Serial measurement of the circulating levels of tumour necrosis factor and its soluble receptors 1 and 2 for monitoring leprosy patients during multidrug treatment

Leprosy is an infectious and contagious spectral disease accompanied by a series of immunological events triggered by the host response to the aetiologic agent, Mycobacterium leprae . The induction and maintenance of the immune/inflammatory response in leprosy are linked to multiple cell interactions and soluble factors, primarily through the action of cytokines. The purpose of the present study was to evaluate the serum levels of tumour necrosis factor (TNF)-α and its soluble receptors (sTNF-R1 and sTNF-R2) in leprosy patients at different stages of multidrug treatment (MDT) in comparison with non-infected individuals and to determine their role as putative biomarkers of the severity of leprosy or the treatment response. ELISA was used to measure the levels of these molecules in 30 healthy controls and 37 leprosy patients at the time of diagnosis and during and after MDT. Our results showed increases in the serum levels of TNF-α and sTNF-R2 in infected individuals in comparison with controls. The levels of TNF-α, but not sTNF-R2, decreased with treatment. The current results corroborate previous reports of elevated serum levels of TNF-α in leprosy and suggest a role for sTNF-R2 in the control of this cytokine during MDT.     

Habitat selection for resting sites by the water opossum (Chironectes minimus) in the Brazilian Atlantic Forest

We evaluated the selection of resting sites occupied by the water opossum Chironectes minimus, between 2004 and 2010, in streams of the Brazilian Atlantic Forest. Fourteen radio-tracked adult (males and females) opossums used natural cavities as resting sites. Opossums selected narrow river stretches and selected their resting sites mainly according to characteristics favoring protection against adverse weather conditions. Likewise, opossums avoided disturbed habitats and established their resting sites in well-preserved riparian forest sites, selecting river sections containing a high density of trees and a high proportion of forest cover between the river banks and 50 m from the river. Besides increasing our knowledge on this species habitat selection, such findings further highlight this species’ sensitivity to human disturbance.     

Biogenic antimicrobial silver nanoparticles produced by fungi

Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35?±?10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11–1.75 μg/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 μg/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications.     

Potentiation of high hydrostatic pressure inactivation of Mycobacterium by combination with physical and chemical conditions

Mycobacterium abscessus is an important hospital-acquired pathogen involved in infections associated with medical, surgical, and biopharmaceutical materials. In this work, we investigated the pressure-induced inactivation of two strains [2544 and American Type Culture Collection (ATCC) 19977] of M. abscessus in combination with different temperatures and pH conditions. For strain 2544, exposure to 250 MPa for 90 min did not significantly inactivate the bacteria at 20 °C, whereas at ?15 °C, there was complete inactivation. Exposure to 250 MPa at ≥60 °C caused rapid inactivation, with no viable bacteria after 45 min. With 45 min of exposure, there were no viable bacteria at any temperature when a higher pressure (350 MPa) was used. Extremes of pH (4 or 9) also markedly enhanced the pressure-induced inactivation of bacteria at 250 MPa, with complete inactivation after 45 min. In comparison, exposure of this strain to the disinfecting agent glutaraldehyde (0.5 %) resulted in total inactivation within 5 min. Strain 19977 was more sensitive to high pressure but less sensitive to glutaraldehyde than strain 2544. These results indicate that high hydrostatic pressure in combination with other physical parameters may be useful in reducing the mycobacterial contamination of medical materials and pharmaceuticals that are sensitive to autoclaving.     

Leishmanicidal activity of amphotericin B encapsulated in PLGA–DMSA nanoparticles to treat cutaneous leishmaniasis in C57BL/6 mice

