185 research outputs found
Krill oil, vitamin D and Lactobacillus reuteri cooperate to reduce gut inflammation
Current research into original therapies to treat intestinal inflammation is focusing on no-drug therapies. KLD is a mixture of krill oil (KO), probiotic Lactobacillus reuteri (LR), and vitamin D (VitD3). The aim of this study was to assess in vitro and in vivo the potential cooperative effects of KLD in reducing gut inflammation. Colorectal adenocarcinoma cell lines, CACO2 and HT29, and C57BL/6 mice were used for in vitro and in vivo analyses, respectively. Cells were exposed to cytomix (interferon gamma + tumour necrosis factor alpha (TNF-a)) to induce inflammation or co-exposed to cytomix and KO, LR and VitD3 alone or to cytomix and KLD. Animals were treated for 7 days with dextran sodium sulphate (DSS) to induce colitis or with DSS and KLD. In vitro assays: F-actin expression was analysed by immunofluorescence; scratch test and trans-epithelial electric resistance test were performed to measure wound healing; adhesion/invasion assays of adhesive and invasive Escherichia coli (AIEC) bacteria were made; mRNA expression of TNF-α, interleukin (IL)-8 and vitamin D receptor (VDR) was detected by quantitative PCR. In vivo assays: body weight, clinical score, histological score and large intestine weight and length were estimated; mRNA expression of TNF-α, IL-1ß, IL-6, IL-10 by quantitative PCR; VDR expression was detected by quantitative PCR and immunohistochemistry. In vitro: KLD restores epithelial cell-cell adhesion and mucosal healing during inflammation, while decreases the adhesiveness and invasiveness of AIEC bacteria and TNF-α and IL-8 mRNA expression and increases VDR expression. In vivo: KLD significantly improves body weight, clinical score, histological score and large intestine length of mice with DSS-induced colitis and reduces TNF-α, IL-1ß and IL-6 mRNA levels, while increases IL-10 mRNA and VDR levels. KLD has significant effects on the intestinal mucosa, strongly decreasing inflammation, increasing epithelial restitution and reducing pathogenicity of harmful commensal bacteria
Stretched exponential relaxation for growing interfaces in quenched disordered media
We study the relaxation for growing interfaces in quenched disordered media.
We use a directed percolation depinning model introduced by Tang and Leschhorn
for 1+1-dimensions. We define the two-time autocorrelation function of the
interface height C(t',t) and its Fourier transform. These functions depend on
the difference of times t-t' for long enough times, this is the steady-state
regime. We find a two-step relaxation decay in this regime. The long time tail
can be fitted by a stretched exponential relaxation function. The relaxation
time is proportional to the characteristic distance of the clusters of pinning
cells in the direction parallel to the interface and it diverges as a power
law. The two-step relaxation is lost at a given wave length of the Fourier
transform, which is proportional to the characteristic distance of the clusters
of pinning cells in the direction perpendicular to the interface. The stretched
exponential relaxation is caused by the existence of clusters of pinning cells
and it is a direct consequence of the quenched noise.Comment: 4 pages and 5 figures. Submitted (5/2002) to Phys. Rev.
Rapid Mixing for Lattice Colorings with Fewer Colors
We provide an optimally mixing Markov chain for 6-colorings of the square
lattice on rectangular regions with free, fixed, or toroidal boundary
conditions. This implies that the uniform distribution on the set of such
colorings has strong spatial mixing, so that the 6-state Potts antiferromagnet
has a finite correlation length and a unique Gibbs measure at zero temperature.
Four and five are now the only remaining values of q for which it is not known
whether there exists a rapidly mixing Markov chain for q-colorings of the
square lattice.Comment: Appeared in Proc. LATIN 2004, to appear in JSTA
Griffiths singularities in the two dimensional diluted Ising model
We study numerically the probability distribution of the Yang-Lee zeroes
inside the Griffiths phase for the two dimensional site diluted Ising model and
we check that the shape of this distribution is that predicted in previous
analytical works. By studying the finite size scaling of the averaged smallest
zero at the phase transition we extract, for two values of the dilution, the
anomalous dimension, , which agrees very well with the previous estimated
values.Comment: 11 pages and 4 figures, some minor changes in Fig. 4, available at
http://chimera.roma1.infn.it/index_papers_complex.htm
Metastability in the dilute Ising model
Consider Glauber dynamics for the Ising model on the hypercubic lattice with
a positive magnetic field. Starting from the minus configuration, the system
initially settles into a metastable state with negative magnetization. Slowly
the system relaxes to a stable state with positive magnetization. Schonmann and
Shlosman showed that in the two dimensional case the relaxation time is a
simple function of the energy required to create a critical Wulff droplet.
The dilute Ising model is obtained from the regular Ising model by deleting a
fraction of the edges of the underlying graph. In this paper we show that even
an arbitrarily small dilution can dramatically reduce the relaxation time. This
is because of a catalyst effect---rare regions of high dilution speed up the
transition from minus phase to plus phase.Comment: 49 page
Cutoff for the Ising model on the lattice
Introduced in 1963, Glauber dynamics is one of the most practiced and
extensively studied methods for sampling the Ising model on lattices. It is
well known that at high temperatures, the time it takes this chain to mix in
on a system of size is . Whether in this regime there is
cutoff, i.e. a sharp transition in the -convergence to equilibrium, is a
fundamental open problem: If so, as conjectured by Peres, it would imply that
mixing occurs abruptly at for some fixed , thus providing
a rigorous stopping rule for this MCMC sampler. However, obtaining the precise
asymptotics of the mixing and proving cutoff can be extremely challenging even
for fairly simple Markov chains. Already for the one-dimensional Ising model,
showing cutoff is a longstanding open problem.
