364 research outputs found
The renin angiotensin system in the central nervous system
The first evidences indicating that angiotensin II (ANG II) was a peptide with action on the brain were shown in 1961 when it was found that the intraventricular injection of ANG II induces a centrally mediated pressor response (1). As a neuropeptide, ANG II belongs to the class of neuromodulators. The brain renin angiotensin system (RAS) exerts paracrine, autocrine and intracrine functions independently of circulating blood-borne ANG II which has a limited access to the brain by the blood-brain barrier (BBB) in the circumventricular organs (CVOs) (2). Brain-generated ANG II controls several physiological processes like stimulation of thirst, water intake and sodium appetite, acting as a neurotransmitter in neurons of brain areas such as the Subfornical organ (SFO) and Organum vasculosum of the lamina terminalis (OVLT). Generated angiotensins (ANGs) at the central nervous system (CNS) also stimulate endocrine secretions like argininevasopressin (AVP), oxytocin (OT), corticotrophin-releasing hormone (CRH) and adenocorticotrophin (ACTH secretion). Brain ANG II modulates the sympathetic autonomic functions and regulates blood pressure by increasing AVP and ACTH secretion and modulating the baroceptor reflex and the sympathetic output (3). During the last decade it has been established that, apart from its classical actions, ANG II exhibits other effects induced by direct action on its receptors or via local effects of its metabolites (4). Thereby, central actions of ANGs are not exclusively associated with their traditional roles. Indeed, several studies have shown that central ANGs are also involved in sexual behavior, stress, learning, and memory (5).Sociedad Argentina de Fisiologí
4-aminopyridyl-based lead compounds targeting CYP51 prevent spontaneous parasite relapse in a chronic model and improve cardiac pathology in an acute model of Trypanosoma cruzi infection.
BackgroundChagas disease, caused by the protozoan Trypanosoma cruzi, is the leading cause of heart failure in Latin America. The clinical treatment of Chagas disease is limited to two 60 year-old drugs, nifurtimox and benznidazole, that have variable efficacy against different strains of the parasite and may lead to severe side effects. CYP51 is an enzyme in the sterol biosynthesis pathway that has been exploited for the development of therapeutics for fungal and parasitic infections. In a target-based drug discovery program guided by x-ray crystallography, we identified the 4-aminopyridyl-based series of CYP51 inhibitors as being efficacious versus T.cruzi in vitro; two of the most potent leads, 9 and 12, have now been evaluated for toxicity and efficacy in mice.Methodology/principal findingsBoth acute and chronic animal models infected with wild type or transgenic T. cruzi strains were evaluated. There was no evidence of toxicity in the 28-day dosing study of uninfected animals, as judged by the monitoring of multiple serum and histological parameters. In two acute models of Chagas disease, 9 and 12 drastically reduced parasitemia, increased survival of mice, and prevented liver and heart injury. None of the compounds produced long term sterile cure. In the less severe acute model using the transgenic CL-Brenner strain of T.cruzi, parasitemia relapsed upon drug withdrawal. In the chronic model, parasitemia fell to a background level and, as evidenced by the bioluminescence detection of T. cruzi expressing the red-shifted luciferase marker, mice remained negative for 4 weeks after drug withdrawal. Two immunosuppression cycles with cyclophosphamide were required to re-activate the parasites. Although no sterile cure was achieved, the suppression of parasitemia in acutely infected mice resulted in drastically reduced inflammation in the heart.Conclusions/significanceThe positive outcomes achieved in the absence of sterile cure suggest that the target product profile in anti-Chagasic drug discovery should be revised in favor of safe re-administration of the medication during the lifespan of a Chagas disease patient. A medication that reduces parasite burden may halt or slow progression of cardiomyopathy and therefore improve both life expectancy and quality of life
Longitudinal Spin Transfer to and Hyperons in Polarized Proton-Proton Collisions at = 200 GeV
The longitudinal spin transfer, , from high energy polarized protons
to and hyperons has been measured for the first time
in proton-proton collisions at with the STAR
detector at RHIC. The measurements cover pseudorapidity, , in the range
and transverse momenta, , up to . The longitudinal spin transfer is found to be for inclusive
and for
inclusive hyperons with and . The dependence on and is presented.Comment: 5 pages, 4 figure
Observation of the antimatter helium-4 nucleus
High-energy nuclear collisions create an energy density similar to that of
the universe microseconds after the Big Bang, and in both cases, matter and
antimatter are formed with comparable abundance. However, the relatively
short-lived expansion in nuclear collisions allows antimatter to decouple
quickly from matter, and avoid annihilation. Thus, a high energy accelerator of
heavy nuclei is an efficient means of producing and studying antimatter. The
antimatter helium-4 nucleus (), also known as the anti-{\alpha}
(), consists of two antiprotons and two antineutrons (baryon
