1,807 research outputs found
Clonal and microclonal mutational heterogeneity in high hyperdiploid acute lymphoblastic leukemia.
High hyperdiploidy (HD), the most common cytogenetic subtype of B-cell acute lymphoblastic leukemia (B-ALL), is largely curable but significant treatment-related morbidity warrants investigating the biology and identifying novel drug targets. Targeted deep-sequencing of 538 cancer-relevant genes was performed in 57 HD-ALL patients lacking overt KRAS and NRAS hotspot mutations and lacking common B-ALL deletions to enrich for discovery of novel driver genes. One-third of patients harbored damaging mutations in epigenetic regulatory genes, including the putative novel driver DOT1L (n=4). Receptor tyrosine kinase (RTK)/Ras/MAPK signaling pathway mutations were found in two-thirds of patients, including novel mutations in ROS1, which mediates phosphorylation of the PTPN11-encoded protein SHP2. Mutations in FLT3 significantly co-occurred with DOT1L (p=0.04), suggesting functional cooperation in leukemogenesis. We detected an extraordinary level of tumor heterogeneity, with microclonal (mutant allele fraction <0.10) KRAS, NRAS, FLT3, and/or PTPN11 hotspot mutations evident in 31/57 (54.4%) patients. Multiple KRAS and NRAS codon 12 and 13 microclonal mutations significantly co-occurred within tumor samples (p=4.8x10-4), suggesting ongoing formation of and selection for Ras-activating mutations. Future work is required to investigate whether tumor microheterogeneity impacts clinical outcome and to elucidate the functional consequences of epigenetic dysregulation in HD-ALL, potentially leading to novel therapeutic approaches
Performance Evaluation of Staged Bosch Process for CO2 Reduction to Produce Life Support Consumables
Utilizing carbon dioxide to produce water and hence oxygen is critical for sustained manned missions in space, and to support both NASA's cabin Atmosphere Revitalization System (ARS) and In-Situ Resource Utilization (ISRU) concepts. For long term missions beyond low Earth orbit, where resupply is significantly more difficult and costly, open loop ARS, like Sabatier, consume inputs such as hydrogen. The Bosch process, on the other hand, has the potential to achieve complete loop closure and is hence a preferred choice. However, current single stage Bosch reactor designs suffer from a large recycle penalty due to slow reaction rates and the inherent limitation in approaching thermodynamic equilibrium. Developmental efforts are seeking to improve upon the efficiency (hence reducing the recycle penalty) of current single stage Bosch reactors which employ traditional steel wool catalysts. Precision Combustion, Inc. (PCI), with support from NASA, has investigated the potential for utilizing catalysts supported over short-contact time Microlith substrates for the Bosch reaction to achieve faster reaction rates, higher conversions, and a reduced recycle flows. Proof-of-concept testing was accomplished for a staged Bosch process by splitting the chemistry in two separate reactors, first being the reverse water-gas-shift (RWGS) and the second being the carbon formation reactor (CFR) via hydrogenation and/or Boudouard. This paper presents the results from this feasibility study at various operating conditions. Additionally, results from two 70 hour durability tests for the RWGS reactor are discussed
Relationships between Larval and Juvenile Abundance of Winter-Spawned Fishes in North Carolina, USA
We analyzed the relationships between the larval and juvenile abundances of selected estuarine-dependent fishes that spawn during the winter in continental shelf waters of the U.S. Atlantic coast. Six species were included in the analysis based on their ecological and economic importance and relative abundance in available surveys: spot Leiostomus xanthurus, pinfish Lagodon rhomboides, southern flounder Paralichthys lethostigma, summer flounder Paralichthys dentatus, Atlantic croaker Micropogonias undulatus, and Atlantic menhaden Brevoortia tyrannus. Cross-correlation analysis was used to examine the relationships between the larval and juvenile abundances within species. Tests of synchrony across species were used to find similarities in recruitment dynamics for species with similar winter shelf-spawning life-history strategies. Positive correlations were found between the larval and juvenile abundances for three of the six selected species (spot, pinfish, and southern flounder). These three species have similar geographic ranges that primarily lie south of Cape Hatteras. There were no significant correlations between the larval and juvenile abundances for the other three species (summer flounder, Atlantic croaker, and Atlantic menhaden); we suggest several factors that could account for the lack of a relationship. Synchrony was found among the three southern species within both the larval and juvenile abundance time series. These results provide support for using larval ingress measures as indices of abundance for these and other species with similar geographic ranges and winter shelf-spawning life-history strategies
Influence of County-Level Geographic/Ancestral Origin on Glioma Incidence and Outcomes in Us Hispanics
BACKGROUND: Glioma incidence is 25% lower in Hispanics than White non-Hispanics. The US Hispanic population is diverse, and registry-based analyses may mask incidence differences associated with geographic/ancestral origins.
METHODS: County-level glioma incidence data in Hispanics were retrieved from the Central Brain Tumor Registry of the United States. American Community Survey data were used to determine the county-level proportion of the Hispanic population of Mexican/Central American and Caribbean origins. Age-adjusted incidence rate ratios and incidence rate ratios (IRRs) quantified the glioma incidence differences across groups. State-level estimates of admixture in Hispanics were obtained from published 23andMe data.
