Habilidade de centralização, transporte do canal e modificações de superfície do ProTaper F2 e F3 utilizados em rotação contínua e movimento reciprocante em canais curvos

Aims: To evaluate the centering ability, canal transportation and surface modifications of F2 and F3 ProTaper Universal (PT) instruments used in continuous rotation (CR) and reciprocating motion (RM) for the preparation of curved root canals. Material and methods: sixty mesiobuccal root canals of upper molars with curvatures between 25º and 35° were divided into three groups: I - PT in CR up to F3; II - PT in RM up to F3; III - F2 and F3 PT instruments in RM. Cone Beam Computed Tomography images were obtained before and after instrumentation. The scans were superimposed to determine the centering ability and canal transportation in apical, medium and cervical thirds. The apical 6 mm of the F2 and F3 files were evaluated under Scanning Electron Microscope before and after 1, 3 and 6 uses to assess distortion, surface wear and fracture. The statistical analysis of centering ability and canal transportation were performed by Kruskal–Wallis and ANOVA, respectively. The scores for deformation and surface wear were compared using ANOVA. Fisher’s exact test was used for the evaluation of instrument fracture. Results: there were no significant differences between groups regarding centering ability and canal transportation, as well as, for distortion, surface wear and fracture (p>.05). Conclusion: F2 and F3 instruments can be used for curved canals instrumentation. However, when used for entire canal preparation, F2 and F3 should be discarded after single use.Objetivos: avaliar a centralização, transporte do canal e modificações de superfície dos intrumentos ProTaper Universal (PT) F2 e F3 utilizados em movimento de rotação continua (CR) e movimento reciprocante (RM) no preparo de canais curvos. Materiais e métodos: sessenta canais mesiovestibulares de molares superiores com curvaturas entre 25o e 35o foram divididos em três grupos: I – PT em CR até F3; II – PT em RM até F3; III – instrumentos F2 e F3 em RM. Foram obtidas imagens de Tomografia Computadorizada Cone Beam antes e após a instrumentação. As imagens foram sobrepostas para determinar a centralização e transporte do canal nos terços apical, médio e cervical. Os 6 mm apicais dos instrumentos F2 e F3 foram avaliados por Microscopia Eletrônica de Varredura antes e após 1, 3 e 6 usos para verificar distorções, desgaste de superfície e fratura. A análise estatística da centralização e transporte do canal foi feita pelos testes de Kruskall-Wallis e ANOVA, respectivamente. Os escores de deformação e desgaste de superfície foram comparados pelo teste de ANOVA. O teste exato de Fisher foi utilizado para avaliar a fratura dos instrumentos. Resultados: não houve diferença estatística entre os grupos testados quanto aos testes de centralização e transporte do canal, assim como para distorção, desgaste de superfície e fratura dos instrumentos (p>.05). Conclusões: os instrumentos F2 e F3 podem ser utilizados no prepare de canais curvos. Entretanto, quando usados para o preparo completo do canal radicular, F2 e F3 devem ser descartados após uso único

Myb-binding Protein 1a (Mybbp1a) Regulates Levels and Processing of Pre-ribosomal RNA

Ribosomal RNA gene transcription, co-transcriptional processing, and ribosome biogenesis are highly coordinated processes that are tightly regulated during cell growth. In this study we discovered that Mybbp1a is associated with both the RNA polymerase I complex and the ribosome biogenesis machinery. Using a reporter assay that uncouples transcription and RNA processing, we show that Mybbp1a represses rRNA gene transcription. In addition, overexpression of the protein reduces RNA polymerase I loading on endogenous rRNA genes as revealed by chromatin immunoprecipitation experiments. Accordingly, depletion of Mybbp1a results in an accumulation of the rRNA precursor in vivo but surprisingly also causes growth arrest of the cells. This effect can be explained by the observation that the modulation of Mybbp1a protein levels results in defects in pre-rRNA processing within the cell. Therefore, the protein may play a dual role in the rRNA metabolism, potentially linking and coordinating ribosomal DNA transcription and pre-rRNA processing to allow for the efficient synthesis of ribosomes