We settle the above by establishing cutoff and its location at the high
temperature regime of the Ising model on the lattice with periodic boundary
conditions. Our results hold for any dimension and at any temperature where
there is strong spatial mixing: For this carries all the way to the
critical temperature. Specifically, for fixed , the continuous-time
Glauber dynamics for the Ising model on with periodic boundary
conditions has cutoff at , where is
the spectral gap of the dynamics on the infinite-volume lattice. To our
knowledge, this is the first time where cutoff is shown for a Markov chain
where even understanding its stationary distribution is limited.
The proof hinges on a new technique for translating to mixing
which enables the application of log-Sobolev inequalities. The technique is
general and carries to other monotone and anti-monotone spin-systems.Comment: 34 pages, 3 figure
Percolation transition and the onset of non exponential relaxation in fully frustrated models
We numerically study the dynamical properties of fully frustrated models in 2
and 3 dimensions. The results obtained support the hypothesis that the
percolation transition of the Kasteleyn-Fortuin clusters corresponds to the
onset of stretched exponential autocorrelation functions in systems without
disorder. This dynamical behavior may be due to the ``large scale'' effects of
frustration, present below the percolation threshold. Moreover these results
are consistent with the picture suggested by Campbell et al. in space of
configurations.Comment: 8 pages, 11 figures, revised versio
Transient expression of the 5alpha-reductase type 2 isozyme in the rat brain in late fetal and early postnatal life
The enzyme 5alpha-reductase plays a key role on several brain functions controlling the formation of anxiolytic/anesthetic steroids derived from progesterone and deoxycorticosterone, the conversion of testosterone to dihydrotestosterone, and the removal of excess of potentially neurotoxic steroids. Two 5alpha-reductase isoforms have been cloned: 5alpha-reductase type 1 is widely distributed in the body, and 5alpha-reductase type 2 is confined to androgen-dependent structures. In this study, the gene expression of the two 5alpha-reductase isozymes has been analyzed in fetal, postnatal, and adult rat brains by RT-PCR followed by Southern analysis. 5Alpha-reductase type 1 messenger RNA is always detectable in the rat brain [from gestational day 14 (GD14) to adulthood]. 5Alpha-reductase type 2 messenger RNA expression is undetectable on GD14, increases after GD18, peaks on postnatal day 2, then decreases gradually, becoming low in adulthood. This pattern of expression appears to be correlated with the rate of production of testosterone by the testis. The possible control by androgens of gene expression of the two isozymes has been studied in brain tissues of animals exposed in utero to the androgen antagonist flutamide; the sex of the animals was determined by genetic sex screening of the SRY gene located on the Y-chromosome. In the brain of male embryos, flutamide treatment inhibited the expression of 5alpha-reductase type 2; this effect was much less pronounced in females. Moreover, 5alpha-reductase type 2 gene expression in cultured hypothalamic neurons is highly induced by testosterone and by the phorbol ester 12-O-tetradecanoyl-phorbol-13 acetate. The transient, androgen-regulated, expression of 5alpha-reductase type 2 overlaps the critical period of development, which may be important for sexual differentiation of the brain and for the formation of anxiolytic/anesthetic steroids involved in the stress responses associated with parturition
Implicazioni geodinamiche delle recenti misure geodetiche nello Stretto di Messina
Il 28 dicembre 1908 lo Stretto di Messina veniva colpito da un disastroso evento sismico di ms=7.5. L'evento è il più forte tra i terremoti italiani degli utimi 100 anni.Published3-143.3. Geodinamica e struttura dell'interno della TerraN/A or not JCRrestricte
Epigenome and Environment: effects of a PCB exposure on epigenome during early development in the rat
Introduction: Epigenetic represents the genome programming to express appropriate set of genes in a temporal and spatial way during life. Epigenetic signature is dynamic and responsive to environment, especially in critical periods of development. Deregulation of epigenetic mechanisms may be responsible for incorrect transcription patterns, resulting in
stable modifications of key physiological processes. Exposure to PCBs (polychlorinated biphenyls) during gestation and lactation, modifies the gene expression of important mediators of sex steroid action and of their receptors. Androgen receptor (AR) could also act as co-regulator of histone modifications enzymes.
Aim: to evaluate whether prenatal administration of a reconstituted PCB mixture is able to influence epigenome Results: PCBs reduce histone post-translational modifications (H3K4me3 and H4K16Ac) in a dimorphic way, possibly as the result of a decreased expression of the histone modification enzymes, Jarid1b and SirtT1. AR gene and protein expression is also reduced, especially in females. ChIP performed against H3K4me3 shows a correlation between the expression of some genes involved in embryonic differentiation (e.g., TSHR and GabaRr3) and histone post- translational gene modifications.
Conclusion: the influence of PCB exposure during differentiation on epigenome is dimorphic and affects chromatin packaging, probably through an impairment of interaction between androgen receptor and histone modification enzymes
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