Esophageal squamous cell carcinoma (ESCC), the major histologic subtype of esophageal cancer, is a devastating disease characterized by distinctly high incidences and mortality rates. However, there ...remains limited understanding of molecular events leading to development and progression of the disease, which are of paramount importance to defining biomarkers for diagnosis, prognosis, and personalized treatment. By high-throughout transcriptome sequence profiling of nontumor and ESCC clinical samples, we identified a subset of significantly differentially expressed genes involved in integrin signaling. The Rab25 gene implicated in endocytic recycling of integrins was the only gene in this group significantly downregulated, and its downregulation was confirmed as a frequent event in a second larger cohort of ESCC tumor specimens by quantitative real-time PCR and immunohistochemical analyses. Reduced expression of Rab25 correlated with decreased overall survival and was also documented in ESCC cell lines compared with pooled normal tissues. Demethylation treatment and bisulfite genomic sequencing analyses revealed that downregulation of Rab25 expression in both ESCC cell lines and clinical samples was associated with promoter hypermethylation. Functional studies using lentiviral-based overexpression and suppression systems lent direct support of Rab25 to function as an important tumor suppressor with both anti-invasive and -angiogenic abilities, through a deregulated FAK-Raf-MEK1/2-ERK signaling pathway. Further characterization of Rab25 may provide a prognostic biomarker for ESCC outcome prediction and a novel therapeutic target in ESCC treatment.
Stellar feedback from high-mass stars (e.g., H ii regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential ...high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1-MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H ii region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass-velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass-velocity diagram of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M☉, assuming a dust temperature of ≤20 K. The shocks from the expanding H ii regions ("B" and "C") to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H ii regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.
Abstract We observe the magnetic field morphology toward a nearby star-forming filamentary cloud, G202.3+2.5, using James Clerk Maxwell Telescope/POL-2 850 μ m thermal dust polarization observations ...with an angular resolution of 14.″4 (∼0.053 pc). The average magnetic field orientation is found to be perpendicular to the filaments, while showing different behaviors in the four subregions, suggesting various effects from the filaments’ collision in these subregions. With the kinematics obtained by the N 2 H + observation by IRAM, we estimate the plane-of-sky magnetic field strength by two methods, the classical Davis–Chandrasekhar–Fermi (DCF) method and the angular dispersion function (ADF) method, giving B pos,dcf and B pos,adf of ∼90 and ∼53 μ G. We study the relative importance between the gravity ( G ), magnetic field ( B ), and turbulence ( T ) in the four subregions, and find G > T > B , G ≥ T > B , G ∼ T > B , and T > G > B in the north tail, west trunk, south root, and east wing, respectively. In addition, we investigate the projection effects on the DCF and ADF methods, based on a similar simulation case, and find the 3D magnetic field strength may be underestimated by a factor of ∼3 if applying the widely used statistical B pos -to- B 3D factor when using the DCF or ADF methods, which may further underestimate/overestimate the related parameters.
The Padoan and Nordlund model of the stellar initial mass function (IMF) is derived from low-order statistics of supersonic turbulence, neglecting gravity (e.g., gravitational fragmentation, ...accretion, and merging). In this work, the predictions of that model are tested using the largest numerical experiments of supersonic hydrodynamic (HD) and magnetohydrodynamlc (MHD) turbulence to date ( similar to 1000 super(3) computational zones) and three different codes (Enzo, Zeus, and the Stagger code). The model predicts a power-law distribution for large masses, related to the turbulence-energy power-spectrum slope and the shock-jump conditions. This power-law mass distribution is confirmed by the numerical experiments. The model also predicts a sharp difference between the HD and MHD regimes, which is recovered in the experiments as well, implying that the magnetic field, even below energy equipartition on the large scale, is a crucial component of the process of turbulent fragmentation. These results suggest that the stellar IMF of primordial stars may differ from that in later epochs of star formation, due to differences in both gas temperature and magnetic field strength. In particular, we find that the IMF of primordial stars born in turbulent clouds may be narrowly peaked around a mass of order 10 M unk, as long as the column density of such clouds is not much in excess of 10 super(22) cm super(-2).
In order to understand the initial conditions and early evolution of star formation in a wide range of Galactic environments, we carried out an investigation of 64 Planck Galactic cold clumps (PGCCs) ...in the second quadrant of the Milky Way. Using the 13CO and C18O J = 1-0 lines and 850 m continuum observations, we investigated cloud fragmentation and evolution associated with star formation. We extracted 468 clumps and 117 cores from the 13CO line and 850 m continuum maps, respectively. We made use of the Bayesian distance calculator and derived the distances of all 64 PGCCs. We found that in general, the mass-size plane follows a relation of m ∼ r1.67. At a given scale, the masses of our objects are around 1/10 of that of typical Galactic massive star-forming regions. Analysis of the clump and core masses, virial parameters, densities, and mass-size relation suggests that the PGCCs in our sample have a low core formation efficiency (∼3.0%), and most PGCCs are likely low-mass star-forming candidates. Statistical study indicates that the 850 m cores are more turbulent, more optically thick, and denser than the 13CO clumps for star formation candidates, suggesting that the 850 m cores are likely more appropriate future star formation candidates than the 13CO clumps.