Effect of calcium hypochlorite on the bond strength of the AH Plus sealer to dentin

Objetivo: avaliar o efeito do uso de hipoclorito de cálcio (Ca(OCl)2) como irrigante na resistência de adesão do cimento AH Plus (De Trey-Dentsply, Konstanz, Ale-manha) à dentina pelo teste de micro push-out. Mate-riais e método: trinta e três dentes humanos monorradi-culares foram seccionados transversalmente na junção amelocementária e divididos em três grupos: hipoclori-to de sódio (NaOCl) 2,5%, hipoclorito de cálcio 2,5% e soro fisiológico. Os canais foram preparados, irriga-dos ao final com EDTA 17% e obturados com cones de guta percha e cimento AH Plus. Após armazenagem por 7 dias, em 100% de umidade e a 37°C, os dentes foram seccionados transversalmente ao longo do eixo da raiz. Foram obtidas três fatias de cada dente (n=33), que foram submetidas ao ensaio de push-out. O tipo de falha foi analisado por fractografia e classificado em fa-lha adesiva, coesiva ou mista. Os valores de resistência de união foram analisados pelo teste de Kruskal-Wallis, com nível de significância de 95%. Resultados: o grupo Ca(OCl)2 2,5% apresentou a menor média de resistên-cia de adesão, diferindo estatisticamente do NaOCl e do soro fisiológico (p0,05). Conclusões: a falha predominante em todos os grupos foi a do tipo adesiva. O Ca(OCl)2 2,5% teve um efeito negativo sobre a força de adesão do AH Plus à dentina radicular quando comparado ao NaOCl 2,5%.Objective: to evaluate the effect of calcium hypochlo-rite (Ca(OCl)2) as an irrigant on the bond strength of the AH Plus sealer (De Trey-Dentsply, Konstanz, Germany) to dentin, using the micro push-out test. Materials and method: thirty-three single-rooted human teeth were cross-sectioned on the cementoenamel junction and di-vided into three groups: 2.5% sodium hypochlorite (Na-OCl), 2.5% calcium hypochlorite, and saline solution. The canals were prepared, irrigated with 17% EDTA at the end, and filled with gutta-percha cones and AH Plus sealer. After being stored for seven days at 100% humi-dity and 37ºC, the teeth were cross-sectioned along the root axis. Three slices of each tooth (n=33) were obtai-ned and subjected to the push-out test. Failure mode was analyzed by fractography and classified as adhe-sive, cohesive, or mixed. Bond strength values were analyzed by the Kruskall-Wallis test at 95% significan-ce level. Results: the 2.5% Ca(OCl)2 group showed the lowest bond strength mean, differing statistically from 2.5% NaOCl and saline solution (p0.05). Conclusion: the adhesive failure was predominant in all groups. The 2.5% Ca(OCl)2 had a negative effect on the bond strength of AH Plus to the root dentin when compared to 2.5% NaOCl

Profiling of Flavonol Derivatives for the Development of Antitrypanosomatidic Drugs

Flavonoids represent a potential source of new antitrypanosomatidic leads. Starting from a library of natural products, we combined target-based screening on pteridine reductase 1 with phenotypic screening on Trypanosoma brucei for hit identification. Flavonols were identified as hits, and a library of 16 derivatives was synthesized. Twelve compounds showed EC50 values against T. brucei below 10 \u3bcM. Four X-ray crystal structures and docking studies explained the observed structure-activity relationships. Compound 2 (3,6-dihydroxy-2-(3-hydroxyphenyl)-4H-chromen-4-one) was selected for pharmacokinetic studies. Encapsulation of compound 2 in PLGA nanoparticles or cyclodextrins resulted in lower in vitro toxicity when compared to the free compound. Combination studies with methotrexate revealed that compound 13 (3-hydroxy-6-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one) has the highest synergistic effect at concentration of 1.3 \u3bcM, 11.7-fold dose reduction index and no toxicity toward host cells. Our results provide the basis for further chemical modifications aimed at identifying novel antitrypanosomatidic agents showing higher potency toward PTR1 and increased metabolic stability

