18 resultados para radical shifts

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Background and Purpose: Becoming proficient in laparoscopic surgery is dependent on the acquisition of specialized skills that can only be obtained from specific training. This training could be achieved in various ways using inanimate models, animal models, or live patient surgery-each with its own pros and cons. Currently, there are substantial data that support the benefits of animal model training in the initial learning of laparoscopy. Nevertheless, whether these benefits extent themselves to moderately experienced surgeons is uncertain. The purpose of this study was to determine if training using a porcine model results in a quantifiable gain in laparoscopic skills for moderately experienced laparoscopic surgeons. Materials and Methods: Six urologists with some laparoscopic experience were asked to perform a radical nephrectomy weekly for 10 weeks in a porcine model. The procedures were recorded, and surgical performance was assessed by two experienced laparoscopic surgeons using a previously published surgical performance assessment tool. The obtained data were then submitted to statistical analysis. Results: With training, blood loss was reduced approximately 45% when comparing the averages of the first and last surgical procedures (P = 0.006). Depth perception showed an improvement close to 35% (P = 0.041), and dexterity showed an improvement close to 25% (P = 0.011). Total operative time showed trends of improvement, although it was not significant (P = 0.158). Autonomy, efficiency, and tissue handling were the only aspects that did not show any noteworthy change (P = 0.202, P = 0.677, and P = 0.456, respectively). Conclusions: These findings suggest that there are quantifiable gains in laparoscopic skills obtained from training in an animal model. Our results suggest that these benefits also extend to more advanced stages of the learning curve, but it is unclear how far along the learning curve training with animal models provides a clear benefit for the performance of laparoscopic procedures. Future studies are necessary to confirm these findings and better understand the impact of this learning tool on surgical practice.

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High pressure NMR spectroscopy has developed into an important tool for studying conformational equilibria of proteins in solution. We have studied the amide proton and nitrogen chemical shifts of the 20 canonical amino acids X in the random-coil model peptide Ac-Gly-Gly-X-Ala-NH2, in a pressure range from 0.1 to 200 MPa, at a proton resonance frequency of 800 MHz. The obtained data allowed the determination of first and second order pressure coefficients with high accuracy at 283 K and pH 6.7. The mean first and second order pressure coefficients <B-1(15N)> and <B-2(15N)> for nitrogen are 2.91 ppm/GPa and -2.32 ppm/GPa(2), respectively. The corresponding values <B-1(1H)> and <B-2(1H)> for the amide protons are 0.52 ppm/GPa and -0.41 ppm/GPa(2). Residual dependent (1)J(1H15N)-coupling constants are shown.

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Ground state interactions and excited states and transients formed after photolysis and photosensitization of 2-ethylaminodiphenylborinate (2APB) were studied by various techniques. The UV spectrum shows a large absorption band at 235 nm (epsilon = 14,500 M-1 cm(-1)) with a shoulder at 260 nm. The fluorescence spectra show increasing emission intensity with maximum at 300 nm, which shifts to the red up to 10(-3) M concentrations. At higher concentrations, the emission intensity decreases, probably due to the formation of aggregates. UV excitation in deareated solutions shows the formation of two transients at 300 and 360 nm. The latter has a lifetime of 5.7 mu s in ethanol and is totally quenched in the presence of oxygen and assigned to the triplet state of 2APB. The 300 nm peak is not affected by oxygen, has a lifetime in the order of milliseconds, and corresponds to a boron-centered radical species originated from the singlet state. A boron radical can also be obtained by electron transfer from triplet Safranine to the borinate (k(q) = 9.7 x 10(7) M-1 s(-1)) forming the semioxidized form of the dye. EPR experiments using DMPO show that dye-sensitized and direct UV-photolysis of 2ABP renders initially arylboron-centered radicals. (C) 2012 Elsevier B.V. All rights reserved.

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A comparative proteomic approach was performed to identify differentially expressed proteins in plastids at three stages of tomato (Solanum lycopersicum) fruit ripening (mature-green, breaker, red). Stringent curation and processing of the data from three independent replicates identified 1,932 proteins among which 1,529 were quantified by spectral counting. The quantification procedures have been subsequently validated by immunoblot analysis of six proteins representative of distinct metabolic or regulatory pathways. Among the main features of the chloroplast-to-chromoplast transition revealed by the study, chromoplastogenesis appears to be associated with major metabolic shifts: (1) strong decrease in abundance of proteins of light reactions (photosynthesis, Calvin cycle, photorespiration) and carbohydrate metabolism (starch synthesis/degradation), mostly between breaker and red stages and (2) increase in terpenoid biosynthesis (including carotenoids) and stress-response proteins (ascorbate-glutathione cycle, abiotic stress, redox, heat shock). These metabolic shifts are preceded by the accumulation of plastid-encoded acetyl Coenzyme A carboxylase D proteins accounting for the generation of a storage matrix that will accumulate carotenoids. Of particular note is the high abundance of proteins involved in providing energy and in metabolites import. Structural differentiation of the chromoplast is characterized by a sharp and continuous decrease of thylakoid proteins whereas envelope and stroma proteins remain remarkably stable. This is coincident with the disruption of the machinery for thylakoids and photosystem biogenesis (vesicular trafficking, provision of material for thylakoid biosynthesis, photosystems assembly) and the loss of the plastid division machinery. Altogether, the data provide new insights on the chromoplast differentiation process while enriching our knowledge of the plant plastid proteome.

