Structure-function relationship of new crotamine isoform from the Crotalus durissus cascavella

In this work we isolated a novel crotamine like protein from the Crotalus durissus cascavella venom by combination of molecular exclusion and analytical reverse phase HPLC. Its primary structure was:YKRCHKKGGHCFPKEKICLPPSSDLGKMDCRWKRK-CCKKGS GK. This protein showed a molecular mass of 4892.89 da that was determined by Matrix Assisted Laser Desorption Ionization Time-of-flight (MALDI-TOF) mass spectrometry. The approximately pI value of this protein was determined in 9.9 by two-dimensional electrophoresis. This crotamine-like protein isolated here and that named as Cro 2 produced skeletal muscle spasm and spastic paralysis in mice similarly to other crotamines like proteins. Cro 2 did not modify the insulin secretion at low glucose concentration (2.8 and 5.6 mM), but at high glucose concentration (16.7 mM) we observed an insulin secretion increasing of 2.7-3.0-fold than to control. The Na+ channel antagonist tetrodoxin (6 mM) decreased glucose and Cro 2-induced insulin secretion. These results suggested that Na+ channel are involved in the insulin secretion. In this article, we also purified some peptide fragment from the treatment of reduced and carboxymethylated Cro 2 (RC-Cro 2) with cyanogen bromide and protease V8 from Staphylococcus aureus. The isolated pancreatic beta-cells were then treated with peptides only at high glucose concentration (16.7 mM), in this condition only two peptides induced insulin secretion. The amino acid sequence homology analysis of the whole crotamine as well as the biologically-active peptide allowed determining the consensus region of the biologically-active crotamine responsible for insulin secretion was KGGHCFPKE and DCRWKWKCCKKGSG.

Optimal reactive power flow via the modified barrier Lagrangian function approach

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Generalized partition function zeros of 1D spin models and their critical behavior at edge singularities

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparison between Two Methods to Calculate the Transition Matrix of Orbit Motion

Two methods to evaluate the state transition matrix are implemented and analyzed to verify the computational cost and the accuracy of both methods. This evaluation represents one of the highest computational costs on the artificial satellite orbit determination task. The first method is an approximation of the Keplerian motion, providing an analytical solution which is then calculated numerically by solving Kepler's equation. The second one is a local numerical approximation that includes the effect of J(2). The analysis is performed comparing these two methods with a reference generated by a numerical integrator. For small intervals of time (1 to 10s) and when one needs more accuracy, it is recommended to use the second method, since the CPU time does not excessively overload the computer during the orbit determination procedure. For larger intervals of time and when one expects more stability on the calculation, it is recommended to use the first method.

Bone regeneration after demineralized bone matrix and castor oil (Ricinus communis) polyurethane implantation

Innocuous biocompatible materials have been searched to repair or reconstruct bone defects. Their goal is to restore the function of live or dead tissues. This study compared connective tissue and bone reaction when exposed to demineralized bovine bone matrix and a polyurethane resin derived from castor bean (Ricinus communis). Forty-five rats were assigned to 3 groups of 15 animals (control, bovine bone and polyurethane). A cylindrical defect was created on mandible base and filled with bovine bone matrix and the polyurethane. Control group received no treatment. Analyses were performed after 15, 45 and 60 days (5 animals each). Histological analysis revealed connective tissue tolerance to bovine bone with local inflammatory response similar to that of the control group. After 15 days, all groups demonstrated similar outcomes, with mild inflammatory reaction, probably due to the surgical procedure rather than to the material. In the polymer group, after 60 days, scarce multinucleated cells could still be observed. In general, all groups showed good stability and osteogenic connective tissue with blood vessels into the surgical area. The results suggest biocompatibility of both materials, seen by their integration into rat mandible. Moreover, the polyurethane seems to be an alternative in bone reconstruction and it is an inexhaustible source of biomaterial.

