Modulatory effect of Byrsonima basiloba extracts on the mutagenicity of certain direct and indirect-acting mutagens in Salmonella typhimurium assays

Byrsonima basiloba A. Juss. species is a native arboreal type from the Brazilian cerrado (tropical American savanna), and the local population uses it to treat diseases, such as diarrhea and gastric ulcer. It belongs to the Malpighiaceae family, and it is commonly known as murici. Considering the popular use of B. basiloba derivatives and the lack of pharmacological potential studies regarding this vegetal species, the mutagenic and antimutagenic effect of methanol (MeOH) and chloroform extracts were evaluated by the Ames test, using strains TA97a, TA98, TA100, and TA102 of Salmonella typhimurium. No mutagenic activity was observed in any of the extracts. To evaluate the antimutagenic potential, direct and indirect mutagenic agents were used: 4 nitro-o-phenylenediamine, sodium azide, mitomycin C, aflatoxin B1, benzo[a]pyrene, and hydrogen peroxide. Both the extracts evaluated showed antimutagenic activity, but the highest value of inhibition level (89%) was obtained with the MeOH extract and strain TA100 in the presence of aflatoxin B1. Phytochemical analysis of the extracts revealed the presence of n-alkanes, lupeol, ursolic and oleanolic acid, (+)-catechin, quercetin-3-O-α-L-arabinopyranoside, gallic acid, methyl gallate, amentoflavone, quercetin, quercetin-3-O-(2″-O-galloyl)-β-D- galactopyranoside, and quercetin-3-O-(2″-O-galloyl)-α-L- arabinopyranoside. © 2008 Mary Ann Liebert, Inc.

PtSnIr/C anode electrocatalysts: Promoting effect in direct ethanol fuel cells

This study investigates the promoting effect of PtSnIr/C (1:1:1) electrocatalyst anode, prepared by polymeric precursor method, on the ethanol oxidation reaction in a direct ethanol fuel cell (DEFC). All of the materials used were 20% metal m/m on carbon. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Pt, PtOH 2, PtO 2, SnO 2 and IrO 2 at the electrocatalyst surface, indicating a possible decorated particle structure. X-ray diffractometry (XRD) analysis indicated metallic Pt and Ir as well as the formation of an alloy with Sn. Using the PtSnIr/C electrocatalyst prepared here with two times lower loading of Pt than PtSn/C E-tek electrocatalyst, it was possible to obtain the same maximum power density found for the commercial material. The main reaction product was acetic acid probably due to the presence of oxides, in this point the bifunctional mechanism is predominant, but an electronic effect should not be discarded. © 2012 Sociedade Brasileira de Química.

Effect of light curing modes on mechanical properties of direct and indirect composites

Objective. To evaluate the degree of conversion (DC), flexural strength (FS) and Knoop microhardness (KHN) of direct and indirect composite resins polymerized with different curing systems. Materials and methods. Specimens of direct (Z250, 3M/Espe) and indirect (Sinfony, 3M/Espe) restorative materials were made and polymerized using two light curing units: XL2500 (3M/Espe) and Visio system (3M/Espe). Absorption spectra of both composites were obtained on a FTIR spectrometer in order to calculate the DC. FS was evaluated in a universal testing machine and surface microhardness was performed in a microhardness tester (50gf/15s). DC, FS and KHN data were submitted to two-way ANOVA and Tukey's test (α = 0.05). Results. Z250 showed higher DC, FS and KHN compared with Sinfony when the polymerization was carried out with XL2500 (p < 0.05). However, there is no statistical difference in DC between the materials when Visio was used (p > 0.05). Visio showed higher DC and KHN for Z250 and Sinfony than the values obtained using XL2500 light curing (p < 0.05). For FS, no significant difference between curing units was found (p > 0.05). Conclusion. Even though the Visio system could increase DC and KHN for some direct and indirect composites, compared with the conventional halogen curing unit, a high number of monomers did not undergo conversion during the polymerization. © 2013 Informa Healthcare.

