628 research outputs found
Efficacy of DOPE/DC-cholesterol liposomes and GCPQ micelles as AZD6244 nanocarriers in a 3D colorectal cancer in vitro model
Aim: In this work, we use cationic organic nanocarriers as chemotherapy delivery platforms and test them in a colorectal cancer 3D in vitro model. Materials & methods: We used 3beta-(N-[N′,N′-dimethylaminoethane]carbamoyl])cholesterol (DC-chol) and dioleoylphosphatidylethanolamine (DOPE) liposomes and N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) micelles, to deliver AZD6244, a MEK inhibitor, to HCT116 cells cultured as monolayers and in 3D in vitro cancer models (tumoroids). Results: Nanoparticle-mediated drug delivery was superior to the free drug in monolayer experiments and despite their therapeutic effect being hindered by poor diffusion through the cancer mass, GCPQ micelles were also superior in tumoroids. Conclusion: These results support the role of nanoparticles in improving drug delivery and highlight the need to include 3D cancer models in early phases of drug development
Efficacy of DOPE/DC-cholesterol liposomes and GCPQ micelles as AZD6244 nanocarriers in a 3D colorectal cancer in vitro model
AIM: In this work, we use cationic organic nanocarriers as chemotherapy delivery platforms and test them in a colorectal cancer 3D in vitro model. MATERIALS & METHODS: We used 3beta-(N-[N',N'-dimethylaminoethane]carbamoyl])cholesterol (DC-chol) and dioleoylphosphatidylethanolamine (DOPE) liposomes and N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) micelles, to deliver AZD6244, a MEK inhibitor, to HCT116 cells cultured as monolayers and in 3D in vitro cancer models (tumoroids). RESULTS: Nanoparticle-mediated drug delivery was superior to the free drug in monolayer experiments and despite their therapeutic effect being hindered by poor diffusion through the cancer mass, GCPQ micelles were also superior in tumoroids. CONCLUSION: These results support the role of nanoparticles in improving drug delivery and highlight the need to include 3D cancer models in early phases of drug development
Proteome analysis enables separate clustering of normal breast, benign breast and breast cancer tissues
We have used proteomics with cluster analysis for the classification of breast tumour tissues. In our approach, we can distinguish between normal breast, benign breast and breast cancer tissues on the basis of the protein expression profiles. We propose an objective method for the classification of breast tumour specimens
The Milky Way rotation curve in Horava - Lifshitz theory
The Horava - Lifshitz (HL) theory has recently attracted a lot of interest as
a viable solution to some quantum gravity related problems and the presence of
an effective cosmological constant able to drive the cosmic speed up. We show
here that, in the weak field limit, the HL proposal leads to a modification of
the gravitational potential because of two additive terms (scaling respectively
as and ) to the Newtonian potential. We then derive a
general expression to compute the rotation curve of an extended system under
the assumption that the mass density only depends on the cylindrical
coordinates showing that the HL modification induces a dependence of
the circular velocity on the mass function which is a new feature of the
theory. As a first exploratory analysis, we then try fitting the Milky Way
rotation curve using its visible components only in order to see whether the HL
modified potential can be an alternative to the dark matter framework. This
turns out not to be the case so that we argue that dark matter is still needed,
but the amount of dark matter and the dark halo density profile have to be
revised according to the new HL potential.Comment: 10 pages, 1 figure, accepted for publication on MNRA
Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission
Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of
galaxies show a strong evolution from to , but the FIR LF
evolves much stronger than the FUV one. The FUV is dominantly radiated from
newly formed short-lived OB stars, while the FIR is emitted by dust grains
heated by the FUV radiation field. It is known that dust is always associated
with star formation activity. Thus, both FUV and FIR are tightly related to the
star formation in galaxies, but in a very complicated manner. In order to
disentangle the relation between FUV and FIR emissions, we estimate the UV-IR
bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey
datasets. Recently we invented a new mathematical method to construct the BLF
with given marginals and prescribed correlation coefficient. This method makes
use of a tool from mathematical statistics, so called "copula". The copula
enables us to construct a bivariate distribution function from given marginal
distributions with prescribed correlation and/or dependence structure. With
this new formulation and FUV and FIR univariate LFs, we analyze various FUV and
FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR
BLF. The obtained BLFs naturally explain the nonlinear complicated relation
between FUV and FIR emission from star-forming galaxies. Though the faint-end
of the BLF was not well constrained for high- samples, the estimated linear
correlation coefficient was found to be very high, and is remarkably
stable with redshifts (from 0.95 at to 0.85 at ). This implies
the evolution of the UV-IR BLF is mainly due to the different evolution of the
univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres
Dust and the type II-Plateau supernova 2004dj
We present mid-infrared (MIR) spectroscopy of a Type II-plateau supernova, SN
2004dj, obtained with the Spitzer Space Telescope, spanning 106--1393 d after
explosion. MIR photometry plus optical/near-IR observations are also reported.
