215 research outputs found
Are supplements safe? Effects of gallic and ferulic acids on in vitro cell models
Polyphenols display health-promoting properties linked to their biological activities. They are initially absorbed in the small intestine, then they are largely metabolized in the colon, whereupon they are able to exert systemic effects. The health-promoting properties of polyphenols have led to the development of food supplements, which are also largely consumed by healthy people, even if data on their safety are still yet lacking. In the present paper, the content of gallic acid and ferulic acid was analyzed in two supplements, and shown to be higher than the relative contents found in fruit and flour. To evaluate the effects of these phenolic compounds on epithelial intestinal tissue, gallic and ferulic acids were added to a new in vitro model of the intestinal wall at different concentrations. The effects on viability, proliferation and migration of these compounds were respectively tested on three different cell lines (Caco2, L929 and U937), as well as on a tridimensional intestinal model, composed of a mucosal layer and a submucosa with fibroblasts and monocytes. Results indicated that gallic and ferulic acids can exert toxic effects on in vitro cell models at high concentrations, suggesting that an excessive and uncontrolled consumption of polyphenols may induce negative effects on the intestinal wall
Nutraceuticals in the Modulation of the Intestinal Microbiota: Current Status and Future Directions
Pharmaceutical interest in the human intestinal microbiota has increased considerably, because of the increasing number of studies linking the human intestinal microbial ecology to an increasing number of non-communicable diseases. Many efforts at modulating the gut microbiota have been made using probiotics, prebiotics and recently postbiotics. However, there are other, still little-explored opportunities from a pharmaceutical point of view, which appear promising to obtain modifications of the microbiota structure and functions. This review summarizes all in vitro, in vivo and clinical studies demonstrating the possibility to positively modulate the intestinal microbiota by using probiotics, prebiotics, postbiotics, essential oils, fungus and officinal plants. For the future, clinical studies investigating the ability to impact the intestinal microbiota especially by using fungus, officinal and aromatic plants or their extracts are required. This knowledge could lead to effective microbiome modulations that might support the pharmacological therapy of most non-communicable diseases in a near future
Glassy Motion of Elastic Manifolds
We discuss the low-temperature dynamics of an elastic manifold driven through
a random medium. For driving forces well below the depinning force, the
medium advances via thermally activated hops over the energy barriers
separating favorable metastable states. We show that the distribution of
waiting times for these hopping processes scales as a power-law. This power-law
distribution naturally yields a nonlinear glassy response for the driven
medium, .Comment: 4pages, revte
Hydrodynamics of the quantum Hall smectics
We propose a dynamical theory of the stripe phase arising in a
two-dimensional electron liquid near half-integral fillings of high Landau
levels. The system is modelled as a novel type of a smectic liquid crystal with
the Lorentz force dominated dynamics. We calculate the structure factor, the
dispersion relation of the collective modes (magnetophonons), and their
intrinsic attenuation rate. We find strong power-law renormalizations of the
elastic and dissipative coefficients by thermal fluctuations familiar from the
conventional smectics but with different dynamical scaling exponents.Comment: Replaced with the published versio
Gliding dislocations in a driven vortex lattice
The dynamics of dislocations in a two-dimensional vortex lattice is studied
in the presence of a pinning potential and a transport current. In a vortex
lattice drifting with velocity a glide velocity of the dislocation
with respect to the vortex lattice is found to decay like for
large drive. From this result the velocity for the crossover between a regime
of coherent elastic motion and a regime of incoherent plastic motion of
vortices is estimated.Comment: 4 pages Revte
Geraniol Treatment for Irritable Bowel Syndrome: A Double-Blind Randomized Clinical Trial
