18 research outputs found
IgG and fibrinogen driven nanoparticle aggregation
A thorough understanding of how proteins induce nanoparticle (NP) aggregation is crucial when designing in vitro and in vivo assays and interpreting experimental results. This knowledge is also crucial when developing nano-applications and formulation for drug delivery systems. In this study, we found that extraction of immunoglobulin G (IgG) from cow serum results in lower polystyrene NPs aggregation. Moreover, addition of isolated IgG or fibrinogen to fetal cow serum enhanced this aggregation, thus demonstrating that these factors are major drivers of NP aggregation in serum. Counter-intuitively, NP aggregation was inversely dependent on protein concentration; i.e., low protein concentrations induced large aggregates, whereas high protein concentrations induced small aggregates. Protein-induced NP aggregation and aggregate size were monitored by absorbance at 400 nm and dynamic light scattering, respectively. Here, we propose a mechanism behind the protein concentration dependent aggregation; this mechanism involves the effects of multiple protein interactions on the NP surface, surface area limitations, aggregation kinetics, and the influence of other serum proteins.We thank Professor Sara Linse for scientific discussions and advice and Professor Patrik Brundin for enabling access to the light microscope. The project received financial support from Nanometer structure consortium at Lund University (nmC@LU), Lars Hierta Foundation, and the research school FLAK of Lund University
The large area detector onboard the eXTP mission
The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship
mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European
participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target
launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering
unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the
design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy
range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to
200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper
we will provide an overview of the LAD instrument design, its current status of development and anticipated
performance
Relation between the sedimentary organic record and the climatic oscilations in the Holocene attested by palynofacies and organic geochemical analyses from a pond of altitude in southern Brazil
Teachers\u27 Impressions of Children Varying in Pragmatic Skills
Many behaviors and characteristics contribute to teachers\u27 impressions of their students and affect teachers\u27 judgments of such qualities as competence and likeability. Among these behaviors are pragmatic skills, the appropriate use of language in social contexts. One hundred fifty-three experienced school teachers listened to one of five audiotaped conversations between a girl and a school librarian, then rated the girl on several scales. In one tape the girl requested, took turns, responded when spoken to, and maintained the logic of the conversation appropriately. In the others she used pragmatic skills inappropriately. Tape condition had a significant effect on ratings of the girl\u27s likeability. Teachers formed positive impressions of the girl when she used all pragmatic skills appropriately and when she failed to respond promptly when spoken to, and negative impressions of the girl in the other conditions. Implications of these results for teacher training and children\u27s pragmatic and social skills training are discussed
Proteome-Wide Characterization of the RNA-Binding Protein RALY-Interactome Using the in Vivo-Biotinylation-Pulldown-Quant (iBioPQ) Approach
RALY is a member of the heterogeneous
nuclear ribonucleoproteins,
a family of RNA-binding proteins generally involved in many processes
of mRNA metabolism. No quantitative proteomic analysis of RALY-containing
ribonucleoparticles (RNPs) has been performed so far, and the biological
role of RALY remains elusive. Here, we present a workflow for the
characterization of RALY’s interaction partners, termed iBioPQ,
that involves in vivo biotinylation of biotin acceptor peptide (BAP)-fused
protein in the presence of the prokaryotic biotin holoenzyme synthetase
of BirA so that it can be purified using streptavidin-coated magnetic
beads, circumventing the need for specific antibodies and providing
efficient pulldowns. Protein eluates were subjected to tryptic digestion
and identified using data-independent acquisition on an ion-mobility
enabled high-resolution nanoUPLC-QTOF system. Using label-free quantification,
we identified 143 proteins displaying at least 2-fold difference in
pulldown compared to controls. Gene Ontology overrepresentation analysis
revealed an enrichment of proteins involved in mRNA metabolism and
translational control. Among the most abundant interacting proteins,
we confirmed RNA-dependent interactions of RALY with MATR3, PABP1
and ELAVL1. Comparative analysis of pulldowns after RNase treatment
revealed a protein–protein interaction of RALY with eIF4AIII,
FMRP, and hnRNP-C. Our data show that RALY-containing RNPs are much
more heterogeneous than previously hypothesized
RAPID AND EFFICIENT ANTIGEN PROCESSING AND PRESENTATION OF A PROTECTIVE AND IMMUNODOMINANT HLA-B*27-RESTRICTED HEPATITIS C VIRUS-SPECIFIC CD8+T CELL EPITOPE
HLA-B*27 exerts protective effects in hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections. While the immunological and virological features of HLA-B*27-mediated protection are not fully understood, there is growing evidence that the presentation of specific immunodominant HLA-B*27-restricted CD8+ T-cell epitopes contributes to this phenomenon in both infections. Indeed, protection can be linked to single immunodominant CD8+ T-cell epitopes and functional constraints on escape mutations within these epitopes. To better define the immunological mechanisms underlying HLA-B*27-mediated protection in HCV infection, we analyzed the functional avidity, functional profile, antiviral efficacy and naïve precursor frequency of CD8+ T cells targeting the immunodominant HLA-B*27-restricted HCV-specific epitope as well as its antigen processing and presentation. For comparison, HLA-A*02-restricted HCV-specific epitopes were analyzed. The HLA-B*27-restricted CD8+ T-cell epitope was not superior to epitopes restricted by HLA-A*02 when considering the functional avidity, functional profile, antiviral efficacy or naïve precursor frequency. However, the peptide region containing the HLA-B*27-restricted epitope was degraded extremely fast by both the constitutive proteasome and the immunoproteasome. This efficient proteasomal processing that could be blocked by proteasome inhibitors was highly dependent on the hydrophobic regions flanking the epitope and led to rapid and abundant presentation of the epitope on the cell surface of antigen presenting cells. Our data suggest that rapid antigen processing may be a key immunological feature of this protective and immunodominant HLA-B*27-restricted HCV-specific epitope. © 2012 Schmidt et al