RESULTS: Compared to predominantly Caribbean-origin counties, predominantly Mexican/Central American-origin counties had lower age-adjusted risks of glioma (IRR = 0.83; P \u3c 0.0001), glioblastoma (IRR = 0.86; P \u3c 0.0001), diffuse/anaplastic astrocytoma (IRR = 0.78; P \u3c 0.0001), oligodendroglioma (IRR = 0.82; P \u3c 0.0001), ependymoma (IRR = 0.88; P = 0.012), and pilocytic astrocytoma (IRR = 0.76; P \u3c 0.0001). Associations were consistent in children and adults and using more granular geographic regions. Despite having lower glioma incidence, Hispanic glioblastoma patients from predominantly Mexican/Central American-origin counties had poorer survival than Hispanics living in predominantly Caribbean-origin counties. Incidence and survival differences could be partially explained by state-level estimates of European admixture in Hispanics with European admixture associated with higher incidence and improved survival.
CONCLUSIONS: Glioma incidence and outcomes differ in association with the geographic origins of Hispanic communities, with counties of predominantly Mexican/Central American origin at significantly reduced risk and those of Caribbean origin at comparatively greater risk. Although typically classified as a single ethnic group, appreciating the cultural, socioeconomic, and genetic diversity of Hispanics can advance cancer disparities research
Black Hole Mass Measurements of Radio Galaxies NGC 315 and NGC 4261 Using ALMA CO Observations
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 and
Cycle 6 observations of CO(21) and CO(32) emission at 0.2''0.3''
resolution in two radio-bright, brightest group/cluster early-type galaxies,
NGC 315 and NGC 4261. The data resolve CO emission that extends within their
black hole (BH) spheres of influence (), tracing regular
Keplerian rotation down to just tens of parsecs from the BHs. The projected
molecular gas speeds in the highly inclined () disks rises at least
500 km s near their galaxy centers. We fit dynamical models of thin-disk
rotation directly to the ALMA data cubes, and account for the extended stellar
mass distributions by constructing galaxy surface brightness profiles corrected
for a range of plausible dust extinction values. The best-fit models yield
for NGC 315 and
for NGC 4261, the latter of which is larger than previous estimates by a factor
of 3. The BH masses are broadly consistent with the relations between BH
masses and host galaxy properties. These are among the first ALMA observations
to map dynamically cold gas kinematics well within the BH-dominated regions of
radio galaxies, resolving the respective by factors of
510. The observations demonstrate ALMA's ability to precisely measure
BH masses in active galaxies, which will enable more confident probes of
accretion physics for the most massive galaxies.Comment: 24 pages, 11 figures, 4 tables. Accepted for publication in Ap
The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission, which we have previously reported. We present here the light
curves for the Halpha, Hgamma, HeII 4686, and HeI 5876 emission lines and the
time lags for the emission-line responses relative to changes in the continuum
flux. Combining each emission-line time lag with the measured width of the line
in the variable part of the spectrum, we determine a virial mass of the central
supermassive black hole from several independent emission lines. We find that
the masses are generally consistent within the uncertainties. The time-lag
response as a function of velocity across the Balmer line profiles is examined
for six of the AGNs. Finally we compare several trends seen in the dataset
against the predictions from photoionization calculations as presented by
Korista & Goad. We confirm several of their predictions, including an increase
in responsivity and a decrease in the mean time lag as the excitation and
ionization level for the species increases. Further confirmation of
photoionization predictions for broad-line gas behavior will require additional
monitoring programs for these AGNs while they are in different luminosity
states. [abridged]Comment: 37 pages, 18 figures and 15 tables, accepted for publication in the
Astrophysical Journa
The Lick AGN Monitoring Project 2011: Dynamical Modeling of the Broad Line Region in Mrk 50
We present dynamical modeling of the broad line region (BLR) in the Seyfert 1
galaxy Mrk 50 using reverberation mapping data taken as part of the Lick AGN
Monitoring Project (LAMP) 2011. We model the reverberation mapping data
directly, constraining the geometry and kinematics of the BLR, as well as
deriving a black hole mass estimate that does not depend on a normalizing
factor or virial coefficient. We find that the geometry of the BLR in Mrk 50 is
a nearly face-on thick disk, with a mean radius of 9.6(+1.2,-0.9) light days, a
width of the BLR of 6.9(+1.2,-1.1) light days, and a disk opening angle of
25\pm10 degrees above the plane. We also constrain the inclination angle to be
9(+7,-5) degrees, close to face-on. Finally, the black hole mass of Mrk 50 is
inferred to be log10(M(BH)/Msun) = 7.57(+0.44,-0.27). By comparison to the
virial black hole mass estimate from traditional reverberation mapping
analysis, we find the normalizing constant (virial coefficient) to be log10(f)
= 0.78(+0.44,-0.27), consistent with the commonly adopted mean value of 0.74
based on aligning the M(BH)-{\sigma}* relation for AGN and quiescent galaxies.
While our dynamical model includes the possibility of a net inflow or outflow
in the BLR, we cannot distinguish between these two scenarios.Comment: Accepted for publication in ApJ. 8 pages, 6 figure
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