The major goal of this work was to design a new nanoparticle drug delivery system for desoxycholate amphotericin B (D-AMB), based on controlled particle size, looking for the most successful release of the active agents in order to achieve the best site-specific action of the drug at the therapeutically optimal rate and dose regimen. For this, AMB nanoencapsulated in poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) nanoparticles (Nano-D-AMB) has been developed, and its efficacy was evaluated in the treatment of experimental cutaneous leishmaniasis in C57BL/6 mice, to test if our nano-drug delivery system could favor the reduction of the dose frequency required to achieve the same therapeutic level of free D-AMB, and so, an extended dosing interval. Magnetic citrate-coated maghemite nanoparticles were added to this nanosystem (Nano-D-AMB-MG) aiming to increase controlled release of AMB by magnetohyperthermia. Female mice (N = 6/group) were infected intradermally in the right footpad with promastigotes of Leishmania amazonensis in the metacyclic phase, receiving the following intraperitoneal treatments: 1% PBS for 10 consecutive days; D-AMB at 2 mg/kg/day for 10 days (totalizing 20 mg/kg/animal); Nano-D-AMB and Nano-D-AMB-MG at 6 mg/kg on the 1st, 4th and 7th days and at 2 mg/kg on the 10th day, also totalizing 20 mg/kg/animal by treatment end. The Nano-D-AMB-MG group was submitted to an AC magnetic field, allowing the induction of magnetohyperthermia. The evaluations were through paw diameter measurements; parasite number and cell viability were investigated by limiting dilution assay. D-AMB-coated PLGA–DMSA nanoparticles showed the same efficacy as free D-AMB to reduce paw diameter; however, the Nano-D-AMB treatment also promoted a significantly greater reduction in parasite number and cell viability compared with free D-AMB. The nano-drug AMB delivery system appeared more effective than free D-AMB therapy to reduce the dose frequency required to achieve the same therapeutic level. It thus favors a longer interval between doses, as expected with development of a new nano drug delivery system, and may be useful in the treatment of many different pathologies, from cancer to neurodegenerative diseases.     

High levels of Cellular Prion Protein improve astrocyte development

Prion protein (PrP^C) has neuroprotective functions and herein we demonstrate that astrocytes from PrP^C-over-expressing mice are more resistant to induced cell death than wild-type astrocytes. The Stress-Inducible-Protein 1 (STI1), a PrP^C ligand, prevents cell death in both wild-type and PrP^C-over-expressing astrocytes through the activation of protein-kinase-A. Cultured embryonic astrocytes and brain extracts from PrP^C-over-expressing mice show higher glial fibrillary acidic protein expression and reduced vimentin and nestin levels when compared to wild-type astrocytes, suggesting faster astrocyte maturation in the former mice. Our data indicate that PrP^C levels modulate astrocyte development, and that PrP^C–STI1 interaction contributes to protect against astrocyte death.     

Drastic changes in aquatic bacterial populations from the Cuatro Cienegas Basin (Mexico) in response to long-term environmental stress

Understanding the changes of aquatic microbial community composition in response to changes in temperature and ultraviolet irradiation is relevant for predicting biogeochemical modifications in the functioning of natural microbial communities under global climate change scenarios. Herein we investigate shifts in the bacterioplankton composition in response to long-term changes in temperature and UV radiation. For this purpose, 15 mesocosms were seeded with composite aquatic microbial communities from natural pools within the Cuatro Cienegas Basin (Mexican Chihuahuan desert) and were subject to different temperatures and UV conditions. 16S rRNA gene clone libraries were obtained from water samples at the mid-point (4 months) and the end of the experiment (8 months). An increase in bacterial diversity over time was found in the treatment of constant temperature and UV protection, which suggests that stable environments promote the establishment of complex and diverse bacterial community. Drastic changes in the phylogenetic bacterioplankton composition and structure were observed in response to fluctuating temperature and increasing UV radiation and temperature. Fluctuating temperature induced the largest decrease of bacterial richness during the experiment, indicating that frequent temperature changes drive the reduction in abundance of several species, most notably autotrophs. The long-term impact of these environmental stresses reduced diversity and selected for generalist aquatic bacterial populations, such as Porphyrobacter. These changes at the community level occur at an ecological time scale, suggesting that under global warming scenarios cascade effects on the food web are possible if the microbial diversity is modified.     