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Background: The urethrovesical anastomosis is a particular challenging step of robot assisted radical prostatectomy (RARP). Failure to achieve a watertight anastomosis is associated with postoperative urinary leak and its consequences, which include paralytic ileus, prolonged catheterization, urinary peritonitis and possibly re-intervention. The bidirectional barbed suture is a new technology that may lead to improve the quality of the urethrovesical anastomosis. Objective: To present our surgical technique of urethrovesical anastomosis, bladder neck reconstruction and posterior reconstruction, using a bidirectional barbed suture. Material and methods: The bladder neck reconstruction, posterior reconstruction and vesicourethral anastomosis were performed using a 2-0 synthetic absorbable bidirectional monofilament barbed suture Results: All cases were finished successfully without major complication or conversion to laparoscopic or open surgery. Conclusion: The authors successfully modified their RARP technique to take advantage of the properties of the bidirectional barbed suture. Comparative studies that evaluate objective outcomes such as leakage rates and operative time are needed to definitely establish the benefits of this device in comparison to the traditional absorbable monofilament. (C) 2011 AEU. Published by Elsevier Espana, S.L. All rights reserved.

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Lupulones, hops beta-acids, are one of the main constituents of the hops resin and have an important contribution to the overall bacteriostatic activity of hops during beer brewing. The use of lupulones as natural alternatives to antibiotics is increasing in the food industry and also in bioethanol production. However, lupulones are easy oxidizable and have been shown to be very reactive toward 1-hydroxyethyl radical with apparent bimolecular rate constants close to diffusion control k = 2.9 x 10(8) and 2.6 x 10(8) L mol(-1) s(-1) at 25.0 +/- 0.2 degrees C in ethanol water solution (10% of ethanol (v/v)) as probed by EPR and ESI-IT-MS/MS spin-trapping competitive kinetics, respectively. The free energy change for an electron-transfer mechanism is Delta G degrees = 106 kJ/mol as calculated from the oxidation peak potential experimentally determined for lupulones (1.1 V vs NHE) by cyclic voltammetry and the reported reduction potential for 1-hydroxyethyl radical. The major reaction products identified by LC-ESI-IT-MS/MS and ultrahigh-resolution accurate mass spectrometry (orbitrap FT-MS) are hydroxylated lupulone derivatives and 1-hydroxyethyl radical adducts. The lack of pH dependence for the reaction rate constant, the calculated free energy change for electron transfer, and the main reaction products strongly suggest the prenyl side chains at the hops beta-acids as the reaction centers rather than the beta,beta'-triketone moiety.

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We measured the mixing ratios of NO, NO2, O-3, and volatile organic carbon as well as the aerosol light-scattering coefficient on a boat platform cruising on rivers downwind of the city of Manaus (Amazonas State, Brazil) in July 2001 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia-Cooperative LBA Airborne Regional Experiment-2001). The dispersion and impact of the Manaus plume was investigated by a combined analysis of ground-based (boat platform) and airborne trace gas and aerosol measurements as well as by meteorological measurements complemented by dispersion calculations (Hybrid Single-Particle Lagrangian Integrated Trajectory model). For the cases with the least anthropogenic influence (including a location in a so far unexplored region similar to 150 km west of Manaus on the Rio Manacapuru), the aerosol scattering coefficient, sigma(s), was below 11 Mm(-1), NOx mixing ratios remained below 0.6 ppb, daytime O-3 mixing ratios were mostly below 20 ppb and maximal isoprene mixing ratios were about 3 ppb in the afternoon. The photostationary state (PSS) was not established for these cases, as indicated by values of the Leighton ratio, Phi, well above unity. Due to the influence of river breeze systems and other thermally driven mesoscale circulations, a change of the synoptic wind direction from east-northeast to south-southeast in the afternoon often caused a substantial increase of ss and trace gas mixing ratios (about threefold for sigma(s), fivefold for NOx, and twofold for O-3), which was associated with the arrival of the Manaus pollution plume at the boat location. The ratio F reached unity within its uncertainty range at NOx mixing ratios of about 3 ppb, indicating "steady-state" conditions in cases when radiation variations, dry deposition, emissions, and reactions mostly involving peroxy radicals (XO2) played a minor role. The median midday/afternoon XO2 mixing ratios estimated using the PSS method range from 90 to 120 parts per trillion (ppt) for the remote cases (sigma(s) < 11 Mm(-1) and NOx < 0.6 ppb), while for the polluted cases our estimates are 15 to 60 ppt. These values are within the range of XO2 estimated by an atmospheric chemistry box model (Chemistry As A Box model Application-Module Efficiently Calculating the Chemistry of the Atmosphere (CAABA/MECCA)-3.0).

