70 research outputs found
A recipe for simulating the interannual variability of the Asian summer monsoon and its relation with ENSO
Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 28 (2007): 441-460, doi: 10.1007/s00382-006-0190-0.This study investigates how accurately the interannual variability over the Indian
Ocean basin and the relationship between the Indian summer monsoon and the
El Nino Southern Oscillation (ENSO) can be simulated by different modelling
strategies. With a hierarchy of models, from an atmospherical general circulation
model (AGCM) forced by observed SST, to a coupled model with the ocean
component limited to the tropical Pacific and Indian Oceans, the role of heat
fluxes and of interactive coupling is analyzed. Whenever sea surface temperature
anomalies in the Indian basin are created by the coupled model, the inverse relationship
between the ENSO index and the Indian summer monsoon rainfall is
recovered, and it is preserved if the atmospherical model is forced by the SSTs
created by the coupled model. If the ocean model domain is limited to the Indian
Ocean, changes in the Walker circulation over the Pacific during El Nino years
induce a decrease of rainfall over the Indian subcontinent. However the observed
correlation between the ENSO and the Indian Ocean Zonal Mode (IOZM) is
not properly modelled and the two indices are not significantly correlated, independently
on season. Whenever the ocean domain extends to the Pacific, and
ENSO can impact both the atmospheric circulation and the ocean subsurface in
the equatorial Eastern Indian Ocean, modelled precipitation patterns associated
both to ENSO and to the IOZM closely resemble the observations.The experiments described were performed as a contribution to the ENSEMBLES
project funded by the European Commissionâs 6th Framework Programme, contract
number GOCE-CT-2003-505539
Mechanisms of MEOX1 and MEOX2 Regulation of the Cyclin Dependent Kinase Inhibitors p21CIP1/WAF1 and p16INK4a in Vascular Endothelial Cells
Senescence, the state of permanent cell cycle arrest, has been associated
with endothelial cell dysfunction and atherosclerosis. The cyclin dependent
kinase inhibitors p21CIP1/WAF1 and p16INK4a govern the
G1/S cell cycle checkpoint and are essential for determining whether
a cell enters into an arrested state. The homeodomain transcription factor
MEOX2 is an important regulator of vascular cell proliferation and is a direct
transcriptional activator of both p21CIP1/WAF1 and p16INK4a.
MEOX1 and MEOX2 have been shown to be partially functionally redundant during
development, suggesting that they regulate similar target genes in
vivo. We compared the ability of MEOX1 and MEOX2 to activate p21CIP1/WAF1
and p16INK4a expression and induce endothelial cell cycle arrest.
Our results demonstrate for the first time that MEOX1 regulates the MEOX2
target genes p21CIP1/WAF1 and p16INK4a. In addition,
increased expression of either of the MEOX homeodomain transcription factors
leads to cell cycle arrest and endothelial cell senescence. Furthermore, we
show that the mechanism of transcriptional activation of these cyclin dependent
kinase inhibitor genes by MEOX1 and MEOX2 is distinct. MEOX1 and MEOX2 activate
p16INK4a in a DNA binding dependent manner, whereas they induce
p21CIP1/WAF1 in a DNA binding independent manner
Endogenous laminin is required for human airway smooth muscle cell maturation
BACKGROUND: Airway smooth muscle (ASM) contraction underlies acute bronchospasm in asthma. ASM cells can switch between a synthetic-proliferative phenotype and a contractile phenotype. While the effects of extracellular matrix (ECM) components on modulation of ASM cells to a synthetic phenotype have been reported, the role of ECM components on maturation of ASM cells to a contractile phenotype in adult lung is unclear. As both changes in ECM components and accumulation of contractile ASM are features of airway wall remodelling in asthma, we examined the role of the ECM protein, laminin, in the maturation of contractile phenotype in human ASM cells. METHODS: Human ASM cells were made senescence-resistant by stable expression of human telomerase reverse transcriptase. Maturation to a contractile phenotype was induced by 7-day serum deprivation, as assessed by immunoblotting for desmin and calponin. The role of laminin on ASM maturation was investigated by comparing the effects of exogenous laminin coated on culture plates, and of soluble laminin peptide competitors. Endogenous expression of laminin chains during ASM maturation was also measured. RESULTS: Myocyte binding to endogenously expressed laminin was required for ASM phenotype maturation, as laminin competing peptides (YIGSR or GRGDSP) significantly reduced desmin and calponin protein accumulation that otherwise occurs with prolonged serum deprivation. Coating of plastic cell culture dishes with different purified laminin preparations was not sufficient to further promote accumulation of desmin or calponin during 7-day serum deprivation. Expression of α2, ÎČ1 and Îł1 laminin chains by ASM cells was specifically up-regulated during myocyte maturation, suggesting a key role for laminin-2 in the development of the contractile phenotype. CONCLUSION: While earlier reports suggest exogenously applied laminin slows the spontaneous modulation of ASM to a synthetic phenotype, we show for the first time that endogenously expressed laminin is required for ASM maturation to the contractile phenotype. As endogenously expressed laminin chains α2, ÎČ1 and Îł1 are uniquely increased during myocyte maturation, these laminin chains may be key in this process. Thus, human ASM maturation appears to involve regulated endogenous expression of a select set of laminin chains that are essential for accumulation of contractile phenotype myocytes
Evaluation of autologous platelet rich plasma for cardiac surgery: outcome analysis of 2000 patients
Causes of drying trends in northern hemispheric land areas in reconstructed soil moisture data
An inter-comparison of regional climate models for Europe: model performance in present-day climate
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