Caracterização funcional da BaltMTx, uma miotoxina isolada da peçonha de Bothrops alternatus

CHAPTER II: Snake venoms are a complex mixture of organic and inorganic compounds, proteins and peptides such as aminotransferases, acetylcholinesterase, hyaluronidases, L-amino acid oxidase, phospholipase A2, metalloproteases, serine proteases, lectins, disintegrins, and others. Phospholipase A2 directly or indirectly influence the pathophysiological effect on envenomation, as well as their participation in the digestion of the prey. They have several other activities such as hemolytic indirect action, cardiotoxicity, aggregating of platelets, anticoagulant, edema, myotoxic and inflammatory activities. In this work, we describe the functional characterization of BaltMTx, a PLA2 from Bothrops alternatus that inhibits platelet aggregation and present bactericidal effect. The purification of BaltMTx was carried out through three chromatographic steps (ion-exchange on a DEAE-Sephacel column, followed by hydrophobic chromatography on Phenyl–Sepharose and affinity chromatography on HiTrap™ Heparin HP). The protein was purified to homogeneity as judged by its migration profile in SDS–PAGE stained with coomassie blue, and showed a molecular mass of about 15 kDa under reducing conditions and approximately 25 kDa in non-reducing conditions. BaltMTx showed a rather specific inhibitory effect on platelet aggregation induced by epinephrine in human platelet-rich plasma in a dose-dependent manner, whereas it had little or no effect on platelet aggregation induced by collagen or adenosine diphosphate. BaltMTx also showed antibacterial activity against Staphylococcus aureus and Escherichia coli. High concentrations of BatlMTx stimulated the proliferation of Leishmania (Leishmania) infantum and Leishmania (Viania) braziliensis. BaltMTx induced production of inflammatory mediators such as IL-10, IL-12, TNF-α and NO. BaltMTx could be of medical interest as a new tool for the development of novel therapeutic agents for the prevention and treatment of thrombotic disorders as well as bactericidal agent.

Termos de troca, preço das commodities e o crescimento brasileiro : uma análise sob o prisma da restrição externa

This study aims to investigate the relationship between terms of trade and the long-term growth of Brazilian economy, from the perspective of external constraint, between the period 1994 to 2014. For this purpose, it is based on Thirlwall's (1979) original contribution, in order to empirically test the terms of trade contribution for determining the Brazilian growth potential product equivalent with Balance of Payments equilibriun. Using cointegration method, which seeks to analyze the long-term relationship between the variables, and subdividing the period into two sub-periods, 1994-2004 and 2004-2014, we estimate and compare real and hypothetical income elasticities and predicted and observed growth rates, with and without the terms of trade, for each period. The obteined results show that the inclusion of terms of trade in the empirical procedure to test the validity of Thirlwall's Law lead to higher growth rates obtained by the model (hypothetical), for the entire period 1994-2014 and for the sub-period 2004 -2014. This "theoretical" relaxation of the external constraint, caused by the inclusion of the terms of trade in traditional Thirlwall's rule, overestimated the average real growth rate for these periods, while the traditional Thirlwall's Law - without terms of trade - has adapted better to the real behavior of Brazilian economy. Thus, despite having contributed potentially for the relaxation of external constraint on Brazilian growth, the effect of terms of trade may have been offset by the negative performance of other Balance of Payments components, as capital flows and interest, profits and dividends payments abroad.