Fungal communities in Brazilian cassava tubers and food products.

Cassava (Manihot esculenta Crantz) is one of the most widely cultivated foods in the world and is of great socio-economic importance, especially in developing countries. It is predominantly consumed in boiled form, but also is used to produce a number of products, including cassava starch, sour starch, cassava flour and tapioca flour (hydrated cassava starch). Fungal spoilage can occur throughout the production chain, impairing both productivity and quality, as well as posing a potential risk of contamination by mycotoxins. We used multidisciplinary approaches based on phenotypic and molecular data (ITS/BenA/TEF-1a/RPB2 loci) to investigate the mycobiota of 101 samples (including roots, soil and products) collected in the state of São Paulo, Brazil. A total of 20 fungal groups/genera were morphologically characterized, and 37 different species were molecularly identified. The predominant groups in cassava tubers were Fusarium spp., Penicillium spp. and Trichoderma spp. In cassava products, the most frequent groups were Penicillium spp. and Paecilomyces spp. Potentially toxigenic species were also found, including Paecilomyces saturatus, Penicillium citrinum, P. paneum, P. brevicompactum, P. chrysogenum, Fusarium foetens and Fusarium mundagurra. In soil-cultivated cassava samples, the groups found most frequently were Penicillium spp., Cladosporium spp. and Fusarium spp. Some of the species found in cassava tubers and/or product samples were also present in the soil, including F. mundagurra, Neocosmospora solani, P. citrinum and P. brevicompactum. In general, there was a higher occurrence of Penicillium spp., Fusarium spp. and Trichoderma spp., and the predominant species were F. fabacearum and P. citrinum. The mycobiota of Brazilian cassava proved to be extremely diverse, and the occurrence of several species in cassava tubers and/or products are reported herein for the first time. Potentially toxigenic species were found in cassava tubers, cassava products and soil, showing how important it is to constantly monitor these substrates.

Aspergillus section Flavi and aflatoxins in Brazilian cassava (Manihot esculenta Crantz) and products.

Aflatoxins are carcinogenic compounds produced by some species of Aspergillus, especially those belonging to Aspergillus section Flavi. Their occurrence in food may start in the field, in the post-harvest, or during storage due to inadequate handling and storage. Because cassava is a staple food for a high percentage of the Brazilian population, we evaluated the presence of aflatoxin-producing species in cassava tubers, cassava products (cassava flour, cassava starch, sour starch, and tapioca flour), and in soil samples collected from cassava fields. In addition, the levels of aflatoxin contamination in cassava products were quantified. A total of 101 samples were analyzed, and 45 strains of Aspergillus section Flavi were isolated. Among the identified species, Aspergillus flavus, Aspergillus arachidicola, Aspergillus novoparasiticus, and Aspergillus parasiticus were found. The majority of strains (73.3%) tested for their aflatoxin-producing ability in synthetic media was positive. Despite that, cassava and cassava products were essentially free of aflatoxins, and only one sample of cassava flour contained traces of AFB1 (0.35 µg/kg).

Tuning Fe3O4 nanoparticle dispersion through pH in PVA/guar gum/electrospun membranes.

Polyvinyl Alcohol (PVA)/guar gum (GG) membranes with different loads of paramagnetic iron oxide Fe3O4 nanoparticles were successfully electrospun using both non-alkaline and alkaline stock solutions. The nanoparticle homogeneity distribution was clearly enhanced in fibers obtained from alkaline stock solutions. This is mainly due to the interaction between GG and the metallic ion, which also leads to further dispersion of remained uncoated nanoparticles in the mixture. It was also noticed that GG favors nanoparticle stability in the mixture and contributes to nanoparticle encapsulation. X-ray results showed that all membranes were semi-crystalline. FTIR-ATR spectra showed that Fe-O absorption band intensity improved with increasing nanoparticle load, reaching saturation at 3.5mg/ml Fe3O4 concentration under alkaline conditions. VSM analyses showed that the nanoparticles are paramagnetic and were successfully incorporated by the fibers. In vitro biocompatibility tests using L929 cells indicates adequate levels of cytotoxicity and cell adhesion/proliferation assays for both membranes obtained from non-alkaline and alkaline stock solutions. Therefore, they have potential for biomedical applications as biodegradable wound dressing.

Chemically sulfated galactomannan from Dimorphandra gardneriana seed: characterization and toxicity evaluation.

Dimorphandra gardneriana galactomannan (DG) was sulfated in pyridine:formamide using chlorosulfonic acid as the sulfation agent. The degree of substitution was 0.32, determined from the sulfur percentage. Confirmation of sulfation was obtained by FTIR spectroscopy through the presence of an asymmetrical SO stretching vibration at 1,259 cm(-1). NMR data showed that the sulfation occurred on primary hydroxyl groups. NMR and GPC data indicate degradation during reaction with elimination of galactose. At the maximum tested concentration of 1,000 µg/mL, unmodified DG polysaccharide did not show a statistically significant cytotoxicity in Vero cells by the MTT method. Therefore, the CC50>1,000 µg/mL obtained for the sulfated polysaccharides from D. gardneriana in Vero cells point to its lower cytotoxicity than the sulfated galactomannan from Mimosa scabrella.

Electronic properties and charge transfer phenomena in Pt nanoparticles on γ-Al2O3: size, shape, support, and adsorbate effects.

