Effects of malathion and cadmium on acetylcholinesterase activity and metallothionein levels in the fish Seriola dumerilli

The potential use of acetylcholinesterase (AChE) and metallothionein (MT) responses as biomarker of organophosphorous (OPs) and trace metal were assessed in fish Seriola dumerilli exposed to 0, 4, 6 mg/kg of malathion for 2, 7 and 13 days, and to 0, 50, 100, 250 mu g/kg of Cd for 2 days. Brain AChE was significantly inhibited after 2 and 7 days of malathion exposure, in a dose-response manner, but no inhibition was observed after 13 days of exposure. When exposed to Cd for 2 days, S. dumerelli presented an increase in AChE activity at a concentration of 50 mu g/kg, but a strong and dose-dependent AChE inhibition at 100 and 250 mu g/kg. Cd treatment also caused a rapid increase in MTs concentration in liver, even at the lower concentration. Our experiments indicate that the measurement of hepatic MT concentration and brain AChE activity in S. dumerilli would be useful biomarkers of OP and Cd exposure and/or effects.

Modulation of coronary flow and cardiomyocyte size by sensory fibers

Cardiac tissue is densely innervated by sensory neurons that an believed to play important modulatory roles in cardiac functions. In this study, pretreatment of neonate mts with capsaicin was performed. In adult rats, cardiomyocyte size and amount of fibrous tissue in left ventricles as well as in vitro coronary flow were evaluated, the chronotropic and inotropic responses to beta-adrenoceptor agonists (norepinephrine and isoproterenol), muscarinic agonists (carbachol and pilocarpine), and calcitonin gene-related peptide (CGRP) were also investigated with the use of the isolated right atria preparation. Capsaicin pretreatment significantly (P<0.05) reduced both basal coronary flow (18% reduction) and cardiomyocyte size (34% reduction) without affecting the amount of fibrous tissues in the left ventricles. The positive inotropic and chronotropic effects in response to norepinephrine in the isolated rat heart did not significantly differ between control and capsaicin-treated rats, Similarly, the positive chronotropic effects in response to norepinephrine, isoproterenol, and CGRP as well as the negative chronotropic responses to carbachol and pilocarpine in the isolated light atria were not affected by capsaicin pretreatment, Our data are consistent with the suggestion that reductions of both basal coronary flow and cardiomyocyte size seen in hearts from capsaicin-pretreated rats may be consequences of CGRP depletion. The cardiomyocyte size reduction produced by capsaicin treatment may be related to a modulatory role of CGRP as a growth factor.

Correlation among immune response, morphogenesis of the granulomatous reaction and spleen lymphoid structure in murine experimental paracoccidioidomycosis

We studied the correlation among cellular immune response, the pattern of lung granulomatous lesions and alterations in spleen lymphoid structure in Swiss mice inoculated intravenously with Paracoccidioides brasiliensis strain 18. The animals were evaluated at 24, 48 and 96 h after infection and further studied weekly for 18 weeks by: (i) the macrophage migration inhibition test with phytohemagglutinin (PHA) and P. brasiliensis antigen (PbAg); and (ii) histopathology of the lung and spleen lesions. One group of animals was gamma -irradiated (8 Gy), infected under the same conditions and evaluated for the pattern of lung granulomatous lesions and spleen lymphoid structure at 24, 48 and 96 h after infection. During the first week of infection, the non-irradiated animals presented a positive response to PHA and PbAg, compact granulomas in the lungs and a typical hyperplasia of the spleen white pulp. However, from weeks 2 to 5, a depression of the cell-mediated immunity (CMI) response to PHA and PbAg was observed in association with granulomas presenting only large mononuclear cells and lacking both giant cells and a peripheral halo of small mononuclear cells. This pattern of granuloma formation was similar to that seen in gamma -irradiated animals, whose cells involved in CMI were absent. After week 7, the non-irradiated animals showed granulomas characterized by the presence of giant cells and a peripheral halo of small mononuclear cells. This type of granuloma was formed concomitantly with recovery of the CMI and of the lymphoid structure of the spleen. The results showed a correlation among granulomas composed of large mononuclear cells, hypoplasia of the splenic tissue and impaired CMI. This correlation indicated that although granuloma morphogenesis per se does not depend on the activation of CMI, this response is important at later stages during modulation of the cellular composition of the granulomas.

