RESUMEN
We have studied the involvement of receptor interacting protein kinase-1 (RIP1) and dsRNA-activated protein kinase (PKR) in external dsRNA-induced apoptotic and necrotic cell death in Jurkat T cell lymphoma. Our results suggest that RIP1 plays an imported role in dsRNA-induced apoptosis and necrosis. We demonstrated that contrary to necrosis, protein synthesis is inhibited in apoptosis. Here, we show that phosphorylation of translation initiation factor 2-alpha (eukaryotic initiation factor 2-alpha (eIF2-alpha)) and its kinase, PKR, occur in dsRNA-induced apoptosis but not in necrosis. These events are caspase-dependent and coincide with the appearance of the caspase-mediated PKR fragments, N-terminal domain (ND) and kinase domain (KD). Our immunoprecipitation experiments demonstrated that both fragments could independently co-precipitate with full-length PKR. Expression of PKR-KD leads to PKR and eIF2-alpha phosphorylation and inhibits protein translation, whereas that of PKR-ND does not. Co-expression of PKR-ND and PKR-KD promotes their interaction with PKR, PKR and eIF2-alpha phosphorylation and suppresses protein translation better than PKR-KD alone. Our findings suggest a caspase-dependent mode of activation of PKR in apoptosis in which the PKR-KD fragment interacts with and activates intact PKR. PKR-ND facilitates the interaction of PKR-KD with full-length PKR and thus the activation of the kinase and amplifies the translation inhibitory signal.
Asunto(s)
Caspasas/metabolismo , Fragmentos de Péptidos/metabolismo , Biosíntesis de Proteínas , eIF-2 Quinasa/metabolismo , Apoptosis/efectos de los fármacos , Inhibidores de Caspasas , Línea Celular , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Humanos , Inmunoprecipitación , Células Jurkat , Necrosis , Fosforilación/efectos de los fármacos , Unión Proteica/efectos de los fármacos , Biosíntesis de Proteínas/efectos de los fármacos , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Estructura Terciaria de Proteína/efectos de los fármacos , ARN Bicatenario/farmacología , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Transducción de Señal/efectos de los fármacos , eIF-2 Quinasa/biosíntesisRESUMEN
The air quality in Parisian subway stations is a great concern to users and the public authorities. Particle concentration is one of the major problems; indeed concentrations observed in stations are generally superior to those collected in the street. The subway generates its own particles from wheels / rail contact, braking, the ground... One of the ways explored to lower this level of particles is a removal treatment: the principle is to treat the ambient air using a suitable system placed in stations. Following literature, the process chosen by Paris Transport Authority is the electrostatic precipitator. An electrostatic precipitator prototype from the Recycl'Air company is installed in May 2001 in a closed station on the 5th line (Italy Place -Bobigny). Results show that, by the end of approximately one year, the efficiency has fallen by 15% and it is therefore necessary to clean the precipitation cartridges. A consideration has also been made on the possibility to equip an entire subway station. According to the results obtained, about twenty filters placed in the top of a non mechanically ventilated station would permit to half an initial concentration in particles of 230 microg m(-3).
Asunto(s)
Contaminación del Aire/prevención & control , Monitoreo del Ambiente/métodos , Material Particulado/análisis , Vías Férreas , Electricidad Estática , Precipitación Química , Paris , Tamaño de la PartículaRESUMEN
The degradation of aqueous solutions of pentachlorophenol (PCP) in a three-stage sonochemical reactor operating in the continuous flow mode has been investigated. The experimental reactor may be considered as a series of three high-frequency ultrasonic units. The influence of several parameters such as ultrasonic power, reactor volume and volumetric feed flow rate on the reactor performance is reported. Application of classical basic chemical engineering principles leads to a model that enables us to predict the PCP concentration within the reactor. In steady state, experimental conversion rates are shown to be in good agreement with model predictions.
Asunto(s)
Pentaclorofenol/química , Contaminantes Químicos del Agua , Modelos Químicos , Soluciones , Ultrasonido , AguaRESUMEN
In relation to design and modeling of sonochemical reactors, the hydrodynamic behaviour of a high-frequency ultrasonic reactor has been investigated. Residence time distribution (RTD) measurements have been performed by means of a tracer method. The influence of ultrasound on the response to an inlet pulse was evidenced. It was shown that the reactor behaves like a completely stirred tank reactor (CSTR) as soon as ultrasonic irradiation operates. Preliminary observations on acoustic streaming occurring within the reactor will also be presented.