275 research outputs found
Middle Cranial Fossa (MCF) Approach without the use of Lumbar Drain for the Management of Spontaneous Cerebral Spinal Fluid (CSF) Leaks
Objective: To determine the efficacy and morbidity of repairing spontaneous cerebrospinal fluid (CSF) leaks with the middle cranial fossa (MCF) approach without the use of a lumbar drain (LD), as perioperative use of LD remains controversial.
Study Design: Retrospective review from 2003 to 2015.
Setting: University of Iowa Hospitals and Clinics and Indiana University Health Center.
Patients: Those with a confirmed lateral skull base spontaneous CSF leaks and/or encephaloceles.
Intervention: MCF approach for repair of spontaneous CSF leak and/or encephalocele without the use of lumbar drain. Assessment of patient age, sex, body mass index (BMI), and medical comorbidities.
Main Outcome Measure: Spontaneous CSF leak patient characteristics (age, sex, BMI, obstructive sleep apnea) were collected. Length of stay (LOS), hospital costs, postoperative complications, CSF leak rate, and need for LD were calculated.
Results: Sixty-five operative MCF repairs were performed for spontaneous CSF leaks on 60 patients (five had bilateral CSF leaks). CSF diversion with LD was used in 15 of 60 patients, mostly before 2010. After 2010, only three of 44 patients (6.7%) had postoperative otorrhea requiring LD. The use of LD resulted in significantly longer LOS (3.6â±â1.6 versus 8.7â±â2.9 d) and hospital costs ($29,621). There were no postoperative complications in 77% (50 of 65) of cases. Three cases required return to the operating room for complications including frontal subdural hematoma (1), subdural CSF collection (1), and tension pneumocephalus (1). No patients experienced long-term neurologic sequelae or long-term CSF leak recurrence with an average length of follow-up of 19.5 months (range 3â137 mo). The average patient BMI was 37.5â±â8.6âkg/m2. The average age was 57.5â±â11.4 years and 68% were female. Obstructive sleep apnea was present in 43.3% (26 of 60) of patients.
Conclusion: The morbidity of the MCF craniotomy for repair of spontaneous CSF leaks is low and the long-term efficacy of repair is high. Universal use of perioperative lumbar drain is not indicated and significantly increases length of stay and hospital costs. Obesity and obstructive sleep apnea are highly associated with spontaneous CSF leaks
The First Spatially Resolved Mid-IR Spectra of NGC 1068 Obtained at Diffraction-limited Resolution with LWS at Keck I Telescope
We present spatially resolved mid-IR spectra of NGC 1068 with a
diffraction-limited resolution of 0.25\arcsec using the Long Wavelength
Spectrometer (LWS) at the Keck I telescope. The mid-infrared image of NGC 1068
is extended along the N-S direction. Previous imaging studies have shown the
extended regions are located inside the ionization cones indicating that the
mid-infrared emission arises perhaps from the inner regions of the narrow-line
clouds instead of the proposed dusty torus itself. The spatially resolved
mid-IR spectra were obtained at two different slit position angles, +8.0 and
-13.0 degrees across the elongated regions in the mid-IR. From these spectra,
we found only weak silicate absorption toward the northern extended regions but
strong in the nucleus and the southern extended regions. This is consistent
with a model of a slightly inclined cold obscuring torus which covers much of
the southern regions but is behind the northern extension. While a detailed
analysis of the spectra requires a radiative transfer model, the lack of
silicate emission from the northern extended regions prompts us to consider a
dual dust population model as one of the possible explanations in which a
different dust population exists in the ionization cones compared to that in
the dusty torus. Dust inside the ionization cones may lack small silicate
grains giving rise to only a featureless continuum in the northern extended
regions while dust in the dusty torus has plenty of small silicate grains to
produce the strong silicate absorption lines towards the nucleus and the
southern extended regions.Comment: Accepted to Ap
Intraoperative electrocochleographic characteristics of auditory neuropathy spectrum disorder in cochlear implant subjects