number B=-4). It has not been observed previously, although the {\alpha}
particle was identified a century ago by Rutherford and is present in cosmic
radiation at the 10% level. Antimatter nuclei with B < -1 have been observed
only as rare products of interactions at particle accelerators, where the rate
of antinucleus production in high-energy collisions decreases by about 1000
with each additional antinucleon. We present the observation of the antimatter
helium-4 nucleus, the heaviest observed antinucleus. In total 18
counts were detected at the STAR experiment at RHIC in 10 recorded Au+Au
collisions at center-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon
pair. The yield is consistent with expectations from thermodynamic and
coalescent nucleosynthesis models, which has implications beyond nuclear
physics.Comment: 19 pages, 4 figures. Submitted to Nature. Under media embarg
Strangeness Enhancement in Cu+Cu and Au+Au Collisions at \sqrt{s_{NN}} = 200 GeV
We report new STAR measurements of mid-rapidity yields for the ,
, , , , ,
particles in Cu+Cu collisions at \sNN{200}, and mid-rapidity
yields for the , , particles in Au+Au at
\sNN{200}. We show that at a given number of participating nucleons, the
production of strange hadrons is higher in Cu+Cu collisions than in Au+Au
collisions at the same center-of-mass energy. We find that aspects of the
enhancement factors for all particles can be described by a parameterization
based on the fraction of participants that undergo multiple collisions
Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at = 200 GeV
Forward-backward multiplicity correlation strengths have been measured with
the STAR detector for Au+Au and collisions at =
200 GeV. Strong short and long range correlations (LRC) are seen in central
Au+Au collisions. The magnitude of these correlations decrease with decreasing
centrality until only short range correlations are observed in peripheral Au+Au
collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate
(CGC) predict the existence of the long range correlations. In the DPM the
fluctuation in the number of elementary (parton) inelastic collisions produces
the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is
in qualitative agreement with the predictions from the DPM and indicates the
presence of multiple parton interactions.Comment: 6 pages, 3 figures The abstract has been slightly modifie
K/pi Fluctuations at Relativistic Energies
We report results for fluctuations from Au+Au collisions at
= 19.6, 62.4, 130, and 200 GeV using the STAR detector at the
Relativistic Heavy Ion Collider. Our results for fluctuations in
central collisions show little dependence on the incident energies studied and
are on the same order as results observed by NA49 at the Super Proton
Synchrotron in central Pb+Pb collisions at = 12.3 and 17.3 GeV.
We also report results for the collision centrality dependence of
fluctuations as well as results for , ,
, and fluctuations. We observe that the
fluctuations scale with the multiplicity density, , rather than the
number of participating nucleons.Comment: 6 pages, 4 figure
Forward Neutral Pion Transverse Single Spin Asymmetries in p+p Collisions at \sqrt{s}=200 GeV
We report precision measurements of the Feynman-x dependence, and first
measurements of the transverse momentum dependence, of transverse single spin
asymmetries for the production of \pi^0 mesons from polarized proton collisions
at \sqrt{s}=200 GeV. The x_F dependence of the results is in fair agreement
with perturbative QCD model calculations that identify orbital motion of quarks
and gluons within the proton as the origin of the spin effects. Results for the
p_T dependence at fixed x_F are not consistent with pQCD-based calculations.Comment: 6 pages, 4 figure
An Effective Assessment of Simvastatin-Induced Toxicity with NMR-Based Metabonomics Approach
BACKGROUND: Simvastatin, which is used to control elevated cholesterol levels, is one of the most widely prescribed drugs. However, a daily excessive dose can induce drug-toxicity, especially in muscle and liver. Current markers for toxicity reflect mostly the late stages of tissue damage; thus, more efficient methods of toxicity evaluation are desired. METHODOLOGY/PRINCIPAL FINDINGS: As a new way to evaluate toxicity, we performed NMR-based metabonomics analysis of urine samples. Compared to conventional markers, such as AST, ALT, and CK, the urine metabolic profile provided clearer distinction between the pre- and post-treatment groups treated with toxic levels of simvastatin. Through multivariate statistical analysis, we identified marker metabolites associated with the toxicity. Importantly, we observed that the treatment group could be further categorized into two subgroups based on the NMR profiles: weak toxicity (WT) and high toxicity (HT). The distinction between these two groups was confirmed by the enzyme values and histopathological exams. Time-dependent studies showed that the toxicity at 10 days could be reliably predicted from the metabolic profiles at 6 days. CONCLUSIONS/SIGNIFICANCE: This metabonomics approach may provide a non-invasive and effective way to evaluate the simvastatin-induced toxicity in a manner that can complement current measures. The approach is expected to find broader application in other drug-induced toxicity assessments
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