A magnanimidade da teoria: interpretar a ética em teoria da literatura

Tese de doutoramento, Teoria da Literatura, Universidade de Lisboa, Faculdade de Letras, 2003Um dos pressupostos desta tese consiste na ideia segundo a qual o pensamento ético só adquire propriedade conceptual se preliminarmente pudermos definir ‘acção’. Como se procura demonstrar no capítulo I, saber o que é uma acção não se constitui, no entanto, como tarefa que descobre e estabelece propriedades intrínsecas e estáveis, mas como descrição de certas ocorrências, nos termos das pessoas que procuram explicar e descrever acções. Assim, o pensamento ético é algo que se constitui a partir da coerência e racionalidade de certas descrições de acções particulares e não um sistema de regras ou prescrições. Defende-se que a coerência estrutural destas descrições determina não apenas a consideração moral das acções, mas também a possibilidade do conhecimento entre as pessoas e a certeza, mais poética do que epistemológica, da sua existência. Se uma certa estabilidade do texto ético e uma certeza suficiente acerca do conhecimento humano dependem da configuração mais ou menos padronizada das acções humanas e do funcionamento mental, assumem especial relevância cognitiva e ética os casos e fenómenos de irracionalidade na realização de acções e formação de crenças. De facto, como se sugere no capítulo II, estes casos suscitam perplexidades éticas e cognitivas e assinalam o carácter provisório e conceptualmente circunscrito das nossas descrições sobre acções e pessoas, no contexto restrito do pensamento filosófico e ético. Importa por isso considerar outros textos em que a acção se constitui como motivo de estrutura argumentativa e objecto de análise. A consideração da tragédia e, sobretudo, a análise da teorização poética de Aristóteles acerca do texto trágico formam o capítulo III desta tese. A determinação ética da argumentação técnica da Poética é tão relevante para o entendimento da tragédia quanto, para a ética, conduta moral e compreensão da irracionalidade, é de absoluta pertinência uma particular descrição da acção trágica e da peculiaridade de certas actividades interpretativas exigidas não só por esse entendimento trágico de acção, mas por qualquer texto.ABSTRACT - One of the central ideas of this thesis is that ethical thinking acquires conceptual accuracy only when we can define ‘action’. As it is suggested in chapter I, to know what an action is is not, nevertheless, an activity which finds and establishes intrinsic and stable properties, but a description of some phenomena, in the vocabulary of those who seek to explain and to describe actions. Thus, ethical thinking is derived from the coherence and rationality of descriptions of particular actions and is not, therefore, a system of rules and prescriptions. It is argued that the structural coherence of these descriptions determines not only the moral apprehension of actions, but also the possibility of knowledge of persons and the assurance, more poetical than epistemological, of their existence. If a certain stability of the ethical text and a sufficient certainty about human knowledge depend on a more or less standard configuration of human actions and of mental functioning, then irrational episodes and phenomena in action and belief assume a particular cognitive and ethical relevance. As proposed in chapter II, these cases excite some ethical and cognitive perplexities and show the provisional and conceptually circumscribed character of our descriptions of actions and persons, in the strict realm of philosophy and ethics. It is necessary, therefore, to consider other texts in which action is constituted as the cause for the argumentative structure and object of analysis. The consideration of tragedy and, mostly, of the treatment of the tragic text in Aristotle’s Poetics constitutes an important part of this task and is sketched in chapter III. The ethical influence of the technical arguments of the Poetics is therefore relevant to the understanding of tragedy. A particular description of tragic action and of the specificity of interpretative activities is required not only by the understanding of action in tragedy as by the description of ethical patterns of moral behaviour and the comprehension of irrationality in any text.Fundação Calouste Gulbenkian: Bolsa de Curta Duraçã

