The aging analysis of natural rubber-Copaifera oblongifolia extract membranes.

Natural rubber (NR), derived from Hevea brasiliensis, has properties for biomedical applications. Several studies indicate that these properties can be amplified when we associate another bioproduct. However, there are no studies of aging aspects of this biomaterial regarding changes in functionality, structure and composition. The objective was to evaluate the aging process of natural rubber membranes - copaiba (NRC) subjected to controlled conditions of time, light and presence of oxygen. The NRC was prepared and stored in the presence or absence of light and vacuum, for periods of 30, 60 and 90 days. Subsequently, the membranes were characterized through the techniques of wettability, infrared spectroscopy, thermal analysis, scanning microscopy and antioxidant activity. The wettability analysis, showed that NRC membranes both in the zero time and in the aging time were hydrophilic. Through thermogravimetric analysis and differential exploratory analysis the membranes remained thermally stable. The scanning electronic microscopy, indicated no morphological alterations during the observed period. After 90 days, the packaged membranes showed satisfactory antioxidant activity. Our results suggest that the membranes were resistant to the storage period, since they maintained their chemical, thermal, morphological and antioxidant characteristics. Hence, it corroborates to use of membranes as a possible curative for biomedical applications.

NATURAL RUBBER - PROPOLIS MEMBRANE IMPROVES WOUND HEALING IN SECOND-DEGREE BURNING MODEL.

Our aim was to evaluate effects of natural rubber membrane (NR) associated with aqueous propolis extract (P) on the wound healing in rats burn model. The membranes were characterized for wettability and pore presence after the membrane preparation by casting the liquid solution in Petri dishes, at different temperatures (27 and 60 °C). Male Wistar rats were divided into treatment groups (n = 5 per group: control without treatment, silver sulfadiazine, NR, NRP) initiated immediately after second-degree burn and maintained during 10 days. The NRP membranes presented hydrophilic and porous characteristics. Macroscopic analysis from lesions showed that all groups presented crust formation. At the end of the experiment, the lesions treated with NRP membranes prepared at 60 °C had a higher regression percentage indicating a faster wound healing. The biopsies showed that the treatment with the NRP membranes induced a wound healing with collagen production, angiogenesis, reepithelization, and a small number of inflammatory cells, characterized by the crust detachment and the epithelium formation. In conclusion, NRP membranes are promising as a dressing for the burns treatment since were able to accelerate the healing process and tissue repair without the curative switch.

Evaluation of Boldine Activity against Intracellular Amastigotes of Leishmania amazonensis.

Leishmaniasis is a neglected and endemic disease that affects poorest population mainly in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate in vitro activity of boldine against Leishmania amazonensis murine cell infection. Boldine ((S)-2,9-dihydroxy-1,10-dimethoxy-aporphine) is an aporphine alkaloid found abundantly in the leaves/bark of boldo (Peumus boldus Molina), a widely distributed tree native to Chile. The in vitro system consisted of murine macrophage infection with amastigotes of L. amazonensis treated with different concentrations from 50 to 600 µg/ml of boldine for 24 hr. Intracellular parasite destruction was assessed by morphological examination and boldine cytotoxicity to macrophages was tested by the MTT viability assay. When cells were treated with 100 µg/ml of boldine the reduction of parasite infection was 81% compared with untreated cultures cells. Interestingly, boldine-treatment caused a concentration-dependent decrease of macrophage infection that culminated with 96% of reduction when cells were submitted to 600 µg/ml of boldine. Cell cultures exposed to 100 µg/ml of boldine and 300 µg/ml of Glucantime® during 24 hr showed a significant reduction of 50% in parasitized cells compared with cell cultures exposed just to Glucantime®. The study showed that treatment with boldine produces a better effect than treatment with the reference antimonial drug, glucantime, in L. amazonensis infected macrophage. Our results suggest that boldine is a potentially useful agent for the treatment of leishmaniasis.

Life cycle and vectorial competence of Triatoma williami (Galvão, Souza e Lima, 1965) under the influence of different blood meal sources.

Triatoma williami is naturally infected by Trypanosoma cruzi, the ethiological agent of Chagas disease, the most significant cause of morbidity and mortality in South and Central America.The possibility of domiciliation of T. williami increases the risk of human T. cruzi vetorial transmission. Despite this, there is a lack of data demonstrating the bionomic aspects, the vectorial competence or the natural ecotope and the wild hosts of T. williami. This study describes for the first time the life cycle of T. williami under the influence of two blood meal sources and also evaluates the vectorial potential of the species. The development of two groups of hundred triatomines was followed over the nymphal stages and adulthood. Each group was exposed to a sole blood meal source, mammalian or bird. The average egg-to-adult development time in both groups was similar, except by shorter stages of N3 and N4 in triatomines fed on mammals. The group fed on birds needed more blood feedings to suffer the ecdysis and had higher cumulative mortality in the nymphal stages. Although the observed delay at defecation of adults after feeding, our results suggest that T. williami in the third and fifth nymphal stages may be good vectors.

Infection by Leishmania amazonensis in mice: a potential model for chronic hypoxia.

