4,153 research outputs found
Fecal Viral Community Responses to High-Fat Diet in Mice.
Alterations in diet can have significant impact on the host, with high-fat diet (HFD) leading to obesity, diabetes, and inflammation of the gut. Although membership and abundances in gut bacterial communities are strongly influenced by diet, substantially less is known about how viral communities respond to dietary changes. Examining fecal contents of mice as the mice were transitioned from normal chow to HFD, we found significant changes in the relative abundances and the diversity in the gut of bacteria and their viruses. Alpha diversity of the bacterial community was significantly diminished in response to the diet change but did not change significantly in the viral community. However, the diet shift significantly impacted the beta diversity in both the bacterial and viral communities. There was a significant shift away from the relatively abundant Siphoviridae accompanied by increases in bacteriophages from the Microviridae family. The proportion of identified bacteriophage structural genes significantly decreased after the transition to HFD, with a conserved loss of integrase genes in all four experimental groups. In total, this study provides evidence for substantial changes in the intestinal virome disproportionate to bacterial changes, and with alterations in putative viral lifestyles related to chromosomal integration as a result of shift to HFD.IMPORTANCE Prior studies have shown that high-fat diet (HFD) can have profound effects on the gastrointestinal (GI) tract microbiome and also demonstrate that bacteria in the GI tract can affect metabolism and lean/obese phenotypes. We investigated whether the composition of viral communities that also inhabit the GI tract are affected by shifts from normal to HFD. We found significant and reproducible shifts in the content of GI tract viromes after the transition to HFD. The differences observed in virome community membership and their associated gene content suggest that these altered viral communities are populated by viruses that are more virulent toward their host bacteria. Because HFD also are associated with significant shifts in GI tract bacterial communities, we believe that the shifts in the viral community may serve to drive the changes that occur in associated bacterial communities
INTEGRAL Spectroscopy of IRAS 17208-0014: Implications for the Evolutionary Scenarios of Ultraluminous Infrared Galaxies
New integral field optical fiber spectroscopy obtained with the INTEGRAL
system, together with archival {\it {\it HST}} WFPC2 and NICMOS images, have
been used to investigate the ultraluminous infrared galaxy IRAS 172080014,
one of the coldest and most luminous objects in the IRAS 1 Jy sample. The 2D
gas velocity field identifies the {\it optically faint} K-band nucleus as the
{\it true} dynamical nucleus of the galaxy, and shows that the 3 kpc, tilted (i
35 degree) disk is rotating at Vsin= 250 km s. The
kinematical, morphological and photometric evidence presented here supports the
idea that in IRAS 17208-0014 we are witnessing a luminous, cool ULIRG which is
at the final coalescence phase of a system composed of two spirals with m
m, a mass ratio of 2:1, each consisting of a disk+bulge internal
structure, that have been involved in a prograde encounter. This system will
most likely evolve into an intermediate-mass ( L) elliptical. The
multifrequency empirical evidence gathered so far shows no trace of a luminous
QSO, and indicates that starbursts dominate the energy output in this galaxy.
Therefore IRAS 172080014 questions the universality of the ULIRG to QSO
evolutionary scenario proposed by Sanders and collaborators, and supports the
one recently proposed by Colina et al, where two low mass disk galaxies would
produce luminous cool ULIRGs that would not evolve into a QSO phase. (abridge)Comment: Astrophysical Journal (in press
Dielectric antenna effects in integrating line piezoelectric sensors for optoacoustic imaging
This work studies the adverse effects, as regards noise, of immersing in
water an integrating line piezoelectric detector devoted to optoacoustic
imaging. We found that the sensor, in conjunction with the acoustic coupling
medium (water), behaves as a resonant dielectric antenna. This phenomenon
limits the performance of the system because it efficiently captures unwanted
electromagnetic signals. The requirement of good acoustic coupling between the
water and the sensor precluded the use of a standard metallic shielding
enclosure. Therefore, we resorted to a silver-paint based electrical shield
deposited on the detector. This easy-to-implement and low-cost solution
significantly increases the signal to noise ratio and does not degrade the
acoustic performance. The noise reduction allows the use of a better
transimpedance amplifier with higher gain and bandwidth; thus achieving a very
sensitive, low-noise detection system.Comment: 7 pages, 7 figures, 1 table, submitted to Meas. Sci. Technol. on
March 24, 202
Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative
Monolayer Langmuir–Blodgett (LB) films of 1,4-bis(pyridin-4-ylethynyl)benzene (1) together with the “STM touch-to-contact” method have been used to study the nature of metal–monolayer–metal junctions in which the pyridyl group provides the contact at both molecule–surface interfaces. Surface pressure vs area per molecule isotherms and Brewster angle microscopy images indicate that 1 forms true monolayers at the air–water interface. LB films of 1 were fabricated by deposition of the Langmuir films onto solid supports resulting in monolayers with surface coverage of 0.98 × 10-9 mol·cm-2. The morphology of the LB films that incorporate compound 1 was studied using atomic force microscopy (AFM). AFM images indicate the formation of homogeneous, monomolecular films at a surface pressure of transference of 16 mN·m-1. The UV–vis spectra of the Langmuir and LB films reveal that 1 forms two dimensional J-aggregates. Scanning tunneling microscopy (STM), in particular the “STM touch-to-contact” method, was used to determine the electrical properties of LB films of 1. From these STM studies symmetrical I–V curves were obtained. A junction conductance of 5.17 × 10-5 G0 results from the analysis of the