302 research outputs found
Optimal Hemodialysis Prescription: Do Children Need More Than a Urea Dialysis Dose?
When prescribing hemodialysis in children, the clinician should first establish an adequate regimen, before seeking to optimize the treatment (Fischbach et al. 2005). A complete dialysis dose should consist of a urea dialysis dose and a determined convective volume. Intensified and more frequent dialysis regimens should not be considered exclusively as rescue therapy. Interestingly, a recent single-center study demonstrated that frequent on-line HDF provides an optimal dialysis prescription, both in terms of blood pressure control (and therefore avoidance of left ventricular hypertrophy), and catch-up growth, that is, no malnutrition or cachexia and less resistance to growth hormone. Nevertheless, this one-center experience would benefit from a prospective randomized study
Erratum to “Optimal Hemodialysis Prescription: Do Children Need More Than a Urea Dialysis Dose?”
On the interpretation of Michelson-Morley experiments
Recent proposals for improved optical tests of Special Relativity have
renewed interest in the interpretation of such tests. In this paper we discuss
the interpretation of modern realizations of the Michelson-Morley experiment in
the context of a new model of electrodynamics featuring a vector-valued photon
mass. This model is gauge invariant, unlike massive-photon theories based on
the Proca equation, and it predicts anisotropy of both the speed of light and
the electric field of a point charge. The latter leads to an orientation
dependence of the length of solid bodies which must be accounted for when
interpreting the results of a Michelson-Morley experiment. Using a simple model
of ionic solids we show that, in principle, the effect of orientation dependent
length can conspire to cancel the effect of an anisotropic speed of light in a
Michelson-Morley experiment, thus, complicating the interpretation of the
results.Comment: To appear in Phys.Lett.
PAA7 PHARMACOECONOMIC OUTCOMES OF LEVALBUTEROL AND RACEMIC ALBUTEROL IN HOSPITALIZED PATIENTS REQUIRING NEBULIZATION THERAPY (POLARIS)
Human Skin Permeation Enhancement Using PLGA Nanoparticles Is Mediated by Local pH Changes
The steady improvement and optimization of transdermal permeation is a constant and
challenging pharmaceutical task. In this study the influence of poly(lactide-co-glycolide) (PLGA)
nanoparticles on the dermal permeation of the anti-inflammatory drug flufenamic acid (FFA) was
investigated. For this aim, different vehicles under non-buffered and buffered conditions and different
skin models (human heat separated epidermis and reconstructed human epidermis equivalents)
were tested. Permeation experiments were performed using static Franz diffusion cells under infinite
dosing conditions. Already the presence of drug-free nanoparticles increased drug permeation
across the skin. Drug permeation was even enhanced when applying drug-loaded nanoparticles. In
contrast, buffered vehicles with different pH values (pH 5.4–7.4) revealed the influence of the pH
on the permeation of FFA. The change of the surrounding pH of the biodegradable nanoparticulate
system was demonstrated and visualized using pH-sensitive fluorescent probes. While a potential
contribution of hair follicles could be ruled out, our data suggest that the enhanced permeation of
FFA through human skin in the presence of PLGA nanoparticles is mediated by a locally decreased
pH during hydrolytic degradation of this polymer. This hypothesis is supported by the observation
that skin permeation of the weak base caffeine was not affected
Nonaffine rubber elasticity for stiff polymer networks
We present a theory for the elasticity of cross-linked stiff polymer
networks. Stiff polymers, unlike their flexible counterparts, are highly
anisotropic elastic objects. Similar to mechanical beams stiff polymers easily
deform in bending, while they are much stiffer with respect to tensile forces
(``stretching''). Unlike in previous approaches, where network elasticity is
derived from the stretching mode, our theory properly accounts for the soft
bending response. A self-consistent effective medium approach is used to
calculate the macroscopic elastic moduli starting from a microscopic
characterization of the deformation field in terms of ``floppy modes'' --
low-energy bending excitations that retain a high degree of non-affinity. The
length-scale characterizing the emergent non-affinity is given by the ``fiber
length'' , defined as the scale over which the polymers remain straight.
The calculated scaling properties for the shear modulus are in excellent
agreement with the results of recent simulations obtained in two-dimensional
model networks. Furthermore, our theory can be applied to rationalize bulk
rheological data in reconstituted actin networks.Comment: 12 pages, 10 figures, revised Section II
Laying Eyes on Headlights: Eye Movements Suggest Facial Features in Cars
Humans’ proneness to see faces even in inanimate structures such as cars has long been noticed, yet empirical evidence is scarce. To examine this tendency of anthropomorphism, participants were asked to compare specific features (such as the eyes) of a face and a car front presented next to each other. Eye movement patterns indicated on which visual information participants relied to solve the task and clearly revealed the perception of facial features in cars, such as headlights as eyes or grille as nose. Most importantly, a predominance of headlights was found in attracting and guiding people’s gaze irrespective of the feature they were asked to compare – equivalent to the role of the eyes during face perception. This response to abstract configurations is interpreted as an adaptive bias of the respective inherent mechanism for face perception and is evolutionarily reasonable with regard to a »better safe than sorry« strategy
pH-mediated upregulation of AQP1 gene expression through the Spi-B transcription factor
Background: Bicarbonate-based peritoneal dialysis (PD) fluids enhance the migratory capacity and damage-repair ability of human peritoneal mesothelial cells by upregulating AQP1. However, little is known about the underlying molecular mechanisms.
Results: Here we used HEK-293T cells to investigate the effect of pH on AQP1 gene transcription levels. We found that AQP1 mRNA levels increases with pH. Transfection of HEK-293T cells with luciferase reporter vectors containing different regions of the AQP1 promoter identified an upstream region in the AQP1 gene between − 2200 and – 2300 bp as an enhancer required for pH-mediated regulation of AQP1 expression. Site-directed mutagenesis of this specific promoter region revealed a critical region between − 2257 and − 2251 bp, and gene knock-down experiments and ChIP assays suggested that the Spi-B transcription factor SPIB is involved in pH-mediated regulation of AQP1 expression.
Conclusions: We identified an upstream region in the AQP1 gene and the transcription factor SPIB that are critically involved in pH-mediated regulation of AQP1 expression. These findings provide the basis for further studies on the pH- and buffer-dependent effects of PD fluids on peritoneal membrane integrity and function
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