The rational search for natural neolignans

A rational method of search for natural neolignans of desired structures is outlined. This involves consultation of a collection of chemical profiles of plant families. The profiles are assembled considering the biosynthetic class (in the present case lignoids), subclass (neolignans), structural types (neolignan skeleta) and relative frequency of substitutional derivatives belonging to each type (known compounds). The method is of course applicable to ani class of natural products. Its use in the case of neolignans is here selected as an exemple in view of the recently discovered antagonism towards PAF of kadsurenone, a representative of this subclass of phytochemicals. Application of the chemical profiles to phylogenetic studies is illustrated.

Chemical and pharmacological investigation of Solanum species of Brazil: a search for solasodine and other potentially useful therapeutic agents

A systematic search for solasodine, an important staring material for the partial synthesis of steroidal hormones as well as other potentially bioactive constituents of various Solanum species of Brazil has been undertaken. Thus, the fruits of S. paludosum, S. asperum, S. sessiliforum and Solanum sp. were found to contain significant amounts of solasodine. The root bark of S. paludosum which showe durare like activity yelded tomatidenol and another yet unidentified alkaloid responsible for the biological activity. The fruits of S. asperum yelded a new spirosolane alkaloid, solaparnaine. The stem bark of S. pseudo-quina showed convulsive and exitatory activity from which (25S)-isosolafloridine was identified as the active principle. In addition, the latter alkaloid was also found to show antimicrobial activity.

Molecular characterisation of intermediate snail hosts and the search for resistance genes

The relationship between schistosomes and their intermediate hosts is an extremely intricate one with strains and species of the parasite depending on particular species of snail, which in turn may vary in their susceptibility to the parasites. In order to gain a better understanding of the epidemiology of the disease we have been investigating the use of molecular markers for snail identification and for studying host-parasite relationships. In this paper we will draw on examples concerning schistosomiasis in West and East Africa to illustrate how a molecular analysis can be used as part of a "total evidence" approach to characterisation of Bulinus species and provide insights into parasite transmission. Particular emphasis is given to ribosomal RNA genes (rRNA), random amplified polymorphic DNA (RAPDs) and the mitochondrial gene cytochrome oxidase I (COI). Snails resistant to infection occur naturally and there is a genetic basis for this resistance. In Biomphalaria glabrata resistance to Schistosoma mansoni is known to be a polygenic trait and we have initiated a preliminary search for snail genomic regions linked to, or involved in, resistance by using a RAPD based approach in conjunction with progeny pooling methods. We are currently characterising a variety of STSs (sequence tagged sites) associated with resistance. These can be used for local linkage and interval mapping to define genomic regions associated with the resistance trait. The development of such markers into simple dot-blot or specific PCR-based assays may have a direct and practical application for the identification of resistant snails in natural populations.

The search for new antimalarial drugs from plants used to treat fever and malaria or plants ramdomly selected: a review

In this review we discuss the ongoing situation of human malaria in the Brazilian Amazon, where it is endemic causing over 610,000 new acute cases yearly, a number which is on the increase. This is partly a result of drug resistant parasites and new antimalarial drugs are urgently needed. The approaches we have used in the search of new drugs during decades are now reviewed and include ethnopharmocology, plants randomly selected, extracts or isolated substances from plants shown to be active against the blood stage parasites in our previous studies. Emphasis is given on the medicinal plant Bidens pilosa, proven to be active against the parasite blood stages in tests using freshly prepared plant extracts. The anti-sporozoite activity of one plant used in the Brazilian endemic area to prevent malaria is also described, the so called "Indian beer" (Ampelozizyphus amazonicus, Rhamnaceae). Freshly prepared extracts from the roots of this plant were totally inactive against blood stage parasites, but active against sporozoites of Plasmodium gallinaceum or the primary exoerythrocytic stages reducing tissue parasitism in inoculated chickens. This result will be of practical importance if confirmed in mammalian malaria. Problems and perspectives in the search for antimalarial drugs are discussed as well as the toxicological and clinical trials to validate some of the active plants for public health use in Brazil.

Search for Borrelia sp. in ticks collected from potential reservoirs in an urban forest reserve in the State of Mato Grosso do Sul, Brazil: a short report

A total of 128 ticks of the genus Amblyomma were recovered from 5 marsupials (Didelphis albiventris) - with 4 recaptures - and 17 rodents (16 Bolomys lasiurus and 1 Rattus norvegicus) captured in an urban forest reserve in Campo Grande, State of Mato Grosso do Sul, Brazil. Of the ticks collected, 95 (78.9%) were in larval form and 22 (21.1%) were nymphs; the only adult (0.8%) was identified as A. cajennense. Viewed under dark-field microscopy in the fourth month after seeding, 9 cultures prepared from spleens and livers of the rodents, blood of the marsupials, and macerates of Amblyomma sp. nymphs revealed spiral-shaped, spirochete-like structures resembling those of Borrelia sp. Some of them showed little motility, while others were non-motile. No such structures could be found either in positive Giemsa-stained culture smears or under electron microscopy. No PCR amplification of DNA from those cultures could be obtained by employing Leptospira sp., B. burgdorferi, and Borrelia sp. primers. These aspects suggest that the spirochete-like structures found in this study do not fit into the genera Borrelia or Leptospira, requiring instead to be isolated for proper identification.

