9,912 research outputs found
Regulation of transforming growth factor-beta 1 gene expression by glucocorticoids in normal human T lymphocytes.
Glucocorticoids (GC) modulate immune function in a number of ways, including suppression of T cell proliferation and other IL-2-mediated T cell functions. These inhibitory effects are similar to those induced by transforming growth factor-beta 1 (TGF-beta 1), a cytokine with potent T cell inhibiting activities. We examined the hypothesis that GC effects may be at least partially achieved through modulation of the expression of the TGF-beta 1 gene in activated T cells. Normal T cells were cultured with or without purified phytohemagglutinin (PHA-p) and 4 beta-phorbol 12-myristate 13-acetate (PMA) in the presence or absence of the synthetic GC, dexamethasone (100-200 micrograms/ml). The production of latent and active forms of TGF beta by these cells were analyzed by immunoblotting and bioassays. The steady-state levels of TGF-beta 1 mRNA were analyzed in total RNA from these cells by Northern hybridizations using a human TGF-beta 1 cDNA. The results showed that dexamethasone caused an increase in TGF beta production and a dose-dependent two to fourfold increase in TGF-beta 1 mRNA in activated as well as in unstimulated T cells, 1 h after exposure of the cultures to the steroid. The increase in TGF-beta 1 mRNA levels by dexamethasone was further potentiated two to threefold by cycloheximide, suggesting that the steroid effect may be due to inhibition of the synthesis of proteins that decrease TGF-beta 1 gene transcription or the stability of its transcripts. Finally, in vitro nuclear transcription studies indicated the dexamethasone effects on TGF-beta 1 gene expression to be largely transcriptional
Dynamical heterogeneities as fingerprints of a backbone structure in Potts models
We investigate slow non-equilibrium dynamical processes in two-dimensional
--state Potts model with both ferromagnetic and couplings. Dynamical
properties are characterized by means of the mean-flipping time distribution.
This quantity is known for clearly unveiling dynamical heterogeneities. Using a
two-times protocol we characterize the different time scales observed and
relate them to growth processes occurring in the system. In particular we
target the possible relation between the different time scales and the spatial
heterogeneities originated in the ground state topology, which are associated
to the presence of a backbone structure. We perform numerical simulations using
an approach based on graphics processing units (GPUs) which permits to reach
large system sizes. We present evidence supporting both the idea of a growing
process in the preasymptotic regime of the glassy phases and the existence of a
backbone structure behind this processes.Comment: 9 pages, 7 figures, Accepted for publication in PR
The limits of participatory democracy: social movements and the displacement of disagreement in South America
100 Gbps PON L-band downstream transmission using IQ-MZM CD digital pre-compensation and DD ONU receiver
We propose a downstream direct-detection 100G-PON solution aided by chromatic dispersion digital pre-compensation using an IQ-MZM, allowing L-band operation and 29 dB power budget with low ONU complexity and without requiring single-sideband modulation
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