Electronic conduction and electrocatalysis by supramolecular tetraruthenated copper porphyrazine films

A new tetraruthenated copper(II)-tetra(3,4-pyridyl)porphyrazine species, [CuTRPyPz]4+, has been synthesized and fully characterized by means of analytical, spectroscopic and electrochemical techniques. This À-conjugated system contrasts with the related meso-tetrapyridylporphyrins by exhibiting strong electronic interaction between the coordinated peripheral complexes and the central ring. Based on favorable À-stacking and electrostatic interactions, layer-by-layer assembled films were successfully generated from the appropriate combination of [CuTRPyPz]4+ with copper(II)-tetrasulfonated phtalocyanine, [CuTSPc]4-. Their conducting and electrocatalytic properties were investigated by means of impedance spectroscopy and rotating disc voltammetry, exhibiting metallic behavior near the Ru(III/II) redox potential, as well as enhanced catalytic activity for the oxidation of nitrite and sulphite ions.Uma nova espécie cobre(II)-tetra(3,4-piridil) porfirazina tetrarrutenada, [CuTRPyPz]4+ foi sintetizada e sua caracterização conduzida por meio de métodos analíticos, espectroscópicos e eletroquímicos. Sua extensa conjugação-À a distingue dos derivados análogos da meso-tetrapiridilporfirina, levando à ocorrência de interações eletrônicas mais fortes entre os complexos periféricos e o anel porfirazínico central. Com base nas interações eletrostáticas e de empilhamento-À, foram realizadas montagens, camada-por-camada, de filmes funcionais, combinando-se a [CuTRPyPz]4+ com a ftalocianina de cobre(II) tetrassulfonada, [CuTSPc]4-. As propriedades condutoras e eletrocatalíticas desses filmes foram investigadas através de técnicas de impedância e de voltametria de disco rotatório, observando-se um comportamento metálico nas proximidades do potencial do par redox Ru(III)/(II), bem como uma pronunciada atividade catalítica na oxidação de íons nitrito e sulfito, em meio aquoso.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Instituto do Milênio de Materiais Complexo

Proteins of Leishmania (Viannia) shawi confer protection associated with Th1 immune response and memory generation

<p>Abstract</p> <p>Background</p> <p><it>Leishmania (Viannia) shawi </it>parasite was first characterized in 1989. Recently the protective effects of soluble leishmanial antigen (SLA) from <it>L. (V.) shawi </it>promastigotes were demonstrated using BALB/c mice, the susceptibility model for this parasite. In order to identify protective fractions, SLA was fractionated by reverse phase HPLC and five antigenic fractions were obtained.</p> <p>Methods</p> <p>F1 fraction was purified from L. (V.) shawi parasite extract by reverse phase HPLC. BALB/c mice were immunized once a week for two consecutive weeks by subcutaneous routes in the rump, using 25 μg of F1. After 1 and 16 weeks of last immunization, groups were challenged in the footpad with L. (V.) shawi promastigotes. After 2 months, those same mice were sacrificed and parasite burden, cellular and humoral immune responses were evaluated.</p> <p>Results</p> <p>The F1 fraction induced a high degree of protection associated with an increase in IFN-γ, a decrease in IL-4, increased cell proliferation and activation of CD8⁺T lymphocytes. Long-term protection was acquired in F1-immunized mice, associated with increased CD4⁺central memory T lymphocytes and activation of both CD4⁺and CD8⁺T cells. In addition, F1-immunized groups showed an increase in IgG2a levels.</p> <p>Conclusions</p> <p>The inductor capability of antigens to generate memory lymphocytes that can proliferate and secrete beneficial cytokines upon infection could be an important factor in the development of vaccine candidates against American Tegumentary Leishmaniasis.</p

Crotapotin Induced Modification Of T Lymphocyte Proliferative Response Through Interference With Pge2 Synthesis.

The immunosuppressive property has been demonstrated for the venom of the Crotalus durissus terrificus. Using a simple, novel method for obtaining crotapotin and phospholipase A2 isoforms from venom, it was possible to demonstrate that the addition of crotapotin to cultures of isolated lymphocytes resulted in a significant inhibition of the cellular proliferative response to Concanavalin A. This reduction in blastogenic response of lymphocytes is accompanied by a significant increase in the production of PGE2 by macrophages. This effect on the innate immune response suggests that this compound may modify the subsequent adaptative immune response.42433-

Characterization of the insulinotropic action of a phospholipase A2 isolated from Crotalus durissus collilineatus rattlesnake venom on rat pancreatic islets