pseudolinear (ohmic) region of the I–V curves. This value is higher than that of the conductance values of LB films of phenylene-ethynylene derivatives contacted by amines, thiols, carboxylate, trimethylsilylethynyl or acetylide groups. In addition, the single molecule I–V curve of 1 determined using the I(s) method is in good agreement with the I–V curve obtained for the LB film, and both curves fit well with the Simmons model. Together, these results not only indicate that the mechanism of transport through these metal–molecule–metal junctions is non-reso- nant tunneling, but that lateral interactions between molecules within the LB film do not strongly influence the molecule conduc- tance. The results presented here complement earlier studies of single molecule conductance of 1 using STM-BJ methods, and support the growing evidence that the pyridyl group is an efficient and effective anchoring group in sandwiched metal–monolayer–metal junctions prepared under a number of different conditions
Las hormonas sexuales modulan el crecimiento renal compensador (CRC) y la función renal en la uninefrectomía (uNx)
The role played by sexual hormones and vasoactive substances in the compensatory renal growth (CRG) that follows uninephrectomy (uNx) is still controversial. Intact and gonadectomized adult Wistar rats of both sexes, with and without uNx, performed at 90 days age, were studied at age 150 days. Daily urine volume, electrolyte excretion and kallikrein activity (UKa) were determined. Afterwards, glomerular filtration rate and blood pressure were measured, the kidneys weighed and DNA, protein and RNA studied to determine nuclei content and cell size. When the remnant kidney weight at age 150 days was compared with the weight of the kidney removed at the time of uNx, male uNx rats showed the greatest CRG (50%) while growth in the other uNx groups was 25%, 15% and 19% in orchidectomized, female and ovariectomized rats, respectively. The small CRG observed in the uNx female rats was accompanied by the lowest glomerular filtration value, 0.56 ± 0.02 ml/min/g kwt compared, with the other uNx groups, p < 0.05. Cell size (protein or RNA/DNA) was similar for all the groups except for uNx orchidectomized rats. In this group the cytoplasmatic protein or RNA content was lower than in the other groups while DNA (nuclei content) was similar. Some degree of hyperplasia was determined by DNA content in the uNx groups. Male sexual hormones positively influenced CRG and its absence modulated cell size. Female sexual hormones, instead, did not appear to stimulate CRG. The kallikrein kinin system may not be involved in CRG.La importancia que pueden tener las hormonas sexuales y sustancias vasoactivas sobre el crecimiento renal compensador (CRC) que sigue a la uninefrectomía es aún materia de debate. Se estudiaron ratas Wistar de ambos sexos, a los 150 días de vida, intactas y gonadectomizadas con y sin uNx, realizada a los 90 días de vida. Se midió volumen urinario diario y excreción de electrolitos y actividad de kalikreína urinaria. Se midió filtrado glomerular y presión arterial media extrayéndose luego los riñones que fueron pesados y preparados para estudios histológicos y determinación de ADN, ARN y proteínas para estimar contenido nuclear y tamaño celular. El CRC fue calculado comparando el peso del riñón al momento de las uNx (90 dias de vida) con aquel obtenido a los 150 días de vida. En las ratas macho uNx se observó el mayor CRC (50%) mientras que, en los otros grupos uNx solo alcanzó un 25%, 15% y 19%. El filtrado glomerular acompañó los cambios morfológicos observándose el menor filtrado en las ratas hembras uNx respecto al resto de los grupos 0.56 ± 0.02, p < 0.05. El tamaño celular (proteína o ARN/ ADN) fue similar para todos los grupos excepto para los orquidectomizados uNx, cuyo contenido citoplasmático fue menor. El contenido nuclear (ADN) fue semejante en todos los grupos. Se observó que el CRC está influenciado positivamente por las hormonas sexuales masculinas y su ausencia modula el tamaño celular. La falta de hormonas sexuales femeninas, en cambio, afecta negativamente el CRC. El sistema kalikreína kinina no parecería estar involucrado en el CRC.Fil: Azurmendi, Pablo Javier. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; ArgentinaFil: Oddo, Elisabet M.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; ArgentinaFil: Toledo, Jorge E.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; ArgentinaFil: Martin, Rodolfo Santiago. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; ArgentinaFil: Ibarra, Fernando R.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; ArgentinaFil: Arrizurieta, Elvira. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Medicas; Argentin
Towards a metallic top contact electrode in molecular electronic devices exhibiting a large surface coverage by photoreduction of silver cations
In this contribution the photoreduction of silver ions coordinated onto a Langmuir–Blodgett monolayer is presented as an effective method for the deposition of the top contact electrode in metal/monolayer/metal devices. Silver cations were incorporated from an aqueous AgNO3 sub-phase of Langmuir films of 4,4'-(1,4-phenylenebis(ethyne-2,1-diyl))dibenzoic acid upon the transference of these films onto a metallic substrate. Subsequent irradiation of the silver-ion functionalized Langmuir–Blodgett films with 254 nm light results in the photoreduction of silver cations to produce metallic silver nanoparticles, which are distributed over the organic monolayer and exhibit a surface coverage as large as 76% of the monolayer surface. Electrical properties of these metal/monolayer/metal devices were determined by recording I–V curves, which show a sigmoidal behaviour indicative of well-behaved junctions free of metallic filaments and short-circuits. The integrity of the organic monolayer upon the irradiation process and formation of the silver top-contact electrode has also been demonstrated through cyclic voltammetry experiments
Outcomes after angiography with sodium bicarbonate and acetylcysteine
Background:
Intravenous sodium bicarbonate and oral acetylcysteine are widely used to prevent acute kidney injury and associated adverse outcomes after angiography without definitive evidence of their efficacy.
