851 research outputs found
Protein kinase WNK2 as a tumour suppressor gene in malignant gliomas
Malignant glioblastomas are the most common and lethal adult brain tumours, with patients dying within two years from diagnosis. Little is known about the molecular mechanisms underlying the formation and/or development of these tumours, which present a very invasive phenotype within the brain and are genetically heterogeneous and highly resistant to both chemo- and radio-therapies. Recently, the promoter region of the protein kinase WNK2 gene was found to be hypermethylated in 29 of 31 infiltrative gliomas and about 80% of meningiomas. We have previously described that the experimental depletion of WNK2 expression decreases RhoA activity whilst leading to increased Rac1 activity. Because RhoA/Rac1 activities are important for cell migration and glioblastomas are very invasive tumours, we tested the effects of WNK2 on wound-healing assays in glioma cell lines SW1088 and A172. SW1088 cells express endogenous WNK2 and we observed that wound closure was increased upon experimental depletion of endogenous WNK2. In contrast, A172 cells display complete promoter region methylation and WNK2 re-expression was found to decrease migration. Consistently, we observed an increase in Rac1 activity in SW1088 cells upon WNK2 down-regulation, but lower levels of active Rac1 in A172 cells stably expressing WNK2 cDNA when compared with an equivalent cell line stably transfected with the same empty vector. Our studies indicate that loss of WNK2 expression promotes Rac1 activation and may contribute to the highly invasive phenotype that glioblastomas present. We also observed that, in a panel of glioblastoma cell lines, WNK2 promoter methylation correlates with a marked deregulation in Akt, MEK1/2 and ERK1/2 activities, suggesting WNK2 may also be important for tumour cell survival and cell cycle progression.FC
NEOTECTÔNICA NA BACIA DO ALTO RIO GRANDE: APLICAÇÕES EM SUA PORÇÃO MANTIQUEIRENSE
O trabalho tem por objetivo levar a efeito investigações acerca do quadro neotectônico vigente na bacia do alto Rio Grande em sua porção contida na Serra da Mantiqueira, sul de Minas Gerais. A discussão se pautou nos resultados obtidos por interpretações cartográficas, trabalhos de campo e mensuração dos seguintes índices geomórficos: Fator Assimetria de Bacias de Drenagem, Fator de Simetria Topográfica Transversal, Relação Declividade X Extensão do Curso, perfil longitudinal principais canais
Cardiovascular autonomic modulation differences between moderate-intensity continuous and high-intensity interval aerobic training in women with PCOS: A randomized trial
Background: Moderate-intensity continuous training (MICT) is strongly recommended for polycystic ovarian syndrome (PCOS) treatment. However, recent studies have suggested that high-intensity interval training (HIIT) would promote great benefits for cardiac autonomic control. Therefore, we investigated whether the benefits of HIIT related to cardiovascular autonomic control were greater than those of MICT in women with PCOS.
Methods: Women with PCOS were randomly allocated through a blind draw into three groups: control, MICT, and HIIT. The control group did not undergo exercise, whereas those in the MICT and HIIT groups underwent 16 weeks of aerobic physical training. All groups were evaluated before and after the 16 weeks of intervention in the following aspects: quantification of serum lipids, testosterone, fasting insulin and blood glucose; physical fitness through cardiopulmonary testing; analysis of heart rate variability (HRV) by linear (time domain and frequency domain) and non-linear (symbolic analysis) methods, analysis of blood pressure variability (BPV) and spontaneous baroreflex sensitivity (BRS).
Results: The final analysis, each group comprised 25 individuals. All groups had similar baseline parameters. After 16 weeks, intragroup comparison showed that the MICT and HIIT groups had a reduction in baseline heart rate (P < 0.001; P < 0.001, respectively) and testosterone levels P < 0.037; P < 0.012, respectively) associated with an increase in VO2peak (MICT, P < 0.001; HIIT, P < 0.001). The MICT (P < 0.36) and HIIT (P < 0.17) groups also showed an increase in cardiac vagal modulation, however only observed in the non-linear analysis. The intergroup comparison showed no differences between the MICT and HIIT groups in any of the hormonal, metabolic and autonomic parameters evaluated, including testosterone, peak oxygen uptake (VO2peak), HRV, BPV and BRS.
Conclusion: HIIT and MICT showed similar results for the different parameters evaluated. This suggests that both training protocols can be recommended for the treatment of PCOS. Brazilian Clinical Trials Registry (RBR-78qtwy)
Crossover and self-averaging in the two-dimensional site-diluted Ising model
Using the newly proposed probability-changing cluster (PCC) Monte Carlo
algorithm, we simulate the two-dimensional (2D) site-diluted Ising model. Since
we can tune the critical point of each random sample automatically with the PCC
algorithm, we succeed in studying the sample-dependent and the sample
average of physical quantities at each systematically. Using the
finite-size scaling (FSS) analysis for , we discuss the importance of
corrections to FSS both in the strong-dilution and weak-dilution regions. The
critical phenomena of the 2D site-diluted Ising model are shown to be
controlled by the pure fixed point. The crossover from the percolation fixed
point to the pure Ising fixed point with the system size is explicitly
demonstrated by the study of the Binder parameter. We also study the
distribution of critical temperature . Its variance shows the power-law
dependence, , and the estimate of the exponent is consistent
with the prediction of Aharony and Harris [Phys. Rev. Lett. {\bf 77}, 3700
(1996)]. Calculating the relative variance of critical magnetization at the
sample-dependent , we show that the 2D site-diluted Ising model
exhibits weak self-averaging.Comment: 6 pages including 6 eps figures, RevTeX, to appear in Phys. Rev.
Geometric K-Homology of Flat D-Branes
We use the Baum-Douglas construction of K-homology to explicitly describe
various aspects of D-branes in Type II superstring theory in the absence of
background supergravity form fields. We rigorously derive various stability
criteria for states of D-branes and show how standard bound state constructions
are naturally realized directly in terms of topological K-cycles. We formulate
the mechanism of flux stabilization in terms of the K-homology of non-trivial
fibre bundles. Along the way we derive a number of new mathematical results in
topological K-homology of independent interest.Comment: 45 pages; v2: References added; v3: Some substantial revision and
corrections, main results unchanged but presentation improved, references
added; to be published in Communications in Mathematical Physic
An overview of jets and outflows in stellar mass black holes
In this book chapter, we will briefly review the current empirical
understanding of the relation between accretion state and and outflows in
accreting stellar mass black holes. The focus will be on the empirical
connections between X-ray states and relativistic (`radio') jets, although we
are now also able to draw accretion disc winds into the picture in a systematic
way. We will furthermore consider the latest attempts to measure/order jet
power, and to compare it to other (potentially) measurable quantities, most
importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in
the Space Sciences Series of ISSI - The Physics of Accretion on to Black
Holes (Springer Publisher
Eschar-associated Spotted Fever Rickettsiosis, Bahia, Brazil
In Brazil, Brazilian spotted fever was once considered the only tick-borne rickettsial disease. We report eschar-associated rickettsial disease that occurred after a tick bite. The etiologic agent is most related to Rickettsia parkeri, R. africae, and R. sibirica and probably widely distributed from São Paulo to Bahia in the Atlantic Forest
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
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