Sodium trimetaphosphate and hexametaphosphate impregnated with silver nanoparticles: characteristics and antimicrobial efficacy

This study aimed to synthesize and characterize materials containing silver nanoparticles (AgNP) with polyphosphates (sodium trimetaphosphate (TMP) or sodium hexametaphosphate (HMP), and evaluate their effect against Candida albicans and Streptococcus mutans. The minimum inhibitory concentration (MIC) was determined, which was followed by the quantification of the biofilm by counting colony-forming units (CFUs), the amount of metabolic activity, and the total biomass. The MICs revealed greater effectiveness of composites containing 10% Ag (TMP + Ag10% (T10) and HMP + Ag10% (H10)) against both microorganisms. It was observed that T10 and H10 reduced the formation of biofilms by 56–76% for C. albicans and by 52–94% for S. mutans for total biomass and metabolic activity. These composites promoted significant log reductions in the number of CFUs, between 0.45–1.43 log₁₀ for C. albicans and 2.88–3.71 log₁₀ for S. mutans (p < .001). These composites demonstrated significant antimicrobial activity, especially against S. mutans, and may be considered a potential alternative for new dental materials.     

Novel Myxobolus and Ellipsomyxa species (Cnidaria: Myxozoa) parasiting Brachyplatystoma rousseauxii (Siluriformes: Pimelodidae) in the Amazon basin,Brazil

We describe two novel myxosporean parasites from Brachyplatystoma rousseauxii, an economically important freshwater catfish from the Amazon basin, Brazil. Myxobolus tapajosi n. sp., was found in the gill filaments of 23.5% of 17 fish, with myxospores round to oval in frontal view and biconvex in lateral view: length 15 (13.5–17) μm and width 10.7 (9.6–11.4) μm; polar capsules equal, length 5.8 (4.6–7.1) μm and width 3 (2.3–3.8) μm containing polar tubules with 6–7 turns. Ellipsomyxa amazonensis n. sp. myxospores were found floating freely or inside plasmodia in the gall bladder of 23.5% of fish. The myxospores were ellipsoidal with rounded extremities: length 12.8 (12.3–13.6) μm and width 7.6 (6.7–8.7) μm; with two equal, slightly pyriform polar capsules, length 3.8 (3.8–4.0) μm and width 3.1 (2.5–3.4) μm, containing polar tubules with 2–3 turns. We combined spore morphometry, small-subunit ribosomal DNA data, specific host, and phylogenetic analyses, to identify both of these parasites as new myxozoan species. Maximum likelihood and Bayesian analyses showed that Myxobolus tapajosi n. sp. clustered in a basal branch in a subclade of parasites from exclusively South American pimelodid fishes. Ellipsomyxa amazonensis n. sp. clustered within the marine Ellipsomyxa lineage, but we suspect that although the parasite was collected in freshwater, its hosts perform a large migration throughout the Amazon basin and may have become infected from a brackish/marine polychaete host during the estuary phase of its life.     

Strong distance-dependent effects for a spatially aggregated tropical species

A fundamental aspect of the Janzen–Connell Hypothesis (JCH) is that distance- and density-dependent mortality reduce the local dominance of species and cause regular rather than random or aggregated spatial patterns. Despite this explicit linkage between process and pattern, very few studies have explored how JCH processes translate into the spatial distributions of adult populations. In field experiments, we assessed germination, mortality and growth of conspecific and heterospecific seedlings beneath and away from Esenbeckia leiocarpa, a highly aggregated tropical tree species. We also investigated the effects of vertebrates using exclosures in the field, and the effects of pathogens in a soil sterilization shadehouse experiment. Germination of conspecifics underneath Esenbeckia was reduced by 64 % and mortality increased 28–123 % when compared to seedlings growing under other tree species; 99–100 % of Esenbeckia seedlings died under conspecifics. Heterospecifics were much less affected by Esenbeckia canopies. However, we found no evidence that either vertebrate herbivores or soil pathogens affected seed germination and seedling performance. Although many tropical tree species are aggregated, our results are the first to demonstrate strong negative distance-dependence for an aggregated species and one of the few to explore germination in the context of the JCH and show differences between conspecifics and heterospecifics, thus suggesting a broader role for Janzen–Connell processes as determinants of the distribution and abundance of tree species in tropical forests.     

Evaluation of Cytotoxic and Anti-Inflammatory Activities of Extracts and Lectins from Moringa oleifera Seeds

Background

The extract from Moringa oleifera seeds is used worldwide, especially in rural areas of developing countries, to treat drinking water. M. oleifera seeds contain the lectins cmol and WSMoL, which are carbohydrate-binding proteins that are able to reduce water turbidity because of their coagulant activity. Studies investigating the ability of natural products to damage normal cells are essential for the safe use of these substances. This study evaluated the cytotoxic and anti-inflammatory properties of the aqueous seed extract, the extract used by population to treat water (named diluted seed extract in this work), and the isolated lectins cmol and WSMoL.

Methodology/Principal Findings

The data showed that the aqueous seed extract and cmol were potentially cytotoxic to human peripheral blood mononuclear cells, while WSMoL and diluted seed extract were not cytotoxic. The M. oleifera aqueous seed extract and the lectins cmol and WSMoL were weakly/moderately cytotoxic to the NCI-H292, HT-29 and HEp-2 cancer cell lines and were not hemolytic to murine erythrocytes. Evaluation of acute toxicity in mice revealed that the aqueous seed extract (2.000 mg/kg) did not cause systemic toxicity. The aqueous seed extract, cmol and WSMoL (6.25 µg/mL) and diluted seed extract at 50 µg/mL exhibited anti-inflammatory activity on lipopolyssaccharide-stimulated murine macrophages by regulating the production of nitric oxide, TNF-α and IL-1β. The aqueous seed extract reduced leukocyte migration in a mouse model of carrageenan-induced pleurisy; the myeloperoxidase activity and nitric oxide, TNF-α and IL-1β levels were similarly reduced. Histological analysis of the lungs showed that the extract reduced the number of leukocytes.

