Genetic diversity and genetic exchange in Trypanosoma cruzi: dual drug-resistant "progeny" from episomal transformants

Extensive characterisation of Trypanosoma cruzi by isoenzyme phenotypes has separated the species into three principal zymodeme groups, Z1, Z2 and Z3, and into many individual zymodemes. There is marked diversity within Z2. A strong correlation has been demonstrated between the strain clusters determined by isoenzymes and those obtained using random amplified polymorphic DNA (RAPD) profiles. Polymorphisms in ribosomal RNA genes, in mini-exon genes, and microsatellite fingerprinting indicate the presence of at least two principal T. cruzi genetic lineages. Lineage 1 appears to correspond with Z2 and lineage 2 with Z1. Z1 (lineage 2) is associated with Didelphis. Z2 (lineage 1) may be associated with a primate host. Departures from Hardy-Weinberg equilibrium and linkage disequilibrium indicate that propagation of T. cruzi is predominantly clonal. Nevertheless, two studies show putative homozygotes and heterozygotes circulating sympatrically: the allozyme frequencies for phosphoglucomutase, and hybrid RAPD profiles suggest that genetic exchange may be a current phenomenon in some T. cruzi transmission cycles. We were able to isolate dual drug-resistant T. cruzi biological clones following copassage of putative parents carrying single episomal drug-resistant markers. A multiplex PCR confirmed that dual drug-resistant clones carried both episomal plasmids. Preliminary karyotype analysis suggests that recombination may not be confined to the extranuclear genome.

Trypanosoma cruzi -- the vector-parasite paradox

Trypanosoma cruzi and the majority of its insect vectors (Hemiptera, Reduviidae, Triatominae) are confined to the Americas. But while recent molecular studies indicate a relatively ancient origin for the parasite (~65 million years ago) there is increasing evidence that the blood-sucking triatomine vectors have evolved comparatively recently (<5 mya). This review examines the evidence for these ideas, and attempts to reconcile the apparent paradox by suggesting that marsupial opossums (Didelphidae) may have played a role, not just as original reservoir hosts, but also as original vectors of the parasite.

Epidemiology and control of malaria in Colombia

Malaria is currently one of the most serious public health problems in Colombia with an endemic/epidemic transmission pattern that has maintained endemic levels and an average of 105,000 annual clinical cases being reported over the last five years. Plasmodium vivax accounts for approximately 70% of reported cases with the remainder attributed almost exclusively to Plasmodium falciparum. A limited number of severe and complicated cases have resulted in mortality, which is a downward trend that has been maintained over the last few years. More than 90% of the malaria cases in Colombia are confined to 70 municipalities (about 7% of the total municipalities of Colombia), with high predominance (85%) in rural areas. The purpose of this paper is to review the progress of malaria-eradication activities and control measures over the past century within the eco-epidemiologic context of malaria transmission together with official consolidated morbidity and mortality reports. This review may contribute to the formulation of new antimalarial strategies and policies intended to achieve malaria elimination/eradication in Colombia and in the region.

Natural Leishmania sp. reservoirs and phlebotomine sandfly food source identification in Ibitipoca State Park, Minas Gerais, Brazil

Leishmania spp are distributed throughout the world and different species are associated with varying degrees of disease severity. However, leishmaniasis is thought to be confined to areas of the world where its insect vectors, sandflies, are present. Phlebotomine sandflies obtain blood meals from a variety of wild and domestic animals and sometimes from humans. These vectors transmit Leishmania spp, the aetiological agent of leishmaniasis. Identification of sandfly blood meals has generally been performed using serological methods, although a few studies have used molecular procedures in artificially fed insects. In this study, cytochrome b gene (cytB) polymerase chain reaction (PCR) was performed in DNA samples isolated from 38 engorged Psychodopygus lloydi and the expected 359 bp fragment was identified from all of the samples. The amplified product was digested using restriction enzymes and analysed for restriction fragment length polymorphisms (RFLPs). We identified food sources for 23 females; 34.8% yielded a primate-specific banding profile and 26.1% and 39.1% showed banding patterns specific to birds or mixed restriction profiles (rodent/marsupial, human/bird, rodent/marsupial/human), respectively. The food sources of 15 flies could not be identified. Two female P. lloydi were determined to be infected by Leishmania using internal transcribed spacer 1 and heat shock protein 70 kDa PCR-RFLP. The two female sandflies, both of which fed on rodents/marsupials, were further characterised as infected with Leishmania (Viannia) braziliensis. These results constitute an important step towards applying methodologies based on cytB amplification as a tool for identifying the food sources of female sandflies.