Fracture strength of bovine incisors after intra-radicular treatment with MTA in an experimental immature tooth model

Aim To evaluate, using an experimental immature tooth model, the fracture resistance of bovine incisors submitted to different reinforcement treatments with mineral trioxide aggregate (MTA).Methodology An immature tooth model was created by sectioning the coronal and apical portions of 40 bovine incisors 8 mm above and 12 mm below the cementoenamel junction. The root canals were irrigated with 1.0% sodium hypochlorite. They were enlarged both coronally and apically using number 703 carbide burs (ISO: 500-104-168-007-021) and their internal diameter was standardized to 2.1 mm. The specimens were assigned to four groups (n = 10): GI-control (without filling); GII-apical MTA plug + filling with gutta-percha and endodontic sealer; GIII-filling with MTA; GIV-apical MTA plug + filling with MTA + metallic post (Reforpost I). A polyether impression material was used to simulate the periodontal ligament. The specimens were submitted to a compressive load at a crosshead speed of 0.5 mm min(-1) in a servo-hydraulic universal testing machine (MTS 810) applied at 45 degrees to the long axis of the tooth until failure. Data were submitted to statistical analysis by the Kruskal-Wallis test at 5% significance level.Results GIV presented the highest fracture resistance (32.7N) and differed significantly from the other groups (P < 0.05). No statistically difference was found between GII (16.6N) and GIII (23.4N) (P > 0.05). GIII had a significantly higher fracture resistance than GI (P < 0.05).Conclusions the use of MTA + metallic post as an intra-radicular reinforcement treatment increased the resistance to fracture of weakened bovine teeth in an experimental immature tooth model.

Dialysable leukocyte extracts modify the course of experimental paracoccidioidomycosis in the Syrian hamster

The effect of dialysable leukocyte extracts (DLE) obtained from hamsters immunized with Paracoccidioides brasiliensis (immune DLE) and from non-immunized hamsters (non-immune DLE) was studied in hamsters inoculated with P. brasiliensis by the intratesticular route. Treatment with immune or non-immune DLE was started during the third week of infection and was repeated at 7, 11, 15 and 19 weeks. A group of untreated infected animals was used as control. Animals were submitted to the delayed hypersensitivity skin test to P. brasiliensis antigen (PbAg) in vivo and assayed in vitro by the macrophage migration inhibition test in the presence of Phytohemagglutinin (PHA) and PbAg and by immunodiffusion for specific antibody. The animals were sacrificed at 4, 8, 12, 16 and 20 weeks. The morphology and extension of the lesions were studied at the inoculation site, and in lymph nodes, lungs, liver, spleen and kidneys. In contrast to the controls, animals treated with both DLEs maintained a positive cell-mediated immune response throughout the experiment and developed less extensive infection with a significantly lower number of fungi in the lesions. The results suggest that immune and non-immune DLE preparations modified the evolution of experimental paracoccidioidomycosis with equal efficiency. This similarity may be explained by the immunoregulatory activities of both extracts.