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The content of isoorientin in passion fruit rinds (Passiflora Mulls fo. flavicarpa O. Degener) was determined by HPTLC (high performance thin layer chromatography) with densitometric analysis. The results revealed a higher amount of isoorientin in healthy rinds of P edulis (92.275 +/- 0.610 mg L-1) than in rinds with typical symptoms of PWV (Passion fruit Woodiness Virus) infection (28.931 +/- 0.346 mg L-1). The HPTLC data, allied to assays of radical scavenging activity, suggest the potential of P Mulls rinds as a natural source of flavonoids or as a possible functional food.

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Erectile dysfunction (ED) and urinary incontinence are common complications following radical prostatectomy (RP). Although pelvic-floor biofeedback training (PFBT) may improve urinary continence following RP, its effects on the recovery of potency are unknown. Fifty-two patients selected for RP were prospectively randomized for a treatment group (n=26) receiving PFBT once a week for 3 months and home exercises or a control group (n=26), in which patients received verbal instructions to contract the pelvic floor. Erectile function (EF) was evaluated with the International Index of Erectile Function-5 (IIEF-5) before surgery and 1, 3, 6 and 12 months postoperatively. Patients were considered potent when they had a total IIEF-5 score >20. Continence status was assessed and defined as the use of no pads. Groups were comparable in terms of age, body mass index, diabetes, pathological tumor stage and neurovascular bundle preservation. A significant reduction in IIEF-5 scores was observed after surgery in both groups. In the treatment group, 8 (47.1%) patients recovered potency 12 months postoperatively, as opposed to 2 (12.5%) in the control group (P=0.032). The absolute risk reduction was 34.6% (95% confidence interval (CI): 3.8-64%) and the number needed to treat was 3 (95% CI: 1.5-17.2). A strong association between recovery of potency and urinary continence was observed, with continent patients having a 5.4 higher chance of being potent (P=0.04). Early PFBT appears to have a significant impact on the recovery of EF after RP. Urinary continence status was a good indicator of EF recovery, with continent patients having a higher chance of being potent.

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All doublet and quartet electronic states correlating with the first dissociation channel of SeCl and some Rydberg states are investigated theoretically at the CASSCF/MRCI level of theory using extended basis sets, including the contribution of spin-orbit effects. The similarity of the potential energy curves with those of SeF suggests that spectroscopic constants for the ground (X (2)Pi) and the first excited quartet (a(4)Sigma) of SeCl could also be determined via an emission resulting from the reaction of selenium with atomic chlorine. The coupling constant of the ground state at R-e is estimated as -1610 cm (1). The potential energy curves calculated and the derived spectroscopic constants do not support the interpretation and assignment of the scarce transitions recorded experimentally as due to (2)Pi-(2)Pi emissions. That the few observed lines might arise from transitions from the state b(4)Sigma(-)(1/2) to a very high vibrational level of the state a(4)Sigma(-)(1/2) is an open possibility, however, the number of vibrational states and the calculated Delta G(1/2) differ significantly from the reported ones. (C) 2012 Elsevier B. V. All rights reserved.

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We prove that the prime radical rad M of the free Malcev algebra M of rank more than two over a field of characteristic not equal 2 coincides with the set of all universally Engelian elements of M. Moreover, let T(M) be the ideal of M consisting of all stable identities of the split simple 7-dimensional Malcev algebra M over F. It is proved that rad M = J(M) boolean AND T(M), where J(M) is the Jacobian ideal of M. Similar results were proved by I. Shestakov and E. Zelmanov for free alternative and free Jordan algebras.