The adequacy of artificial oviposition substrates for laboratory rearing of Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae)

Studies in the laboratory tested the suitability of synthetic wool string, cotton string, cheesecloth, and commercial cotton ball as artificial oviposition substrates for the small green stink bug, Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae). In confined cages, 54% of total egg masses was laid on synthetic wool string, 31% on cotton string, and only 15% on cheesecloth. In an additional test, the best substrate selected, synthetic wool string, received 92% of egg masses compared to 8% on the commonly used substrate, cotton ball. Synthetic wool string received the most egg masses of any size, in particular those in the range 11-20 eggs/mass. Because the eggs of P. guildinii are laid in two parallel double rows, the egg masses fit the wool string perfectly.

Three-dimensional interpolation of soil data: fertility and pedomorphological features in southern Brazil

The graphical representation of spatial soil properties in a digital environment is complex because it requires a conversion of data collected in a discrete form onto a continuous surface. The objective of this study was to apply three-dimension techniques of interpolation and visualization on soil texture and fertility properties and establish relationships with pedogenetic factors and processes in a slope area. The GRASS Geographic Information System was used to generate three-dimensional models and ParaView software to visualize soil volumes. Samples of the A, AB, BA, and B horizons were collected in a regular 122-point grid in an area of 13 ha, in Pinhais, PR, in southern Brazil. Geoprocessing and graphic computing techniques were effective in identifying and delimiting soil volumes of distinct ranges of fertility properties confined within the soil matrix. Both three-dimensional interpolation and the visualization tool facilitated interpretation in a continuous space (volumes) of the cause-effect relationships between soil texture and fertility properties and pedological factors and processes, such as higher clay contents following the drainage lines of the area. The flattest part with more weathered soils (Oxisols) had the highest pH values and lower Al3+ concentrations. These techniques of data interpolation and visualization have great potential for use in diverse areas of soil science, such as identification of soil volumes occurring side-by-side but that exhibit different physical, chemical, and mineralogical conditions for plant root growth, and monitoring of plumes of organic and inorganic pollutants in soils and sediments, among other applications. The methodological details for interpolation and a three-dimensional view of soil data are presented here.

Behaviour of pre-parturient sows housed in intensive outdoor or indoor systems

This work compared the behaviour of pre-parturient sows housed in intensive confined and outdoor systems, during the morning and afternoon prior to delivery. Eight sows were kept individually in farrowing crates or in paddocks with access to fresh pasture from 8 to 10 days before expected parturition. All outdoor sows built a nest within 24 hours before farrowing. On the morning and afternoon before farrowing they spent 6.5% of the time collecting grass and 7.5% of the time organizing the nest. Outdoor sows were observed more often than confined sows rooting (4.60% vs. 0.25%), feeding (10.2% vs. 3.0%), standing (51% vs. 13%) and walking (8% vs. 0%). Indoor sows redirected the nesting behaviour to other behaviours like attempts to dig the ground, nosing, biting and rooting parts of the crate, feeder or drinker, during 4.7% of the time. They also spent more time than outdoor sows inactive (85% vs. 60%), lying (72% vs. 41%), drinking (2.1% vs. 0.5%) and vacuum chewing (3.7% vs. 0.1%). The pre-parturient behaviour of sows was considerably affected by the husbandry system. The outdoor system appears to be more appropriate for the sows' welfare than the conventional confinement.

Síntese de polímeros condutores em matrizes sólidas hospedeiras

This review discusses the methods used to prepare conductive polymers in confined environments. This spatial restriction causes formation of defect-free polymer chains in the interlayer as porous cavities of inorganic hosts. The properties of the different composites obtained are a synergist combination of the characteristics of the inorganic host and the polymer. This opens new perspectives for the preparation of these materials and widens its potential applications.

Espectrofotometria de longo caminho óptico em espectrofotômetro de duplo-feixe convencional: uma alternativa simples para investigações de amostras com densidade óptica muito baixa

We describe the design and tests of a set-up mounted in a conventional double beam spectrophotometer, which allows the determination of optical density of samples confined in a long liquid core waveguide (LCW) capillary. Very long optical path length can be achieved with capillary cell, allowing measurements of samples with very low optical densities. The device uses a custom optical concentrator optically coupled to LCW (TEFLON® AF). Optical density measurements, carried out using a LCW of ~ 45 cm, were in accordance with the Beer-Lambert Law. Thus, it was possible to analyze quantitatively samples at concentrations 45 fold lower than that regularly used in spectrophotometric measurements.

Construção de uma célula de gás de baixo custo para análise no infravermelho

Infrared spectroscopy is a versatile technique used for qualitative and quantitative determination of all types of molecular species. As far as analysis of confined or flowing gases is concerned, different types of cell can be found in the market, but they are often very expensive. This study describes the construction of a very efficient gas cell with good reproducibility for qualitative infrared analysis of confined or flowing gases, using easily available and low-cost materials.