CELL-MEDIATED AND HUMORAL IMMUNE-RESPONSES IN IMMUNIZED AND OR DERMATOBIA-HOMINIS INFESTED RABBITS

The cell-mediated and humoral immune response of rabbits to antigens from larvae of Dermatobia hominis were analyzed by leucocyte migration inhibition factor assay (MIF), immunodiffusion (ID) and passive hemagglutination (PH) test in rabbits immunized with D. hominis extract, in rabbits immunized and infested with the parasite and rabbits infested with D. hominis. Twenty rabbits were divided into five groups: Group 1, rabbits immunized with a crude antigen extract, evaluated for 40 weeks at 4 week intervals; Group 2, rabbits immunized and infested with newly hatched larvae at 14 weeks post immunization (PI) and evaluated as Group 1; Group 3, rabbits immunized, evaluated for 28 weeks at 2 week intervals; Group 4, rabbits immunized and infested at 4 weeks PI and evaluated as Group 3; Group 5, rabbits infested and evaluated for 24 weeks at 2 week intervals. Different patterns of reactivity were observed in the infested and immunized animals: immunized rabbits developed antibodies and cellular immune responses earlier and at higher levels during immunization than the infested rabbits; the infestation at 14 weeks PI, when the cell-mediated and humoral immune response began to decrease, or at 4 weeks PI when these parameters were at higher levels, elicited an anamnestic response. After the spontaneous elimination of larvae by the host, from the 4th week PI onwards, high titers of antibodies and migration inhibition indices were maintained for a long period. These results suggest that the onset of cellular and humoral immune responses after immunization may be important as a biological control of myiasis and contribute to better understanding of the immune defense mechanism of the host against D. hominis.

Role of Paracoccidioides brasiliensis cell wall fraction containing beta-glucan in tumor necrosis factor-alpha production by human monocytes: correlation with fungicidal activity

The polysaccharide fraction of Paracoccidioides brasiliensis mycelial cell wall (F1 fraction), the active component of which is composed of beta-glucan, was investigated in regard to the activation of human monocytes for fungal killing. The cells were primed with interferon-gamma (IFN-gamma) or F1 (100 and 200 mug ml(-1)) or F1 (100 and 200 mug ml(-1)) plus IFN-gamma for 24 h and then evaluated for H2O2 release. In other experiments, the cells were pretreated with the same stimuli, challenged with a virulent strain of P. brasiliensis and evaluated for fungicidal activity and levels of tumor necrosis factor (TNF-alpha) in the supernatants. F1 increased the levels of H2O2 in a similar manner to IFN-gamma. However, a synergistic effect between these two activators was not detected. on the contrary, a significant fungicidal activity was only obtained after priming with IFN-gamma plus F1. This higher activity was associated with high levels of TNF-alpha in the supernatants of the cocultures. Overall, P. brasiliensis F1 fraction induced human monocytes to release relatively high levels of TNF-alpha, which, in combination with IFN-gamma, is responsible for the activation of human monocytes for effective killing of P. brasiliensis.

Effect of cytokines on the in vitro fungicidal activity of monocytes from paracoccidioidomycosis patients

Peripheral blood monocytes obtained from paracoccidioidomycosis patients and healthy individuals were preactivated with recombinant gamma interferon (IFN-gamma) in different concentrations (250, 500 and 1000 U/ml) and evaluated for fungicidal activity against Paracoccidiodes brasiliensis strain 18 (Pb 18, high-virulence strain) and strain 265 (Pb 265, low-virulence strain) by plating of cocultures and counting of colony-forming units, after 10 d. Monocytes from healthy individuals failed to present fungicidal activity against P. brasiliensis even after IFN-gamma activation at the three concentrations. However, patient, monocytes activated with IFN-gamma (1 000 U/ml) showed a significant fungicidal activity when compared to that obtained with non-activated or activated cells with other IFN-gamma concentrations (250 and 500 U/ml). Moreover,,patient monocytes presented higher fungicidal activity than the control, even before the activation process. These results may be explained by the activation state of patients' cells as a function of the in vivo contact with the fungus, which was confirmed by their higher capacity to release H2O2 in vitro. Unlike the results obtained with Ph 18, patient and control cells presented a significant fungicidal activity against Pb 265, after priming with IFN-gamma. These results are explained by the higher levels of TNF-alpha in supernatants of cultures challenged with Pb 265. Moreover, higher levels of the cytokine were obtained in patient cell supernatants. Taken together, our results suggest that for effective killing of P. brasiliensis by monocytes, an initial activation signal induced by IFN-gamma is necessary to stimulate the cells to produce TNF-alpha. This cytokine may be involved, through an autocrine pathway, in the final phase activation process. The effectiveness of this process seems to depend on the virulence of the fungal strain and the activation state of the challenged cells. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All fights reserved.

