45 research outputs found
Multimodality imaging in vivo for preclinical assessment of tumor-targeted doxorubicin nanoparticles.
This study presents a new multimodal imaging approach that includes high-frequency ultrasound, fluorescence intensity, confocal, and spectral imaging to improve the preclinical evaluation of new therapeutics in vivo. Here we use this approach to assess in vivo the therapeutic efficacy of the novel chemotherapy construct, HerDox during and after treatment. HerDox is comprised of doxorubicin non-covalently assembled in a viral-like particle targeted to HER2+ tumor cells, causing tumor cell death at over 10-fold lower dose compared to the untargeted drug, while sparing the heart. Whereas our initial proof-of-principle studies on HerDox used tumor growth/shrinkage rates as a measure of therapeutic efficacy, here we show that multimodal imaging deployed during and after treatment can supplement traditional modes of tumor monitoring to further characterize the particle in tissues of treated mice. Specifically, we show here that tumor cell apoptosis elicited by HerDox can be monitored in vivo during treatment using high frequency ultrasound imaging, while in situ confocal imaging of excised tumors shows that HerDox indeed penetrated tumor tissue and can be detected at the subcellular level, including in the nucleus, via Dox fluorescence. In addition, ratiometric spectral imaging of the same tumor tissue enables quantitative discrimination of HerDox fluorescence from autofluorescence in situ. In contrast to standard approaches of preclinical assessment, this new method provides multiple/complementary information that may shorten the time required for initial evaluation of in vivo efficacy, thus potentially reducing the time and cost for translating new drug molecules into the clinic
Generalized Warped Disk Equations
The manner in which warps in accretion disks evolve depends on the magnitude of the viscosity. ... See full text for complete abstract
Investigating photoexcitation-induced mitochondrial damage by chemotherapeutic corroles using multimode optical imaging
We recently reported that a targeted, brightly fluorescent gallium corrole (HerGa) is highly effective for breast tumor detection and treatment. Unlike structurally similar porphryins, HerGa exhibits tumor-targeted toxicity without the need for photoexcitation. We have now examined whether photoexcitation further modulates HerGa toxicity, using multimode optical imaging of live cells, including two-photon excited fluorescence, differential interference contrast (DIC), spectral, and lifetime imaging. Using two-photon excited fluorescence imaging, we observed that light at specific wavelengths augments the HerGa-mediated mitochondrial membrane potential disruption of breast cancer cells in situ. In addition, DIC, spectral, and fluorescence lifetime imaging enabled us to both validate cell damage by HerGa photoexcitation and investigate HerGa internalization, thus allowing optimization of light dose and timing. Our demonstration of HerGa phototoxicity opens the way for development of new methods of cancer intervention using tumor-targeted corroles
Disk Imaging Survey of Chemistry with SMA: II. Southern Sky Protoplanetary Disk Data and Full Sample Statistics
This is the second in a series of papers based on data from DISCS, a
Submillimeter Array observing program aimed at spatially and spectrally
resolving the chemical composition of 12 protoplanetary disks. We present data
on six Southern sky sources - IM Lup, SAO 206462 (HD 135344b), HD 142527, AS
209, AS 205 and V4046 Sgr - which complement the six sources in the Taurus star
forming region reported previously. CO 2-1 and HCO+ 3-2 emission are detected
and resolved in all disks and show velocity patterns consistent with Keplerian
rotation. Where detected, the emission from DCO+ 3-2, N2H+ 3-2, H2CO 3-2 and
4-3,HCN 3-2 and CN 2-1 are also generally spatially resolved. The detection
rates are highest toward the M and K stars, while the F star SAO 206462 has
only weak CN and HCN emission, and H2CO alone is detected toward HD 142527.
These findings together with the statistics from the previous Taurus disks,
support the hypothesis that high detection rates of many small molecules depend
on the presence of a cold and protected disk midplane, which is less common
around F and A stars compared to M and K stars. Disk-averaged variations in the
proposed radiation tracer CN/HCN are found to be small, despite two orders of
magnitude range of spectral types and accretion rates. In contrast, the
resolved images suggest that the CN/HCN emission ratio varies with disk radius
in at least two of the systems. There are no clear observational differences in
the disk chemistry between the classical/full T Tauri disks and transitional
disks. Furthermore, the observed line emission does not depend on measured
accretion luminosities or the number of infrared lines detected, which suggests
that the chemistry outside of 100 AU is not coupled to the physical processes
that drive the chemistry in the innermost few AU.Comment: accepted for publication in ApJ, 41 pages including 7 figure
Atmospheric circulation of hot Jupiters: Coupled radiative-dynamical general circulation model simulations of HD 189733b and HD 209458b
We present global, three-dimensional numerical simulations of HD 189733b and
HD 209458b that couple the atmospheric dynamics to a realistic representation
of non-gray cloud-free radiative transfer. The model, which we call the
Substellar and Planetary Atmospheric Radiation and Circulation (SPARC) model,
adopts the MITgcm for the dynamics and uses the radiative model of McKay,
Marley, Fortney, and collaborators for the radiation. Like earlier work with
simplified forcing, our simulations develop a broad eastward equatorial jet,
mean westward flow at higher latitudes, and substantial flow over the poles at
low pressure. For HD 189733b, our simulations without TiO and VO opacity can
explain the broad features of the observed 8 and 24-micron light curves,
including the modest day-night flux variation and the fact that the planet/star
flux ratio peaks before the secondary eclipse. Our simulations also provide
reasonable matches to the Spitzer secondary-eclipse depths at 4.5, 5.8, 8, 16,
and 24 microns and the groundbased upper limit at 2.2 microns. However, we
substantially underpredict the 3.6-micron secondary-eclipse depth, suggesting
that our simulations are too cold in the 0.1-1 bar region. Predicted temporal
variability in secondary-eclipse depths is ~1% at Spitzer bandpasses,
consistent with recent observational upper limits at 8 microns. We also show
that nonsynchronous rotation can significantly alter the jet structure. For HD
209458b, we include TiO and VO opacity; these simulations develop a hot (>2000
K) dayside stratosphere. Despite this stratosphere, we do not reproduce current
Spitzer photometry of this planet. Light curves in Spitzer bandpasses show
modest phase variation and satisfy the observational upper limit on day-night
phase variation at 8 microns. (abridged)Comment: 20 pages (emulate-apj format), 21 figures, final version now
published in ApJ. Includes expanded discussion of radiative-transfer methods
and two new figure
A Spatially Resolved Inner Hole in the Disk around GM Aurigae
We present 0.3 arcsec resolution observations of the disk around GM Aurigae
with the Submillimeter Array (SMA) at a wavelength of 860 um and with the
Plateau de Bure Interferometer at a wavelength of 1.3 mm. These observations
probe the distribution of disk material on spatial scales commensurate with the
size of the inner hole predicted by models of the spectral energy distribution.