Hypoxia is a common feature of injured and infected tissues. Hypoxia inducible factors 1α and 2α (HIF-1α, HIF-2α) are heterodimeric transcription factors mediating the cellular responses to hypoxia and also the vascular endothelial growth factor (VEGF). VEGF is a cytokine which can be induced by hypoxia, whose pathogenic mechanisms are still unclear and which is the subject of debate. Murine cutaneous lesions during Leishmania amazonensis parasite infection are chronic, although they are small and self-controlled in C57BL/6 mice and severe in BALB/c mice. In the present study we examined the presence of hypoxia, HIF-1α, HIF-2α and VEGF during the course of infection in both mouse strains. Hypoxia was detected in lesions from BALB/c mice by pimonidazole marking, which occurred earlier than in lesions from C57Bl/6 mice. The lesions in the BALB/c mice showed HIF-1α and HIF-2α expression in the cytoplasm of macrophages and failed to promote any VEGF expression, while lesions in the C57BL/6 mice showed HIF-2α nuclear accumulation and subsequent VEGF expression. In conclusion, the animal models of leishmaniasis demonstrated a diversity of patterns of expression, cell localization and activity of the main transducers of hypoxia and may be useful models for studying the pathogenic mechanisms of HIF-1α and HIF-2α during chronic hypoxic diseases.

Phlebotomine fauna (Diptera: Psychodidae: Phlebotominae) in a residential area and in a fragment of savanna vegetation in the municipality of Pontal do Araguaia, Mato Grosso, Brazil.

Identification of phlebotomine species in endemic areas is fundamental for analyzing the eco-epidemiological determinants of leishmaniasis. This study had the aim of investigating the phlebotomine fauna in an urban area and in a fragment of native savanna in the municipality of Pontal do Araguaia, State of Mato Grosso, Brazil, using CDC light traps. One hundred and twenty-three phlebotomine specimens belonging to seventeen different species were caught. Our results indicate synanthropic potential among vector species for leishmaniasis, such as the species Lutzomyia cruzi, L. sallesi and L. whitmani. The species L. cerradincola had never been recorded in this region, such that this is the first report of this species in the State of Mato Grosso.

Phlebotomine fauna (Diptera: Psychodidae: Phlebotominae) in a residential area and in a fragment of savanna vegetation in the municipality of Pontal do Araguaia, Mato Grosso, Brazil / Fauna flebotomínica (Diptera: Psychodidae: Phlebotominae) em área residencial e em fragmento de cerrado no município de Pontal do Araguaia, Mato Grosso, Brasil

Identification of phlebotomine species in endemic areas is fundamental for analyzing the eco-epidemiological determinants of leishmaniasis. This study had the aim of investigating the phlebotomine fauna in an urban area and in a fragment of native savanna in the municipality of Pontal do Araguaia, State of Mato Grosso, Brazil, using CDC light traps. One hundred and twenty-three phlebotomine specimens belonging to seventeen different species were caught. Our results indicate synanthropic potential among vector species for leishmaniasis, such as the species Lutzomyia cruzi, L. sallesi and L. whitmani. The species L. cerradincola had never been recorded in this region, such that this is the first report of this species in the State of Mato Grosso.

A identificação das espécies de flebotomíneos em áreas endêmicas é fundamental para analisar os determinantes eco-epidemiológicos das leishmanioses. Este trabalho teve como objetivo verificar a fauna flebotomínica em área urbana e em fragmento de cerrado nativo no município de Pontal do Araguaia, Mato Grosso utilizando armadilhas luminosas tipo CDC. Foram capturados 123 flebotomíneos pertencentes a 17 espécies diferentes. Nossos resultados indicam potencial sinantrópico de espécies vetoras das leishmanioses, como as espécies Lutzomyia cruzi, L. sallesi e L. whitmani. A espécie L. cerradincola não havia sido registrada na região, sendo este o primeiro relato desta espécie no Estado de Mato Grosso.

Phlebotomine fauna (Diptera: Psychodidae: Phlebotominae) in a residential area and in a fragment of savanna vegetation in the municipality of Pontal do Araguaia, Mato Grosso, Brazil / Fauna flebotomínica (Diptera: Psychodidae: Phlebotominae) em área residencial e em fragmento de cerrado no município de Pontal do Araguaia, Mato Grosso, Brasil

Identification of phlebotomine species in endemic areas is fundamental for analyzing the eco-epidemiological determinants of leishmaniasis. This study had the aim of investigating the phlebotomine fauna in an urban area and in a fragment of native savanna in the municipality of Pontal do Araguaia, State of Mato Grosso, Brazil, using CDC light traps. One hundred and twenty-three phlebotomine specimens belonging to seventeen different species were caught. Our results indicate synanthropic potential among vector species for leishmaniasis, such as the species Lutzomyia cruzi, L. sallesi and L. whitmani. The species L. cerradincola had never been recorded in this region, such that this is the first report of this species in the State of Mato Grosso.(AU)

A identificação das espécies de flebotomíneos em áreas endêmicas é fundamental para analisar os determinantes eco epidemiológicos das leishmanioses. Este trabalho teve como objetivo verificar a fauna flebotomínica em área urbana e em fragmento de cerrado nativo no município de Pontal do Araguaia, Mato Grosso utilizando armadilhas luminosas tipo CDC. Foram capturados 123 flebotomíneos pertencentes a 17 espécies diferentes. Nossos resultados indicam potencial sinantrópico de espécies vetoras das leishmanioses, como as espécies Lutzomyia cruzi, L. sallesi e L. whitmani. A espécie L. cerradincola não havia sido registrada na região, sendo este o primeiro relato desta espécie no Estado de Mato Grosso.(AU)

A novel organotellurium compound (RT-01) as a new antileishmanial agent.

