Durability of Microtensile Bond to Nonetched and Etched Feldspar Ceramic: Self-adhesive Resin Cements vs Conventional Resin

Purpose: The objective of this study was to evaluate the effect of thermocycling (TC), self-adhesive resin cements and surface conditioning on the microtensile bond strength (mu TBS) between feldspathic ceramic blocks and resin cements.Materials and Methods: Fifty-six feldspathic ceramic blocks (10 x 7 x 5 mm) (Vita Mark II) were divided into groups according to the factors "resin cement" (3 cements) and "surface conditioning" (no conditioning or conditioning [10% hydrofluoric acid etching for 5 min + silanization]) (n = 8): group 1: conditioning+Variolink II (control group); group 2: no conditioning+Biscem; group 3: no conditioning+RelyX U100; group 4: no conditioning+Maxcem Elite; group 5: conditioning+Biscem; group 6: conditioning+RelyX U100; group 7: conditioning+Maxcem Elite. The ceramic-cement blocks were sectioned to produce non-trimmed bar specimens (adhered cross-sectional area: 1 +/- 0.1 mm(2)), which were divided into two storage conditions: dry, mu TBS immediately after cutting; TC (12,000x, 5 degrees C/55 degrees C). Statistical significance was deterimined using two-way ANOVA (7 strategies and 2 storage conditions) and the post-hoc Tukey test (p<0.05).Results: Resin cement and thermocycling affected the mu TBS significantly (p = 0.001). In the dry condition, group 5 (18 +/- 6.5 MPa) presented the lowest values of mu TBS when compared to the other groups. TC decreased the mean mu TBS values significantly (p<0.05) for all resin cements tested (9.7 +/- 2.3 to 22.1 +/- 6.3 MPa), except for the resin cement RelyX U100 (22.1 +/- 6.3 MPa). In groups 3 and 4, it was not possible to measure mu TBS, since these groups had 100% pre-test failures during sectioning. Moreover, the same occurred in group 2 after TC, where 100% failure was observed during thermocycling (spontaneous failures).Conclusion: Hydrofluoric acid etching and silanization of the feldspathic ceramic surface are essential for bonding self-adhesive resin cement to a feldspathic ceramic, regardless of the resin cement used. Non-etched ceramic is not recommended.

Integrability vs supersymmetry: Poisson structures of the pohlmeyer reduction

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

cAMP signaling pathway controls glycogen metabolism in Neurospora crassa by regulating the glycogen synthase gene expression and phosphorylation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A systematic approach to identify STRE-binding proteins of the gsn glycogen synthase gene promoter in Neurospora crassa

The gene encoding glycogen synthase in Neurospora crassa (gsn) is transcriptionally down-regulated when mycelium is exposed to a heat shock from 30 to 45 degrees C. The gsn promoter has one stress response element (STRE) motif that is specifically bound by heat shock activated nuclear proteins. In this work, we used biochemical approaches together with mass spectrometric analysis to identify the proteins that bind to the STRE motif and could participate in the gsn transcription regulation during heat shock. Crude nuclear extract of heat-shocked mycelium was prepared and fractionated by affinity chromatography. The fractions exhibiting DNA-binding activity were identified by electrophoretic mobility shift assay (EMSA) using as probe a DNA fragment containing the STRE motif DNA-protein binding activity was confirmed by Southwestern analysis. The molecular mass (MM) of proteins was estimated by fractionating the crude nuclear extract by SDS-PAGE followed by EMSA analysis of the proteins corresponding to different MM intervals. Binding activity was detected at the 30-50 MM kDa interval. Fractionation of the crude nuclear proteins by IEF followed by EMSA analysis led to the identification of two active fractions belonging to the pIs intervals 3.54-4.08 and 6.77-7.31. The proteins comprising the MM and pI intervals previously identified were excised from a 2-DE gel, and subjected to mass spectrometric analysis (MALDI-TOF/TOF) after tryptic digestion. The proteins were identified by search against the MIPS and MIT N. crassa databases and five promising candidates were identified. Their structural characteristics and putative roles in the gsn transcription regulation are discussed.

A Genome-wide Screen for Neurospora crassa Transcription Factors Regulating Glycogen Metabolism

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ambient pH Controls Glycogen Levels by Regulating Glycogen Synthase Gene Expression in Neurospora crassa. New Insights into the pH Signaling Pathway

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Size, taxonomic and biomass distributions of flying insects in Central Amazonia: Forest edge vs. understory

Significantly more individuals and biomass of flying insects were present at the forest edge than in the understory throughout the year, as monitored by flight interception traps, in Central Amazonia. Numbers and biomass of flying insects increased at higher rates at the edge with rainfall, associated with termite swarming behavior and increased Homopteran density. The most abundant insects were Diptera, Coleoptera, Hymenoptera and Isoptera, whose ranked abundances varied with respect to forest edge and understory, as well as with season.

