122 research outputs found
Structure of the Milky Way stellar halo out to its outer boundary with blue horizontal-branch stars
We present the structure of the Milky Way stellar halo beyond Galactocentric
distances of kpc traced by blue horizontal-branch (BHB) stars, which
are extracted from the survey data in the Hyper Suprime-Cam Subaru Strategic
Program (HSC-SSP). We select BHB candidates based on photometry,
where the -band is on the Paschen series and the colors that involve the
-band are sensitive to surface gravity. About 450 BHB candidates are
identified between kpc and 300 kpc, most of which are beyond the reach
of previous large surveys including the Sloan Digital Sky Survey. We find that
the global structure of the stellar halo in this range has substructures, which
are especially remarkable in the GAMA15H and XMM-LSS fields in the HSC-SSP. We
find that the stellar halo can be fitted to a single power-law density profile
with an index of () with (without) these fields and
its global axial ratio is (). Thus, the stellar halo may be
significantly disturbed and be made in a prolate form by halo substructures,
perhaps associated with the Sagittarius stream in its extension beyond kpc. For a broken power-law model allowing different power-law indices
inside/outside a break radius, we obtain a steep power-law slope of outside a break radius of kpc ( kpc) for the case
with (without) GAMA15H and XMM-LSS. This radius of kpc might be as close
as a halo boundary if there is any, although larger BHB sample is required from
further HSC-SSP survey to increase its statistical significance.Comment: 12 pages, 8 figures, revised version, accepted for publication in
PAS
Epitaxially stabilized iridium spinel oxide without cations in the tetrahedral site
Single-crystalline thin film of an iridium dioxide polymorph Ir2O4 has been
fabricated by the pulsed laser deposition of LixIr2O4 precursor and the
subsequent Li-deintercalation using soft chemistry. Ir2O4 crystallizes in a
spinel (AB2O4) without A cations in the tetrahedral site, which is
isostructural to lambda-MnO2. Ir ions form a pyrochlore sublattice, which is
known to give rise to a strong geometrical frustration. This Ir spinel was
found to be a narrow gap insulator, in remarkable contrast to the metallic
ground state of rutile-type IrO2. We argue that an interplay of strong
spin-orbit coupling and a Coulomb repulsion gives rise to an insulating ground
state as in a layered perovskite Sr2IrO4.Comment: 9 pages, 3 figure
Aldehyde Dehydrogenase Activity as a Marker of Quality in Cryopreserved Cord Blood
We investigated the effects of cryopreservation on CD34+ cells and aldehyde dehydrogenase (ALDH) -positive cells (ALDH (+) cells) in the umbilical cord blood (UCB) of unrelated donors. Ten units of UCB were collected at the Kanagawa Cord Blood Bank from September 2009 to November 2010. These UCB units were frozen for 2 weeks or 1 year, and then assayed for quality by flow cytometry analysis and colony-forming assay. We found that both ALDH (+) cells and the numbers of total colony-forming units and colony-forming units of granulocyte/macrophage from the isolated CD34+ cells were significantly decreased after all cryopreservation. The numbers of ALDH (+) /CD34+ cells, ALDH (+) /CD34+CD38- cells, and total colony-forming units from the cryopreserved UCB units continued to decrease over time with cryopreservation. In contrast, levels of traditional primitive surface markers were not significantly decreased in CD34+ cells and CD34+CD38- cells after cryopreservation, although this result depended on the duration of cryopreservation. These findings suggested that ALDH (+) cells could be a new marker for assessing cryopreserved UCB quality prior to hematopoietic cell transplantation
Neurocognitive Evaluation of Japanese Childhood Cancer Survivors
Long-term cognitive effects following acute lymphoblastic leukemia treatment have been reported for Caucasians; however, these data remain unclear for other ethnicities and the treatment of other cancers. Here, we assessed cognitive function in Japanese childhood cancer survivors. This study enrolled 53 Japanese survivors of childhood cancer (mean age, 9.5 years; 36 boys and 17 girls). We evaluated performance-based cognitive function using the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-Ⅳ). Deviation intelligence quotients (IQ) for verbal comprehension (VC), perceptual reasoning (PR), processing speed (PS), and working memory (WM) were compared with the standardized mean and standard deviation (SD; 100 and 15, respectively). We classified patients into three groups depending on the cumulative methotrexate (MTX) dose (none, 1–19g/m2, and>20g/m2). Full-scale IQ was within normal range at 104.8 (SD, 12.9), although there were significant differences among the four WISC–Ⅳ index scores (P<0.001). The PS score (97.1±15.5) was significantly lower than the VC (107.2±15.8) and PR (105.3±14.2) scores (both P<0.005). WM performance decreased in an MTX dose-dependent manner (107.8, 102.6, and 96.5 for none, 1–19g/m2, and higher than 20g/m2, respectively; P=0.05). Japanese childhood cancer survivors, including those in the non-MTX group, demonstrated significant PS impairment. High-dose MTX treatment might be associated with neurocognitive deficiencies, particularly in WM. Although current treatments are associated with high cure rates, future research and interventions are required to improve cognitive function in these patients
Prostaglandin E2 Reverses Aberrant Production of an Inflammatory Chemokine by Microglia from Sandhoff Disease Model Mice through the cAMP-PKA Pathway
Background: Sandhoff disease (SD) is a neurodegenerative lysosomal b-hexosaminidase (Hex) deficiency involving excessive accumulation of undegraded substrates, including terminal GlcNAc-oligosaccharides and GM2 ganglioside. Microglia-mediated neuroinflammation contributes to the pathogenesis and progression of SD. Our previous study demonstrated that MIP-1a, a putative pathogenic factor for SD, is up-regulated in microglial cells derived from SD model mice (SD-Mg) through activation of Akt and JNK. Methodology/Principal Findings: In this study, we first demonstrated that prostaglandin E2 (PGE2), which is one of the lipid mediators derived from arachidonic acid and is known to suppress activation of microglia, reduced the aberrant MIP-1a production by SD-Mg to the same level as by WT-Mg. PGE2 also attenuated the activation of Akt and JNK. The inhibition of MIP-1a production and the activation of Akt and JNK occurred through the EP2 and 4/cAMP/PKA signaling pathway in the murine microglia derived from SD model mice. Conclusions/Significance: We propose that PGE2 plays a role as a negative regulator of MIP-1a production in th
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