This study presents a systematic detailed experimental and theoretical investigation of the electronic properties of size-controlled free and γ-Al(2)O(3)-supported Pt nanoparticles (NPs) and their evolution with decreasing NP size and adsorbate (H(2)) coverage. A combination of in situ X-ray absorption near-edge structure (XANES) and density functional theory (DFT) calculations revealed changes in the electronic characteristics of the NPs due to size, shape, NP-adsorbate (H(2)) and NP-support interactions. A correlation between the NP size, number of surface atoms and coordination of such atoms, and the maximum hydrogen coverage stabilized at a given temperature is established, with H/Pt ratios exceeding the 1 : 1 ratio previously reported for bulk Pt surfaces.

In situ coarsening study of inverse micelle-prepared Pt nanoparticles supported on γ-Al2O3: pretreatment and environmental effects.

The thermal stability of inverse micelle prepared Pt nanoparticles (NPs) supported on nanocrystalline γ-Al(2)O(3) was monitored in situ under different chemical environments (H(2), O(2), H(2)O) via extended X-ray absorption fine-structure spectroscopy (EXAFS) and ex situ via scanning transmission electron microscopy (STEM). Drastic differences in the stability of identically synthesized NP samples were observed upon exposure to two different pre-treatments. In particular, exposure to O(2) at 400 °C before high temperature annealing in H(2) (800 °C) was found to result in the stabilization of the inverse micelle prepared Pt NPs, reaching a maximum overall size after moderate coarsening of ∼1 nm. Interestingly, when an analogous sample was pre-treated in H(2) at ∼400 °C, a final size of ∼5 nm was reached at 800 °C. The beneficial role of oxygen in the stabilization of small Pt NPs was also observed in situ during annealing treatments in O(2) at 450 °C for several hours. In particular, while NPs of 0.5 ± 0.1 nm initial average size did not display any significant sintering (0.6 ± 0.2 nm final size), an analogous thermal treatment in hydrogen leads to NP coarsening (1.2 ± 0.3 nm). The same sample pre-dosed and annealed in an atmosphere containing water only displayed moderate sintering (0.8 ± 0.3 nm). Our data suggest that PtO(x) species, possibly modifying the NP/support interface, play a role in the stabilization of small Pt NPs. Our study reveals the enhanced thermal stability of inverse micelle prepared Pt NPs and the importance of the sample pre-treatment and annealing environment in the minimization of undesired sintering processes affecting the catalytic performance of nanosized particles.

Atividade anti-HSV-1 in vitro de galactomanana quimicamente sulfatada de sementes de Leucaena leucocephala / In vitro anti-HSV-1 activity of a chemically sulfated galactomannan from Leucaena leucocephala seeds

Obteve-se uma galactomanana quimicamente sulfatada (LLS-2) a partir de polissacarídeo extraído de sementes de Leucaena leucocephala, a qual apresentou 15.2% de sulfato e grau de derivatização de 0,60, e, seu efeito antiviral sobre a replicação do vírus Herpes simplex tipo 1 (HSV-1) em células Vero foi avaliado pela metodologia de redução do número de unidades formadoras de placas. LLS-2 apresentou 93.7% de inibição da replicação viral à concentração de 2,5 ?g/ml, quando adicionado durante as etapas iniciais de replicação, com um índice de seletividade maior que 1.000, sugerindo que LLS-2 inibe a ligação de HSV-1 às células hospedeiras.

A galactomannan extracted from the seeds of Leucaena leucocephala was sulfated chemically, yielding a polymer (LLS-2) with 15.2% sulfate by weight (degree of sulfation 0.60), and its effect on the replication of Herpes simplex virus 1 (HSV-1) in Vero cells was investigated. When added during infection and early replication, LLS-2 showed 93.7% inhibition of HSV-1 replication at a concentration of 2.5 ?g/mL, according to the reduction in the number of viral plaques, and a selectivity index higher than 1,000, suggesting that it inhibits HSV-1 binding to the host cell.

Surgical and endovascular treatment of unruptured cerebral aneurysms at university hospitals.

OBJECTIVE: To compare complications of surgical clipping and coil embolization in the treatment of unruptured aneurysms. BACKGROUND: Surgical clipping has been the preferred treatment for unruptured cerebral aneurysms but endovascular coil embolization is an increasingly employed alternative. No direct comparisons of the techniques are available to guide clinical decision making. METHODS: We performed a cohort study of patients treated for unruptured cerebral aneurysms at 60 university hospitals from January 1994 through June 1997 using the University HealthSystem Consortium database. The database was validated by chart review from one of the participant universities. The main outcome measures were in-hospital mortality and adverse outcomes, defined as in-hospital deaths and discharges to nursing homes or rehabilitation hospitals. RESULTS: The primary treatment modality was surgical in 2,357 cases and endovascular in 255 cases. Adverse outcomes were significantly more common in surgical cases (18.5%) compared to endovascular cases (10.6%) (p = 0.002), and the difference was not altered after adjusting for age, sex, race, transfer admissions, emergency room admissions, and year of treatment (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.4 to 3.3; p = 0.001). In-hospital mortality was also increased in surgical cases (2.3% versus 0.4%; p = 0.039), but the difference was not significant in the multivariable model (OR 6.3, 95% CI 0.9 to 46.1; p = 0.07). Length of stay and hospital charges were significantly greater for surgical cases (p < 0.0001 for each), and these differences were not affected by risk adjustment. CONCLUSION: Endovascular coil embolization resulted in fewer adverse outcomes than surgery for unruptured cerebral aneurysms treated at the university hospitals studied. Although these results should be seen as preliminary, the magnitude of difference and current predominance of surgery appear to justify a randomized trial.