An early-time MIR excess is attributed to emission from non-silicate dust
formed within a cool dense shell (CDS). Most of the CDS dust condensed between
50 d and 165 d, reaching a mass of 0.3 x 10^{-5} Msun. Throughout the
observations much of the longer wavelength (>10 microns) part of the continuum
is explained as an IR echo from interstellar dust. The MIR excess strengthened
at later times. We show that this was due to thermal emission from warm,
non-silicate dust formed in the ejecta. Using optical/near-IR line-profiles and
the MIR continua, we show that the dust was distributed as a disk whose radius
appeared to be slowly shrinking. The disk radius may correspond to a grain
destruction zone caused by a reverse shock which also heated the dust. The
dust-disk lay nearly face-on, had high opacities in the optical/near-IR
regions, but remained optically thin in the MIR over much of the period
studied. Assuming a uniform dust density, the ejecta dust mass by 996 d was 0.5
+/- 0.1) x 10^{-4} Msun, and exceeded 10^{-4}Msun by 1393 d. For a dust density
rising toward the center the limit is higher. Nevertheless, this study suggests
that the amount of freshly-synthesized dust in the SN 2004dj ejecta is
consistent with that found from previous studies, and adds further weight to
the claim that such events could not have been major contributors to the cosmic
dust budget.Comment: ApJ in press; minor changes c.f. v
Jets and gamma-ray emission from isolated accreting black holes
The large number of isolated black holes (IBHs) in the Galaxy, estimated to
be 10^8, implies a very high density of 10^-4 pc^-3 and an average distance
between IBHs of 10 pc. Our study shows that the magnetic flux, accumulated on
the horizon of an IBH because of accretion of interstellar matter, allows the
Blandford-Znajeck mechanism to be activated. Thus, electron-positron jets can
be launched. We have performed 2D numerical modelling which allowed the jet
power to be estimated. Their inferred properties make such jets a feasible
electron accelerator which, in molecular clouds, allows electron energy to be
boosted up to 1 PeV. For the conditions expected in molecular clouds the
radiative cooling time should be comparable to the escape time. Thus these
sources can contribute both to the population of unidentified point-like
sources and to the local cosmic ray (CR) electron spectrum. The impact of the
generated electron CRs depends on the diffusion rate inside molecular clouds
(MCs). If the diffusion regime in a MC is similar to Galactic diffusion, the
produced electrons should rapidly escape the cloud and contribute to the
Galactic CR population at very high energies >100 TeV. However, due to the
modest jet luminosity (at the level of 10^35 erg s^-1) and low filling factor
of MC, these sources cannot make a significant contribution to the spectrum of
cosmic ray electrons at lower energies. On the other hand, if the diffusion
within MCs operates at a rate close to the Bohm limit, the CR electrons
escaping from the source should be confined in the cloud, significantly
contributing to the local density of CRs. The IC emission of these
locally-generated CRs may explain the variety of gamma ray spectra detected
from nearby MCs.Comment: 6 pages, accepted by MNRA
AKARI and BLAST Observations of the Cassiopeia A Supernova Remnant and Surrounding Interstellar Medium
We use new large area far infrared maps ranging from 65 - 500 microns
obtained with the AKARI and the Balloon-borne Large Aperture Submillimeter
Telescope (BLAST) missions to characterize the dust emission toward the
Cassiopeia A supernova remnant (SNR). Using the AKARI high resolution data we
find a new "tepid" dust grain population at a temperature of ~35K and with an
estimated mass of 0.06 solar masses. This component is confined to the central
area of the SNR and may represent newly-formed dust in the unshocked supernova
ejecta. While the mass of tepid dust that we measure is insufficient by itself
to account for the dust observed at high redshift, it does constitute an
additional dust population to contribute to those previously reported. We fit
our maps at 65, 90, 140, 250, 350, and 500 microns to obtain maps of the column
density and temperature of "cold" dust (near 16 K) distributed throughout the
region. The large column density of cold dust associated with clouds seen in
molecular emission extends continuously from the surrounding interstellar
medium to project on the SNR, where the foreground component of the clouds is
also detectable through optical, X-ray, and molecular extinction. At the
resolution available here, there is no morphological signature to isolate any
cold dust associated only with the SNR from this confusing interstellar
emission. Our fit also recovers the previously detected "hot" dust in the
remnant, with characteristic temperature 100 K.Comment: Accepted for publication in the Astrophysical Journal. Maps and
related data are available at http://blastexperiment.info
Optical and infrared observations of the Type IIP SN2002hh from day 3 to 397
We present optical and infrared (IR) observations of the type IIP SN2002hh
from 3 to 397 days after explosion. The optical spectroscopic (4-397d) and
photometric (3-278d) data are complemented by spectroscopic (137-381d) and
photometric (137-314d) data acquired at IR wavelengths. This is the first time
L-band spectra have ever been successfully obtained for a supernova at a
distance beyond the Local Group. The VRI light curves in the first 40 days
reveal SN2002hh to be a SN IIP (plateau) - the most common of all core-collapse
supernovae. SN2002hh is one of the most highly extinguished supernovae ever
investigated. To provide a good match between its early-time spectrum and a
coeval spectrum of the Type IIP SN1999em, as well as maintaining consistency
with KI interstellar absorption, we invoke a 2-component extinction model. One
component is due to the combined effect of the interstellar medium of our Milky
Way Galaxy and the SN host galaxy, while the other component is due to a "dust
pocket" where the grains have a mean size smaller than in the interstellar
medium. The early-time optical light curves of SNe 1999em and 2002hh are
generally well-matched, as are the radioactive tails of these two SNe and
SN1987A. The late-time similarity of the SN2002hh optical light curves to those
of SN1987A, together with measurements of the optical/IR luminosity and [FeII]
1.257mu emission indicate that 0.07 +- 0.02 Msun of Ni 56 was ejected by
SN2002hh. [... ABRIDGED...] From the [OI] 6300,6364 A doublet luminosity we
infer a 16-18 Msun main-sequence progenitor star. The progenitor of SN2002hh
was probably a red supergiant with a substantial, dusty wind.Comment: 32 pages, 30 figures, accepted for publication in MNRA
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