Geraniol is an acyclic monoterpene alcohol with well-known anti-inflammatory and antimicrobial properties which has shown eubiotic activity towards gut microbiota (GM) in patients with irritable bowel syndrome (IBS). Methods: Fifty-six IBS patients diagnosed according to Rome III criteria were enrolled in an interventional, prospective, multicentric, randomized, double-blinded, placebo-controlled trial. In the treatment arm, patients received a low-absorbable geraniol food supplement (LAGS) once daily for four weeks. Results: Patients treated with LAGS showed a significant reduction in their IBS symptoms severity score (IBS-SSS) compared to the placebo (195 vs. 265, p = 0.001). The rate of responders according to IBS-SSS (reduction ≥ 50 points) was significantly higher in the geraniol vs placebo group (52.0% vs. 16.7%, p = 0.009) mainly due to the IBS mixed subtype. There were notable differences in the microbiota composition after geraniol administration, particularly a significant decrease in a genus of Ruminococcaceae, Oscillospira (p = 0.01), a decreasing trend for the Erysipelotrichaceae and Clostridiaceae families (p = 0.1), and an increasing trend for other Ruminococcaceae taxa, specifically Faecalibacterium (p = 0.09). The main circulating proinflammatory cytokines showed no differences between placebo and geraniol arms. Conclusion: LAGS was effective in treating overall IBS symptoms, together with an improvement in the gut microbiota profile, especially for the IBS mixed subtype
Dislocations and the critical endpoint of the melting line of vortex line lattices
We develop a theory for dislocation-mediated structural transitions in the
vortex lattice which allows for a unified description of phase transitions
between the three phases, the elastic vortex glass, the amorphous vortex glass,
and the vortex liquid, in terms of a free energy functional for the dislocation
density. The origin of a critical endpoint of the melting line at high magnetic
fields, which has been recently observed experimentally, is explained.Comment: 4 pages, 1 figur
Nonequilibrium dislocation dynamics and instability of driven vortex lattices in two dimensions
We consider dislocations in a vortex lattice that is driven in a
two-dimensional superconductor with random impurities. The structure and
dynamics of dislocations is studied in this genuine nonequilibrium situation on
the basis of a coarse-grained equation of motion for the displacement field.
The presence of dislocations leads to a characteristic anisotropic distortion
of the vortex density that is controlled by a Kardar-Parisi-Zhang nonlinearity
in the coarse-grained equation of motion. This nonlinearity also implies a
screening of the interaction between dislocations and thereby an instability of
the vortex lattice to the proliferation of free dislocations.Comment: published version with minor correction
Vortex avalanches and magnetic flux fragmentation in superconductors
We report results of numerical simulations of non isothermal dendritic flux
penetration in type-II superconductors. We propose a generic mechanism of
dynamic branching of a propagating hotspot of a flux flow/normal state
triggered by a local heat pulse. The branching occurs when the flux hotspot
reflects from inhomogeneities or the boundary on which magnetization currents
either vanish, or change direction. Then the hotspot undergoes a cascade of
successive splittings, giving rise to a dissipative dendritic-type flux
structure. This dynamic state eventually cools down, turning into a frozen
multi-filamentary pattern of magnetization currents.Comment: 4 pages, 4 figures, accepted to Phys. Rev. Let
Physics of B_c mesons
In the framework of potential models for heavy quarkonium the mass spectrum
for the system () is considered. Spin-dependent splittings, taking
into account a change of a constant for effective coulomb interaction between
the quarks, and widths of radiative transitions between the () levels
are calculated. In the framework of QCD sum rules, masses of the lightest
vector and pseudoscalar states are estimated, scaling relation
for leptonic constants of heavy quarkonia is derived, and the leptonic constant
is evaluated. The decays are considered in the framework of
both the potential models and the QCD sum rules, where the significance of
Coulomb-like corrections is shown. The relations, following from the
approximate spin symmetry for the heavy quarks in the heavy quarkonium, are
analysed for the form factors of the semileptonic weak exclusive decays of
. The lifetime is evaluated with the account of the corrections to
the spectator mechanism of the decay, because of the quark binding into the
meson. The total and differential cross sections of the production in
different interactions are calculated. The analytic expressions for the
fragmentational production cross sections of are derived. The possibility
of the practical search in the current and future experiments at
electron-positron and hadron colliders is analysed.Comment: 81 page, latex, ihep.sty is required and attached in the end of the
file after \end{document}, figures are not availabl
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