Leishmaniasis is a neglected disease and endemic in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate the effect of RT-01, an organotellurane compound presenting biological activities, in 2 experimental systems against Leishmania amazonensis. The in vitro system consisted of promastigotes and amastigotes forms of the parasite, and the in vivo system consisted of L. amazonensis infected BALB/c mice, an extremely susceptible mouse strain. The compound proved to be toxic against promastigotes and amastigotes. The study also showed that treatment with RT-01 produces an effect similar to that treatment with the reference antimonial drug, Glucantime, in L. amazonensis infected mice. The best results were obtained following RT-01 intralesional administration (720 microg/kg/day); mice showed significant delay in the development of cutaneous lesions and decreased numbers of parasites obtained from the lesions. Significant differences in tissue pathology consisted mainly of no expressive accumulation of inflammatory cells and well-preserved structures in the skin tissue of RT-01-treated mice compared with expressive infiltration of infected cells replacing the skin tissue in lesions of untreated mice. These findings highlight the fact that the apparent potency of organotellurane compounds, together with their relatively simple structure, may represent a new avenue for the development of novel drugs to combat parasitic diseases.

Hyperbaric oxygen therapy reduces the size of Leishmania amazonensis-induced soft tissue lesions in mice.

In this study we determined whether exposing mice to hyperbaric oxygen (HBO) would alter various disease parameters of a susceptible mouse strain infected with Leishmania amazonensis. BALB/c mice exposed to HBO (100% O2 at a pressure of 2.5 ATA, 1h before parasite inoculation and subsequently for 20 days) showed significant delay in lesion development and reduction in lesion parasite burdens compared with HBO-unexposed mice. Circulating levels of interferon gamma (IFN-gamma) and tumor necrosis factor (TNF-alpha) were significantly elevated in HBO-exposed as compared to HBO-unexposed mice. Concanavalin A-stimulated lymph nodes cultures from HBO-exposed mice released significantly more IFN-gamma and less interleukin 10 (IL-10) than cultures from HBO-unexposed mice, consistent with a skewed Th1 response. These results demonstrate, for the first time, that HBO can play a pathogen control role during leishmaniasis. Further studies are needed to elucidate whether hyperoxia alone or increased atmospheric pressure alone can exert a similar effect.

Hypoxia modulates expression of the 70-kD heat shock protein and reduces Leishmania infection in macrophages.

Hypoxia, a microenvironmental factor present in diseased tissues, has been recognized as a specific metabolic stimulus or a signal of cellular response. Experimental hypoxia has been reported to induce adaptation in macrophages such as differential migration, elevation of proinflammatory cytokines and glycolytic enzyme activities, and decreased phagocytosis of inert particles. In this study we demonstrate that although exposure to hypoxia (5% O2, 5% CO2, and balanced N2) did not change macrophage viability, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cleavage and proliferation, it significantly reduced expression of the 70-kD heat shock protein (HSP70), which was restored to prehypoxia levels after reoxygenation. The influence of low oxygen tension on macrophage functional activity was also studied, i.e. the ability of these cells to maintain or resist infection by a microorganism. We demonstrate that macrophages from two different sources (a murine cell line and primary cells) exposed to hypoxia were efficiently infected with Leishmania amazonensis, but after 24 h showed a reduction in the percentage of infected cells and of the number of intracellular parasites per macrophage, indicating that hypoxia induced macrophages to kill the intracellular parasites. These results support the notion that hypoxia, a microenvironmental factor, can modulate macrophage protein expression and functional activity.

Effect of hypoxia on macrophage infection by Leishmania amazonensis.

In the present study, we compared the effect of 5% oxygen tension (hypoxia) with a normal tension of 21% oxygen (normoxia) on macrophage infection by the protozoan parasite Leishmania amazonensis. Macrophages from different sources (human cell line U937, murine cell line J774, and murine peritoneal macrophages) exposed to hypoxia showed a reduction of the percentage of infected cells and the number of intracellular parasites per cell. Observations on the kinetics of infection indicated that hypoxia did not depress L. amazonensis phagocytosis but induced macrophages to reduce intracellular parasitism. Furthermore, hypoxia did not act synergistically with gamma-interferon and bacterial lipopolysaccharides in macrophages to induce killing of parasites. Experiments also indicated no correlation between nitric oxide production and control of infection in macrophages under hypoxic condition. Thus, we have provided the first evidence that hypoxia, which occurs in various pathological conditions, can alter macrophage susceptibility to a parasitic infection.