8,049 research outputs found
Differential miRNA expression profiling reveals miR-205-3p to be a potential radiosensitizer for low- dose ionizing radiation in DLD-1 cells
Indexación: Scopus.Departamento de Oncología Básico-Clínica, Facultad de Medicina, Universidad de Chile, Santiago, Chile 2Comisión Chilena de Energía Nuclear, Santiago, Chile 3Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Chile 4Departamento de Ciencias Físicas, Universidad Andres Bello, Santiago, Chile 5Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile 6Current Address: Center of Excellence in Precision Medicine, Pfizer, Chile. on IR responsive modeling. This work was supported by Anillo grant ACT1115 and ACT172101, PIA Program, CONICYT; the Chilean doctoral fellowship 21130246Enhanced radiosensitivity at low doses of ionizing radiation (IR) (0.2 to 0.6 Gy) has been reported in several cell lines. This phenomenon, known as low doses hyperradiosensitivity (LDHRS), appears as an opportunity to decrease toxicity of radiotherapy and to enhance the effects of chemotherapy. However, the effect of low single doses IR on cell death is subtle and the mechanism underlying LDHRS has not been clearly explained, limiting the utility of LDHRS for clinical applications. To understand the mechanisms responsible for cell death induced by low-dose IR, LDHRS was evaluated in DLD-1 human colorectal cancer cells and the expression of 80 microRNAs (miRNAs) was assessed by qPCR array. Our results show that DLD-1 cells display an early DNA damage response and apoptotic cell death when exposed to 0.6 Gy. miRNA expression profiling identified 3 over-expressed (miR-205-3p, miR-1 and miR-133b) and 2 downregulated miRNAs (miR-122-5p, and miR-134-5p) upon exposure to 0.6 Gy. This miRNA profile differed from the one in cells exposed to high-dose IR (12 Gy), supporting a distinct low-dose radiation-induced cell death mechanism. Expression of a mimetic miR- 205-3p, the most overexpressed miRNA in cells exposed to 0.6 Gy, induced apoptotic cell death and, more importantly, increased LDHRS in DLD-1 cells. Thus, we propose miR-205-3p as a potential radiosensitizer to low-dose IR. © Andaur et al.http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path[]=25405&path[]=7956
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Nanotailoring Stereolithography Resins for Unique Applications using Carbon Nanotubes
Nanostructured materials and exploiting their properties in stereolithography (SL) may open
new markets for unique rapidly manufactured functional devices. Controlled amounts of multiwalled carbon nanotubes (MWCNTs) were successfully dispersed in SL epoxy-based resins and
complex three-dimensional (3D) parts were successfully fabricated by means of a multi-material
SL setup. The effect of the nanosized filler was evaluated using mechanical testing. Small
dispersions of MWCNTs resulted in significant effects on the physical properties of the
polymerized resin. A MWCNT concentration of .05 wt% (w/v) in DSM Somos® WaterShed™
11120 resin increased the ultimate tensile stress and fracture stress an average of 17% and 37%,
respectively. Electron microscopy was used to examine the morphology of the nanocomposite
and results showed affinity between the MWCNTs and SL resin and identified buckled
nanotubes that illustrated strong interfacial bonding. These improved physical properties may
provide opportunities for using nanocomposite SL resins in end-use applications. Varying types
and concentrations of nanomaterials can be used to tailor existing SL resins for particular
applications.Mechanical Engineerin
The Origin of \lya Absorption Systems at ---Implications from the Hubble Deep Field
The Hubble Deep Field images have provided us with a unique chance to relate
statistical properties of high-redshift galaxies to statistical properties of
\lya absorption systems. Combining an {\em empirical} measure of the galaxy
surface density versus redshift with an {\em empirical} measure of the gaseous
extent of galaxies, we predict the number density of \lya absorption systems
that originate in extended gaseous envelopes of galaxies versus redshift. We
show that at least 50% and as much as 100% of observed \lya absorption systems
of W\apg0.32 \AA can be explained by extended gaseous envelops of galaxies.