Differences in the hydroxylation pattern of flavonoids alter their chemoprotective effect against direct- and indirect-acting mutagens

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

The effect of alloying in Pt-Sn/C electrocatalysts in the performance of a direct ethanol fuel cell

Work on Pt-Sn-C catalysts for ethanol oxidation showed that a thermal treatment at moderate temperatures leads to a significant increase in activity. The best activity was observed for Pt3Sn1 thermally treated at 200 degrees C and ascribed to a Pt3Sn1 phase plus a cleaning effect. However, electronic effects may be very important and these were not evaluated in the Pt3Sn1 phase. Therefore, in this work we investigated the effect of the degree of alloy on the electronic structure of Pt3Sn1 electrocatalysts by performing electrochemical in situ X-ray absorption (XAS) experiments in the Pt L-III XANES region. Overall, the results show that although the occupancy of the Pt 5d band depends on the degree of alloy other factors, such as the presence of tin oxides/hydroxides in the materials, have to be considered to understand the performance of the DEFC.

Effect of neem extract on the cotton aphid

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

Influence of data structure on the estimation of the additive genetic direct and maternal covariance for early growth traits in Nellore cattle

The objective of the present study was to investigate the effect of data structure on estimated genetic parameters and predicted breeding values of direct and maternal genetic effects for weaning weight (WW) and weight gain from birth to weaning (BWG), including or not the genetic covariance between direct and maternal effects. Records of 97,490 Nellore animals born between 1993 and 2006, from the Jacarezinho cattle raising farm, were used. Two different data sets were analyzed: DI_all, which included all available progenies of dams without their own performance; DII_all, which included DI_all + 20% of recorded progenies with maternal phenotypes. Two subsets were obtained from each data set (DI_all and DII_all): DI_1 and DII_1, which included only dams with three or fewer progenies; DI_5 and DII_5, which included only dams with five or more progenies. (Co)variance components and heritabilities were estimated by Bayesian inference through Gibbs sampling using univariate animal models. In general, for the population and traits studied, the proportion of dams with known phenotypic information and the number of progenies per dam influenced direct and maternal heritabilities, as well as the contribution of maternal permanent environmental variance to phenotypic variance. Only small differences were observed in the genetic and environmental parameters when the genetic covariance between direct and maternal effects was set to zero in the data sets studied. Thus, the inclusion or not of the genetic covariance between direct and maternal effects had little effect on the ranking of animals according to their breeding values for WW and BWG. Accurate estimation of genetic correlations between direct and maternal genetic effects depends on the data structure. Thus, this covariance should be set to zero in Nellore data sets in which the proportion of dams with phenotypic information is low, the number of progenies per dam is small, and pedigree relationships are poorly known. (c) 2012 Elsevier B.V. All rights reserved.

Effect of Oral Supplementation of the Linoleic and Gammalinolenic Acids on the Diabetic Pregnant Rats

The aim of this work was to evaluate the direct protective action of oral fatty acid supplementation against the deleterious effect of hyperglycemia on maternal reproductive outcomes; fetal growth and development on female Wistar rats. The animals were distributed into four experimental groups: G1= non-diabetic without supplementation (Control group); G2= non-diabetic treated with linoleic (LA) and gammalinolenic acid (GLA) (1 mL of Gamaline-V/day); G3= diabetic without supplementation and G4= diabetic treated with LA and GLA. Diabetes was induced by streptozotocin (40 mg/kg). At day 21 of pregnancy, the gravid uterus was weighed and dissected to count the dead and live fetuses, resorption, implantation, and corpora lutea numbers. The fetuses were analyzed for external and internal anomalies. The treatment with Gamaline-V supplementation to diabetic rats interfered in the maternal reproductive outcome (reduced number of live fetuses and embryonic implantation); however, it protected the deleterious on the incidence of congenital anomalies caused by hyperglycemia.