The data clearly indicate a sharp decrease in millimeter optical depth at the
disk center, consistent with a deficit of material at distances less than ~20
AU from the star. We refine the accretion disk model of Calvet et al. (2005)
based on the unresolved spectral energy distribution (SED) and demonstrate that
it reproduces well the spatially resolved millimeter continuum data at both
available wavelengths. We also present complementary SMA observations of CO
J=3-2 and J=2-1 emission from the disk at 2" resolution. The observed CO
morphology is consistent with the continuum model prediction, with two
significant deviations: (1) the emission displays a larger CO J=3-2/J=2-1 line
ratio than predicted, which may indicate additional heating of gas in the upper
disk layers; and (2) the position angle of the kinematic rotation pattern
differs by 11 +/- 2 degrees from that measured at smaller scales from the dust
continuum, which may indicate the presence of a warp. We note that
photoevaporation, grain growth, and binarity are unlikely mechanisms for
inducing the observed sharp decrease in opacity or surface density at the disk
center. The inner hole plausibly results from the dynamical influence of a
planet on the disk material. Warping induced by a planet could also potentially
explain the difference in position angle between the continuum and CO data
sets.Comment: 12 pages, 6 figures, accepted for publication in Ap
Photoexcitation of tumor-targeted corroles induces singlet oxygen-mediated augmentation of cytotoxicity
The tumor-targeted corrole particle, HerGa, displays preferential toxicity to tumors in vivo and can be tracked
via fluorescence for simultaneous detection, imaging, and treatment. We have recently uncovered an additional
feature of HerGa in that its cytotoxicity is enhanced by light irradiation. In the present study, we
have elucidated the cellular mechanisms for HerGa photoexcitation-mediated cell damage using fluorescence
optical imaging. In particular, we found that light irradiation of HerGa produces singlet oxygen, causing mitochondrial damage and cytochrome c release, thus promoting apoptotic cell death. An understanding of the
mechanisms of cell death induced by HerGa, particularly under conditions of light-mediated excitation, may
direct future efforts in further customizing this nanoparticle for additional therapeutic applications and enhanced
potency
Resolved Images of Large Cavities in Protoplanetary Transition Disks
Circumstellar disks are thought to experience a rapid "transition" phase in
their evolution that can have a considerable impact on the formation and early
development of planetary systems. We present new and archival high angular
resolution (0.3" = 40-75 AU) Submillimeter Array (SMA) observations of the 880
micron dust continuum emission from 12 such transition disks in nearby
star-forming regions. In each case, we directly resolve a dust-depleted disk
cavity around the central star. Using radiative transfer calculations, we
interpret these dust disk structures in a homogeneous, parametric model
framework by reproducing their SMA visibilities and SEDs. The cavities in these
disks are large (R_cav = 15-73 AU) and substantially depleted of small
(~um-sized) dust grains, although their mass contents are still uncertain. The
structures of the remnant material at larger radii are comparable to normal
disks. We demonstrate that these large cavities are common among the
millimeter-bright disk population, comprising at least 20% of the disks in the
bright half of the millimeter luminosity (disk mass) distribution. Utilizing
these results, we assess some of the physical mechanisms proposed to account
for transition disk structures. As has been shown before, photoevaporation
models do not produce the large cavity sizes, accretion rates, and disk masses
representative of this sample. It would be difficult to achieve a sufficient
decrease of the dust optical depths in these cavities by particle growth alone:
substantial growth (to meter sizes or beyond) must occur in large (tens of AU)
regions of low turbulence without also producing an abundance of small
particles. Given those challenges, we suggest instead that the observations are
most commensurate with dynamical clearing due to tidal interactions with
low-mass companions --young brown dwarfs or giant planets on long-period
orbits.Comment: ApJ, in pres