Silicon and rice disease management

The element silicon (Si) is not considered an essential nutrient for plant function. Nevertheless, Si is absorbed from soil in large amounts that are several fold higher than those of other essential macronutrients in certain plant species. Its beneficial effects have been reported in various situations, especially under biotic and abiotic stress conditions. The most significant effect of Si on plants, besides improving their fitness in nature and increasing agricultural productivity, is the restriction of parasitism. There has been a considerable amount of research showing the positive effect of Si in controlling diseases in important crops. Rice (Oryza sativa), in particular, is affected by the presence of Si, with diseases such as blast, brown spot and sheath blight becoming more severe on rice plants grown in Si-depleted soils. The hypothesis underlying the control of some diseases in both mono- and di-cots by Si has been confined to that of a mechanical barrier resulting from its polymerization in planta. However, some studies show that Si-mediated resistance against pathogens is associated with the accumulation of phenolics and phytoalexins as well as with the activation of some PR-genes. These findings strongly suggest that Si plays an active role in the resistance of some plants to diseases rather than forming a physical barrier that impedes penetration by fungal pathogens.

Adsorption of hidrogen peroxide on the surface of silica - titania mixed oxide obtained by the sol-gel processing method

This work describes the sol-gel mixed oxide SiO2/TiO2 property, ST, as prepared, and submitted to heat treatment a 773 K, STC. SEM and EDS images show, within magnification used, a uniform distribution of the TiO2 particles in SiO2/TiO2 matrix. Both, ST and STC adsorb hydrogen peroxide on the surface and through EPR and UV-Vis diffuse reflectance spectra, it was possible to conclude that the species on the surface is the peroxide molecule attached to the Lewis acid site of titanium particle surface, alphaTi(H2O2)+. As the material is very porous, presumably the hydrogen peroxide molecule is confined in the matrix pores on the surface, a reason why the adsorbed species presents an exceptional long lived stability.

Formal semantics for propositional attitudes

Contemporary logic is confined to a few paradigmatic attitudes such as belief, knowledge, desire and intention. My purpose is to present a general model-theoretical semantics of propositional attitudes of any cognitive or volitive mode. In my view, one can recursively define the set of all psychological modes of attitudes. As Descartes anticipated, the two primitive modes are those of belief and desire. Complex modes are obtained by adding to primitive modes special cognitive and volitive ways or special propositional content or preparatory conditions. According to standard logic of attitudes (Hintikka), human agents are either perfectly rational or totally irrational. I will proceed to a finer analysis of propositional attitudes that accounts for our imperfect but minimal rationality. For that purpose I will use a non standard predicative logic according to which propositions with the same truth conditions can have different cognitive values and I will explicate subjective in addition to objective possibilities. Next I will enumerate valid laws of my general logic of propositional attitudes. At the end I will state principles according to which minimally rational agents dynamically revise attitudes of any mode.

Swine manure post-treatment technologies for pathogenic organism inactivation

Swine manure agricultural use is a common practice in Brazil. Their physic-chemical characteristics favor its use as biofertilizer, but the presence of pathogens may become a risk to human health. This research presents a qualitative study of the main alternatives of pig manure disinfection, analyzing efficiency, advantages and limitations of each procedure. The disinfection studies reported in literature are based on the following treatments: alkaline, thermal, biological, chemical, and physical. The greater efficiencies are in thermal treatment (> 4 log: 60 °C), chemical treatment (3 to 4 log: 30mg Cl- L-1; 3 to 4 log: 40 mg O3 L-1) and physical treatment (3 a 4 log: 220 mJ UV radiation cm-2). The biological treatment (anaerobiosis) also promotes the pathogen reduction of swine manure, however with lower efficiency (1 to 2 log). The selection of the treatment should consider: implementation and operation cost, necessity of preliminary treatment, efficiency obtained and destination of the treated manure (agricultural use, water reuse). Brazilian regulation does not have specific guidelines for the microbiological quality of animal production effluents that is very important to be considered due to confined animal feeding operation transformation in the last years in the country.

Histoplasmose como causa de perfuração intestinal em paciente com síndrome da imunodeficiência adquirida

Thirty-four years old patient, female, husband died of AIDS (Acquired Immunodeficiency Síndrome). She's confined to Hospital Universitário João de Barros Barreto, with a positive tesT for AIDS, fever, 10 kg/month of weight loss, diarrhea with gummy faeces, productive cough, yellowish sputum. The therapy was initiated, symptomatic, associated to Epivir, Saquinavir and AZT. The searching exams for Alcohol Ácid Resistant Bacili and fungi in the sputum were negative. At the hemogram was shown a pancytopenia, the esophagogastroduodenunscopy showed light esophago moniliasis. During commitment presented a perforating acute abdomen chart, the abdominal radiography showed hidroair levels, pneumoperitoneum, enlarced bowels with swollen wall. She was undertaken a surgery with diagnosis hypothesis of cytomegalovirus perforation, which accordin to literature is the most frequent cause of intestinal perforation in patients with AIDS.