Methods:
Using a 2-by-2 factorial design, we randomly assigned 5177 patients at high risk for renal complications who were scheduled for angiography to receive intravenous 1.26% sodium bicarbonate or intravenous 0.9% sodium chloride and 5 days of oral acetylcysteine or oral placebo; of these patients, 4993 were included in the modified intention-to-treat analysis. The primary end point was a composite of death, the need for dialysis, or a persistent increase of at least 50% from baseline in the serum creatinine level at 90 days. Contrast-associated acute kidney injury was a secondary end point.
Results:
The sponsor stopped the trial after a prespecified interim analysis. There was no interaction between sodium bicarbonate and acetylcysteine with respect to the primary end point (P=0.33). The primary end point occurred in 110 of 2511 patients (4.4%) in the sodium bicarbonate group as compared with 116 of 2482 (4.7%) in the sodium chloride group (odds ratio, 0.93; 95% confidence interval [CI], 0.72 to 1.22; P=0.62) and in 114 of 2495 patients (4.6%) in the acetylcysteine group as compared with 112 of 2498 (4.5%) in the placebo group (odds ratio, 1.02; 95% CI, 0.78 to 1.33; P=0.88). There were no significant between-group differences in the rates of contrast-associated acute kidney injury.
Conclusions:
Among patients at high risk for renal complications who were undergoing angiography, there was no benefit of intravenous sodium bicarbonate over intravenous sodium chloride or of oral acetylcysteine over placebo for the prevention of death, need for dialysis, or persistent decline in kidney function at 90 days or for the prevention of contrast-associated acute kidney injury. (Funded by the U.S. Department of Veterans Affairs Office of Research and Development and the National Health and Medical Research Council of Australia; PRESERVE ClinicalTrials.gov number, NCT01467466.
Impact of Higher Order and Soft Gluon Corrections on the Extraction of Higher Twist Effects in DIS
The impact of recently calculated next-to-next-to-leading order QCD
corrections and soft gluon resummations on the extraction of higher twist
contributions to the deep-inelastic structure function F_2 is studied using the
BCDMS and SLAC data. It is demonstrated to which extent the need for higher
twist terms is diminishing due to these higher order effects in the kinematical
region, 0.35 \le x \le 0.85 and Q^2>1.2 GeV^2, investigated. In addition,
theoretical uncertainties in the extraction of higher twist contributions are
discussed, and comparisons to results obtained previously are made.Comment: 16 pages, 3 figure
Automated Olfactory Bulb Segmentation on High Resolutional T2-Weighted MRI
The neuroimage analysis community has neglected the automated segmentation of
the olfactory bulb (OB) despite its crucial role in olfactory function. The
lack of an automatic processing method for the OB can be explained by its
challenging properties. Nonetheless, recent advances in MRI acquisition
techniques and resolution have allowed raters to generate more reliable manual
annotations. Furthermore, the high accuracy of deep learning methods for
solving semantic segmentation problems provides us with an option to reliably
assess even small structures. In this work, we introduce a novel, fast, and
fully automated deep learning pipeline to accurately segment OB tissue on
sub-millimeter T2-weighted (T2w) whole-brain MR images. To this end, we
designed a three-stage pipeline: (1) Localization of a region containing both
OBs using FastSurferCNN, (2) Segmentation of OB tissue within the localized
region through four independent AttFastSurferCNN - a novel deep learning
architecture with a self-attention mechanism to improve modeling of contextual
information, and (3) Ensemble of the predicted label maps. The OB pipeline
exhibits high performance in terms of boundary delineation, OB localization,
and volume estimation across a wide range of ages in 203 participants of the
Rhineland Study. Moreover, it also generalizes to scans of an independent
dataset never encountered during training, the Human Connectome Project (HCP),
with different acquisition parameters and demographics, evaluated in 30 cases
at the native 0.7mm HCP resolution, and the default 0.8mm pipeline resolution.
We extensively validated our pipeline not only with respect to segmentation
accuracy but also to known OB volume effects, where it can sensitively
replicate age effects
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