8,153 research outputs found
Central oxytocin and food intake: focus on macronutrient-driven reward
Centrally acting oxytocin (OT) is known to terminate food consumption in response to excessive stomach distension, increase in salt loading, and presence of toxins. Hypothalamic-hindbrain OT pathways facilitate these aspects of OT-induced hypophagia. However, recent discoveries have implicated OT in modifications of feeding via reward circuits: OT has been found to differentially affect consumption of individual macronutrients in choice and no-choice paradigms. In this mini-review, we focus on presenting and interpreting evidence that defines OT as a key component of mechanisms that reduce eating for pleasure and shape macronutrient preferences. We also provide remarks on challenges in integrating the knowledge on physiological and pathophysiological states in which both OT activity and macronutrient preferences are affected
Plasma Kinetics in the Ethanol/Water/Air Mixture in "Tornado" Type Electrical Discharge
This paper presents the results of a theoretical and experimental study of
plasma-assisted reforming of ethanol into molecular hydrogen in a new
modification of the "tornado" type electrical discharge. Numerical modeling
clarifies the nature of the non-thermal conversion and explains the kinetic
mechanism of nonequilibrium plasma-chemical transformations in the gas-liquid
system and the evolution of hydrogen during the reforming as a function of
discharge parameters and ethanol-to-water ratio in the mixture. We also propose
a scheme of chemical reactions for plasma kinetics description. It is shown
that some characteristics of the investigated reactor are at least not inferior
to characteristics of other plasma chemical reactors.Comment: 27 pages, 14 figures, 3 tables, accepted for publication in Journal
of Physics
Plasmodium falciparum glutamate dehydrogenase a is dispensable and not a drug target during erythrocytic development
<p>Background: Plasmodium falciparum contains three genes encoding potential glutamate dehydrogenases. The protein encoded by gdha has previously been biochemically and structurally characterized. It was suggested that it is important for the supply of reducing equivalents during intra-erythrocytic development of Plasmodium and, therefore, a suitable drug target.</p>
<p>Methods: The gene encoding the NADP(H)-dependent GDHa has been disrupted by reverse genetics in P. falciparum and the effect on the antioxidant and metabolic capacities of the resulting mutant parasites was investigated.</p>
<p>Results: No growth defect under low and elevated oxygen tension, no up-or down-regulation of a number of antioxidant and NADP(H)-generating proteins or mRNAs and no increased levels of GSH were detected in the D10(Delta gdha) parasite lines. Further, the fate of the carbon skeleton of [(13)C] labelled glutamine was assessed by metabolomic studies, revealing no differences in the labelling of a-ketoglutarate and other TCA pathway intermediates between wild type and mutant parasites.</p>
<p>Conclusions: First, the data support the conclusion that D10(Delta gdha) parasites are not experiencing enhanced oxidative stress and that GDHa function may not be the provision of NADP(H) for reductive reactions. Second, the results imply that the cytosolic, NADP(H)-dependent GDHa protein is not involved in the oxidative deamination of glutamate but that the protein may play a role in ammonia assimilation as has been described for other NADP(H)dependent GDH from plants and fungi. The lack of an obvious phenotype in the absence of GDHa may point to a regulatory role of the protein providing glutamate (as nitrogen storage molecule) in situations where the parasites experience a limiting supply of carbon sources and, therefore, under in vitro conditions the enzyme is unlikely to be of significant importance. The data imply that the protein is not a suitable target for future drug development against intra-erythrocytic parasite development.</p>
Structure of the Draco Dwarf Spheroidal Galaxy
This article studies the structure of the Draco dwarf spheroidal galaxy with
an emphasis on the question of whether the spatial distribution of its stars
has been affected by the tidal interaction with the Milky Way, using R- and
V-band CCD photometry for eleven fields. The article reports coordinates for
the center, a position angle of the major axis, and the ellipticity. It also
reports the results of searches for asymmetries in the structure of Draco.
These results, and searches for a ``break'' in the radial profile and for the
presence of principal sequences of Draco in a color-magnitude diagram for
regions more than 50 arcmin from the center, yield no evidence that tidal
forces from the Milky Way have affected the structure of Draco.Comment: 25 pages, 11 figures, 3 tables. Accepted for publication in A
On Kinematic Substructure in the Sextans Dwarf Spheroidal Galaxy
We present multifiber echelle radial velocity results for 551 stars in the
Sextans dwarf spheroidal galaxy and identify 294 stars as probable Sextans
members. The projected velocity dispersion profile of the binned data remains
flat to a maximum angular radius of . We introduce a nonparametric
technique for estimating the projected velocity dispersion surface, and use
this to search for kinematic substructure. Our data do not confirm previous
reports of a kinematically distinct stellar population at the Sextans center.
Instead we detect a region near the Sextans core radius that is kinematically
colder than the overall Sextans sample with 95% confidence.Comment: accepted for publication in ApJ Letters; 4 figures (2 color
Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV: Measurement for Sculptor
This article presents a measurement of the proper motion of the Sculptor
dwarf spheroidal galaxy determined from images taken with the Hubble Space
Telescope using the Space Telescope Imaging Spectrograph in the imaging mode.Comment: 38 pages, 15 figures, 6 tables, Accepted for publication in AJ, March
200
Photometry and spectroscopy of faint candidate spectrophotometric standard DA white dwarfs
We present precise photometry and spectroscopy for 23 candidate
spectrophotometric standard white dwarfs. The selected stars are distributed in
the Northern hemisphere and around the celestial equators and are all fainter
than r ~ 16.5 mag. This network of stars, when established as standards,
together with the three Hubble Space Telescope primary CALSPEC white dwarfs,
will provide a set of spectrophotometric standards to directly calibrate data
products to better than 1%. These new faint standard white dwarfs will have
enough signal-to-noise ratio in future deep photometric surveys and facilities
to be measured accurately while still avoiding saturation in such surveys. They
will also fall within the dynamic range of large telescopes and their
instruments for the foreseeable future. This paper discusses the provenance of
the observational data for our candidate standard stars. The comparison with
models, reconciliation with reddening, and the consequent derivation of the
full spectral energy density distributions for each of them is reserved for a
subsequent paper.Comment: 31 pages, 17 figures, 10 tables, ApJ in press (accepted on December
23rd, 2018
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