Polar Actions on Berger Spheres

The object of this article is to study a torus action on a so-called Berger sphere. We also make some comments on polar actions on naturally reductive homogeneous spaces. Finally, we prove a rigidity-type theorem for Riemannian manifolds carrying a polar action with a fix point

A Berger type normal holonomy theorem for complex submanifolds

We prove a kind of Berger-Simons' Theorem for the normal holonomy group of a complex submanifold of the projective spac

In vitro characterization and inhibition of the CXCR4/CXCL12 chemokine axis in human uveal melanoma cell lines

<p>Abstract</p> <p>Purpose</p> <p>The CXCR4/CXCL12 chemokine axis may play a critical role in guiding CXCR4+ circulating malignant cells to organ specific locations that actively secrete its ligand CXCL12 (SDF-1) such as bone, brain, liver, and lungs. We sought to characterize the presence of the CXCR4/CXCL12 axis in five uveal melanoma (UM) cell lines in vitro. The ability of TN14003, a synthetic peptide inhibitor that targets the CXCR4 receptor complex, to inhibit this axis was also assessed.</p> <p>Methods</p> <p>Immunocytochemistry was performed against CXCR4 to confirm expression of this chemokine receptor in all five UM cell lines. Flow cytometry was preformed to evaluate CXCR4 cell surface expression on all five UM cell lines. A proliferation assay was also used to test effects TN14003 would have on cellular proliferation. Inhibition of cellular migration by specifically inhibiting the CXCR4/CXCL12 axis with TN14003 was also investigated. The binding efficacy of TN14003 to the CXCR4 receptor was assessed through flow cytometric methods.</p> <p>Results</p> <p>The CXCR4 receptor was present on all five UM cell lines. All five cell lines expressed different relative levels of surface CXCR4. TN14003 did not affect the proliferation of the five cell lines (p > 0.05). All cell lines migrated towards the chemokine CXCL12 at a level greater than the negative control (p < 0.05). All 5 cell lines pre-incubated with TN14003 prevented cellular migration towards chemokine CXCL12 (p < 0.01). TN14003 preferentially binds CXCR4 to native ligand CXCL12.</p> <p>Conclusion</p> <p>Interfering with the CXCR4/CXCL12 axis, using TN14003 was shown to effectively down regulate UM cell migration in vitro. Knowing that UM expresses the CXCR4 receptor, these CXCR4+ cells may be less likely to colonize distant organs that secrete the CXCL12 ligand, if treated with an inhibitor that binds CXCR4. Further studies should be pursued in order to test TN14003 efficacy in vivo.</p

Equilibration times in numerical simulation of structural glasses: Comparing parallel tempering and conventional molecular dynamics

Generation of equilibrium configurations is the major obstacle for numerical investigation of the slow dynamics in supercooled liquid states. The parallel tempering (PT) technique, originally proposed for the numerical equilibration of discrete spin-glass model configurations, has recently been applied in the study of supercooled structural glasses. We present an investigation of the ability of parallel tempering to properly sample the liquid configuration space at different temperatures, by mapping the PT dynamics into the dynamics of the closest local potential energy minima (inherent structures). Comparing the PT equilibration process with the standard molecular dynamics equilibration process we find that the PT does not increase the speed of equilibration of the (slow) configurational degrees of freedom.Comment: 5 pages, 3 figure

The apparent eta Carinae's long-term evolution and the critical role played by the strengthening of P Cygni absorption lines