The use of glucan as immunostimulant in the treatment of paracoccidioidomycosis

A group of 10 patients, nine of them seriously infected with Paracoccidioides brasiliensis (G1), received glucan (beta-1,3 polyglucose) as an immunostimulant intravenously once a week for one month, followed by monthly doses (10 mg) over an ii-month period, together with a specific anti-fungal agent as an immunostimulant. A second group of eight moderately infected patients (G2) was treated with only the anti-fungal agent. Among the patients in G1, there was only one case of relapse compared with five in G2. Values for the erythrocyte sedimentation rate (ESR) showed a significant difference (P < 0.01) post-treatment in G1 patients, when compared with the pretreatment levels. There was also a significant reduction (P < 0.001) in the level of serum antibodies to P. brasiliensis in the G1 patients in post-treatment examinations. The phytohemagglutinin (PHA) skin test showed a positive reaction among the patients in G1 (P < 0.01) post-treatment and there was a tendency towards an increase in the number of CD4+ T lymphocytes in both groups after treatment. The serum level of tumor necrosis factor (TNF) proved to be significantly higher (P < 0.02) in the G1 patients during treatment. In the G1 patients, the correlation between ESR and TNF tended to be negative whereas that between ESR and serum antibodies was positive. The present results indicate that the patients who received glucan, in spite of being more seriously ill, had a stronger and more favorable response to therapy.

Study of bronchoalveolar lavage fluid in paracoccidioidomycosis: cytopathology and alveolar macrophage function in response to gamma interferon; comparison with blood monocytes

Patients with paracoccidioidomycosis (PCM) present marked involvement of the lungs during the course of the mycosis. The purpose of this work was to obtain bronchoalveolar lavage (BAL) fluid from these patients to study the cytopathology, TNF levels and the oxidative and fungicidal response of alveolar macrophages (AMs) to in vitro incubation with recombinant IFN-gamma. To compare the lung and blood compartments, these determinations were also made in plasma and blood monocytes (BMs) obtained from the same patients. The cytopathology of BAL fluid revealed a predominance of macrophages, but with the presence of neurrophil exudation, and rare lymphocytes and epithelioid and giant cells. Comparison of the oxidative status and fungicidal activity of AMs and circulating BMs demonstrated that both cell types are highly activated for these two functions when compared to control cells. However, TNF levels were higher in BAL fluid than in plasma. The possible mechanisms involved in the hyperresponsiveness of cells from PCM patients are discussed. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

Effect of thermal treatments on tensile strength of commercially cast pure titanium and Ti-6Al-4V alloys

Heating titanium structures is assumed to relieve tensions induced by the casting process as well as possibly optimizing some mechanical properties. The aim of this investigation was to evaluate the effect of thermal treatments on tensile strength of commercially pure titanium (CP Ti) and Ti-6Al-4V alloy. Thirty dumbbell rods, with diameters of 3.0 mm at the central segment and lengths of 42 mm, were cast for each metal using the Rematitan System. CP Ti and Ti-6Al-4V specimens were randomly divided into three groups of ten: a control group that received no thermal treatment and two test groups. One (T1) was heated at 750°C for 2 h and the other (T2) was annealed at 955°C for 1 h and aged at 620°C for 2 h. Tensile strength was measured with a universal testing machine (MTS model 810). Tensile strength means and standard deviations were statistically compared using a Kruskal-Wallis test at a α = 0.05 significance level. No statistically significant differences in tensile strength were observed among CP Ti groups. For the Ti-6Al-4V alloy, the control and T1 groups revealed statistically higher tensile strengths when compared to the T2 group, with no significant difference between the control and T1 groups. © 2005 Springer Science + Business Media, Inc.