Addressing climate change with behavioral science: a global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions’ effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior—several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people’s initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Influence of surfactants addition on the properties of sodium and calcium hypochlorite

O objetivo do presente estudo foi o de avaliar a influência da associação dos tensoativos cetrimida 0,2%, cetrimida 0,1% e cloreto de benzalcônio 0,008% aos hipocloritos de sódio e de cálcio 2,5% nas propriedades de pH, quantidade de cloro livre, tensão superficial, ângulo de contato, dissolução pulpar e atividade antimicrobiana. O pH e a concentração de cloro ativo foram avaliados por pHmetro digital e pela titulação, respectivamente. A tensão superficial foi mensurada através da técnica do anel de platina com um tensiômetro de Du Noüy. O ângulo de contato das soluções em bases de dentina humana foi aferido pelo software Drop Shape Analyzer. Para a análise da dissolução pulpar foram utilizados fragmentos de polpas bovinas e os resultados foram expressos por percentual de perda de massa. A atividade antimicrobiana frente ao Enterococcus faecalis foi realizada pelo método de difusão em Ágar. Os resultados mostraram que a associação de tensoativos aos hipocloritos de sódio e cálcio não alterou as propriedades de pH, cloro livre e dissolução pulpar das soluções. O hipoclorito de cálcio apresentou o maior valor de tensão superficial (72,13 ± 1,82 mN/m). Quando associados aos tensoativos, os hipocloritos de sódio e cálcio tiveram uma redução significativa da tensão superficial. O mesmo foi observado para o ângulo de contato. Os tensoativos apresentam atividade antimicrobiana. A associação dos hipocloritos à cetrimida 0,2% ou 0,1% aumentou o halo de inibição frente ao Enterococcus faecalis. Concluiu-se que a associação de tensoativos não modificaram as propriedades de pH, cloro livre e dissolução pulpar dos hipocloritos de sódio e cálcio 2,5%. Porém, ela foi capaz de diminuir a tensão superficial e o ângulo de contato das soluções. Ainda, a associação da cetrimida 0,2% e 0,1% melhorou a capacidade antimicrobiana dos hipocloritos.The aim of this study was to evaluate the influence of surfactants 0,2% or 0,1% cetrimide or 0,008% benzalkonium chloride on 2.5% sodium and calcium hypochlorite in the properties of pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. The pH and free chlorine content were evaluated by digital pHmeter and by titration, respectively. Surface tension was measured by the platinum ring technique with a Du Noüy tensiometer. Solution’s contact angle in human dentin surfaces was checked by Drop Shape Analyzer software. Bovine pulps were used for pulp dissolution analysis and the dissolving capacity was expressed by percentual weight loss. Antimicrobial activity over Enterococcus faecalis was evaluated through the ágar diffusion method. The surfactants association on sodium and calcium hypochlorites did not alter pH, free chlorine content and pulp dissolution properties. Calcium hypochlorite had the higher surface tension (72,13 ± 1,82 mN/m). However, when sodium and calcium hypochlorite were associated to surfactants, a significant reduction of surface tension occured. The same was observed for contact angle analysis. The surfactants used in this study have antimicrobial activity. The association of 0,2% or 0,1% cetrimide enhanced antimicrobial activity of both hypochlorites. It was possible to conclude that surfactants association did not alter pH, free chlorine content and pulp dissolution properties of 2,5% sodium and calcium hypochlorite. It was capable to reduce surface tension and contact angle of the solutions. Moreover, the 0,2% or 0,1% cetrimide association increased antimicrobial activity of hypochlorite