Over the entire 20th century, Eta Carinae (\ec) has displayed a unique spectrum, which recently has been evolving towards that of a typical LBV. The two competing scenarios to explain such evolution are: (1) a dissipating occulter in front of a stable star or (2) a decreasing mass loss rate of the star. The first mechanism simultaneously explains why the central star appears to be secularly increasing its apparent brightness while its luminosity does not change; why the Homunculus' apparent brightness remains almost constant; and why the spectrum seen in direct light is becoming more similar to that reflected from the Homunculus (and which resembles a typical LBV). The second scenario does not account for these facts and predicts an increase in the terminal speed of the wind, contrary to observations. In this work, we present new data showing that the P Cygni absorption lines are secularly strengthening, which is not the expected behaviour for a decreasing wind-density scenario. CMFGEN modelling of the primary's wind with a small occulter in front agrees with observations. One could argue that invoking a dissipating coronagraphic occulter makes this object even more peculiar than it already appears to be. However, on the contrary, it solves the apparent contradictions between many observations. Moreover, by assigning the long-term behaviour to circumstellar causes and the periodic variations due to binarity, a star more stable after the 1900s than previously thought is revealed, contrary to the earlier paradigm of an unpredictable object.Comment: 17 pages, 12 figures, submitted to MNRA

Identification of Novel Pax8 Targets in FRTL-5 Thyroid Cells by Gene Silencing and Expression Microarray Analysis

The differentiation program of thyroid follicular cells (TFCs), by far the most abundant cell population of the thyroid gland, relies on the interplay between sequence-specific transcription factors and transcriptional coregulators with the basal transcriptional machinery of the cell. However, the molecular mechanisms leading to the fully differentiated thyrocyte are still the object of intense study. The transcription factor Pax8, a member of the Paired-box gene family, has been demonstrated to be a critical regulator required for proper development and differentiation of thyroid follicular cells. Despite being Pax8 well-characterized with respect to its role in regulating genes involved in thyroid differentiation, genomics approaches aiming at the identification of additional Pax8 targets are lacking and the biological pathways controlled by this transcription factor are largely unknown.To identify unique downstream targets of Pax8, we investigated the genome-wide effect of Pax8 silencing comparing the transcriptome of silenced versus normal differentiated FRTL-5 thyroid cells. In total, 2815 genes were found modulated 72 h after Pax8 RNAi, induced or repressed. Genes previously reported to be regulated by Pax8 in FRTL-5 cells were confirmed. In addition, novel targets genes involved in functional processes such as DNA replication, anion transport, kinase activity, apoptosis and cellular processes were newly identified. Transcriptome analysis highlighted that Pax8 is a key molecule for thyroid morphogenesis and differentiation.This is the first large-scale study aimed at the identification of new genes regulated by Pax8, a master regulator of thyroid development and differentiation. The biological pathways and target genes controlled by Pax8 will have considerable importance to understand thyroid disease progression as well as to set up novel therapeutic strategies

biological properties of hsc scientific basis for hsct

Hematopoiesis—from the Greek term for "blood making"—is the adaptive process by which mature and functional blood cells are continuously replaced over the entire lifetime of an individual. Erythrocytes, platelets, and the various subsets of leukocytes all have finite although different life spans. As a consequence, the daily production of red blood cells, platelets, and neutrophils in homeostatic conditions amount to more than 300 billion cells

Amyloid Plaques Beyond Aβ: A Survey of the Diverse Modulators of Amyloid Aggregation

Aggregation of the amyloid-β (Aβ) peptide is strongly correlated with Alzheimer’s disease (AD). Recent research has improved our understanding of the kinetics of amyloid fibril assembly and revealed new details regarding different stages in plaque formation. Presently, interest is turning toward studying this process in a holistic context, focusing on cellular components which interact with the Aβ peptide at various junctures during aggregation, from monomer to cross-β amyloid fibrils. However, even in isolation, a multitude of factors including protein purity, pH, salt content, and agitation affect Aβ fibril formation and deposition, often producing complicated and conflicting results. The failure of numerous inhibitors in clinical trials for AD suggests that a detailed examination of the complex interactions that occur during plaque formation, including binding of carbohydrates, lipids, nucleic acids, and metal ions, is important for understanding the diversity of manifestations of the disease. Unraveling how a variety of key macromolecular modulators interact with the Aβ peptide and change its aggregation properties may provide opportunities for developing therapies. Since no protein acts in isolation, the interplay of these diverse molecules may differentiate disease onset, progression, and severity, and thus are worth careful consideration