The Central Nervous System as Target for Antihypertensive Actions of a Proline-Rich Peptide from Bothrops jararaca Venom

Pyroglutamyl proline-rich oligopeptides, present in the venom of the pit viper Bothrops jararaca (Bj-PROs), are the first described naturally occurring inhibitors of the angiotensin I-converting enzyme (ACE). The inhibition of ACE by the decapeptide Bj-PRO-10c (

(1)H, (15)N and (13)C assignments of the Rhipicephalus (Boophilus) microplus anti-microbial peptide microplusin

Microplusin, a Rhipicephalus (Boophilus) microplus anti-microbial peptide (AMP) is the first member of a new family of cysteine-rich AMPs with histidine-rich regions at the N- and C-termini, which is being fully characterized by biophysical and biochemical methods. Here we report the NMR resonance assignments for (1)H, (15)N, and (13)C nuclei in the backbone and side chains of the microplusin as basis for further studies of structure, backbone dynamics and interactions mapping.

The Estrous Cycle Modulates Small Leucine-Rich Proteoglycans Expression in Mouse Uterine Tissues

In the pregnant mouse uterus, small leucine-rich proteoglycans (SLRPs) are drastically remodeled within a few hours after fertilization, suggesting that ovarian hormone levels modulate their synthesis and degradation. In this study, we followed by immunoperoxidase approach, the presence of four members of the SLRP family (decorin, lumican, biglycan, and fibromodulin) in the uterine tissues along the estrous cycle of the mouse. All molecules except fibromodulin, which predominates in the myometrium, showed a striking modulation in their distribution in the endometrial stroma, following the rise in the level of estrogen. Moreover, notable differences in the distribution of SLRPs were observed between superficial and deep stroma, as well as between the internal and external layers of the myometrium. Only biglycan and fibromodulin were expressed in the luminal and glandular epithelia. All four SLRPs were found in cytoplasmic granules of mononucleated cells. The pattern of distribution of the immunoreaction for these molecules in the uterine tissues was found to be estrous cycle-stage dependent, suggesting that these molecules undergo ovarian hormonal control and probably participate in the preparation of the uterus for decidualization and embryo implantation. In addition, this and previous results from our laboratory suggest the existence of two subpopulations of endometrial fibroblasts that may be related to the centrifugal development of the decidua. Anat Rec, 292:138-153, 2009. (c) 2008 Wiley-Liss, Inc.

Rainforest Aerosols as Biogenic Nuclei of Clouds and Precipitation in the Amazon

The Amazon is one of the few continental regions where atmospheric aerosol particles and their effects on climate are not dominated by anthropogenic sources. During the wet season, the ambient conditions approach those of the pristine pre-industrial era. We show that the fine submicrometer particles accounting for most cloud condensation nuclei are predominantly composed of secondary organic material formed by oxidation of gaseous biogenic precursors. Supermicrometer particles, which are relevant as ice nuclei, consist mostly of primary biological material directly released from rainforest biota. The Amazon Basin appears to be a biogeochemical reactor, in which the biosphere and atmospheric photochemistry produce nuclei for clouds and precipitation sustaining the hydrological cycle. The prevailing regime of aerosol-cloud interactions in this natural environment is distinctly different from polluted regions.

Relative roles of biogenic emissions and Saharan dust as ice nuclei in the Amazon basin

Some aerosol particles, known as ice nuclei, can initiate ice formation in clouds, thereby influencing precipitation, cloud dynamics and the amount of incoming and outgoing solar radiation. In the absence of biomass burning, aerosol mass concentrations in the Amazon basin are low(1). Tropical forests emit primary biological particles directly into the atmosphere; secondary organic aerosols form from the emission and oxidation of biogenic gases(2). In addition, particles derived from biomass burning in central Africa, marine aerosols, and windblown dust from North Africa(3-5) often reach the central part of the Amazon basin during the wet season. The contribution of these aerosol sources to ice nucleation in the region is uncertain. Here we present observations of the concentration and elemental composition of ice nuclei in the Amazon basin during the wet season. Using transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, we show that ice nuclei are primarily composed of carbonaceous material and dust. We show that biological particles dominate the carbonaceous fraction, whereas import of Saharan dust explains the intermittent appearance of dust-containing nuclei. We conclude that ice-nucleus concentration and abundance can be explained almost entirely by local emissions of biological particles supplemented by import of Saharan dust. Using a simple model, we tentatively suggest that the contribution of local biological particles to ice nucleation is increased at higher atmospheric temperatures, whereas the contribution of dust particles is increased at lower temperatures.

Measurement of thermal neutron cross section and resonance integral for the (165)Ho(n, gamma)(166g)Ho reaction

The ground state thermal neutron cross section and the resonance integral for the (165)Ho(n, gamma)(166)Ho reaction in thermal and 1/E regions, respectively, of a thermal reactor neutron spectrum have been measured experimentally by activation technique. The reaction product, (166)Ho in the ground state, is gaining considerable importance as a therapeutic radionuclide and precisely measured data of the reaction are of significance from the fundamental point of view as well as for application. In this work, the spectrographically pure holmium oxide (Ho(2)O(3)) powder samples were irradiated with and without cadmium covers at the IEA-RI reactor (IPEN, Sao Paulo), Brazil. The deviation of the neutron spectrum shape from 1/E law was measured by co-irradiating Co, Zn, Zr and Au activation detectors with thermal and epithermal neutrons followed by regression and iterative procedures. The magnitudes of the discrepancies that can occur in measurements made with the ideal 1/E law considerations in the epithermal range were studied. The measured thermal neutron cross section at the Maxwellian averaged thermal energy of 0.0253 eV is 59.0 +/- 2.1 b and for the resonance integral 657 +/- 36b. The results are measured with good precision and indicated a consistency trend to resolve the discrepant status of the literature data. The results are compared with the values in main libraries such as ENDF/B-VII, JEF-2.2 and JENDL-3.2, and with other measurements in the literature.

