Analysis of the interaction of influenza virus polymerase complex with human cell factors

12 pages, 4 figures.-- PMID: 18491320 [PubMed].-- Supplementary information (Suppl. figure S1, 2 pages) available at: http://www.wiley-vch.de/contents/jc_2120/2008/pro200700508_s.pdfThe influenza virus polymerase is formed by the PB1, PB2 and PA subunits and is required for virus transcription and replication in the nucleus of infected cells. Here we present the characterisation of the complexes formed intracellularly by the influenza polymerase in human cells. The virus polymerase was expressed by cotransfection of the polymerase subunits cDNAs, one of which fused to the tandem-affinity purification (TAP) tag. The intracellular complexes were purified by the TAP approach, which involves IgG-Sepharose and calmodulin-agarose chromatography, under very mild conditions. The purified complexes contained the heterotrimeric polymerase and a series of associated proteins that were not apparent in purifications of untagged polymerase used as a control. Several influenza polymerase-associated proteins were identified by MALDI-MS and their presence in purified polymerase-containing complexes were verified by Western blot. Their relevance for influenza infection was established by colocalisation with virus ribonucleoproteins in human infected cells. Most of the associated human factors were nuclear proteins involved in cellular RNA synthesis, modification and nucleo-cytoplasmic export, but some were cytosolic proteins involved in translation and transport. The interactions recognised in this proteomic approach suggest that the influenza polymerase might be involved in steps of the infection cycle other than RNA replication and transcription.N. J. was a fellow from Ministerio de Educación y Ciencia. E. T. was a fellow from Instituto de Salud Carlos III. P. G. was a fellow from Gobierno Vasco. This work was supported by the Spanish Ministry of Education and Science (Ministerio de Educación y Ciencia) (grant BFU2004-491), the VIRHOST Program financed by Comunidad de Madrid, European Vigilance Network for the Management of Antiviral Drug Resistance (VIRGIL) and the FLUPOL strep project (SP5B-CT-2007-044263).Peer reviewe

On the neural networks of empathy: A principal component analysis of an fMRI study

© 2008 Nomi et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Frequency drift in MR spectroscopy at 3T

Purpose: Heating of gradient coils and passive shim components is a common cause of instability in the B-0 field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites.Method: A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC).Results: Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p &lt; 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI.Discussion: This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.</p

Cloning and characterization of acetylcholinesterase of green pufferfish tetraodon nigroviridis

In an open pilot study, the authors tested whether the nonpeptide glycoprotein (GP) IIb/IIIa antagonist tirofiban, a blocker of platelet aggregation, prevents the transition of ischemic brain tissue into the infarct proper as defined by MRI (perfusion-weighted/T2-weighted) in patients with acute ischemic stroke. The infarct volume (T2 lesion after 1 week) was smaller in treated patients (n = 10) compared with matched control subjects (n = 10; p = 0.029) with similar initial perfusion deficit (TTP-maps). The authors conclude that GP IIb/IIIa antagonists have. therapeutic potential in acute stroke therapy

Beta Peak Frequencies at Rest Correlate with Endogenous GABA+/Cr Concentrations in Sensorimotor Cortex Areas

<div><p>Neuronal oscillatory activity in the beta band (15–30 Hz) is a prominent signal within the human sensorimotor cortex. Computational modeling and pharmacological modulation studies suggest an influence of GABAergic interneurons on the generation of beta band oscillations. Accordingly, studies in humans have demonstrated a correlation between GABA concentrations and power of beta band oscillations. It remains unclear, however, if GABA concentrations also influence beta peak frequencies and whether this influence is present in the sensorimotor cortex at rest and without pharmacological modulation. In the present study, we investigated the relation between endogenous GABA concentration (measured by magnetic resonance spectroscopy) and beta oscillations (measured by magnetoencephalography) at rest in humans. GABA concentrations and beta band oscillations were measured for left and right sensorimotor and occipital cortex areas. A significant positive linear correlation between GABA concentration and beta peak frequency was found for the left sensorimotor cortex, whereas no significant correlations were found for the right sensorimotor and the occipital cortex. The results show a novel connection between endogenous GABA concentration and beta peak frequency at rest. This finding supports previous results that demonstrated a connection between oscillatory beta activity and pharmacologically modulated GABA concentration in the sensorimotor cortex. Furthermore, the results demonstrate that for a predominantly right-handed sample, the correlation between beta band oscillations and endogenous GABA concentrations is evident only in the left sensorimotor cortex.</p></div

