Calprotectin (S100A8/S100A9) and Myeloperoxidase: Co-Regulators of Formation of Reactive Oxygen Species

Inflammatory mediators trigger polymorphonuclear neutrophils (PMN) to produce reactive oxygen species (ROS: O2-, H2O2, ∙OH). Mediated by myeloperoxidase in PMN, HOCl is formed, detectable in a chemiluminescence (CL) assay. We have shown that the abundant cytosolic PMN protein calprotectin (S100A8/A9) similarly elicits CL in response to H2O2 in a cell-free system. Myeloperoxidase and calprotectin worked synergistically. Calprotectin-induced CL increased, whereas myeloperoxidase-triggered CL decreased with pH > 7.5. Myeloperoxidase needed NaCl for CL, calprotectin did not. 4-hydroxybenzoic acid, binding ∙OH, almost abrogated calprotectin CL, but moderately increased myeloperoxidase activity. The combination of native calprotectin, or recombinant S100A8/A9 proteins, with NaOCl markedly enhanced CL. NaOCl may be the synergistic link between myeloperoxidase and calprotectin. Surprisingly- and unexplained- at higher concentration of S100A9 the stimulation vanished, suggesting a switch from pro-oxidant to anti-oxidant function. We propose that the ∙OH is predominant in ROS production by calprotectin, a function not described before

Nicotine-enhanced oxidation of low-density lipoprotein and its components by myeloperoxidase/H2O2/Cl- system

In this study, the effect of nicotine on the LDL oxidation by the MPO/H2O2/Cl- system and the effect of HOCl on LDL and some of its components, such as methyl linoleate, vitamin E and the amino acid tryptophan were explored. Nicotine, in micromolar concentrations, enhanced the tryptophan oxidation, either present in LDL or free, in solution. Nicotine also decreased the formation of conjugated dienes and oxygen consumption in a methyl linoleate / HOCl system, and there was evidence to suggest an increase in chlorohydrin formation. Acceleration of the vitamin E oxidation by HOCl was also observed in the presence of nicotine. These data show that the interaction of nicotine and HOCl can promote significant biochemical modifications in LDL particle and some of its components involved in the pathogenesis of cardiovascular and other diseases.Nesse estudo, nós avaliamos o efeito da nicotina sobre a oxidação da LDL pelo sistema MPO/H2O2/Cl- e o efeito do HOCl sobre a LDL e alguns de seus componentes, tais como metil linoleato, vitamina E e o aminoácido triptofano. Nicotina, em concentração micromolar, amplia a oxidação do triptofano, livre em solução ou presente na LDL. A nicotina promove a diminuição da formação de dienos conjugados e consumo de oxigênio no sistema metil linoleato/HOCl, e houve evidência que sugere aumento na formação de clorohidrinas. O aumento da oxidação da vitamina E pelo HOCl também foi observada na presença de nicotina. Esses dados mostram que a interação da nicotina e HOCl pode promover alterações bioquímicas significativas na partícula de LDL e alguns de seus componentes envolvidos na patogênese de doenças cardiovasculares e de outras doenças.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Estadual Paulista, Instituto de Química Departamento de Bioquímica e Tecnologia QuímicaUniversidade Estadual Paulista, Faculdade de Ciências Farmacêuticas de AraraquaraUNICENTRO Departamento de FarmáciaUniversidade Estadual Paulista, Instituto de Química Departamento de Bioquímica e Tecnologia QuímicaUniversidade Estadual Paulista, Faculdade de Ciências Farmacêuticas de AraraquaraFAPESP: 1999/10229-

Incidence de l'expérience de l'opérateur sur la pose de la digue dentaire : évaluation prélimaire sur simulateur

The dental dam placement is a mandatory prerequisite before any endodontic treatment. Nevertheless, international prevalence studies reveal that its use remains limited. One of the main reasons given by the practitioners is the time required to its placement. Therefore, this work has been performed to evaluate the influence of the operator experience on the rubber dam placement time, on dental simulator. In the first part, we will describe the dental dam and the main advantages of its use in conservative dentistry and endodontics. Prevalence studies conducted on the dental dam set up in different countries will be also presented in this part. The second part will present the implementation of the experimental study, the material used and the group constitution. The results of this preliminary study will be presented in a third part before being discussed.La mise en place de la digue dentaire est un prérequis obligatoire lors de tout traitement endodontique. Cependant, les études de prévalence, au niveau international, révèlent que son utilisation reste limitée. Une des principales raisons évoquées par les praticiens est le temps nécessaire à sa pose. C’est pourquoi, ce travail a été réalisé afin d’évaluer l’influence de l’expérience de l’opérateur sur le temps de pose de la digue dentaire sur simulateur. La première partie consiste en la présentation de généralités sur la digue dentaire et les avantages majeurs procurés par son utilisation en odontologie conservatrice et endodontie. Les principales études de prévalence menées dans différent pays sur la pose de la digue dentaire seront également présentées dans cette partie. Dans un second temps, nous décrirons la mise en œuvre de l’étude menée, le matériel utilisé ainsi que la constitution des groupes d’études. La troisième partie présentera les résultats obtenus dans cette étude préliminaire et ces deniers seront discutés