Viability of OPS Vitrified Sheep Embryos After Direct Transfer

The aim of this study was to evaluate the viability in the effect of open pulled straw (OPS) vitrification procedure of sheep embryos after direct transference. Embryos were produced in vivo and cryopreserved in slow freezing or OPS vitrification. The survival rates of cryopreserved embryos were compared to non-frozen standard pattern. In a first set of experiments, embryos at morula and blastocyst stages were dived in ethylene glycol (1.5 M) and frozen in an automatic freezer. After being thawed, they were directly or indirectly transferred to ewes recipient. A second group of embryos were drawn into OPS and plunged into liquid nitrogen after being exposed at room temperature for 1 min and 45 s in 10% EG plus 10% dimethyl sulphoxide (DMSO), then again for 30 s in 20% EG + 20% DMSO + 0.5 M sucrose. After being warmed, embryos were also directly transferred using a French mini straw as the catheter for the transplantation process or after in vitro dilution of cryoprotectants (two-step-process). No significant difference was observed among fresh, frozen or vitrified embryos on pregnancy rate (50.0%, 38.6% and 55.8%). However, when we evaluated only the direct transference, the pregnancy rate of OPS vitrified embryos was higher than that of frozen embryos (57.1% vs 34.8%) (p = 0.07). In addition, vitrified morulae had a higher pregnancy rate than the one with frozen embryos (64.0% vs 38.9%) (p = 0.07). Finally, our results indicate that OPS vitrification technique in association with direct transference improves the viability of sheep embryos with potential applications to field conditions.

Direct and transdentinal antibacterial activity of chlorhexidine

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytotoxic effect of a 35% hydrogen peroxide bleaching gel on odontoblast-like MDPC-23 cells

Objective. This study evaluated transenamel and transdentinal cytotoxic effects of a bleaching gel on the MDPC-23 cell line.Study design. Discs obtained from bovine incisors were placed in a metallic device to simulate an in vivo pulp chamber. Groups were formed according to the enamel surface treatment: G1: 35% H(2)O(2) bleaching gel; G2: 35% H2O2 bleaching gel + halogen light; G3: halogen light; and G4: control. Cell metabolism was evaluated by the methyltetrazolium assay and cell morphology by scanning electron microscopy.Results. Cell metabolism decreased by 31.7%, 41.6%, and 11.5% in G1, G2, and G3, respectively. Cytotoxic effects observed in G2 were significantly more severe compared with G3 and G4. In G1 and G2, a smaller number of viable cells with major morphologic alterations remained adhered to dentin.Conclusion. The bleaching gel associated with light presented transenamel and transdentinal cytotoxic effects characterised by direct damage to odontoblasts and decrease of their metabolic activity. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 458-464)

In vitro effect of low-level laser on odontoblast-like cells

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

Subfornical organ mediates pressor effect of angiotensin: Influence of nitric oxide synthase inhibitors, AT(1) and AT(2) angiotensin antagonist's receptors

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Immunohistochemical detection of estrogen receptor beta in alveolar bone cells of estradiol-treated female rats: possible direct action of estrogen on osteoclast life span

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Differential effect of plant lectins on mast cells of different origins

Histamine release induced by plant lectins was studied with emphasis on the carbohydrate specificity, external calcium requirement, metal binding sites, and mast cell heterogeneity and on the importance of antibodies bound to the mast cell membrane to the lectin effect. Peritoneal mast cells were obtained by direct lavage of the rat peritoneal cavity and guinea pig intestine and hamster cheek pouch mast cells were obtained by dispersion with collagenase type IA. Histamine release was induced with concanavalin A (Con A), lectins from Canavalia brasiliensis, mannose-specific Cymbosema roseum, Maackia amurensis, Parkia platycephala, Triticum vulgaris (WGA), and demetallized Con A and C. brasiliensis, using 1-300 µg/ml lectin concentrations applied to Wistar rat peritoneal mast cells, peaking on 26.9, 21.0, 29.1, 24.9, 17.2, 10.7, 19.9, and 41.5%, respectively. This effect was inhibited in the absence of extracellular calcium. The lectins were also active on hamster cheek pouch mast cells (except demetallized Con A) and on Rowett nude rat (animal free of immunoglobulins) peritoneal mast cells (except for mannose-specific C. roseum, P. platycephala and WGA). No effect was observed in guinea pig intestine mast cells. Glucose-saturated Con A and C. brasiliensis also released histamine from Wistar rat peritoneal mast cells. These results suggest that histamine release induced by lectins is influenced by the heterogeneity of mast cells and depends on extracellular calcium. The results also suggest that this histamine release might occur by alternative mechanisms, because the usual mechanism of lectins is related to their binding properties to metals from which depend the binding to sugars, which would be their sites to bind to immunoglobulins. In the present study, we show that the histamine release by lectins was also induced by demetallized lectins and by sugar-saturated lectins (which would avoid their binding to other sugars). Additionally, the lectins also released histamine from Rowett nude mast cells that are free of immunoglobulins.