Effect of the association of nystatin with a tissue conditioner on its ultimate tensile strength

Purpose: This study evaluated the ultimate tensile strength of a tissue conditioner without nystatin incorporation (GI - control group) and the same tissue conditioner modified by the addition of nystatin in two concentrations: GII - 500,000 International Units (U) and GIII - 1,000,000 U, in which each milligram of the medicament corresponded to 6079 U. Materials and Methods: Dumbbell-shaped specimens (N = 7) with a central cross-sectional area of 33 × 6 × 3 mm were produced for the three experimental groups. After polymerization following manufacturer's instructions, specimens were immersed in distilled water at 37°C for either 24 hours or 7 days and then tested in tension in the MTS 810 at 40 mm/minute. Data were analyzed by two-way ANOVA followed by Tukey's test, at 95% level of confidence. Results: The means (force-grams (gf) ± standard deviation) of the ultimate tensile strength were: GI - 634.29 ± 122.80; GII - 561.92 ± 133.56; and GIII - 547.30 ± 73.47 for 24-hour storage, and GI - 536.68 ± 54.71; GII - 467.50 ± 143.51; and GIII - 500.62 ± 159.76 for 7-day storage. There were no statistically significant differences among the three experimental groups (p > 0.05). The ultimate tensile strength means of all experimental groups after 7 days were significantly lower than those observed after 24 hours (p = 0.04). Conclusions: The results of this study suggest that the addition of nystatin into the tissue conditioner investigated in concentrations below 1,000,000 U did not affect its ultimate tensile strength. Copyright © 2006 by The American College of Prosthodontists.

Influence of the final temperature of investment healting on the tensile strength and Vickers hardness of CP TI and TI-6AL-4V alloy

The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430°C (control group), 480°C and 530°C. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430°C, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50) and (352.95, 339.36, 344.76 - mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey' s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

Tensile bond strength of self-etching versus total-etching adhesive systems under different dentinal substrate conditions

The use of acid etchants to produce surface demineralization and collagen network exposure, allowing adhesive monomers interdiffusion and consequently the formation of a hybrid layer, has been considered the most efficient mechanism of dentin bonding. The aim of this study was to compare the tensile bond strength to dentin of three adhesive systems, two self-etching ones (Clearfil SE Bond - CSEB and One Up Bond F - OUBF) and one total-etching one (Single Bond - SB), under three dentinal substrate conditions (wet, dry and re-wet). Ninety human, freshly extracted third molars were sectioned at the occlusal surface to remove enamel and to form a flat dentin wall. The specimens were restored with composite resin (Filtek Z250) and submitted to tensile bond strength testing (TBS) in an MTS 810. The data were submitted to two-way ANOVA and Tukey's test (p = 0.05). Wet dentin presented the highest TBS values for SB and CSEB. Dry dentin and re-wet produced significantly lower TBS values when using SB. OUBF was not affected by the different conditions of the dentin substrate, producing similar TBS values regardless of the surface pretreatments.

Effect of light-curing units on push-out fiber post bond strength in root canal dentin

The purpose of this study was to evaluate the effectiveness of different light-curing units on the bond strength (push-out) of glass fiber posts in the different thirds of the root (cervical, middle and apical) with different adhesive luting resin systems (dual-cure total-etch; dual-cured and self-etch bonding system; and dual-cure self-adhesive cements), Disks of the samples (n = 144) were used, with approximately 1 mm of thickness of 48 bovine roots restored with glass fiber posts, that were luted with resin cements photo-activated by halogen LCU (QTH, Optilux 501) and blue LED (Ultraled), with power densities of 600 and 550 mW/cm 2, respectively. A universal testing machine (MTS 810 Material Test System) was used with a 1 mm diameter steel rod at cross-head speed of 0.5 mm/min until post extrusion, with load cell of 50 kg, for evaluation of the push-out strength in the different thirds of each sample. The push-out strength values in kgf were converted to MPa and analyzed through Analysis of Variance and Tukey's test, at significance level of 5%. The results showed that there were no statistical differences between the QTH and LED LCUs. The self-adhesive resin cement had lower values of retention. The total-etch and self-adhesive system resin cements seem to be a possible alternative for glass fiber posts cementation into the radicular canal and the LED LCU can be applied as an alternative to halogen light on photo-activation of dual-cured resin cements. © 2009 Pleiades Publishing, Ltd.