Effect of essential oils from Eucalyptus on the growth of aflatoxigenic species

In Brazil, Eucalyptus species has been cultivated as source of energy and cellulose. They represent the most important cultivated forest in the country. In production areas, the leaves from the trees decay on the soil as green fertilizer. In this study were evaluated pure and blends of essential oils from different species of eucalyptus trees grown in Brazil for antifungal activity against aflatoxigenic species Aspergillus flavus and A. parasiticus. These fungal species can grow and contaminate grains during the storage period under high r.h. conditions, with an eventual production of aflatoxins. Antifungal activity was evaluated by the radial growth measurement of the fungi inoculated on maize meal extract agar basic medium. The eucalyptus oils were evaluated in a contact assay and a fumigant assay using pure and blended oils. Six concentrations of pure and blended oils were evaluated at the following doses: 0, 2, 4, 16, 32 and 84 μL per 20 mL of fungi culture medium. Fungal inocula from conidia suspensions containing 106 spores/mL was inoculated by a needle. Glass Petri dishes were incubated for 9 days at 28°C (± 0.3°C) in the dark. Antifungal activity was observed in all pure and blended oils, in different concentrations of contact and fumigant assay, for both fungi. Eucalyptus stageiriana oil and E. stageiriana + the hybrid E. grandis x E. urophylla oils blend controlled the total fungal growth at the lowest dose (20 μL). Keywords: Essential oil; Eucalyptus spp.; Aspergillus flavus; Aspergillus parasiticus; Antifungal activity

Peptide:lipid ratio and membrane surface charge determine the mechanism of action of the antimicrobial peptide BP100. Conformational and functional studies

The cecropin-melittin hybrid antimicrobial peptide BP100 (H-KKLFKKILKYL-NH2) is selective for Gram-negative bacteria, negatively charged membranes, and weakly hemolytic. We studied BP100 conformational and functional properties upon interaction with large unilamellar vesicles, LUVs, and giant unilamellar vesicles, GUVs, containing variable proportions of phosphatidylcholine (PC) and negatively charged phosphatidylglycerol (PG). CD and NMR spectra showed that upon binding to PG-containing LUVs BP100 acquires a-helical conformation, the helix spanning residues 3-11. Theoretical analyses indicated that the helix is amphipathic and surface-seeking. CD and dynamic light scattering data evinced peptide and/or vesicle aggregation, modulated by peptide: lipid ratio and PG content. BP100 decreased the absolute value of the zeta potential () of LUVs with low PG contents; for higher PG, binding was analyzed as an ion-exchange process. At high salt, BP100-induced LUVS leakage requires higher peptide concentration, indicating that both electrostatic and hydrophobic interactions contribute to peptide binding. While a gradual release took place at low peptide:lipid ratios, instantaneous loss occurred at high ratios, suggesting vesicle disruption. Optical microscopy of GUVs confirmed BP100-promoted disruption of negatively charged membranes. the mechanism of action of BP100 is determined by both peptide:lipid ratio and negatively charged lipid content While gradual release results from membrane perturbation by a small number of peptide molecules giving rise to changes in acyl chain packing, lipid clustering (leading to membrane defects), and/or membrane thinning, membrane disruption results from a sequence of events large-scale peptide and lipid clustering, giving rise to peptide-lipid patches that eventually would leave the membrane in a carpet-like mechanism. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Institut Nacional de Ciencia e Tecnologia de fluidos complexos (INCTFCx)Nude de Apoio Pesquisa de Fluidos Complexos (NAPFCx)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ São Paulo, Inst Chem, Dept Biochem, BR-05513970 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilUniv Fed Rio de Janeiro, Inst Med Biochem, Nucl Magnet Resonance Natl Ctr, Rio de Janeiro, BrazilEmbrapa Recursos Genet & Biotecnol, BR-70770917 Brasilia, DF, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilFAPESP: 2007/50970-5FAPESP: 2013/08166-5Web of Scienc

DODAB and DODAC bilayer-like aggregates in the micromolar surfactant concentration domain

In the millimolar concentration domain (typically 1 mM), dioctadecyldimethylammonium bromide and chloride (DODAX, X representing Br- or Cl- counterions) molecules assemble in water as large unilamellar vesicles. Differential scanning calorimetry (DSC) is a suitable technique to obtain the melting temperature (Tm) characteristic of surfactant bilayers, while fluorescence spectroscopy detects formation of surfactant aggregates, like bilayers. These two techniques were combined to investigate the assemble of DODAX molecules at micromolar concentrations, from 10 to 100 micromolar. At 1 mM surfactant, Tm ~ 45 ºC and 49 oC, respectively for DODAB and DODAC. DSC and fluorescence of Nile Red were used to show the formation of DODAX aggregates, at the surfactant concentration as low as 10 micromolar, whose Tm decreases monotonically with increasing DODAX concentration to attain the value for the ordinary vesicles. The data indicate that these aggregates are organized as bilayer-like structures.Fundação para a Ciência e a Tecnologia (FCT

