Interferon y Stimulation Modulates the Proteolytic Activity and Cleavage Site Preference of 20S Mouse Proteasomes

The proteasome is a 700-kD multisubunit enzyme complex with several proteolytically active sites. The enzyme complex is involved in both ubiquitin-dependent and -independent protein degradation and may contribute to the processing of antigens presented by major histocompatibility complex (MHC) class I molecules. Here we demonstrate that treatment of mouse fibroblast cells with 20 U interferon qr (IFN-y) for 3 d induces a change in the proteasome subunit composition and that the B-type subunit LMP2, which is encoded in the MHC class II region, is incorporated into the enzyme complex. This is paralleled by reduction of the homologous 6-subunit. IFN-3' stimulation results in a downregulation of the chymotrypsin-like Suc-LLVY-MCA peptide hydrolyzing activity of 20S proteasomes whereas the trypsin-like activity remains unaffected. When tested as a substrate a synthetic 25-mer polypeptide whose sequence covers the antigenic nonapeptide YPHFMPTNL of the MCMV pp89, 20S proteasomes of IFN-3'-induced cells exhibit altered chymotrypsin-like cleavage site preferences. In the absence of IFN-qr induction, the naturally processed nonamer peptide that is presented by MHC class.I molecules appears as a minor cleavage product. IFN-'y activation does not result in an increase of the final peptide but results in a different set of peptides. We hypothesize that these peptides represent precursor peptides that can be trimmed to final peptide size

Design of unstructured block ramps: A state-of-the-art Review

River hydrodynamicsInteraction with structure

Comparison of Subjective Responses to Oral and Intravenous Alcohol Administration under Similar Systemic Exposures

Objective To test whether an individual's subjective responses to alcohol are similar when the breath alcohol concentration (BrAC) trajectory resulting from oral administration is matched by intravenous administration. Background Individuals perceive the effects of alcohol differently, and the variation is commonly used in research assessing the risk for developing an alcohol use disorder. Such research is supported by both oral and intravenous alcohol administration techniques, and any differences attributable to the route employed should be understood. Methods We conducted a 2‐session, within‐subject study in 44 young adult, healthy, non‐dependent drinkers (22 females and 22 males). In the first session, subjects ingested a dose of alcohol which was individually calculated, on the basis of total body water, to yield a peak BrAC near 80 mg/dl, and the resulting BrAC trajectory was recorded. A few days later, subjects received an intravenous alcohol infusion rate profile, pre‐computed to replicate each individual's oral alcohol BrAC trajectory. In both sessions, we assessed 4 subjective responses to alcohol: SEDATION, SIMULATION, INTOXICATION, and HIGH; at baseline and frequently for 4 hours. We compared the individuals’ baseline‐corrected responses at peak BrAC and at half‐peak BrAC on both the ascending and descending limbs. We also computed and compared Pearson‐product moment correlations of responses by route of administration, the Mellanby measure of acute adaptation to alcohol, and the area under the entire response curve for each subjective response. Results No significant differences in any measure could be attributed to the route of alcohol administration. Eleven of 12 response comparisons were significantly correlated across the routes of alcohol administration, with 9 surviving correction for multiple measures, as did the Mellanby effect and area under the response curve correlations. Conclusion The route of alcohol administration has a minimal effect on subjective responses to alcohol when an individual's BrAC exposure profiles are similar

The autophagic machinery is necessary for removal of cell corpses from the developing retinal neuroepithelium

12 páginas, 8 figuras -- PAGS nros. 1279-1290Autophagy is a homoeostatic process necessary for the clearance of damaged or superfluous proteins and organelles. The recycling of intracellular constituents also provides energy during periods of metabolic stress, thereby contributing to cell viability. In addition, disruption of autophagic machinery interferes with embryonic development in several species, although the underlying cellular processes affected remain unclear. Here, we investigate the role of autophagy during the early stages of chick retina development, when the retinal neuroepithelium proliferates and starts to generate the first neurons, the retinal ganglion cells. These two developmental processes are accompanied by programmed cell death. Upon treatment with the autophagic inhibitor 3-methyladenine, retinas accumulated numerous TdT-mediated dUTP nick-end labelling-positive cells that correlated with a lack of the ‘eat-me’ signal phosphatidylserine (PS). In consequence, neighbouring cells did not engulf apoptotic bodies and they persisted as individual cell corpses, a phenotype that was also observed after blockade of phagocytosis with phospho-L-Serine. Supplying the retinas with methylpyruvate, a cell-permeable substrate for ATP production, restored ATP levels and the presentation of PS at the cell surface. Hence, engulfment and lysosomal degradation of apoptotic bodies were also re-established. Together, these data point to a novel role for the autophagic machinery during the development of the central nervous systemThis research was supported by grants from the Spanish Ministerio de Educación y Ciencia (BFU2006-00508 to PB and SAF2007-66175 to EJdlR) and Comunidad de Madrid (CCG06-CSIC/SAL-0821 to PB). MAM is a FPU Fellow and PB is a Ramón y Cajal Fellow (both Ministerio de Educación y Ciencia programs)Peer reviewe

Particle contact laws and their properties for simulation of fluid-sediment interaction with coupled SPH-DEM model

The transport of sediment due to the interaction of fluid and solids is a prevalent geophysical process. The detailed modelling of the interaction between the fluid and the sediment particles is still a challenging task. In the present study we model the fluid phase by smoothed particle hydrodynamics (SPH) using the classical approach where the fluid is assumed to be weakly compressible. The sediment, in terms of solid spheres made of granite, is modelled by the discrete element method (DEM). Both of them are meshfree particle methods but SPH is a continuum approach and DEM describes the motion and interaction of discrete solid objects. The interaction between SPH and DEM particles is modelled as particle-to-particle contact in combination with a boundary condition at the solid interface. Therefore, a contact law is used to capture the collision process and to ensure balancing of collision forces. In doing so, two contact types have to be modelled, i.e. sediment-sediment and fluid-sediment. The approach and properties these contact types are presented in detail. Advantages and drawbacks of the approaches are discussed based on examples