135 research outputs found
Time-, spin-, and angle-resolved photoemission spectroscopy with a 1-MHz 10.7-eV pulse laser
We describe a setup of time-, spin-, and angle-resolved photoemission
spectroscopy (tr-SARPES) employing a 10.7-eV (=115.6 nm) pulse laser
at 1-MHz repetition rate as a probe photon source. This equipment effectively
combines technologies of a high-power Yb:fiber laser, ultraviolet-driven
harmonic generation in Xe gas, and a SARPES apparatus equipped with
very-low-energy-electron-diffraction (VLEED) spin detectors. A high repetition
rate (1 MHz) of the probe laser allows experiments with the photoemission
space-charge effects significantly reduced, despite a high flux of 10
photons/s on the sample. The relatively high photon energy (10.7 eV) also
brings the capability of observing a wide momentum range that covers the entire
Brillouin zone of many materials while ensuring high momentum resolution. The
experimental setup overcomes a low efficiency of spin-resolved measurements,
which gets even more severe for the pump-probed unoccupied states, and affords
for investigating ultrafast electron and spin dynamics of modern quantum
materials with energy and time resolutions of 25 meV and 360 fs, respectively.Comment: 11 pages, 7 figure
Itinerant ferromagnetism mediated by giant spin polarization of metallic ligand band in van der Waals magnet Fe5GeTe2
We investigate near-Fermi-energy (EF) element-specific electronic and spin
states of ferromagnetic van der Waals (vdW) metal Fe5GeTe2. The soft x-ray
angle-resolved photoemission spectroscopy (SX-ARPES) measurement provides
spectroscopic evidence of localized Fe 3d band. We also find prominent
hybridization between the localized Fe 3d band and the delocalized Ge/Te p
bands. This picture is strongly supported from direct observation of the
remarkable spin polarization of the ligand p bands near EF, using x-ray
magnetic circular dichroism (XMCD) measurements. The strength of XMCD signal
from ligand element Te shows the highest value, as far as we recognize, among
literature reporting finite XMCD signal for none-magnetic element in any
systems. Combining SX-ARPES and elemental selective XMCD measurements, we
collectively point an important role of giant spin polarization of the
delocalized ligand Te states for realizing itinerant long-range ferromagnetism
in Fe5GeTe2. Our finding provides a fundamental elemental selective view-point
for understanding mechanism of itinerant ferromagnetism in low dimensional
compounds, which also leads insight for designing exotic magnetic states by
interfacial band engineering in heterostructures
Non-B DB: a database of predicted non-B DNA-forming motifs in mammalian genomes
Although the capability of DNA to form a variety of non-canonical (non-B) structures has long been recognized, the overall significance of these alternate conformations in biology has only recently become accepted en masse. In order to provide access to genome-wide locations of these classes of predicted structures, we have developed non-B DB, a database integrating annotations and analysis of non-B DNA-forming sequence motifs. The database provides the most complete list of alternative DNA structure predictions available, including Z-DNA motifs, quadruplex-forming motifs, inverted repeats, mirror repeats and direct repeats and their associated subsets of cruciforms, triplex and slipped structures, respectively. The database also contains motifs predicted to form static DNA bends, short tandem repeats and homo(purineβ’pyrimidine) tracts that have been associated with disease. The database has been built using the latest releases of the human, chimp, dog, macaque and mouse genomes, so that the results can be compared directly with other data sources. In order to make the data interpretable in a genomic context, features such as genes, single-nucleotide polymorphisms and repetitive elements (SINE, LINE, etc.) have also been incorporated. The database is accessed through query pages that produce results with links to the UCSC browser and a GBrowse-based genomic viewer. It is freely accessible at http://nonb.abcc.ncifcrf.gov
IgG4-related kidney diseases and conditions: Renal pelvic and ureteral diseases
In the literature on IgG4-related urinary tract diseases, reports of cases with involvement of the renal pelvis and ureters are increasing. IgG4-related renal pelvic and ureteral lesions accompany extra-renal organ involvement, including IgG4-related type 1 autoimmune pancreatitis, sialadenitis, and orbital disease, and are characterized by the common pathological features of IgG4-related disease (IgG4-RD), including substantial numbers of IgG4-positive plasma cells, storiform fibrosis, and stenosis in the affected organs. Similar to other mucosal organs affected in IgG4-RD, these inflammatory findings are observed within the fibroadipose tissue in the renal hilum and around the ureters. The urothelial epithelium covering the renal pelvis and ureter is preserved. Nodular lesions such as pseudotumors can also form and it is important to differentiate these from malignant tumors. At present, comprehensive diagnostic criteria that include pathological parameters have been proposed for IgG4-RD; however, obtaining diagnostic findings in small biopsy specimens is often challenging. Therefore, the diagnosis can only be rendered following careful consideration of the patientβs clinical, serologic, radiologic, and pathologic features, including the possibility of involvement in other organs. Β© Springer Japan 2016.[Book Chapter
TGF-Ξ² Inducible Early Gene 1 Regulates Osteoclast Differentiation and Survival by Mediating the NFATc1, AKT, and MEK/ERK Signaling Pathways