Burkholderia sp. SCMS54 reduces cadmium toxicity and promotes growth in tomato

Cadmium (Cd) can enter soil through the use of fertilisers, calcareous, pesticides and industrial and/or domestic effluents. Cd can leach into groundwater and be taken up by plants, potentially leading to reductions in plant growth and yield. In soil, plant roots interact with heavy metal (HM)‐tolerant microorganisms that may promote plant growth. Soil microorganisms may also be able to solubilise or mobilise soil metals, thereby acting as bioremediators. A better understanding of the interaction among plants, metals, microorganisms and soil will lead to improved plant tolerance. Two multi‐tolerant bacteria from the Burkholderia genus were isolated from Cd‐contaminated and Cd‐uncontaminated soil of a coffee plantation. In addition to its high tolerance to Cd, the strain SCMS54 produces indole‐acetic acid (IAA), solubilises inorganic phosphate and produces siderophores, demonstrating its potential to contribute to beneficial plant–microorganism interactions. When interacting with tomato plants exposed to Cd, the bacterium led to decreases in plant peroxide and chlorosis levels, promoted relative plant growth and decreased the root absorption of Cd, resulting in increased plant tolerance to this highly toxic HM. The results indicated that the inoculation of tomato plants with Burkholderia sp. SCMS54 promotes better growth in plants cultivated in the presence of Cd. This phenomenon appears to be attributed to a mechanism that decreases Cd concentrations in the roots via a beneficial interaction between the bacteria and the plant roots.     

XX/XO, a rare sex chromosome system in Potamotrygon freshwater stingray from the Amazon Basin, Brazil

Potamotrygonidae is a representative family of South American freshwater elasmobranchs. Cytogenetic studies were performed in a Potamotrygon species from the middle Negro River, Amazonas, Brazil, here named as Potamotrygon sp. C. Mitotic and meiotic chromosomes were analyzed using conventional staining techniques, C-banding, and detection of the nucleolus organizing regions (NOR) with Silver nitrate (Ag-NOR). The diploid number was distinct between sexes, with males having 2n = 67 chromosomes, karyotype formula 19m + 8sm + 10st + 30a, and fundamental number (FN) = 104, and females having 2n = 68 chromosomes, karyotype formula 20m + 8sm + 10st + 30a, and FN = 106. A large chromosome, corresponding to pair number two in the female karyotype, was missing in the male complement. Male meiotic cells had 33 bivalents plus a large univalent chromosome in metaphase I, and n = 33 and n = 34 chromosomes in metaphase II. These characteristics are consistent with a sex chromosome system of the XX/XO type. Several Ag-NOR sites were identified in both male and female karyotypes. Positive C-banding was located only in the centromeric regions of the chromosomes. This sex chromosome system, which rarely occurs in fish, is now being described for the first time among the freshwater rays of the Amazon basin.     

Effects of an evaporative cooling system on plasma cortisol, IGF-I, and milk production in dairy cows in a tropical environment

Access to an evaporative cooling system can increase production in dairy cows because of improved thermal comfort. This study aimed to evaluate the impact of ambient temperature on thermoregulation, plasma cortisol, insulin-like growth factor 1 (IGF-I), and productive status, and to determine the efficiency of an evaporative cooling system on physiological responses under different weather patterns. A total of 28 Holstein cows were divided into two groups, one with and the other without access to a cooling system with fans and mist in the free stall. The parameters were analyzed during morning (0700 hours) and afternoon milking (1430 hours) under five different weather patterns throughout the year (fall, winter, spring, dry summer, and rainy summer). Rectal temperature (RT), body surface temperature (BS), base of tail temperature (TT), and respiratory frequency (RF) were lower in the morning (P?<?0.01). The cooling system did not affect RT, and both the groups had values below 38.56 over the year (P?=?0.11). Cortisol and IGF-I may have been influenced by the seasons, in opposite ways. Cortisol concentrations were higher in winter (P?<?0.05) and IGF-I was higher during spring-summer (P?<?0.05). The air temperature and the temperature humidity index showed positive moderate correlations to RT, BS, TT, and RF (P?<?0.001). The ambient temperature was found to have a positive correlation with the physiological variables, independent of the cooling system, but cooled animals exhibited higher milk production during spring and summer (P?<?0.01).