14 research outputs found
The unphysical nature of the SL(2,R) symmetry and its associated condensates in Yang-Mills theories
BRST cohomology methods are used to explain the origin of the SL(2,R)
symmetry in Yang-Mills theories. Clear evidence is provided for the unphysical
nature of this symmetry. This is obtained from the analysis of a local
functional of mass dimension two and constitutes a no-go statement for giving a
physical meaning to condensates associated with the symmetry breaking of
SL(2,R).Comment: 5 pages (revtex4), final version to appear in Phys. Rev.
Scaling and finte-size-scaling in the two dimensional random-coupling Ising ferromagnet
It is shown by Monte Carlo method that the finite size scaling (FSS) holds in
the two dimensional random-coupled Ising ferromagnet. It is also demonstrated
that the form of universal FSS function constructed via novel FSS scheme
depends on the strength of the random coupling for strongly disordered cases.
Monte Carlo measurements of thermodynamic (infinite volume limit) data of the
correlation length () up to along with measurements of
the fourth order cumulant ratio (Binder's ratio) at criticality are reported
and analyzed in view of two competing scenarios. It is demonstrated that the
data are almost exclusively consistent with the scenario of weak universality.Comment: 9 pages, 4figuer
Critical behavior of weakly-disordered anisotropic systems in two dimensions
The critical behavior of two-dimensional (2D) anisotropic systems with weak
quenched disorder described by the so-called generalized Ashkin-Teller model
(GATM) is studied. In the critical region this model is shown to be described
by a multifermion field theory similar to the Gross-Neveu model with a few
independent quartic coupling constants. Renormalization group calculations are
used to obtain the temperature dependence near the critical point of some
thermodynamic quantities and the large distance behavior of the two-spin
correlation function. The equation of state at criticality is also obtained in
this framework. We find that random models described by the GATM belong to the
same universality class as that of the two-dimensional Ising model. The
critical exponent of the correlation length for the 3- and 4-state
random-bond Potts models is also calculated in a 3-loop approximation. We show
that this exponent is given by an apparently convergent series in
(with the central charge of the Potts model) and
that the numerical values of are very close to that of the 2D Ising
model. This work therefore supports the conjecture (valid only approximately
for the 3- and 4-state Potts models) of a superuniversality for the 2D
disordered models with discrete symmetries.Comment: REVTeX, 24 pages, to appear in Phys.Rev.
Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction
BACKGROUND: Myocardial fibrosis is a hallmark of cardiac remodeling
and functionally involved in heart failure development, a leading cause
of deaths worldwide. Clinically, no therapeutic strategy is available that
specifically attenuates maladaptive responses of cardiac fibroblasts, the
effector cells of fibrosis in the heart. Therefore, our aim was to develop
novel antifibrotic therapeutics based on naturally derived substance library
screens for the treatment of cardiac fibrosis.
METHODS: Antifibrotic drug candidates were identified by functional
screening of 480 chemically diverse natural compounds in primary human
cardiac fibroblasts, subsequent validation, and mechanistic in vitro and
in vivo studies. Hits were analyzed for dose-dependent inhibition of
proliferation of human cardiac fibroblasts, modulation of apoptosis, and
extracellular matrix expression. In vitro findings were confirmed in vivo
with an angiotensin II–mediated murine model of cardiac fibrosis in both
preventive and therapeutic settings, as well as in the Dahl salt-sensitive rat
model. To investigate the mechanism underlying the antifibrotic potential
of the lead compounds, treatment-dependent changes in the noncoding
RNAome in primary human cardiac fibroblasts were analyzed by RNA
deep sequencing.
RESULTS: High-throughput natural compound library screening
identified 15 substances with antiproliferative effects in human cardiac
fibroblasts. Using multiple in vitro fibrosis assays and stringent selection
algorithms, we identified the steroid bufalin (from Chinese toad venom)
and the alkaloid lycorine (from Amaryllidaceae species) to be effective
antifibrotic molecules both in vitro and in vivo, leading to improvement
in diastolic function in 2 hypertension-dependent rodent models of
cardiac fibrosis. Administration at effective doses did not change plasma
damage markers or the morphology of kidney and liver, providing the first
toxicological safety data. Using next-generation sequencing, we identified
the conserved microRNA 671-5p and downstream the antifibrotic
selenoprotein P1 as common effectors of the antifibrotic compounds.
CONCLUSIONS: We identified the molecules bufalin and lycorine as drug
candidates for therapeutic applications in cardiac fibrosis and diastolic
dysfunction
Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction
BACKGROUND: Myocardial fibrosis is a hallmark of cardiac remodeling
and functionally involved in heart failure development, a leading cause
of deaths worldwide. Clinically, no therapeutic strategy is available that
specifically attenuates maladaptive responses of cardiac fibroblasts, the
effector cells of fibrosis in the heart. Therefore, our aim was to develop
novel antifibrotic therapeutics based on naturally derived substance library
screens for the treatment of cardiac fibrosis.
METHODS: Antifibrotic drug candidates were identified by functional
screening of 480 chemically diverse natural compounds in primary human
cardiac fibroblasts, subsequent validation, and mechanistic in vitro and
in vivo studies. Hits were analyzed for dose-dependent inhibition of
proliferation of human cardiac fibroblasts, modulation of apoptosis, and
extracellular matrix expression. In vitro findings were confirmed in vivo
with an angiotensin II–mediated murine model of cardiac fibrosis in both
preventive and therapeutic settings, as well as in the Dahl salt-sensitive rat
model. To investigate the mechanism underlying the antifibrotic potential
of the lead compounds, treatment-dependent changes in the noncoding
RNAome in primary human cardiac fibroblasts were analyzed by RNA
deep sequencing.
RESULTS: High-throughput natural compound library screening
identified 15 substances with antiproliferative effects in human cardiac
fibroblasts. Using multiple in vitro fibrosis assays and stringent selection
algorithms, we identified the steroid bufalin (from Chinese toad venom)
and the alkaloid lycorine (from Amaryllidaceae species) to be effective
antifibrotic molecules both in vitro and in vivo, leading to improvement
in diastolic function in 2 hypertension-dependent rodent models of
cardiac fibrosis. Administration at effective doses did not change plasma
damage markers or the morphology of kidney and liver, providing the first
toxicological safety data. Using next-generation sequencing, we identified
the conserved microRNA 671-5p and downstream the antifibrotic
selenoprotein P1 as common effectors of the antifibrotic compounds.
CONCLUSIONS: We identified the molecules bufalin and lycorine as drug
candidates for therapeutic applications in cardiac fibrosis and diastolic
dysfunction