81 research outputs found
Avancées et nouvelles technologies en Toxinologie
Collection Rencontres en Toxinologie ISSN 1760-6004 ; http://sfet.asso.fr/images/stories/SFET/pdf/Ebook-RT18-2010-signets-110322.pdfInternational audienc
SEQUĂNCIA DE ESTRATIFICAĂĂO DE UMA RESTAURAĂĂO CLASSE IV COM RESINAS COMPOSTAS EMPRESS DIRECT
A constante melhoria das propriedades fĂsico-mecĂąnicas que caracterizam os compĂłsitos de uso direto permite a obtenção de resultados estĂ©ticos e funcionais com uma alta previsibilidade. As resinas compostas Empress Direct (Ivoclar/Vivadent) sĂŁo materiais nanohĂbridos com partĂculas cerĂąmicas distribuĂdas na matriz orgĂąnica do material. Para a restauração de uma cavidade classe IV, esse tipo de compĂłsito permite excelentes resultados Ăłpticos de mimetizar a estrutura dental a ser restaurada com longevidade clĂnica e manutenção do brilho superficial garantidos. ApĂłs a remoção da restauração antiga de coloração insatisfatĂłria, o procedimento de hibridização foi realizado com um sistema adesivo convencional de dois passos. ApĂłs a realização do condicionamento do esmalte por 30 segundos e da dentina por 15 segundos, o sistema adesivo Adper Single Bond foi aplicado, conforme as recomendaçÔes do fabricante. A estratificação foi iniciada pela confecção da face palatina com uma resina de esmalte acromĂĄtico Trans-20. Na sequĂȘncia, o corpo da restauração simulando a dentina foi confeccionado com resinas opacas Bleach-Dentin. Na ponta dos mamelos no terço incisal foi utilizada uma resina Trans-Opal para caracterizar os efeitos Ăłpticos de opalescĂȘncia. A porção do elemento dental correspondente ao esmalte foi confeccionada com a resina translĂșcida Bleach XL-Enamel. Na ĂĄrea proximal, foi inserida uma resina acromĂĄtica de esmalte Trans-30 para proporcionar efeito de profundidade Ă restauração. Percebe-se que esses compĂłsitos permitem a obtenção de restauraçÔes com uma previsibilidade dos resultados a serem obtidos e a satisfação por parte dos pacientes. Um material com excelentes propriedades mecĂąnicas e Ăłtima lisura e brilho superficial apĂłs os procedimentos de acabamento e polimento permitem uma longevidade clĂnica assegurada.Palavras-chave: Resina composta. EstĂ©tica dental. Sorriso
Toxines et Transferts ioniques
Collection Rencontres en Toxinologie, ISSN 1760-6004 ; http://sfet.asso.fr/international/images/stories/SFET/pdf/Ebook-RT19-2011-signets.pdfInternational audienc
Brevenal Inhibits Pacific Ciguatoxin-1B-Induced Neurosecretion from Bovine Chromaffin Cells
Ciguatoxins and brevetoxins are neurotoxic cyclic polyether compounds produced by dinoflagellates, which are responsible for ciguatera and neurotoxic shellfish poisoning (NSP) respectively. Recently, brevenal, a natural compound was found to specifically inhibit brevetoxin action and to have a beneficial effect in NSP. Considering that brevetoxin and ciguatoxin specifically activate voltage-sensitive Na+ channels through the same binding site, brevenal has therefore a good potential for the treatment of ciguatera. Pacific ciguatoxin-1B (P-CTX-1B) activates voltage-sensitive Na+ channels and promotes an increase in neurotransmitter release believed to underpin the symptoms associated with ciguatera. However, the mechanism through which slow Na+ influx promotes neurosecretion is not fully understood. In the present study, we used chromaffin cells as a model to reconstitute the sequence of events culminating in ciguatoxin-evoked neurosecretion. We show that P-CTX-1B induces a tetrodotoxin-sensitive rise in intracellular Na+, closely followed by an increase in cytosolic Ca2+ responsible for promoting SNARE-dependent catecholamine secretion. Our results reveal that brevenal and ÎČ-naphtoyl-brevetoxin prevent P-CTX-1B secretagogue activity without affecting nicotine or barium-induced catecholamine secretion. Brevenal is therefore a potent inhibitor of ciguatoxin-induced neurotoxic effect and a potential treatment for ciguatera
Repression and 3D-restructuring resolves regulatory conflicts in evolutionarily rearranged genomes
Regulatory landscapes drive complex developmental gene expression, but it remains unclear how their integrity is maintained when incorporating novel genes and functions during evolution. Here, we investigated how a placental mammal-specific gene, Zfp42, emerged in an ancient vertebrate topologically associated domain (TAD) without adopting or disrupting the conserved expression of its gene, Fat1. In ESCs, physical TAD partitioning separates Zfp42 and Fat1 with distinct local enhancers that drive their independent expression. This separation is driven by chromatin activity and not CTCF/cohesin. In contrast, in embryonic limbs, inactive Zfp42 shares Fat1âs intact TAD without responding to active Fat1 enhancers. However, neither Fat1 enhancer-incompatibility nor nuclear envelope-attachment account for Zfp42âs unresponsiveness. Rather, Zfp42âs promoter is rendered inert to enhancers by context-dependent DNA methylation. Thus, diverse mechanisms enabled the integration of independent Zfp42 regulation in the Fat1 locus. Critically, such regulatory complexity appears common in evolution as, genome wide, most TADs contain multiple independently expressed genes.We thank the Montpellier Ressources Imagerie facility (BioCampus Montpellier, Centre National de la Recherche Scientifique [CNRS], INSERM, University of Montpellier) and for computer resources from CINECA (ISCRA grant thanks to computer resources from INFN and CINECA [ISCRA Grant HP10C8JWU7]). G.C., Q.S., and F.B. were supported by a grant from the European Research Council (Advanced Grant 3DEpi, 788972) and by the CNRS. This work was funded by EMBO and the Wellcome Trust (ALTF1554-2016 and 206475/Z/17/Z; to M.I.R.) as well as the Deutsche Forschungsgemeinschaft (KR3985/7-3 and MU 880/16-1 to S.M.)
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background:
The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms.
Methods:
International, prospective observational study of 60â109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms.
Results:
âTypicalâ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country.
Interpretation:
This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men
Tetrodotoxin, a Candidate Drug for Nav1.1-Induced Mechanical Pain?
Tetrodotoxin (TTX), the mode of action of which has been known since the 1960s, is widely used in pharmacology as a specific inhibitor of voltage-gated sodium channels (Nav channels). This toxin has contributed to the characterization of the allosteric model of the Nav channel, and to discriminating TTX-sensitive and TTX-resistant subtypes. In addition to its role as a pharmacological tool, TTX is now considered a therapeutic molecule, and its development should lead to its use in certain pathologies involving Nav channels, particularly in the field of pain. Specifically, the blockade of Nav channels expressed in nociceptive fibres is one strategy for alleviating pain and its deleterious consequences on health. Recent work has identified, in addition to the Nav1.7, 1.8 and 1.9 channels, the Nav1.1 subtype on dorsal root ganglion (DRG) neurons as a crucial player in mechanical and non-thermal pain. The sensitivity of Nav1.1 to TTX could be exploited at the therapeutic level, especially in chronic pain conditions
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