Antigenic community between Schistosoma mansoni and Biomphalaria glabrata: on the search of candidate antigens for vaccines

We have previously confirmed the presence of common antigens between Schistosoma mansoni and its vector, Biomphalaria glabrata. Cross-reactive antigens may be important as possible candidates for vaccine and diagnosis of schistosomiasis. Sera from outbred mice immunized with a soluble Biomphalaria glabrata antigen (SBgA) of non-infected B. glabrata snails recognized molecules of SBgA itself and S. mansoni AWA by Western blot. Recognition of several molecules of the SBgA were inhibited by pre-incubation with AWA (16, 30, 36, 60 and 155 kDa). The only specific molecule of AWA, inhibited by SBgA, was a 120 kDa protein. In order to determine which epitopes of SBgA were glycoproteins, the antigen was treated with sodium metaperiodate and compared with non-treated antigen. Molecules of 140, 60 and 24 kDa in the SBgA appear to be glycoproteins. Possible protective effects of the SBgA were evaluated immunizing outbred mice in two different experiments using Freund's Adjuvant. In the first one (12 mice/group), we obtained a significant level of protection (46%) in the total worm load, with a high variability in worm recovery. In the second experiment (22 mice/group), no significant protection was observed, neither in worm load nor in egg production per female. Our results suggest that SBgA constitutes a rich source of candidate antigens for diagnosis and prophylactic studies.

Search for a platelet-activating factor receptor in the Trypanosoma cruzi proteome: a potential target for Chagas disease chemotherapy

Chagas disease (CD) causes the highest burden of parasitic diseases in the Western Hemisphere and is therefore a priority for drug research and development. Platelet-activating factor (PAF) causes the CD parasite Trypanosoma cruzi to differentiate, which suggests that the parasite may express PAF receptors. Here, we explored the T. cruzi proteome for PAF receptor-like proteins. From a total of 23,000 protein sequences, we identified 29 hypothetical proteins that are predicted to have seven transmembrane domains (TMDs), which is the main characteristic of the G protein-coupled receptors (GPCRs), including the PAF receptor. The TMDs of these sequences were independently aligned with domains from 25 animal PAF receptors and the sequences were analysed for conserved residues. The conservation score mean values for the TMDs of the hypothetical proteins ranged from 31.7-44.1%, which suggests that if the putative T. cruzi PAF receptor is among the sequences identified, the TMDs are not highly conserved. These results suggest that T. cruzi contains several GPCR-like proteins and that one of these GPCRs may be a PAF receptor. Future studies may further validate the PAF receptor as a target for CD chemotherapy.

Tecnologias da informação e da comunicação e a polêmica sobre direito autoral: o caso Google Book Search

Anotamos, neste trabalho, reflexões sobre as conseqüências das Tecnologias da Informação e da Comunicação (TICs) para o direito autoral e sobre os atores do processo informativo. Partimos da lei do direito autoral vigente no Brasil, perguntando-nos como tais normas protegem as obras intelectuais no contexto digital e até que ponto há legalidade e legitimidade na digitalização de livros protegidos, disponibilizados on-line, tomando como exemplo o caso "Google Book Search". Constatamos que a lei atual pouco defende os direitos dos autores e dos leitores, pois se volta para a proteção dos interesses privados comerciais, e que a sociedade civil encontra formas de ampliar o fluxo comunicativo em decorrência da facilidade de reprodução e distribuição de cópias de obras intelectuais proporcionada pelas TICs.

Decomposição catalítica de óxidos de nitrogênio

Contaminant gases in the atmosphere constitute an important problem to be solved in the world. The NOx gases produced as a consequence of engine high temperatures are deleterious to environment and human health, as they promote acid rain and can act in the same way as freons in the destruction of the ozone layer in the stratosphere. In this review, three way and selective reduction catalysts for decomposition of these contaminant gases are described. Details about conditions and problems, such as catalyst poisoning, and the search for new catalysts are shown.

In search of true friendship

The present text proposes a discussion on the concept of true friendship. The argument is grounded mostly on Aristotle's Nicomachean Ethics, Owen Flanagan's ethics as human ecology, and on contemporary authors' works about the Greek philosopher's concept of friendship. Given that human beings flourish through 1) exercising capacities, 2) being moral, and 3) having true friendships, difficulties to establish the level of trust required by true friendships turns the search itself (for them) morally valid.

Perfomance evaluation of a direct injection engine using different blends of soybean (Glycine max) methyl biodiesel

Diesel fuel is used widely in Brazil and worldwide. On the other hand, the growing environmental awareness leads to a greater demand for renewable energy resources. Thus, this study aimed to evaluate the use of different blends of soybean (Glycine max) methyl biodiesel and diesel in an ignition compression engine with direct injection fuel. The tests were performed on an electric eddy current dynamometer, using the blends B10, B50 and B100, with 10; 50 e 100% of biodiesel, respectively, in comparison to the commercial diesel B5, with 5% of biodiesel added to the fossil diesel. The engine performance was analyzed trough the tractor power take off (PTO) for each fuel, and the best results obtained for the power and the specific fuel consumption, respectively, were: B5 (44.62 kW; 234.87 g kW-1 h-1); B10 (44.73 kW; 233.78 g kW-1 h-1); B50 (44.11 kW; 250.40 g kW-1 h-1) e B100 (43.40 kW; 263.63 g kW-1 h-1). The best performance occurred with the use of B5 and B10 fuel, without significant differences between these blends. The B100 fuel showed significant differences compared to the other fuels.