The ability of PLA2 and crotapotin, isolated from Crotalus durissus collilineatus rattlesnake venom, to stimulate insulin secretion from isolated rat islets was examined. PLA2 and crotapotin stimulated insulin secretion at 2.8 mmol/L glucose, whereas at a high glucose concentrations (16.7 mmol/L) only PLA2 stimulated secretion. Nifedipine (10 micromol/L) did not alter the ability of PLA2 to increase insulin secretion stimulated by a depolarizing concentration of K+ (30 mmol/L). PLA2 did not affect 14CO2 production but significantly increased the efflux of arachidonic acid from isolated islets. These results indicate that PLA2-stimulated secretion is not dependent on an additional influx of Ca2+ through L-type Ca(2+)-channels but rather is associated with arachidonic acid formation in pancreatic islets.status: publishe

Isolation, homology modeling and renal effects of a C-type natriuretic peptide from the venom of the Brazilian yellow scorpion (Tityus serrulatus)

Mammalian natriuretic peptides (NPs) have been extensively investigated for use as therapeutic agents in the treatment of cardiovascular diseases. Here, we describe the isolation, sequencing and tridimensional homology modeling of the first C-type natriuretic peptide isolated from scorpion venom. In addition, its effects on the renal function of rats and on the mRNA expression of natriuretic peptide receptors in the kidneys are delineated. Fractionation of Tityusserrulatus venom using chromatographic techniques yielded a peptide with a molecular mass of 2190.64Da, which exhibited the pattern of disulfide bridges that is characteristic of a C-type NP (TsNP, T. serrulatus Natriuretic Peptide). In the isolated perfused rat kidney assay, treatment with two concentrations of TsNP (0.03 and 0.1μg/mL) increased the perfusion pressure, glomerular filtration rate and urinary flow. After 60min of treatment at both concentrations, the percentages of sodium, potassium and chloride transport were decreased, and the urinary cGMP concentration was elevated. Natriuretic peptide receptor-A (NPR-A) mRNA expression was down regulated in the kidneys treated with both concentrations of TsNP, whereas NPR-B, NPR-C and CG-C mRNAs were up regulated at the 0.1μg/mL concentration. In conclusion, this work describes the isolation and modeling of the first natriuretic peptide isolated from scorpion venom. In addition, examinations of the renal actions of TsNP indicate that its effects may be related to the activation of NPR-B, NPR-C and GC-C. © 2013 Elsevier Ltd

Vasoconstrictor effect of Africanized honeybee (Apis mellifera L.) venom on rat aorta

Background: Apis mellifera stings are a problem for public health worldwide, particularly in Latin America due to the aggressiveness of its Africanized honeybees. Massive poisoning by A. mellifera venom (AmV) affects mainly the cardiovascular system, and several works have described its actions on heart muscle. Nevertheless, no work on the pharmacological action mechanisms of the AmV in isolated aorta has been reported. Thus, the present work aimed to investigate the actions of AmV and its main fractions, phospholipase A(2) (PLA(2)) and melittin, on isolated aorta rings and a probable action mechanism.Results: AmV and the complex PLA(2) + melittin (0.1-50 mu g/mL) caused contraction in endothelium-containing aorta rings, but neither isolated PLA(2) nor melittin were able to reproduce the effect. Endothelium removal did not change the maximum vasoconstrictor effect elicited by AmV. CA(2+)-free medium, as well as treatment with phentolamine (5 mu M), verapamil (10 mu M), losartan (100 mu M), and U-73122 (10 mu M, a phospholipase C inhibitor), eliminated the AmV-induced contractile effects.Conclusions: In conclusion, AmV caused contractile effect in aorta rings probably through the involvement of voltage-operated calcium channels, AT1 and alpha-adrenergic receptors via the downstream activation of phospholipase C. The protein complex, PLA(2) + melittin, was also able to induce vasoconstriction, whereas the isolated proteins were not

Association of free amino acids with caries experience and mutans streptococci levels in whole saliva of children with early childhood caries

Objective: The aim of the present study was to identify the free amino acid content in whole saliva of children with (CE) and without early childhood caries (CF) (ECC), correlating these findings with caries experience and mutans streptococci (MS) levels in saliva.Design: Seventy-eight healthy children, both genders, 6-71 months age, were selected to participate in the study. Following examination for dmft scores calculation, unstimulated whole saliva was collected from all 78 participants, stored at -80 degrees C, and used for amino acid analysis, on a Biochem 20 plus amino acid analyzer. Stimulated whole saliva was collected from 52 children, transported, diluted and plated on MSB agar medium for detection of MS in cfu/mL.Results: Forty different free amino acids were identified in whole saliva, with great variation in their concentration. A statistically significant relation was found between caries experience and the presence of free proline and glycine. While proline (p = 0.0182) was more frequently absent in the CF group, the absence of glycine (p = 0.0397) was more often observed in the CE group. In the presence of higher levels of MS, free glycine reduced the risk of experiencing dental caries (p = 0.0419). Conversely, the presence of proline was found to increase the risk of experiencing the disease (p = 0.0492).Conclusions: The presence of free proline and absence of free glycine in children with ECC, highly contaminated with MS, increased the chances of experiencing dental caries in the present population. Further studies are needed to better understand this phenomenon. (C) 2008 Elsevier Ltd. All rights reserved