Frequency of serovars and antimicrobial resistance in Shigella spp. from Brazil

A total of 296 Shigella spp. were received from State Public Health Laboratories, during the period from 1999 to 2004, by National Reference Laboratory for Cholera and Enteric Diseases (NRLCED)--IOC/Fiocruz, Rio de Janeiro, Brazil. The frequency of Shigella spp. was: S. flexneri (52.7%), S. sonnei (44.2%), S. boydii (2.3%), and S. dysenteriae (0.6%). The most frequent S. flexneri serovars were 2a and 1b. The highest incidence rates of Shigella isolation were observed in the Southeast (39%) and Northeast (34%) regions and the lowest rate in the South (3%) of Brazil. Strains were further analyzed for antimicrobial susceptibility by disk diffusion method as part of a surveillance program on antimicrobial resistance. The highest rates of antimicrobial resistance were to trimethoprim-sulfamethozaxole (90%), tetracycline (88%), ampicillin (56%), and chloramphenicol (35%). The patterns of antimicrobial resistance among Shigella isolates pose a major difficulty in the determination of an appropriate drug for shigellosis treatment. Continuous monitoring of antimicrobial susceptibilities of Shigella spp. through a surveillance system is thus essential for effective therapy and control measures against shigellosis.     

Synthesis and biological evaluation against Leishmania amazonensis of a series of alkyl-substituted benzophenones

Nine O-alkyl and O-prenyl derivatives were synthesized from commercial 2,4-dihydroxybenzophenone, 4,e4,4′-dihydroxybenzophenone and were evaluated for their leishmanicidal activity against promastigote forms of Leishmania amazonensis, as well their toxicity in murine macrophages. All derivatives exhibited better biological activity than their hydroxylated benzophenones precursors, and new compound LFQM-123 (3c) was 250-fold more active than its precursor 4,4′-dihydroxybenzophenone (3). Moreover, some of the results were comparable to the standard drug Amphotericin B, suggesting that the increase in lipophilicity could facilitate protozoa membrane permeation. In this study we confirmed that benzophenone derivatives exhibit leishmanicidal properties, with relatively low toxicity, and thus could be exploited as promise prototypes for the design and development of new drug for the treatment of leishmaniasis.     

The magic-bead concept: an integrated approach to nitrogen removal with co-immobilized micro-organisms

This paper describes both qualitative and quantitative aspects of simultaneous autotrophic nitrification and heterotrophic denitrification by, respectively, the nitrifierNitrisomonas europaea and either of the denitrifiersPseudomonas denitrificans orParacoccus denitrificans co-immobilized in double-layer gel beads. The system is based on the establishment of well-defined oxic and anoxic zones within the cell supports and on physical separation of the nitrifying and denitrifying populations. Nitrification and denitrification rates were obtained from measured bulk concentrations and head-space analysis. The latter analyses showed that ammonia was primarily converted into molecular nitrogen. Nitrous oxide was not detected. High nitrogen removal rates (up to 5.1 mmol N m^–3 gel s^–1) were achieved in continuous reactors under aerobic conditions. The overall rate of nitrogen removal was controlled by the nitrifying step. The approach followed is, in principle, also suitable to the coupling of other oxidative and reductive bioprocesses having complementary metabolic routes. Two-stage bioconversion processes can be thus conducted as if single-staged, which results in more compact reactor systems.     

Souring control in fluid samples of oil industry using a multiple ligand simultaneous docking (MLSD) strategy

We have used docking techniques in order to propose potential inhibitors to the enzymes adenosine phosphosulfate reductase and adenosine triphosphate sulfurylase that are responsible, among other deleterious effects, for causing souring of oil and gas reservoirs. Three candidates selected through molecular docking revealed new and improved polar and hydrophobic interactions with the above-mentioned enzymes. Microbiological laboratory assays performed subsequently corroborated the results of computer modelling that the three compounds can efficiently control the biogenic sulfide production.     

The effects of the C-terminal amidation of mastoparans on their biological actions and interactions with membrane-mimetic systems

Polycationic peptides may present their C-termini in either amidated or acidic form; however, the effects of these conformations on the mechanisms of interaction with the membranes in general were not properly investigated up to now. Protonectarina-MP mastoparan with an either amidated or acidic C-terminus was utilized to study their interactions with anionic and zwitterionic vesicles, using measurements of dye leakage and a combination of H/D exchange and mass spectrometry to monitor peptide–membrane interactions. Mast cell degranulation, hemolysis and antibiosis assays were also performed using these peptides, and the results were correlated with the structural properties of the peptides. The C-terminal amidation promotes the stabilization of the secondary structure of the peptide, with a relatively high content of helical conformations, permitting a deeper interaction with the phospholipid constituents of animal and bacterial cell membranes. The results suggested that at low concentrations Protonectarina-MP interacts with the membranes in a way that both terminal regions remain positioned outside the external surface of the membrane, while the α-carbon backbone becomes partially embedded in the membrane core and changing constantly the conformation, and causing membrane destabilization. The amidation of the C-terminal residue appears to be responsible for the stabilization of the peptide conformation in a secondary structure that is richer in α-helix content than its acidic congener. The helical, amphipathic conformation, in turn, allows a deeper peptide–membrane interaction, favoring both biological activities that depend on peptide structure recognition by the GPCRs (such as exocytosis) and those activities dependent on membrane perturbation (such as hemolysis and antibiosis).     