Auditory neuropathy spectrum disorder (ANSD) is characterized by an apparent discrepancy between measures of cochlear and neural function based on auditory brainstem response (ABR) testing. Clinical indicators of ANSD are a present cochlear microphonic (CM) with small or absent wave V. Many identified ANSD patients have speech impairment severe enough that cochlear implantation (CI) is indicated. To better understand the cochleae identified with ANSD that lead to a CI, we performed intraoperative round window electrocochleography (ECochG) to tone bursts in children (n = 167) and adults (n = 163). Magnitudes of the responses to tones of different frequencies were summed to measure the âtotal responseâ (ECochG-TR), a metric often dominated by hair cell activity, and auditory nerve activity was estimated visually from the compound action potential (CAP) and auditory nerve neurophonic (ANN) as a ranked âNerve Scoreâ. Subjects identified as ANSD (45 ears in children, 3 in adults) had higher values of ECochG-TR than adult and pediatric subjects also receiving CIs not identified as ANSD. However, nerve scores of the ANSD group were similar to the other cohorts, although dominated by the ANN to low frequencies more than in the non-ANSD groups. To high frequencies, the common morphology of ANSD cases was a large CM and summating potential, and small or absent CAP. Common morphologies in other groups were either only a CM, or a combination of CM and CAP. These results indicate that responses to high frequencies, derived primarily from hair cells, are the main source of the CM used to evaluate ANSD in the clinical setting. However, the clinical tests do not capture the wide range of neural activity seen to low frequency sounds
High resolution mid-infrared spectroscopy of ultraluminous infrared galaxies
(Abridged) We present R~600, 10-37um spectra of 53 ULIRGs at z<0.32, taken
using the IRS on board Spitzer. All of the spectra show fine structure emission
lines of Ne, O, S, Si and Ar, as well as molecular Hydrogen lines. Some ULIRGs
also show emission lines of Cl, Fe, P, and atomic Hydrogen, and/or absorption
features from C_2H_2, HCN, and OH. We employ diagnostics based on the
fine-structure lines, as well as the EWs and luminosities of PAH features and
the strength of the 9.7um silicate absorption feature (S_sil), to explore the
power source behind the infrared emission in ULIRGs. We show that the IR
emission from the majority of ULIRGs is powered mostly by star formation, with
only ~20% of ULIRGs hosting an AGN with a comparable or greater IR luminosity
than the starburst. The detection of the 14.32um [NeV] line in just under half
the sample however implies that an AGN contributes significantly to the mid-IR
flux in ~42% of ULIRGs. The emission line ratios, luminosities and PAH EWs are
consistent with the starbursts and AGN in ULIRGs being more extincted, and for
the starbursts more compact, versions of those in lower luminosity systems. The
excitations and electron densities in the NLRs of ULIRGs appear comparable to
those of lower luminosity starbursts, though there is evidence that the NLR gas
in ULIRGs is more dense. We show that the combined luminosity of the 12.81um
[NeII] and 15.56um [NeIII] lines correlates with both IR luminosity and the
luminosity of the 6.2 micron and 11.2 micron PAH features in ULIRGs, and use
this to derive a calibration between PAH luminosity and star formation rate.
Finally, we show that ULIRGs with 0.8 < S_sil < 2.4 are likely to be powered
mainly by star formation, but that ULIRGs with S_sil < 0.8, and possibly those
with S_sil > 2.4, contain an IR-luminous AGN.Comment: 62 pages in preprint format, 4 tables, 23 figures. ApJ accepte
Cloning Hubble Deep Fields I: A Model-Independent Measurement of Galaxy Evolution
We present a model-independent method of quantifying galaxy evolution in
high-resolution images, which we apply to the Hubble Deep Field (HDF). Our
procedure is to k-correct all pixels belonging to the images of a complete set
of bright galaxies and then to replicate each galaxy image to higher redshift
by the product of its space density, 1/V_{max}, and the cosmological volume.