Conclusion/Significance

This study shows that the extract prepared according to folk use and WSMoL may be non-toxic to mammalian cells; however, the aqueous seed extract and cmol may be cytotoxic to immune cells which may explain the immunosuppressive potential of the extract.     

Interaction between glutamatergic and nitrergic mechanisms mediating cardiovascular responses to L-glutamate injection in the diagonal band of Broca in anesthetized rats

In a previous study, we reported depressor and bradycardiac responses after L-glutamate (L-glu) microinjection into the diagonal band of Broca (dbB) in anesthetized rats. Here, we report the glutamatergic-receptor subtype mediating the cardiovascular effects evoked by L-glu injection into the dbB and the involvement of local nitric oxide (NO) mechanisms as well as peripheral effectors. Microinjections of 100 nL of L-glu (1, 27, 81, 130 or 200 nmol) into the dbB of urethane-anesthetized rats caused short-lasting depressor and bradycardiac responses. Responses were dose-related, with an ED(50) of approximately 81 nmol. This dose was used in later experiments. The cardiovascular responses to L-glu in the dbB were abolished by local pretreatment (100 nL) with the selective N-methyl-D-aspartic acid (NMDA) receptor antagonist LY235959 (4 nmol) but were not affected by pretreatment with the selective non-NMDA receptor antagonist NBQX (4 nmol). Responses to L-glu in the dbB were blocked by local pretreatment with the selective neuronal NO-synthase (nNOS) inhibitor N(omega)-propyl-L-arginine (NPLA, 0.04 nmol); the NO scavenger carboxy-PTIO (C-PTIO, 1 nmol) or the guanylate cyclase inhibitor ODQ (1 nmol). These results suggest that the microinjection of L-glu into the dbB of urethane-anesthetized rats causes dose-related depressor and bradycardiac responses through the NMDA receptor-NO-guanylate cyclase pathway.     

Histoplasmosis as cause of penile ulcer in acquired immune deficiency syndrome (AIDS): three case reports

Background Histoplasma capsulatum is the causative agent of American histoplasmosis. The relationship between disseminated histoplasmosis and AIDS has been well established. Widespread hematogenous dissemination of Histoplasma capsulatum in HIV positive patients can cause a plethora of clinical manifestations; virtually any organic system can be affected. However, genital ulceration by H. capsulatum in patients with AIDS is a real challenge during investigation of the infection due to the great variety of differential diagnoses that are involved. Method The diagnosis was performed by histopathologic study; H. capsulatum was detected by silver staining (Grocott staining) and confirmed by immunocytochemistry. Results We report three cases of histoplasmosis in patients with AIDS, in which we observed genital ulcers, an unusual form of presentation of this disease. In one of these cases, the treatment resulted in total cure. Conclusion The cases reported herein are to illustrate the plurality of pathologies and clinical manifestations, which may affect immunocompromised patients. The correct diagnosis of fungal diseases in these patients following well established treatment will improve the prognosis.     

Transferrin uptake may occur through detergent-resistant membrane domains at the cytopharynx of Trypanosoma cruzi epimastigote forms

Uptake of transferrin by epimastigote forms of the protozoan Trypanosoma cruzi occurs mainly through a cytostome/ cytopharynx, via uncoated endocytic vesicles that bud off from the bottom of the cytopharynx. We have here examined whether detergent-resistant membrane (DRM) domains might be involved in this process. Purified whole cell membrane fractions were assayed for cholesterol levels and used in dot blot analyses. Detergent-resistant membrane markers (cholera B toxin and anti-flotillin-1 antibody) presented positive reaction by dot blots in cholesterol-rich/ protein-poor membrane sub-fractions. The positive dot blot fraction was submitted to lipid composition analysis, showing composition similar to that of raft fractions described for other eukaryotic cells. Immunofluorescence assays allowed the localization of punctual positive signal for flotillin-1, matching the precise cytostome/ cytopharynx location. These data were confirmed by immunofluorescence assays with the co-localization of flotillin-1 and the transferrin uptake site. Our data suggest that DRM domains occur and are integrated at the cytostome/ cytopharynx of T. cruzi epimastigotes, being the main route for transferrin uptake.     

The involvement of tetA and tetE tetracycline resistance genes in plasmid and chromosomal resistance of Aeromonas in Brazilian strains

This study analyzed the involvement of tetA and tetE genes in the tetracycline resistance of 16 strains of genus Aeromonas, isolated from clinical and food sources. Polymerase chain reactions revealed that 37.5% of the samples were positive for tetA, and also 37.5% were tetE positive. One isolate was positive for both genes. Only the isolate A. caviae 5.2 had its resistance associated to the presence of a plasmid, pSS2. The molecular characterization of pSS2 involved the construction of its restriction map and the determination of its size. The digestion of pSS2 with HindIII originated two fragments (A and B) that were cloned separately into the pUC18 vector. The tetA gene was shown to be located on the HindIII-A fragment by PCR. After transforming a tetracycline-sensitive strain with pSS2, the transformants expressed the resistance phenotype and harbored a plasmid whose size was identical to that of pSS2. The results confirmed the association between pSS2 and the tetracycline resistance phenotype, and suggest a feasible dissemination of tetA and tetE among strains of Aeromonas. This study suggests the spreading tetA and tetE genes in Aeromonas in Brazil and describes a resistance plasmid that probably contributes to the dissemination of the resistance.