Thermoset phenolic matrices reinforced with unmodified and surface-grafted furfuryl alcohol sugar cane bagasse and curaua fibers: properties of fibers and composites

Composites based on phenolic matrices and unmodified and chemically modified sugar cane bagasse and curaua fibers were prepared. The fibers were oxidized by chlorine dioxide, mainly phenolic syringyl and guaiacyl units of the lignin polymer, followed by grafting furfuryl alcohol (FA), which is a chemical obtained from a renewable source. The fibers were widely characterized by chemical composition analysis, crystallinity, UV-vis diffuse reflectance spectroscopy, SEM, DSC, TG, tensile strength, and 13C CP-MAS NMR. The composites were analyzed by SEM, impact strength, and DMA. The SEM images and DMA results showed that the oxidation of sugar cane bagasse fibers followed by reaction with FA favored the fiber/matrix interaction at the interface. The same chemical modification was less effective for curaua fibers, probably due to its lower lignin content, since the reaction considered touches mainly the lignin moiety. The tensile strength results obtained showed that the fibers were partially degraded by the chemical treatment, decreasing then the impact strength of the composites reinforced with them. In the continuity of the present project, efforts has been addressed to the optimization of fiber surface modification, looking for reagents preferably obtained from renewable resources and for chemical modifications that intensify the fiber/matrix interaction without loss of mechanical properties.     

Candida sergipensis, a new asexual yeast species isolated from frozen pulps of tropical fruits

Sixteen strains of the new yeast species Candida sergipensis have been isolated from frozen pulps of the tropical fruits umbú ( Spondias tuberosa Avr. Cam.) and mangaba ( Hancornia speciosa Gom.). Candida sergipensis was one of the prevalent species in the yeast community of these substrates. The new asexual ascomycetous yeast is phylogenetically related to Candida spandovensis and Candida sorbophila, species belonging to the Wickerhamiella clade, as evidenced by the sequences of the D1/D2 domains of their large subunit ribosomal DNAs. The species C. sergipensis and C. spandovensis can be separated on the basis of growth on 50% glucose agar, xylose and succinate, negative for the first species and positive for the second. The type culture is strain UFMG-R188 (CBS 9567).     

Praziquantel and albendazole damaging action on in vitro developing Mesocestoides corti (Platyhelminthes: Cestoda)

Parasitic flatworms present several steps of body architecture rearrangement during their fast transition from one developmental stage to another, which are, at least in part, responsible for their evasion from host immune response. Besides, different developmental stages present different degrees of susceptibility to drug action, and the identification of more susceptible stages is of importance for the definition of therapeutical approaches. Mesocestoides corti (syn. Mesocestoides vogae) is considered a good model to study cestode biology because it can be easily manipulated both in vivo and in vitro and due to its relatively close relationship to cestodes of medical relevance, such as those from genera Echinococcus or Taenia. We have analyzed the damaging action of two broad spectrum anthelmintic drugs (praziquantel and albendazole) throughout the in vitro strobilization process of M. corti in order to identify developmental stages or body structures more susceptible to these drugs. Tetrathyridia (larval stage) and segmented-induced worms were cultivated and treated with praziquantel and albendazole. Whole mounted samples, taken from different developmental stages, were fixed and stained with fluorophore-labeled WGA lectin and phalloidin for the analysis of tegument and muscles, respectively. Confocal laser scanning microscopy was used to identify anatomical changes and lesions caused by each anthelmintic drug in a 3D view. We demonstrated that both praziquantel and albendazole cause extensive tissue damage, especially on tegument, and that adult forms were the most susceptible to drug exposure.     

Structural characterization of novel chitin-binding lectins from the genus Artocarpus and their antifungal activity

Two novel chitin-binding lectins from seeds of Artocarpus genus were described in this paper, one from A. integrifolia (jackfruit) and one from A. incisa (breadfruit). They were purified from saline crude extract of seeds using affinity chromatography on chitin column, size-exclusion chromatography and reverse-phase chromatography on the C-18 column. Both are 14 kDa proteins, made up of 3 chains linked by disulfide bonds. The partial amino acid sequences of the two lectins showed they are homologous to each other but not to other plant chitin-binding proteins. Thus, they cannot be classified in any known plant chitin-binding protein family, particularly because of their inter-chain covalent bonds. Their circular dichroism spectra and deconvolution showed a secondary structure content of beta-sheet and unordered elements. The lectins were thermally stable until 80 degrees C and structural changes were observed below pH 6. Both lectins inhibited the growth of Fusarium moniliforme and Saccharomyces cerevisiae, and presented hemagglutination activity against human and rabbit erythrocytes. These lectins were denoted jackin (from jackfruit) and frutackin (from breadfruit).     