TGF-Ξ² Inducible Early Gene-1 (TIEG1) is a KrΓΌppel-like transcription factor (KLF10) that was originally cloned from human osteoblasts as an early response gene to TGF-Ξ² treatment. As reported previously, TIEG1β/β mice have decreased cortical bone thickness and vertebral bone volume and have increased spacing between the trabeculae in the femoral head relative to wildtype controls. Here, we have investigated the role of TIEG1 in osteoclasts to further determine their potential role in mediating this phenotype. We have found that TIEG1β/β osteoclast precursors differentiated more slowly compared to wildtype precursors in vitro and high RANKL doses are able to overcome this defect. We also discovered that TIEG1β/β precursors exhibit defective RANKL-induced phosphorylation and accumulation of NFATc1 and the NFATc1 target gene DC-STAMP. Higher RANKL concentrations reversed defective NFATc1 signaling and restored differentiation. After differentiation, wildtype osteoclasts underwent apoptosis more quickly than TIEG1β/β osteoclasts. We observed increased AKT and MEK/ERK signaling pathway activation in TIEG1β/β osteoclasts, consistent with the roles of these kinases in promoting osteoclast survival. Adenoviral delivery of TIEG1 (AdTIEG1) to TIEG1β/β cells reversed the RANKL-induced NFATc1 signaling defect in TIEG1β/β precursors and eliminated the differentiation and apoptosis defects. Suppression of TIEG1 with siRNA in wildtype cells reduced differentiation and NFATc1 activation. Together, these data provide evidence that TIEG1 controls osteoclast differentiation by reducing NFATc1 pathway activation and reduces osteoclast survival by suppressing AKT and MEK/ERK signaling
A physical analysis of the Y chromosome shows no additional deletions, other than Gr/Gr, associated with testicular germ cell tumour
Testicular germ cell tumour (TGCT) is the most common malignancy in men aged 15β45 years. A small deletion on the Y chromosome known as βgr/gr' was shown to be associated with a two-fold increased risk of TGCT, increasing to three-fold in cases with a family history of TGCT. Additional deletions of the Y chromosome, known as AZFa, AZFb and AZFc, are described in patients with infertility; however, complete deletions of these regions have not been identified in TGCT patients. We screened the Y chromosome in a series of TGCT cases to evaluate if additional deletions of Y were implicated in TGCT susceptibility. Single copy Y chromosome STS markers with an average inter-marker spacing of 128βkb were examined in constitutional DNA of 271 index TGCT patients. Three markers showed evidence of deletions, sY1291, indicative of βgr/gr' (eight out of 271; 2.9%), Y-DAZ3 contained within βgr/gr' (21 out of 271; 7.7%) and a single deletion of the marker G66152 was identified in one TGCT case. No other markers demonstrated deletions. While several regions of the Y chromosome are known to be deleted and associated with infertility, our study provides no evidence to suggest regions of Y deletion, other than βgr/gr', are associated with susceptibility to TGCT in UK patients
Convergent evolution of chicken Z and human X chromosomes by expansion and gene acquisition
In birds, as in mammals, one pair of chromosomes differs between the sexes. In birds, males are ZZ and females ZW. In mammals, males are XY and females XX. Like the mammalian XY pair, the avian ZW pair is believed to have evolved from autosomes, with most change occurring in the chromosomes found in only one sexβthe W and Y chromosomes1, 2, 3, 4, 5. By contrast, the sex chromosomes found in both sexesβthe Z and X chromosomesβare assumed to have diverged little from their autosomal progenitors2. Here we report findings that challenge this assumption for both the chicken Z chromosome and the human X chromosome. The chicken Z chromosome, which we sequenced essentially to completion, is less gene-dense than chicken autosomes but contains a massive tandem array containing hundreds of duplicated genes expressed in testes. A comprehensive comparison of the chicken Z chromosome with the finished sequence of the human X chromosome demonstrates that each evolved independently from different portions of the ancestral genome. Despite this independence, the chicken Z and human X chromosomes share features that distinguish them from autosomes: the acquisition and amplification of testis-expressed genes, and a low gene density resulting from an expansion of intergenic regions. These features were not present on the autosomes from which the Z and X chromosomes originated but were instead acquired during the evolution of Z and X as sex chromosomes. We conclude that the avian Z and mammalian X chromosomes followed convergent evolutionary trajectories, despite their evolving with opposite (female versus male) systems of heterogamety. More broadly, in birds and mammals, sex chromosome evolution involved not only gene loss in sex-specific chromosomes, but also marked expansion and gene acquisition in sex chromosomes common to males and females.National Science Foundation (U.S.)Howard Hughes Medical Institut
NK105, a paclitaxel-incorporating micellar nanoparticle, is a more potent radiosensitising agent compared to free paclitaxel
NK105 is a micellar nanoparticle formulation designed to enhance the delivery of paclitaxel (PTX) to solid tumours. It has been reported to exert antitumour activity in vivo and to have reduced neurotoxicity as compared to that of free PTX. The purpose of this study was to investigate the radiosensitising effect of NK105 in comparison with that of PTX. Lewis lung carcinoma (LLC)-bearing mice were administered a single intravenous (i.v.) injection of PTX or NK105; 24βh after the drug administration, a proportion of the mice received radiation to the tumour site or lung fields. Then, the antitumour activity and lung toxicity were evaluated. In one subset of mice, the tumours were excised and specimens were prepared for analysis of the cell cycle distribution by flow cytometry. Combined NK105 treatment with radiation yielded significant superior antitumour activity as compared to combined PTX treatment with radiation (P=0.0277). On the other hand, a histopathological study of lung sections revealed no significant difference in histopathological changes between mice treated with PTX and radiation and those treated with NK105 and radiation. Flow-cytometric analysis showed that NK105-treated LLC tumour cells showed more severe arrest at the G2/M phase as compared to PTX-treated tumour cells. The superior radiosensitising activity of NK105 was thus considered to be attributable to the more severe cell cycle arrest at the G2/M phase induced by NK105 as compared to that induced by free PTX. The present study results suggest that further clinical trials are warranted to determine the efficacy and feasibility of combined NK105 therapy with radiation
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