Group B streptococcal infection and activation of human astrocytes.

BACKGROUND:Streptococcus agalactiae (Group B Streptococcus, GBS) is the leading cause of life-threatening meningitis in human newborns in industrialized countries. Meningitis results from neonatal infection that occurs when GBS leaves the bloodstream (bacteremia), crosses the blood-brain barrier (BBB), and enters the central nervous system (CNS), where the bacteria contact the meninges. Although GBS is known to invade the BBB, subsequent interaction with astrocytes that physically associate with brain endothelium has not been well studied. METHODOLOGY/PRINCIPAL FINDINGS:We hypothesize that human astrocytes play a unique role in GBS infection and contribute to the development of meningitis. To address this, we used a well- characterized human fetal astrocyte cell line, SVG-A, and examined GBS infection in vitro. We observed that all GBS strains of representative clinically dominant serotypes (Ia, Ib, III, and V) were able to adhere to and invade astrocytes. Cellular invasion was dependent on host actin cytoskeleton rearrangements, and was specific to GBS as Streptococcus gordonii failed to enter astrocytes. Analysis of isogenic mutant GBS strains deficient in various cell surface organelles showed that anchored LTA, serine-rich repeat protein (Srr1) and fibronectin binding (SfbA) proteins all contribute to host cell internalization. Wild-type GBS also displayed an ability to persist and survive within an intracellular compartment for at least 12 h following invasion. Moreover, GBS infection resulted in increased astrocyte transcription of interleukin (IL)-1β, IL-6 and VEGF. CONCLUSIONS/SIGNIFICANCE:This study has further characterized the interaction of GBS with human astrocytes, and has identified the importance of specific virulence factors in these interactions. Understanding the role of astrocytes during GBS infection will provide important information regarding BBB disruption and the development of neonatal meningitis

Dyslipidemia and prediabetes in overweight/obese teens and waist circumference.

Presented at: 8th Biennial Childhood Obesity Conference; June 29-July 2, 2015; San Diego, CA.https://digitalrepository.unm.edu/prc-posters-presentations/1043/thumbnail.jp

Snapshots of a molecular swivel in action

Members of the serine family of site-specific recombinases exchange DNA strands via 180° rotation about a central protein-protein interface. Modeling of this process has been hampered by the lack of structures in more than one rotational state for any individual serine recombinase. Here we report crystal structures of the catalytic domains of four constitutively active mutants of the serine recombinase Sin, providing snapshots of rotational states not previously visualized for Sin, including two seen in the same crystal. Normal mode analysis predicted that each tetramer's lowest frequency mode (i.e. most accessible large-scale motion) mimics rotation: two protomers rotate as a pair with respect to the other two. Our analyses also suggest that rotation is not a rigid body movement around a single symmetry axis but instead uses multiple pivot points and entails internal motions within each subunit

Defects and boundary layers in non-Euclidean plates

We investigate the behavior of non-Euclidean plates with constant negative Gaussian curvature using the F\"oppl-von K\'arm\'an reduced theory of elasticity. Motivated by recent experimental results, we focus on annuli with a periodic profile. We prove rigorous upper and lower bounds for the elastic energy that scales like the thickness squared. In particular we show that are only two types of global minimizers -- deformations that remain flat and saddle shaped deformations with isolated regions of stretching near the edge of the annulus. We also show that there exist local minimizers with a periodic profile that have additional boundary layers near their lines of inflection. These additional boundary layers are a new phenomenon in thin elastic sheets and are necessary to regularize jump discontinuities in the azimuthal curvature across lines of inflection. We rigorously derive scaling laws for the width of these boundary layers as a function of the thickness of the sheet

Rapid grain growth in post-AGB disc systems from far-infrared and sub-millimetre photometry