How stellar feedback from high-mass stars (e.g., H ii regions) influences the surrounding interstellar medium and regulates new star formation is still unclear. To address this question, we observed ...the G9.62+0.19 complex in 850 m continuum with the James Clerk Maxwell Telescope/POL-2 polarimeter. An ordered magnetic field has been discovered in its youngest clump, the G9.62 clump. The magnetic field strength is determined to be ∼1 mG. Magnetic field plays a larger role than turbulence in supporting the clump. However, the G9.62 clump is still unstable against gravitational collapse even if thermal, turbulent, and magnetic field support are taken into account together. The magnetic field segments in the outskirts of the G9.62 clump seem to point toward the clump center, resembling a dragged-in morphology, indicating that the clump is likely undergoing magnetically regulated global collapse. However, the magnetic field in its central region is aligned with the shells of the photodissociation regions and is approximately parallel to the ionization (or shock) front, indicating that the magnetic field therein is likely compressed by the expanding H ii regions that formed in the same complex.
Tumor-initiating cells (TIC), also known as cancer stem cells, are regarded widely as a specific subpopulation of cells needed for cancer initiation and progression. TICs have yet to be identified in ...esophageal tumors that have an increasing incidence in developed countries. Here, we report a CD90(+) cell population found in esophageal squamous cell carcinoma (ESCC), which is endowed with stem cell-like properties and high tumorigenic and metastatic potential. mRNA profiling of these cells suggested pathways through which they drive tumor growth and metastasis, with deregulation of an Ets-1/MMP signaling pathway and epithelial-mesenchymal transition figuring prominently. These cells possessed higher self-renewal activity and were sufficient for tumor growth, differentiation, metastasis, and chemotherapeutic resistance. CD90(+) TICs were isolated and characterized from ESCC clinical specimens as well as ESCC cell lines. In freshly resected clinical specimens, they represented a rare cell population, the levels of which correlated with strong family histories and lymph node metastasis. Our results prompt further study of this CD90(+) population of esophageal TICs as potential therapeutic targets.
Most numerical investigations on the role of magnetic fields in turbulent molecular clouds (MCs) are based on ideal magnetohydrodynamics (MHD). However, MCs are weakly ionized, so that the timescale ...required for the magnetic field to diffuse through the neutral component of the plasma by ambipolar diffusion (AD) can be comparable to the dynamical timescale. We have performed a series of image and image simulations on supersonic but sub-Alfvenic turbulent systems with AD using the heavy-ion approximation developed by Li and coworkers. Our calculations are based on the assumption that the number of ions is conserved, but we show that these results approximately apply to the case of time-dependent ionization in molecular clouds as well. Convergence studies allow us to determine the optimal value of the ionization mass fraction when using the heavy-ion approximation for low Mach number, sub-Alfvenic turbulent systems. We find that ambipolar diffusion steepens the velocity and magnetic power spectra compared to the ideal MHD case. Changes in the density PDF, total magnetic energy, and ionization fraction are determined as a function of the AD Reynolds number. The power spectra for the neutral gas properties of a strongly magnetized medium with a low AD Reynolds number are similar to those for a weakly magnetized medium; in particular, the power spectrum of the neutral velocity is close to that for Burgers turbulence.
ABSTRACT
We investigate the presence of hub-filament systems in a large sample of 146 active proto-clusters, using H13CO+ J = 1-0 molecular line data obtained from the ATOMS survey. We find that ...filaments are ubiquitous in proto-clusters, and hub-filament systems are very common from dense core scales (∼0.1 pc) to clump/cloud scales (∼1–10 pc). The proportion of proto-clusters containing hub-filament systems decreases with increasing dust temperature (Td) and luminosity-to-mass ratios (L/M) of clumps, indicating that stellar feedback from H ii regions gradually destroys the hub-filament systems as proto-clusters evolve. Clear velocity gradients are seen along the longest filaments with a mean velocity gradient of 8.71 km s−1 pc−1 and a median velocity gradient of 5.54 km s−1 pc−1. We find that velocity gradients are small for filament lengths larger than ∼1 pc, probably hinting at the existence of inertial inflows, although we cannot determine whether the latter are driven by large-scale turbulence or large-scale gravitational contraction. In contrast, velocity gradients below ∼1 pc dramatically increase as filament lengths decrease, indicating that the gravity of the hubs or cores starts to dominate gas infall at small scales. We suggest that self-similar hub-filament systems and filamentary accretion at all scales may play a key role in high-mass star formation.
Introduction: Ultrasound guidance is commonly used during central venous cannulation. Subclavian vein is a commonly chosen site, but previous studies found varying results in the ideal positioning of ...the shoulder for subclavian vein cannulation. The objective of this study is to determine which shoulder position results in the greatest cross-sectional area of the right subclavian vein for cannulation.
Methods: In this prospective observational study, ultrasound was performed on healthy adult volunteers to visualise the right subclavian vein in three different shoulder positions: neutral, abduction and retraction. A blinded independent investigator measured the cross-sectional areas by computer software using planimetry method. Statistical analysis was performed by one-way repeated measures analysis of variance.
Results: Forty-four adults participated in the study. The mean cross-sectional area of the right subclavian vein in shoulder neutral, abduction and retraction positions were 1.05 +- 0.33 cm2, 1.01 +- 0.31 cm2 and 0.82 +- 0.28 cm2, respectively. When compared to shoulder retraction, the cross-sectional areas were significantly increased in shoulder neutral (P < 0.01) and abduction (P < 0.01) positions. There was no significant difference between shoulder neutral and abduction position (P = 0.71).
Conclusion: Positioning the shoulder in neutral or abduction results in the greatest cross-sectional area of the right subclavian vein and may be more ideal for ultrasound guided cannulation.
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