Spallation product distributions and neutron multiplicities for accelerator-driven system using the CRISP code

Neutron multiplicities for several targets and spallation products of proton-induced reactions in thin targets of interest to an accelerator-driven system obtained with the CRISP code have been reported. This code is a Monte Carlo calculation that simulates the intranuclear cascade and evaporationl fission competition processes. Results are compared with experimental data, and agreement between each other can be considered quite satisfactory in a very broad energy range of incitant particles and different targets.

Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei

Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the highest-energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [Pierre Auger Collaboration, Science 318 (2007) 938]. The correlation has maximum significance for cosmic rays with energy greater than similar to 6 x 10(19) eV and AGN at a distance less than similar to 75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest-energies originate from extra-galactic sources close enough so that their flux is not significantly attenuated by interaction with the cosmic background radiation (the Greisen-Zatsepin-Kuz`min effect). The angular scale of the correlation observed is a few degrees, which suggests a predominantly light composition unless the magnetic fields are very weak outside the thin disk of our galaxy. Our present data do not identify AGN as the sources of cosmic rays unambiguously, and other candidate sources which are distributed as nearby AGN are not ruled out. We discuss the prospect of unequivocal identification of individual sources of the highest-energy cosmic rays within a few years of continued operation of the Pierre Auger Observatory. (C) 2008 Elsevier B.V. All rights reserved.

FUSION ENHANCEMENT/SUPPRESSION AND IRREVERSIBILITY IN REACTIONS INDUCED BY WEAKLY BOUND NUCLEI

We show that halo effects enhance fusion cross sections of weakly bound systems, comparing with the situation when there is no-halo. We introduce dimensionless fusion functions and energy variable quantity to investigate systematical trends in the fusion cross sections of weakly bound nuclei at near-barrier energies. We observe very clearly complete fusion suppression at energies above the barrier due to dynamic effects of the breakup on fusion. We explain this suppression in terms of the repulsive polarization potential produced by the breakup.

CLUSTER MODEL FOR REACTIONS INDUCED BY WEAKLY BOUND AND/OR EXOTIC HALO NUCLEI WITH MEDIUM-MASS TARGETS

An experimental overview of reactions induced by the stable, but weakly-bound nuclei (6)Li, (7)Li and (9)Be, and by the exotic, halo nuclei (6)He, (8)B, (11)Be and (17)F On medium-mass targets, such as (58)Ni, (59)Co or (64)Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.

Radiative capture of nucleons at astrophysical energies with single-particle states

Radiative capture of nucleons at energies of astrophysical interest is one of the most important processes for nucleosynthesis. The nucleon capture can occur either by a compound nucleus reaction or by a direct process. The compound reaction cross sections are usually very small, especially for light nuclei. The direct capture proceeds either via the formation of a single-particle resonance or a non-resonant capture process. In this work we calculate radiative capture cross sections and astrophysical S-factors for nuclei in the mass region A < 20 using single-particle states. We carefully discuss the parameter fitting procedure adopted in the simplified two-body treatment of the capture process. Then we produce a detailed list of cases for which the model works well. Useful quantities, such as spectroscopic factors and asymptotic normalization coefficients, are obtained and compared to published data. (C) 2010 Elsevier Inc. All rights reserved.

Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets

An experimental overview of reactions induced by the stable, but weakly-bound nuclei (6)Li, (7)Li and (9)Be, and by the exotic, halo nuclei (6)He, (8)B, (11)Be and (17)F on medium-mass targets, such as (58)Ni, (59)Co or (64)Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.

Understanding fusion suppression and enhancement in the (18)O+(58,60,64)Ni systems

Realistic coupled-channel calculation results for the (18)[O] + (58,60,64)Ni systems in the bombarding energy range 34.5 <= E(Lab) <= 6-5 MeV are presented. The overall agreement with existing experimental data is quite good. Our calculations predict an unexpected fusion suppression for above-barrier energies, with an important contribution of the two neutron ((18)O, (16)O) transfer channel couplings. The sub-barrier fusion enhancement and the above barrier suppression, predicted by the calculations, are consistent with the nuclear structure of the Ni region. Comparisons with recently reported similar effects in reactions induced by the (6)He projectile are discussed. (C) 2009 Elsevier B.V. All rights reserved.

Reaction functions for weakly bound systems

We propose a new technique to analyze total reaction cross sections. In this technique, which has been previously applied to fusion reactions, the experimental data are used to build a dimensionless reaction function, which does not depend oil the system size or details of the optical potential. In this way, total reaction cross sections for different systems can be directly compared. We employ this technique to perform a systematic study of reaction cross sections of weakly bound systems in different mass ranges, and compare their reaction functions with the ones of tightly bound systems with similar masses. We show that breakup reactions and neutron transfers in halo systems lead to large reaction functions, well above the ones of typical tightly or weakly bound stable systems. (C) 2009 Elsevier B.V. All rights reserved.