Assessment of artefacts produced by metal posts on CBCT images.

AIM: To evaluate artefact intensity in cone beam computed tomography (CBCT) images of two alloys used in metal posts scanned using different exposure parameters. METHODOLOGY: The sample consisted of 20 single-rooted teeth divided into two groups for use with either a NiCr post or AgPd post. All teeth were scanned with and without their corresponding metal posts and with and without the presence of an extra restored tooth in the arch. The samples were scanned using CS 9000 3D scanner with two exposure protocols: 85 kV 6.3 mA and 85 kV 10 mA. Voxel size and FOV were fixed at 0.100 mm and 5 cm × 3.75 cm. The presence of artefacts was assessed qualitatively by two calibrated observers using the CBCT volume and paired 2D images, and quantitatively by one trained observer, using ImageJ software. Wilcoxon's signed rank, Mann-Whitney, kappa and chi-square tests were used for qualitative analyses. Two-way anova and Tukey's tests were used for quantitative analyses. All analyses were conducted considering the 95% confidence level (α < 0.05). RESULTS: For the CBCT volume qualitative analysis, significant differences were observed between the metal alloys in the presence of an extra restored tooth, with higher artefact intensity for AgPd when assessing hypodense halos and lines (P = 0.006). Images with two restored teeth had significantly more hypodense and hyperdense lines (P = 0.033). When evaluating exposure parameters and number of restored teeth, the paired image quality analysis revealed significant disagreement between observers for diagnostic image quality (P = 0.001). Quantitative artefact analysis revealed higher artefact intensity for the AgPd posts in the presence of two restored teeth. CONCLUSION: Although the exposure parameters tested did not interfere with artefact intensity, post alloys with a higher atomic number and the presence of another metal structure in the arch increased artefact intensity and impaired the diagnostic quality of CBCT images.

Crotoxin Isolated from Crotalus durissus terrificus Venom Modulates the Functional Activity of Dendritic Cells via Formyl Peptide Receptors.

The Crotalus durissus terrificus rattlesnake venom, its main toxin, crotoxin (CTX), and its crotapotin (CA) and phospholipase A2 (CB) subunits modulate the immune system. Formyl peptide receptors (FPRs) and lipoxin A4 (LXA4) are involved in CTX's effect on macrophages and neutrophils. Dendritic cells (DCs) are plasticity cells involved in the induction of adaptive immunity and tolerance maintenance. Therefore, we evaluated the effect of CTX, CA or CB on the maturation of DCs derived from murine bone marrow (BM). According to data, CTX and CB-but not CA-induced an increase of MHC-II, but not costimulatory molecules on DCs. Furthermore, CTX and CB inhibited the expression of costimulatory and MHC-II molecules, secretion of proinflammatory cytokines and NF-κBp65 and p38/ERK1/2-MAPK signaling pathways by LPS-incubated DCs. Differently, CTX and CB induced IL-10, PGE2 and LXA4 secretion in LPS-incubated DCs. Lower proliferation and IL-2 secretion were verified in coculture of CD3+ cells and DCs incubated with LPS plus CTX or CB compared with LPS-incubated DCs. The effect of CTX and CB on DCs was abolished in cultures incubated with a FPRs antagonist. Hence, CTX and CB exert a modulation on functional activity of DCs; we also checked the involvement the FPR family on cell activities.

Evaluation of a Brain Acetylcholinesterase Extraction Method and Kinetic Constants after Methyl-Paraoxon Inhibition in Three Brazilian Fish Species.

Acetylcholinesterase (AChE) is an important enzyme in the control of the neuronal action potential and sensitive to organophosphate inhibition. Brain fish AChE is less sensitive to organophosphate inhibition than AChE from terrestrial animals, although this sensitivity is variable among species and has not yet been fully evaluated in fish species. In this setting, inhibition kinetic constants for progressive irreversible inhibition of brain acetylcholinesterase due to methyl-paraoxon exposure were determined in three fish species (Mugil liza, Genidens genidens and Lagocephalus laevigatus) and hen (Gallus domesticus). Enzyme extraction using a detergent was shown to be adequate, and samples presented activity inhibition in high substrate concentrations and suppression of inhibition by methyl-paraoxon in the presence of the substrate, similar to kinetic patterns from purified enzyme preparations. Catfish (G. genidens) AChE presented the highest sensitivity among the evaluated fish species (IC50 = 1031.20 nM ± 63.17) in comparison to M. liza and L. laevigatus (IC50: 2878.83 ± 421.94 and 2842.5 ± 144.63 nM respectively). The lower dissociation constant (Kd = 20.3 ± 2.95 µM) of catfish AChE showed greater enzyme affinity for methyl-paraoxon, explaining this species higher sensitivity to organophosphates. Hen AChE presented higher ki (900.57 ± 65.3 mM-1min-1) and, consequently, greater sensitivity to methyl-paraoxon, explained by a lower Kd (0.6 ± 0.13 µM). Furthermore, hen AChE did not differentiate between the propionylthiocholine and acetylthiocholine substrates, indicating easier access of methyl-paraoxon to the hen enzyme activity site. The results obtained herein indicate a suitable extraction of AChE and, despite different inhibition kinetic constants, demonstrate that fish AChE is less sensitive to methyl-paraoxon, probably due to reduced access to the catalytic center which provides greater enzyme substrate selectivity.