The set of bright galaxies is itself selected from the HDF, because presently
the HDF provides the highest quality UV images of a redshift-complete sample of
galaxies (31 galaxies with I<21.9, \bar{z}=0.5, and for which V/V_{max} is
spread fairly). These galaxies are bright enough to permit accurate
pixel-by-pixel k-corrections into the restframe UV (\sim 2000 A). We match the
shot noise, spatial sampling and PSF smoothing of the HDF data, resulting in
entirely empirical and parameter-free ``no-evolution'' deep fields of galaxies
for direct comparison with the HDF. In addition, the overcounting rate and the
level of incompleteness can be accurately quantified by this procedure. We
obtain the following results. Faint HDF galaxies (I>24) are much smaller, more
numerous, and less regular than our ``no-evolution'' extrapolation, for any
interesting geometry. A higher proportion of HDF galaxies ``dropout'' in both U
and B, indicating that some galaxies were brighter at higher redshifts than our
``cloned'' z\sim0.5 population.Comment: 51 pages, 23 figures, replacement includes figures not previously
include
Tracing PAHs and Warm Dust Emission in the Seyfert Galaxy NGC 1068
We present a study of the nearby Seyfert galaxy NGC 1068 using mid- and far-
infrared data acquired with the IRAC, IRS, and MIPS instruments aboard the
Spitzer Space Telescope. The images show extensive 8 um and 24 um emission
coinciding with star formation in the inner spiral approximately 15" (1 kpc)
from the nucleus, and a bright complex of star formation 47" (3 kpc) SW of the
nucleus. The brightest 8 um PAH emission regions coincide remarkably well with
knots observed in an Halpha image. Strong PAH features at 6.2, 7.7, 8.6, and
11.3 um are detected in IRS spectra measured at numerous locations inside,
within, and outside the inner spiral. The IRAC colors and IRS spectra of these
regions rule out dust heated by the AGN as the primary emission source; the
SEDs are dominated by starlight and PAH emission. The equivalent widths and
flux ratios of the PAH features in the inner spiral are generally consistent
with conditions in a typical spiral galaxy ISM. Interior to the inner spiral,
the influence of the AGN on the ISM is evident via PAH flux ratios indicative
of a higher ionization parameter and a significantly smaller mean equivalent
width than observed in the inner spiral. The brightest 8 and 24 um emission
peaks in the disk of the galaxy, even at distances beyond the inner spiral, are
located within the ionization cones traced by [O III]/Hbeta, and they are also
remarkably well aligned with the axis of the radio jets. Although it is
possible that radiation from the AGN may directly enhance PAH excitation or
trigger the formation of OB stars that subsequently excite PAH emission at
these locations in the inner spiral, the orientation of collimated radiation
from the AGN and star formation knots in the inner spiral could be
coincidental. (abridged)Comment: 20 pages, 11 figures; AJ, accepted; full resolution version available
at http://spider.ipac.caltech.edu/staff/jhhowell/astro/howelln1068.pd
A Gerbil Model of Sloping Sensorineural Hearing Loss
The goal of the overall project is to develop knowledge about cochlear physiology during cochlear implantation and develop procedures for assessing its status during hearing preservation surgery. As a step toward this goal, for this study, we established an animal model of sloping high frequency sensorineural hearing loss that mimics the hearing condition of candidates for combined electric-acoustic stimulation
Lensing-Induced Structure of Submillimeter Sources: Implications for the Microwave Background
We consider the effect of lensing by galaxy clusters on the angular
distribution of submillimeter wavelength objects. While lensing does not change
the total flux and number counts of submillimeter sources, it can affect the
number counts and fluxes of flux-limited samples. Therefore imposing a flux cut
on point sources not only reduces the overall Poisson noise, but imprints the
correlations between lensing clusters on the unresolved flux distribution.
Using a simple model, we quantify the lensing anisotropy induced in
flux-limited samples and compare this to Poisson noise. We find that while the
level of induced anisotropies on the scale of the cluster angular correlation
length is comparable to Poisson noise for a slowly evolving cluster model, it
is negligible for more realistic models of cluster evolution. Thus the removal
of point sources is not expected to induce measurable structure in the
microwave or far-infrared backgrounds.Comment: 22 pages, 9 figures, accepted to Astrophysical Journa
Antigen-capturing nanoparticles improve the abscopal effect and cancer immunotherapy
Immunotherapy holds tremendous promise for improving cancer treatment1. Administering radiotherapy with immunotherapy has been shown to improve immune responses and can elicit an âabscopal effectâ2. Unfortunately, response rates for this strategy remain low3. Herein, we report an improved cancer immunotherapy approach that utilizes antigen-capturing nanoparticles (AC-NPs). We engineered several AC-NPs formulations and demonstrated that the set of protein antigens captured by each AC-NP formulation is dependent upon NP surface properties. We showed that AC-NPs deliver tumor specific proteins to antigen-presenting cells and significantly improve the efficacy of αPD-1 treatment using the B16F10 melanoma model, generating up to 20% cure rate as compared to 0% without AC-NPs. Mechanistic studies revealed that AC-NPs induced an expansion of CD8+ cytotoxic T cells and increased both CD4+/Treg and CD8+/Treg ratios. Our work presents a novel strategy for improving cancer immunotherapy with nanotechnology
- âŠ