Schottky emission in nanoscopically crystallized Ce-doped SnO2 thin films deposited by sol-gel-dip-coating

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Differential distribution of some extracellular matrix fibers in an experimentally denervated rat megaileum

Absence of enteric neurons is associated with thickening of the intestinal muscularis externa in Chagas' disease. The thickening is due to hyperplasia and hypertrophy of the smooth muscle cells and increased extracellular matrix components. The influence of the nervous system on the structure of the smooth muscle cells and its associated matrix has been poorly investigated. An experimental model of denervation of the ileum in rats was performed by application of the surfactant agent benzalkonium chloride that selectively destroys the myenteric plexus. Three months later, ileal tissue samples were obtained and studied by histochemistry and transmission electron microsocopy. Sham operated rats were used as controls. The diameter of collagen fibrils was evaluated in electron micrographs. The histopathological analysis showed thickening of the muscular layer. The thin and weakly arranged collagen and reticulin fibers surrounding the smooth muscle cells, observed in control cases by Picrosirius polarization (PSP) stain method, corresponded to a population of loosely packed thin collagen fibrils of uniform diameters (mean = 29.16 nm) at the ultrastructural level. In contrast, the thick and strongly birefringent fibers around the muscle cells, observed in the treated group, stained by PSP, corresponded to densely packed thicker fibrils with large variation in diameter (mean = 39.41 nm). Comparison of the data demonstrated statistically significant difference between the groups suggesting that the replacement of loosely arranged reticulin fibers by fibrous tissue (with typical collagen fiber), may alter the biomechanical function resulting in impairment of muscular contraction. (c) 2007 Elsevier Ltd. All rights reserved.

Matrix metalloproteinase (MMP)-2 and MMP-9 activity and localization during ventral prostate atrophy and regrowth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Almost strict total positivity and a class of Hurwitz polynomials

We establish sufficient conditions for a matrix to be almost totally positive, thus extending a result of Craven and Csordas who proved that the corresponding conditions guarantee that a matrix is strictly totally positive. Then we apply our main result in order to obtain a new criteria for a real algebraic polynomial to be a Hurwitz one. The properties of the corresponding extremal Hurwitz polynomials are discussed. (C) 2004 Elsevier B.V. All rights reserved.

Mapping the Wigner distribution function of the Morse oscillator onto a semiclassical distribution function

The mapping of the Wigner distribution function (WDF) for a given bound state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. The purpose of the present work is to obtain values of the potential parameters represented by the number of levels in the case of the Morse oscillator, for which the SDF becomes a faithful approximation of the corresponding WDF. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory. We also discuss the limit h --> 0 for fixed potential parameters.

On the Baker-Akhiezer function in the AKNS scheme

Expressions for the Baker-Akhiezer function and their logarithmic space and time derivatives are derived in terms of the matrix elements of U - V matrices and 'squared basis functions'. These expressions generalize the well known formulas for the KdV equation case and establish links between different forms of the Whitham averaging procedure.

A dynamical gluon mass solution in Mandelstam's approximation

We discuss the pure gauge Schwinger-Dyson equation for the gluon propagator in the Landau gauge within an approximation proposed by Mandelstam many years ago. We show that a dynamical gluon mass arises as a solution. This solution is obtained numerically in the full range of momenta that we have considered without the introduction of any ansatz or asymptotic expression in the infrared region. The vertex function that we use follows a prescription formulated by Cornwall to determine the existence of a dynamical gluon mass in the light cone gauge. The renormalization procedure differs from the one proposed by Mandelstam and allows for the possibility of a dynamical gluon mass. Some of the properties of this solution, such as its dependence on A(QCD) and its perturbative scaling behavior are also discussed.

QCD effective charge and the structure function F-2 at small-x

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cosmological forecasts from photometric measurements of the angular correlation function

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genetic analysis of phosphoprotein and matrix protein of rabies viruses isolated in Brazil

To investigate the genetic characteristics of phosphoprotein (P) and matrix protein (M) genes of variable rabies virus (RV) prevalent in Brazil, the authors genetically characterized the P and M genes from 30 Brazilian RV field isolates. Phylogenetic analysis based on the P and M genes revealed the presence of six RV variants that consisted primarily of three insectivorous bats, the vampire bat, dog and fox in Brazil. Specific amino acid substitutions corresponding to these phylogenetic lineages were observed, with ASP(42) and GlU(62) in the P protein found to be characteristic of Brazilian chiroptera- and carnivora-related RVs, respectively. Amino acid sequence motifs predicted to associate with a viral function in the P and M proteins were conserved among Brazilian RV variants.