The timescales on which astronomical dust grows remain poorly understood, with important consequences for our understanding of processes like circumstellar disk evolution and planet formation.A number of post-asymptotic giant branch stars are found to host optically thick, dust- and gas-rich circumstellar discs in Keplerian orbits. These discs exhibit evidence of dust evolution, similar to protoplanetary discs; however since post-AGB discs have substantially shorter lifetimes than protoplanetary discs they may provide new insights on the grain-growth process. We examine a sample of post-AGB stars with discs to determine the FIR and sub-mm spectral index by homogeneously fitting a sample of data from \textit{Herschel}, the SMA and the literature. We find that grain growth to at least hundreds of micrometres is ubiquitous in these systems, and that the distribution of spectral indices is more similar to that of protoplanetary discs than debris discs. No correlation is found with the mid-infrared colours of the discs, implying that grain growth occurs independently of the disc structure in post-AGB discs. We infer that grain growth to $\sim$mm sizes must occur on timescales $<<10^{5}$ yr, perhaps by orders of magnitude, as the lifetimes of these discs are expected to be $\lesssim10^{5}$~yr and all objects have converged to the same state. This growth timescale is short compared to the results of models for protoplanetary discs including fragmentation, and may provide new constraints on the physics of grain growth.Comment: 13 pages, 7 figures. Accepted for publication in MNRA

Hispanic Immigration to the United States

This chapter presents some of the exceptional characteristics of recent Hispanic immigration to the United States. In 2005, there were nearly 40 million Hispanic immigrants and descendants of Hispanic immigrants living in the U.S. The assimilation experience of this large cultural group does not seem to be following the path past immigrants to the U.S. followed. Most third generation Hispanics in the U.S. still find themselves with income and education levels below the U.S. averages. Most forecasts predict that about 60 million Hispanics and Hispanic-Americans will be living in the U.S. by 2030

Unveiling the mechanisms of solid-state dewetting in Solid Oxide Cells with novel 2D electrodes

During the operation of Solid Oxide Cell (SOC) fuel electrodes, the mobility of nickel can lead to significant changes in electrode morphology, with accompanying degradation in electrochemical performance. In this work, the dewetting of nickel films supported on yttriastabilized zirconia (YSZ), hereafter called 2D cells, is studied by coupling in-situ environmental scanning electron microscopy (E-SEM), image analysis, cellular automata simulation and electrochemical impedance spectroscopy (EIS). Analysis of experimental E-SEM images shows that Ni dewetting causes an increase in active triple phase boundary (aTPB) length up to a maximum, after which a sharp decrease in aTPB occurs due to Ni de-percolation. This microstructural evolution is consistent with the EIS response, which shows a minimum in polarization resistance followed by a rapid electrochemical degradation. These results reveal that neither evaporation-condensation nor surface diffusion of Ni are the main mechanisms of dewetting at 560-800 °C. Rather, the energy barrier for pore nucleation within the dense Ni film appears to be the most important factor. This sheds light on the relevant mechanisms and interfaces that must be controlled to reduce the electrochemical degradation of SOC electrodes induced by Ni dewetting

Patrones biogeográficos de la riqueza de especies y el endemismo de la avifauna en el oeste de México

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos norte y sur. Los análisis de atenuación y de PAE revelaron la existencia de tres grupos principales de áreas: uno ubicado en la sección sur, que comprende desde el este de Oaxaca hasta el sur de Chiapas; otro en la porción norte, abarcando desde el norte de Sonora hasta el norte de Nayarit y Jalisco; y un último para la porción central, desde el sur de Jalisco y el noroeste de Colima hasta el este de Oaxaca, así como la existencia de varios subgrupos al interior de estos.We analyzed patterns of species richness and endemicity in the avifauna of western Mexico from northern Sonora to southeastern Chiapas. The region was subdivided in 24 transects as study units, and analyses were performed using point data obtained from scientific collections and bibliography, helped by the use of a GIS. For the recognition of general biogeographic patterns and regionalization we used two analyses: Parsimony Analysisof Endemicity (PAE), and faunal congruence curves, along with an alternative species level taxonomy. A total of 783 landbird species was recorded, 157 of which are endemic. Results suggest an increase of species richness from north to south and higher concentration of endemism in the middle of the region. Faunal congruence and PAE analyses suggest the presence of three main avifaunal groupings: Oaxaca and Chiapas east of the Isthmus ofTehuantepec, Sonora south to Jalisco, and central Jalisco south to Oaxaca west of the Isthmus, as well as subgroups within these three main groupings