Expanding the Knowledge of the Geographic Distribution of Trypanosoma cruzi TcII and TcV/TcVI Genotypes in the Brazilian Amazon

Trypanosoma cruzi infection is a complex sylvatic enzooty involving a wide range of animal species. Six discrete typing units (DTUs) of T. cruzi, named TcI to TcVI, are currently recognized. One unanswered question concerning the epidemiology of T. cruzi is the distribution pattern of TcII and hybrid DTUs in nature, including their virtual absence in the Brazilian Amazon, the current endemic area of Chagas disease in Brazil. Herein, we characterized biological samples that were collected in previous epizootiological studies carried out in the Amazon Basin in Brazil. We performed T. cruzi genotyping using four polymorphic genes to identify T. cruzi DTUs: mini-exon, 1f8, histone 3 and gp72. This analysis was conducted in the following biological samples: (i) two T. cruzi isolates obtained by culturing of stools from the triatomine species Rhodnius picttipes and (ii) five serum samples from dogs in which trypomastigotes were observed during fresh blood examination. We report for the first time the presence of TcII and hybrid DTUs (TcV/TcVI) in the Amazon region in mixed infections with TcI. Furthermore, sequencing of the constitutive gene, gp72, demonstrated diversity in TcII even within the same forest fragment. These data show that TcII is distributed in the five main Brazilian biomes and is likely more prevalent than currently described. It is very probable that there is no biological or ecological barrier to the transmission and establishment of any DTU in any biome in Brazil.     

Ulva lactuca and U. flexuosa (Chlorophyta,Ulvophyceae) cultivation in Brazilian tropical waters: recruitment,growth, and ulvan yield

Ulva spp. are used in a wide range of commercial applications, including bioremediation, food, bioenergy, pharmaceuticals, and agriculture. The sulfated polysaccharide ulvan obtained from Ulva spp. is of interest for triggering plant defenses against disease. However, the cultivation of Ulva spp. is still in its infancy. This study verified the feasibility of cultivating Ulva lactuca and Ulva flexuosa at two sites on the tropical Brazilian coast. We investigated the following: (a) methods to induce sporulation, (b) comparison of seeding ropes inoculated in vitro versus seeding at sea over 40 days, (c) production and harvest cycles at 15 and 30 days, (d) growth productivity of U. flexuosa at sea and in outdoor tanks, and (e) comparison of ulvan yields from biomass cultivated in tanks and the sea. High nutrient treatment was the most efficient method to induce sporulation (7,540?±?3,133 spores m^?1). Sea-based cultivation of U. flexuosa was only successful at one site. Seeding of ropes in vitro was more efficient than seeding at sea (0.31?±?0.20 g m^?2 day^?1), and 15-day harvest cycles were most efficient (20.1?±?1.8 % day^?1; 0.46?±?0.11 g m^?2 day^?1). Despite differences in plant growth in tanks (27.9?±?4.4 % day^?1) and at sea (20.1?±?1.8 % day^?1), the dry biomass and ulvan yields (17.7?±?5.0 %) did not differ between these systems. Cultivation of U. flexuosa was feasible at sea using in vitro seeding with a production cycle of 15 days in Brazilian tropical waters and tanks with high irradiance and enriched seawater.     

Functional and Taxonomic Diversity of Stinging Wasps in Brazilian Atlantic Rainforest Areas

Vespoidea are the most functionally diverse superfamily of Hymenoptera. Ecological studies involving this family are primarily based on eusocial groups, including ants and social paper wasps. In the present study, we examine stinging wasp (Vespoidea) faunal diversity in the Atlantic Rain Forest, which is one of the most diverse and threatened ecosystems in the World. Three conservation areas were sampled employing a standardized sample protocol. Families and functional groups of Vespoidea were collected in each area, with the exception ants (Formicidae), and analyzed using diversity analyses, to generate taxonomic diversity and distinctness indices. Results indicated Pompilidae was the most diverse family, and the idiobiont parasitoid type was the most diverse functional group in the three study areas. Núcleo Picinguaba of the Parque Estadual da Serra do Mar was taxonomically and functionally the most diverse and species rich area. Parque Estadual Intervales showed the highest number of dominant species and diversity of koinobiont parasitoids, while the Rebio Sooretama exhibited a decrease in several diversity parameters.     

A more accurate profile of Achyrocline satureioides hypocholesterolemic activity

The aim of this study was to investigate the effect of the aqueous extract (AE) of Achyrocline satureioides on serum lipid profile, liver oxidative profile and Na(+),K(+)-ATPase activity of rats submitted to a hyperlipidic diet. The animals were divided into four groups: control (C), AE 10% (A(10)), hyperlipidic (H) and hyperlipidic/AE 10% (HA(10)). In serum, we measured the levels of total cholesterol (TC), high-density lipoprotein, very-low-density lipoprotein, low-density lipoprotein (LDL) and triglyceride (TG). In liver homogenates, we measured the thiobarbituric acid reactive substances, the carbonyl proteins, the non-protein thiols (NPSHs) and the activity of superoxide dismutase, catalase (CAT) and Na(+),K(+)-ATPase. We observed a significant increase in the TC and LDL levels in the H group. A. satureioides prevented these effects, decreased the TG levels in the HA(10) group and increased the NPSH levels in the A(10) and HA(10) groups. The H group showed an increase in the carbonyl protein level and a decrease in CAT and Na(+),K(+)-ATPase activities. With the use of this model, results show that increased levels of lipids are related to a redox imbalance in the liver, which is also related to the inhibition of Na(+),K(+)-ATPase activity, and that chronic administration of the AE of A. satureioides is capable of changing this profile.