Heparin‐integrin interaction in endothelial cells: Downstream signaling and heparan sulfate expression

Endothelial cells (ECs) are a source of physiologically important molecules that are synthesized and released to the blood and/or to the subendothelial extracellular matrix such as a heparan sulfate proteoglycan (HSPG) with antithrombotic properties. Previously, we have shown that heparin stimulates the synthesis and modifies the sulfation pattern of this HSPG. Here the molecular mechanisms involved in the up‐regulation of HSPG synthesis by heparin in endothelial cells were decoded. The cells were stimulated with heparin and the expression of HSPG and intracellular pathways were evaluated by a combination of methods involving confocal microscopy, flow cytometry, Western blotting analyses, and [³⁵S]‐sulfate metabolically labeling of the cells. We observed that the up‐regulation of HSPG synthesis evoked by heparin is dependent on the interaction of heparin with integrin since RGD peptide abolishes the effect. The activation of integrin leads to tyrosine‐phosphorylation of focal adhesion‐associated proteins such as FAK, Src, and paxillin. In addition, heparin induces ERK1/2 phosphorylation and inhibitors of Ras and MEK decreased heparin‐dependent HSPG synthesis. Moreover, heparin also induced intracellular Ca²⁺ release, PLCγ1 (phospholipase Cγ1) and CaMKII (calcium calmodulin kinase II) activation, as well as an increase in nitric oxide (NO) production. Finally, an intracellular Ca²⁺ chelator, Ca²⁺ signaling inhibitors, and an endothelial NO synthase inhibitor were all able to abolish the effect in heparan sulfate synthesis. In conclusion, the heparin‐induced up‐regulation of HSPG expression is associated with the phosphorylation of focal adhesion proteins and Ras/Raf/MEK/ERK MAP and Ca²⁺/NO pathways. J. Cell. Physiol. 227: 2740–2749, 2012. © 2011 Wiley Periodicals, Inc.     

Impact of magnetic nanofillers in the swelling and release properties of κ-carrageenan hydrogel nanocomposites

Natural polysaccharides such as κ-carrageenan are an important class of biomaterials for drug delivery. The incorporation of magnetic nanoparticles in polysaccharide hydrogels is currently being explored as a strategy to confer to the hydrogels novel functionalities valuable for specific bio-applications. Within this context, κ-carrageenan magnetic hydrogel nanocomposites have been prepared and the effect of magnetic (Fe₃O₄) nanofillers in the swelling of the hydrogels and in the release kinetics and mechanism of a model drug (methylene blue) has been investigated. In vitro release studies demonstrated the applicability of the composites in sustained drug release. The mechanism controlling the release seems to be determined by the strength of the gel network and the extent of gel swelling, both being affected by the incorporation of nanofillers. Furthermore, it was demonstrated that the release rate and profile could be tailored using variable Fe₃O₄ nanoparticles load. Thus, this seems to be a promising strategy for the development of drug delivery systems with tailored released behavior.     

Low-dosage inhibition of Dll4 signaling promotes wound healing by inducing functional neo-angiogenesis

Recent findings regarding Dll4 function in physiological and pathological conditions indicate that this Notch ligand may constitute an important therapeutic target. Dll4 appears to be a major anti-angiogenic agent, occupying a central role in various angiogenic pathways. The first trials of anti-Dll4 therapy in mice demonstrated a paradoxical effect, as it reduced tumor perfusion and growth despite leading to an increase in vascular density. This is seen as the result of insufficient maturation of the newly formed vasculature causing a circulatory defect and increased tumor hypoxia. As Dll4 function is known to be closely dependent on expression levels, we envisioned that the therapeutic anti-Dll4 dosage could be modulated to result in the increase of adequately functional blood vessels. This would be useful in conditions where vascular function is a limiting factor for recovery, like wound healing and tissue hypoxia, especially in diabetic patients. Our experimental results in mice confirmed this possibility, revealing that low dosage inhibition of Dll4/Notch signaling causes improved vascular function and accelerated wound healing.     

Assessment of gastroenteric viruses frequency in a children's day care center in Rio De Janeiro, Brazil: a fifteen year study (1994-2008)

This 15-year study aimed to determine the role of the main viruses responsible for acute infantile gastroenteritis cases in a day care center in the city of Rio de Janeiro, Brazil. From 1994 to 2008, 539 fecal samples were obtained from 23 outbreaks as well as sporadic cases that occurred in this period. The detection of Rotavirus group A (RVA), norovirus (NoV) and astrovirus (AstV) was investigated both by classical and molecular methods of viral detection. RVA was detected by enzymatic immune assay and/or polyacrylamide gel electrophoresis and genotyped by using semi-nested multiplex PCR. NoV and AstV were subsequently tested by real time PCR in all RVA-negative samples and genotyped throughout genome sequencing. Three protocols for molecular characterization of NoV nucleotide sequencing were performed with the partial nucleotide sequencing of genomic regions known as region B (polymerase gen), C and D (capsid gen).Viruses were identified in 47.7% (257/539) of the cases, and the detection rates of RVA, NoV and AstV in16.1% (87/539), 33.4% (151/452), and 6.3% (19/301), respectively. Most gastroenteritis cases were reported in autumn and winter, although NoV presented a broader monthly distribution. Viruses' detection rates were significantly higher among children aged less than 24 months old, although NoV cases were detected in all age groups. RVA genotypes as G1P[8], G9P[8], G2P[4], G3P[8] and G1+G3P[8] and RVA was no longer detected after 2005. NoV characterization revealed genotypes variability circulating in the period as GI.2, GI.3, GI.8 GII.2, GII.3, GII.4, GII.4 variants 2001 and 2006b, GII.6, GII.7, GII.12 and GII.17. AstV genotypes 1, 2, 4 and 5 were also characterized. Those data demonstrate the impact of NoV infection in cases of infantile gastroenteritis, surpassing RVA infection responsible for high morbidity rate in children under five years old.