Facile Preparation of Organic Nanoparticles by Interfacial Cross-Linking of Reverse Micelles and Template Synthesis of Subnanometer Au−Pt Nanoparticles

A single- and a double-tailed cationic surfactant with the triallylammonium headgroup formed reverse micelles (RMs) in heptane/chloroform containing a small amount of water. The reverse micelles were cross-linked at the interface upon UV irradiation in the presence of a water-soluble dithiol cross-linker and a photoinitiator. The resulting interfacially cross-linked reverse micelles (ICRMs) of the single-tailed surfactant aggregated in a solvent-dependent fashion, whereas those of the double-tailed were identical in size as the corresponding RMs. The ICRMs could extract anionic metal salts, such as AuCl4− and PtCl62−, from water into the organic phase. Au and Pt metal nanoparticles were produced upon reduction of metal salts. The covalent nature of the ICRMs made the template synthesis highly predictable, with the size of the metal particles controlled by the amount of the metal salt and the method of reduction. Nanoalloys were obtained by combining two metal precursors in the same reaction. Reduction of the ICRM-entrapped aurate also occurred without any external reducing agents, and the gold nanoparticles differed dramatically from those obtained through sodium borohydride reduction. The same template allowed the preparation of luminescent Au4, Au8, and Au13−Au23 clusters, as well as gold nanoparticles several nanometers in size, simply by using different amounts of gold precursor and reducing conditions

In Vivo Approaches Reveal a Key Role for DCs in CD4+ T Cell Activation and Parasite Clearance during the Acute Phase of Experimental Blood-Stage Malaria

Dendritic cells (DCs) are phagocytes that are highly specialized for antigen presentation. Heterogeneous populations of macrophages and DCs form a phagocyte network inside the red pulp (RP) of the spleen, which is a major site for the control of blood-borne infections such as malaria. However, the dynamics of splenic DCs during Plasmodium infections are poorly understood, limiting our knowledge regarding their protective role in malaria. Here, we used in vivo experimental approaches that enabled us to deplete or visualize DCs in order to clarify these issues. To elucidate the roles of DCs and marginal zone macrophages in the protection against blood-stage malaria, we infected DTx (diphtheria toxin)-treated C57BL/6.CD11c-DTR mice, as well as C57BL/6 mice treated with low doses of clodronate liposomes (ClLip), with Plasmodium chabaudi AS (Pc) parasites. The first evidence suggesting that DCs could contribute directly to parasite clearance was an early effect of the DTx treatment, but not of the ClLip treatment, in parasitemia control. DCs were also required for CD4+ T cell responses during infection. The phagocytosis of infected red blood cells (iRBCs) by splenic DCs was analyzed by confocal intravital microscopy, as well as by flow cytometry and immunofluorescence, at three distinct phases of Pc malaria: at the first encounter, at pre-crisis concomitant with parasitemia growth and at crisis when the parasitemia decline coincides with spleen closure. In vivo and ex vivo imaging of the spleen revealed that DCs actively phagocytize iRBCs and interact with CD4+ T cells both in T cell-rich areas and in the RP. Subcapsular RP DCs were highly efficient in the recognition and capture of iRBCs during pre-crisis, while complete DC maturation was only achieved during crisis. These findings indicate that, beyond their classical role in antigen presentation, DCs also contribute to the direct elimination of iRBCs during acute Plasmodium infection.São Paulo Research Foundation grants: (2011/24038-1 [MRDL], 2009/08559-1 [HBdS], CAPES/IGC 04/ 2012 [MRDL, CET])

Selective oxidation of glucose to glucuronic acid by cesium-promoted gold nanoparticle catalyst

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