Accuracy of an ELISA and indirect immunofluorescence for the laboratory diagnosis of American tegumentary leishmaniasis.

We compared the accuracy of ELISA and indirect immunofluorescence (IIF) using Leishmania braziliensis and L. major-like antigens and antigens from the Bio-Manguinhos kit for serological diagnosis of American tegumentary leishmaniasis (ATL). Cut-off values were defined by the area under the receiver-operating characteristic curve. For ELISA, statistical analyses revealed better accuracy [95.7% sensitivity, 100% specificity, 100% positive predictive value (PPV), 97.5% negative predictive value (NPV)] and reliability [intraclass correlation coefficient (ICC): 0.940] for L. braziliensis antigen compared with L. major-like antigen (78.7% sensitivity, 82.8% specificity, 73.3% PPV, 86.6% NPV, ICC: 0.833). ELISA optical density values obtained for both antigens were higher in mucosal forms of ATL. For IIF, sensitivity and specificity were 81.5 and 86.2%, respectively, for the L. braziliensis antigen, compared with 95.4 and 77.7% for the L. major-like antigen and 75.4 and 89.2% for the Bio-Manguinhos kit. No difference in the specificity of the IIF test was observed between antigens, whereas sensitivity differed between the L. braziliensis and L. major-like antigens and the Bio-Manguinhos kit. Parallel ELISA and IIF testing increased sensitivity, irrespective of the antigen employed, and serial testing increased overall specificity. These results support the recommendation that ELISA employing L. braziliensis antigen be used as a diagnostic tool for suspected cases of ATL in L. braziliensis-endemic areas.

Anticonvulsant and sodium channel-blocking properties of novel 10,11-dihydro-5H-dibenz[b,f]azepine-5-carboxamide derivatives.

A series of esters of the major metabolite of oxcarbazepine (2), 10, 11-dihydro-10-hydroxy-5H-dibenz[b,f]azepine-5-carboxamide, were synthesized and evaluated for their anticonvulsant and brain sodium channel-blocking properties. The compounds were assayed intraperitoneally and per os in rats against seizures induced by maximal electroshock (MES). Neurologic deficit was evaluated by the rotarod test. The enantiomeric acetates (R)-11 and (S)-12 were the most active of the series against MES-induced seizures with oral ED(50) values at t(max) of 10.9 +/- 2.3 and 4.7 +/- 0.9 mg/kg, respectively. After intraperitoneal administration, carbamazepine (1) behaved more potently than 2 and all other new dibenz[b, f]azepine-5-carboxamide derivatives in the MES test; compounds 2 and 12 were equally potent. In the rotarod test, low doses of 1 produced considerable motor impairment, which did not occur with 2, enantiomeric alcohols (S)-6, (R)-7, and racemic alcohol 8, or racemic acetate 10 or (R)-11. The potencies of the racemic and enantiomerically pure alcohols 8, (S)-6, and (R)-7 derived from 2 in the MES and rotarod test were found to be similar between them, and consequently they exhibit similar protective index values. All three forms of the alcohol and their corresponding acetates (pairs 8 & 10, 6 & 12, and 7 & 11) were found to differ in the MES or rotarod tests; the ED(50) value for (S)-6 against MES-induced seizures was nearly 3-fold that for (S)-12. The protective index also differed markedly between all stereoisomers of the alcohol and their corresponding acetates, most pronouncedly for compound (S)-12 which attained the highest value (12.5) among all compounds tested. Blockade of voltage-sensitive sodium channels was studied by investigating [(3)H]batrachotoxinin A 20-alpha-benzoate ([(3)H]BTX) binding. Acetates (R)-11 and (S)-12 were more potent than the standards 1 and 2 at inhibiting the binding of [(3)H]BTX to sodium channels and the influx of (22)Na(+) into rat brain synaptosomes. It is concluded that acetates (R)-11 and (S)-12 are not simple metabolic precursors of alcohols (R)-7 and (S)-6 in rodents but that they possess anticonvulsant and sodium channel-blocking properties in their own right.