Histogram analysis reveals a better delineation of tumor volume from background in F-18-FET PET compared to CBV maps in a hybrid PET-MR studie in gliomas

Anatomical imaging with magnetic resonance imaging (MRI) is currently the method of first choice for diagnostic investigation of glial tumors. However, different MR sequences may over- or underestimate tumor size and thus it may not be possible to delineate tumor from adjacent brain. In order to compensate this confinement additonal MR sequences like perfusion weighted MRI (PWI) with regional cerebral blood volume (rCBV) or positron emission tomography (PET) with aminoacids are used to gain further information. Recent studies suggest that both of theses image modalities provide similar diagnostic information. For comparison tumor to brain ratios (TBR) with mean and maximum values are frequently used but results from different studies can often not be checked against each other. Furthermore, especially the maximum TBR in rCBV is at risk to be falsified by artifacts (e.g. blood vessels). These confinements are reduced by the use of histograms since all information of the VOIs are equally displayed. In this study we measured and compared the intersection of tumor and reference tissue histograms in F-18-FET PET and rCBV maps in glioma patients. Methods: Twenty-seven glioma patients with contrast enhancing lesion on T1-weighted MR images were investigated using static F-18-FET PET and rCBV in MRI using a PET-MR hybrid scanner. In all patients diagnosis was confirmed histologically (7 grade II gliomas, 6 grade III gliomas and 14 grade IV gliomas). We generated a set of tumor and reference tissue Volumes-of-Interest (VOIs) based on T1 weighted images in MRI with the tumor VOI defined by contrast enhancement and transferred these VOIs to the corresponding F-18-FET PET scans and rCBV maps. From these VOIs we generated tumor and reference tissue histograms with a unity of one for each curve integral and measured the proportion of the area under the tumor curve that falls into the reference curve for F-18-FET PET and rCBV maps for each patient. Results: The mean proportion of the area under the tumor curve that falls into the reference curve was smaller in FET PET than in rCBV maps (13.1 +/- 19.5% vs. 45.0 +/- 21.3%; p < 0.001). Conclusions: Measuring the intersection of tumor and reference tissue histograms in F-18-FET PET and rCBV maps based on identical VOIs defined in anatomical images with tumor marked by contrast enhancement in T1-weighted images can easily be performed and indicates that tumor volume can better be discriminated from background in F-18-FET PET compared to rCBV in MRI. With this approach artefacts (e.g. blood vessels) impair the results to a lesser degree compared to the mean and especially maximal TBRs which are often used when comparing these two image modalities. (C) 2013 Elsevier B.V. All rights reserved

Beta peak frequencies per MEG ROI and condition.

<p>Beta peak frequencies per MEG ROI and condition.</p

Sensor selection for respective MEG ROIs, individual beta peak frequencies and average beta peak frequencies across MEG ROIs.

<p>A) Sensors for left sensorimotor MEG ROI (orange triangles), right sensorimotor MEG ROI (blue dots) and occipital MEG ROI (black diamonds). B) Individual beta peak frequencies for all 15 subjects (EC+EO condition) for left sensorimotor MEG ROI (orange lines), right sensorimotor MEG ROI (blue lines) and occipital MEG ROI (black lines). Individual beta peak frequencies are highlighted by asterisks. C) Average beta peak frequencies separately for all conditions (EO, EC, EC+EO) and all MEG ROIs. Error bars represent standard deviations.</p