Therefore, we conclude that known galaxies of known gaseous extent must produce
a significant fraction and perhaps all of \lya absorption systems over a large
redshift range.Comment: 12 pages, 3 figures, accepted for publication in the Astrophysical
Journal, April 10, 2000 issu
Hundred joules plasma focus device as a potential pulsed source for in vitro cancer cell irradiation
Indexación: Web of Science; Scopus.Plasma focus devices may arise as useful source to perform experiments aimed to study the effects of pulsed radiation on human cells in vitro. In the present work, a table top hundred joules plasma focus device, namely "PF-400J", was adapted to irradiate colorectal cancer cell line, DLD-1. For pulsed x-rays, the doses (energy absorbed per unit mass, measured in Gy) were measured using thermoluminescence detectors (TLD-100 dosimeters). The neutron fluence and the average energy were used to estimate the pulsed neutron doses. Fifty pulses of x-rays (0.12 Gy) and fifty pulses of neutrons (3.5 μGy) were used to irradiate the cancer cells. Irradiation-induced DNA damage and cell death were assessed at different time points after irradiation. Cell death was observed using pulsed neutron irradiation, at ultralow doses. Our results indicate that the PF-400J can be used for in vitro assessment of the effect of pulsed radiation in cancer cell research.http://recursosbiblioteca.unab.cl:2296/doi/pdf/10.1063/1.499465
Fluctuation-Induced Casimir Forces in Granular Fluids
We have numerically investigated the behavior of driven non-cohesive granular
media and found that two fixed large intruder particles, immersed in a sea of
small particles, experience, in addition to a short range depletion force, a
long range repulsive force. The observed long range interaction is
fluctuation-induced and we propose a mechanism similar to the Casimir effect
that generates it: the hydrodynamic fluctuations are geometrically confined
between the intruders, producing an unbalanced renormalized pressure. An
estimation based on computing the possible Fourier modes explains the repulsive
force and is in qualitative agreement with the simulations.Comment: 4 pages, 3 figures. Accepted in Phys. Rev. Letter
Assessing the Polarization of a Quantum Field from Stokes Fluctuation
We propose an operational degree of polarization in terms of the variance of
the projected Stokes vector minimized over all the directions of the Poincar\'e
sphere. We examine the properties of this degree and show that some problems
associated with the standard definition are avoided. The new degree of
polarization is experimentally determined using two examples: a bright squeezed
state and a quadrature squeezed vacuum.Comment: 4 pages, 2 figures. Comments welcome
Lost and found: the radial quantum number of Laguerre-Gauss modes
We introduce an operator linked with the radial index in the Laguerre-Gauss
modes of a two-dimensional harmonic oscillator in cylindrical coordinates. We
discuss ladder operators for this variable, and confirm that they obey the
commutation relations of the su(1,1) algebra. Using this fact, we examine how
basic quantum optical concepts can be recast in terms of radial modes.Comment: Some minor typos fixed
Density functional electronic spectrum of the cluster and possible local Jahn-Teller distorsions in the La-Ba-Cu-O superconductor
We present a density functional theory (DFT) calculation in the generalized
gradient approximation to study the possibility for the existence of
Jahn-Teller (JT) or pseudo Jahn-Teller (PJT) type local distortions in the
La-Ba-Cu-O superconducting system. We performed the calculation and
correspondingly group theory classification of the electronic ground state of
the CuO elongated octahedra cluster, immersed in a background
simulating the superconductor. Part of the motivation to do this study is that
the origin of the apical deformation of the CuO cluster is not
due to a pure JT effect, having therefore a non {\it a priori} condition to
remove the degeneracy of the electronic ground state of the parent regular
octahedron. We present a comparative analysis of the symmetry classified
electron spectrum with previously reported results using unrestricted
Hartree-Fock calculations (UHF). Both the DFT and UHF calculations produced a
non degenerate electronic ground state, not having therefore the necessary
condition for a pure JT effect. However, the appearance of a degenerate E
state near to the highest occupied molecular orbital in the DFT calculation,
suggests the possibility for a PJT effect responsible for a local distortion of
the oxidized CuO cluster.Comment: 12 pages, 3 figures, submitted to International Journal of Modern
Physics B (IJMPB
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