Purification and properties of acid phosphatase (EC 3.1.3.2) secreted by strain 74A of the mould Neurospora crassa

Both P-i-repressible acid phosphatases, IIb (mycelial) and IIc (extracellular), synthesized by Neurospora crassa and purified to apparent homogeneity by 7.5% PAGE, are monomers, are inhibited by 2 mM ZnCl2 and are nonspecifically stimulated by salts. However, the IIc form is activated by p-nitrophenylphosphate (in a negative cooperativity effect with a K-0.5 of 2.5 mM) whereas form IIb shows Michaelis kinetics, with a K-m of 0.5 mM. Thus, since both enzymatic forms may be expressed by the same gene (pho-3), it is possible that post-translational modifications lead to the excretion of an enzymatic form with altered Michaelis kinetics compared with the enzymatic form retained by the mycelium.

Biochemical characterization of Neurospora crassa glycogenin (GNN), the self-glucosylating initiator of glycogen synthesis

Glycogenin acts in the initiation step of glycogen biosynthesis by catalyzing a self-glucosylation reaction. In a previous work [de Paula et al., Arch. Biochem. Biophys. 435 (2005) 112-124], we described the isolation of the cDNA gnn, which encodes the protein glycogenin (GNN) in Neurospora crassa. This work presents a set of biochemical and functional studies confirming the GNN role in glycogen biosynthesis. Kinetic experiments showed a very low GNN K-m (4.41 mu M) for the substrate UDP-glucose. Recombinant GNN was produced in Escherichia coli and analysis by mass spectroscopy identified a peptide containing an oligosaccharide chain attached to Tyr196 residue. Site-directed mutagenesis and functional complementation of a Saccharomyces cerevisiae mutant strain confirmed the participation of this residue in the GNN self-glucosylation and indicated the Tyr198 residue as an additional, although less active, glucosylation site. The physical interaction between GNN and glycogen synthase (GSN) was analyzed by the two-hybrid assay. While the entire GSN was required for full interaction, the C-terminus in GNN was more important. Furthermore, mutation in the GNN glucosylation sites did not impair the interaction with GSN. (c) 2005 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

Molecular and biochemical characterization of the Neurospora crassa glycogen synthase encoded by the gsn cDNA

Glycogen synthases catalyze the transfer of a glucosyl moiety from a nucleotide phosphosugar to a nascent glycogen chain via an alpha1-->4 linkage. Although many genes coding for glycogen synthases have been described, the enzymes from rabbit and yeast are the best characterized. The fungus Neurospora crassa accumulates glycogen during exponential growth, and mobilizes it at the onset of stationary phase, or when placed at high temperature or starved for carbon. Through a PCR methodology, the gsn cDNA coding for the N. crassa glycogen synthase was isolated, and the amino acid sequence of the protein was deduced. The product of the cDNA seems to be the only glycogen synthase present in N. crassa. Characterization of the gsn cDNA revealed that it codes for a 706-amino acids protein, which is very similar to mammalian and yeast glycogen synthases. Gene expression increased during exponential growth, reaching its maximal level at the end of the exponential growth phase, which is consistent with the pattern of glycogen synthase activity and glycogen level. Expression of the gsn is highly regulated at the transcriptional level. Under culture conditions that induce heat shock, conidiation, and carbon starvation, expression of the gsn gene was decreased, and glycogen synthase activity and glycogen content behaved similarly.

Study of pulmonary experimental paracoccidioidomycosis by analysis of bronchoalveolar lavage cells: Resistant vs. susceptible mice

Adult Swiss (susceptible) and BALB/c (non-susceptible) mice were inoculated by the intravenous route with 1 x 10(6) yeast cells of Paracoccidioides brasiliensis, strain 18. Immunologic parameters, histopathology and features of the bronchoalveolar lavage (BAL) were evaluated at week 2, 4, 8 and 16 post-infection. The pulmonary infection was progressive in Swiss mice and regressive in BALB/c mice. The numbers of total cells, lymphocytes and polymorphonuclear neutrophils increased in BAL, as well as the percentages of giant cells, and CD4 and CD8 positive cells. The ultrastructural study of BAL cells revealed a predominance of macrophages and a frequency of 13.2% of type II pneumocytes. As the infection progressed, the number of fungal cells and spreading macrophages, as well as the stimulated release of H2O2 by macrophages, increased. The animals exhibited an exacerbation of the humoral immune response and a depression of cellular immunity during the infection. There was a good correlation between the intensity and the pattern of the pulmonary histopathology and the cellular findings in the BAL. The present model reproduces some anatomoclinical patterns of the human disease and shows that BAL may be a useful tool in monitoring the pulmonary infection caused by P. brasiliensis.