre de 2015, para examinar también cambios de comportamiento en la comunicación en Twitter en el periodo electoral. La muestra consta de cuatro casos divididos en dos grupos para el análisis de contenido. Por un lado, el perfil en Twitter del Gobierno (@desdelamoncloa) y el del partido gobernante, el Partido Popular (@ppopular) constituyen el grupo de la vieja política. Por otro lado, el Ayuntamiento de Madrid (@madrid) y su partido gobernante, Ahora Madrid (@AhoraMadrid), se integran dentro del grupo de nueva política. Además, unas nubes de palabras presentarán visualmente las principales ideas enviadas por los perfiles. Los resultados indican que Partido Popular y Moncloa mantuvieron un uso diferenciado entre los canales de partido y los institucionales, mientras que en el caso de Ahora Madrid y el Ayuntamiento de Madrid se constataron usos concluyentes y no diferenciados entre el canal del partido y el institucional. Además, se observa que los perfiles de la nueva política aprovechan más las potencialidades de Twitter