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Liquid configurations generated by Metropolis Monte Carlo simulations are used in time-dependent density functional theory calculations of the spectral line shifts and line profiles of the lowest lying excitation of the alkaline earth atoms, Be, Mg, Ca, Sr and Ba embedded in liquid helium. The results are in very good agreement with the available experimental data. Special attention is given to the calculated spectroscopic shift and the associated line broadening. The analysis specifies the inhomogeneous broadening of the three separate contributions due to the splitting of the s -> p transition of the alkaline earth atom in the liquid environment. (C) 2012 Elsevier B. V. All rights reserved.

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This study focused on the structure and composition of archaeal communities in sediments of tropical mangroves in order to obtain sufficient insight into two Brazilian sites from different locations (one pristine and another located in an urban area) and at different depth levels from the surface. Terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene fragments was used to scan the archaeal community structure, and 16S rRNA gene clone libraries were used to determine the community composition. Redundancy analysis of T-RFLP patterns revealed differences in archaeal community structure according to location, depth and soil attributes. Parameters such as pH, organic matter, potassium and magnesium presented significant correlation with general community structure. Furthermore, phylogenetic analysis revealed a community composition distributed differently according to depth where, in shallow samples, 74.3% of sequences were affiliated with Euryarchaeota and 25.7% were shared between Crenarchaeota and Thaumarchaeota, while for the deeper samples, 24.3% of the sequences were affiliated with Euryarchaeota and 75.7% with Crenarchaeota and Thaumarchaeota. Archaeal diversity measurements based on 16S rRNA gene clone libraries decreased with increasing depth and there was a greater difference between depths (<18% of sequences shared) than sites (>25% of sequences shared). Taken together, our findings indicate that mangrove ecosystems support a diverse archaeal community; it might possibly be involved in nutrient cycles and are affected by sediment properties, depth and distinct locations. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

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Abstract Background The family Accipitridae (hawks, eagles and Old World vultures) represents a large radiation of predatory birds with an almost global distribution, although most species of this family occur in the Neotropics. Despite great morphological and ecological diversity, the evolutionary relationships in the family have been poorly explored at all taxonomic levels. Using sequences from four mitochondrial genes (12S, ATP8, ATP6, and ND6), we reconstructed the phylogeny of the Neotropical forest hawk genus Leucopternis and most of the allied genera of Neotropical buteonines. Our goals were to infer the evolutionary relationships among species of Leucopternis, estimate their relationships to other buteonine genera, evaluate the phylogenetic significance of the white and black plumage patterns common to most Leucopternis species, and assess general patterns of diversification of the group with respect to species' affiliations with Neotropical regions and habitats. Results Our molecular phylogeny for the genus Leucopternis and its allies disagrees sharply with traditional taxonomic arrangements for the group, and we present new hypotheses of relationships for a number of species. The mtDNA phylogenetic trees derived from analysis of the combined data posit a polyphyletic relationship among species of Leucopternis, Buteogallus and Buteo. Three highly supported clades containing Leucopternis species were recovered in our phylogenetic reconstructions. The first clade consisted of the sister pairs L. lacernulatus and Buteogallus meridionalis, and Buteogallus urubitinga and Harpyhaliaetus coronatus, in addition to L. schistaceus and L. plumbeus. The second clade included the sister pair Leucopternis albicollis and L. occidentalis as well as L. polionotus. The third lineage comprised the sister pair L. melanops and L. kuhli, in addition to L. semiplumbeus and Buteo buteo. According to our results, the white and black plumage patterns have evolved at least twice in the group. Furthermore, species found to the east and west of the Andes (cis-Andean and trans-Andean, respectively) are not reciprocally monophyletic, nor are forest and non-forest species. Conclusion The polyphyly of Leucopternis, Buteogallus and Buteo establishes a lack of concordance of current Accipitridae taxonomy with the mtDNA phylogeny for the group, and points to the need for further phylogenetic analysis at all taxonomic levels in the family as also suggested by other recent analyses. Habitat shifts, as well as cis- and trans-Andean disjunctions, took place more than once during buteonine diversification in the Neotropical region. Overemphasis of the black and white plumage patterns has led to questionable conclusions regarding the relationships of Leucopternis species, and suggests more generally that plumage characters should be used with considerable caution in the taxonomic evaluation of the Accipitridae.

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The content of isoorientin in passion fruit rinds (Passiflora edulis fo. flavicarpa O. Degener) was determined by HPTLC (high performance thin layer chromatography) with densitometric analysis. The results revealed a higher amount of isoorientin in healthy rinds of P. edulis (92.275 ± 0.610 mg L-1) than in rinds with typical symptoms of PWV (Passion fruit Woodiness Virus) infection (28.931 ± 0.346 mg L-1). The HPTLC data, allied to assays of radical scavenging activity, suggest the potential of P. edulis rinds as a natural source of flavonoids or as a possible functional food.