Effects of Ligands on Unfolding of the Amyloid β-Peptide Central Helix: Mechanistic Insights from Molecular Dynamics Simulations

Polymerization of the amyloid β-peptide (Aβ), a process which requires that the helical structure of Aβ unfolds beforehand, is suspected to cause neurodegeneration in Alzheimer's disease. According to recent experimental studies, stabilization of the Aβ central helix counteracts Aβ polymerization into toxic assemblies. The effects of two ligands (Dec-DETA and Pep1b), which were designed to bind to and stabilize the Aβ central helix, on unfolding of the Aβ central helix were investigated by molecular dynamics simulations. It was quantitatively demonstrated that the stability of the Aβ central helix is increased by both ligands, and more effectively by Pep1b than by Dec-DETA. In addition, it was shown that Dec-DETA forms parallel conformations with β-strand-like Aβ, whereas Pep1b does not and instead tends to bend unwound Aβ. The molecular dynamics results correlate well with previous experiments for these ligands, which suggest that the simulation method should be useful in predicting the effectiveness of novel ligands in stabilizing the Aβ central helix. Detailed Aβ structural changes upon loss of helicity in the presence of the ligands are also revealed, which gives further insight into which ligand may lead to which path subsequent to unwinding of the Aβ central helix

Polyamines: total daily intake in adolescents compared to the intake estimated from the Swedish Nutrition Recommendations Objectified (SNO)

Background: Dietary polyamines have been shown to give a significant contribution to the body pool of polyamines. Knowing the levels of polyamines (putrescine, spermidine, and spermine) in different foods and the contribution of daily food choice to polyamine intake is of interest, due to the association of these bioactive amines to health and disease. Objective: To estimate polyamine intake and food contribution to this intake in adolescents compared to a diet fulfilling the Swedish Nutrition Recommendations. Design: A cross-sectional study of dietary intake in adolescents and an ‘ideal diet’ (Swedish nutrition recommendations objectified [SNO]) list of foods was used to compute polyamine intake using a database of polyamine contents of foods. For polyamine intake estimation, 7-day weighed food records collected from 93 adolescents were entered into dietetic software (Dietist XP) including data on polyamine contents of foods. The content of polyamines in foods recommended according to SNO was entered in the same way. Results: The adolescents’ mean daily polyamine intake was 316±170 µmol/day, while the calculated contribution according to SNO was considerably higher with an average polyamine intake of 541 µmol/day. In both adolescent's intake and SNO, fruits contributed to almost half of the total polyamine intake. The reason why the intake among the adolescents was lower than the one calculated from SNO was mainly due to the low vegetable consumption in the adolescents group. Conclusions: The average daily total polyamine intake was similar to that previously reported in Europe. With an ‘ideal’ diet according to Swedish nutrition recommendations, the intake of this bioactive non-nutrient would be higher than that reported by our adolescents and also higher than that previously reported from Europe

Polyamines in foods: development of a food database

Background: Knowing the levels of polyamines (putrescine, spermidine, and spermine) in different foods is of interest due to the association of these bioactive nutrients to health and diseases. There is a lack of relevant information on their contents in foods. Objective: To develop a food polyamine database from published data by which polyamine intake and food contribution to this intake can be estimated, and to determine the levels of polyamines in Swedish dairy products. Design: Extensive literature search and laboratory analysis of selected Swedish dairy products. Polyamine contents in foods were collected using an extensive literature search of databases. Polyamines in different types of Swedish dairy products (milk with different fat percentages, yogurt, cheeses, and sour milk) were determined using high performance liquid chromatography (HPLC) equipped with a UV detector. Results: Fruits and cheese were the highest sources of putrescine, while vegetables and meat products were found to be rich in spermidine and spermine, respectively. The content of polyamines in cheese varied considerably between studies. In analyzed Swedish dairy products, matured cheese had the highest total polyamine contents with values of 52.3, 1.2, and 2.6 mg/kg for putrescine, spermidine, and spermine, respectively. Low fat milk had higher putrescine and spermidine, 1.2 and 1.0 mg/kg, respectively, than the other types of milk. Conclusions: The database aids other researchers in their quest for information regarding polyamine intake from foods. Connecting the polyamine contents in food with the Swedish Food Database allows for estimation of polyamine contents per portion

Novel aroylated phenylenediamine compounds enhance antimicrobial defense and maintain airway epithelial barrier integrity

Publisher's version (útgefin grein)Aroylated phenylenediamines (APDs) are novel inducers of innate immunity enhancing cathelicidin gene expression in human bronchial epithelial cell lines. Here we present two newly developed APDs and aimed at defining the response and signaling pathways for these compounds with reference to innate immunity and antimicrobial peptide (AMP) expression. Induction was initially defined with respect to dose and time and compared with the APD Entinostat (MS-275). The induction applies to several innate immunity effectors, indicating that APDs trigger a broad spectrum of antimicrobial responses. The bactericidal effect was shown in an infection model against Pseudomonas aeruginosa by estimating bacteria entering cells. Treatment with a selected APD counteracted Pseudomonas mediated disruption of epithelial integrity. This double action by inducing AMPs and enhancing epithelial integrity for one APD compound is unique and taken as a positive indication for host directed therapy (HDT). The APD effects are mediated through Signal transducer and activator of transcription 3 (STAT3) activation. Utilization of induced innate immunity to fight infections can reduce antibiotic usage, might be effective against multidrug resistant bacteria and is in line with improved stewardship in healthcare.Icelandic Center for Research (RANNÍS 173931) and University of Iceland research fund are acknowledged for support. Bryndís Valdimarsdóttir for advises on preparation of conditioned media and cell culture. Kristín Elísabet Alansdóttir for help with confocal microscopy and ImageJ analyses. Thanks to Náttúruverndarsjóður Pálma Jónssonar for early support of this project. We acknowledge Prof. Ronald G. Crystal and collaborators for generously providing us with the BCi-NS1.1 cell line. We thank Snæbjörn Pálsson for advices on statistical analysis.Peer reviewe

LES and RANS of air and oxy-coal combustion in a pilot-scale facility: predictions of radiative heat transfer

The development of carbon capture and storage (CCS) technology is important to permit the use of fossil fuels while honouring commitments to curb greenhouse gas emissions. Coal is a valuable global resource, which is widely available around the world, however its detrimental e ect on climate change will limit its use in a future with strict controls over carbon emissions. Oxyfuel combustion is a promising CCS technology that is being actively pursued in the development of large scale demonstration projects. Under the oxyfuel process for CCS, the combustion gas is replaced with a mixture of recycled ue gas and enriched oxygen. The resulting combustion environment can vary signi cantly from traditional air- red combustion. The development of modelling capabilities will greatly improve the optimisation process to develop oxyfuel technology into an economically viable prospect. This study evaluates the use of large eddy simulation (LES) and Reynoldsaveraged Navier Stokes (RANS) models on the prediction of thermal radiation during coal combustion for both air- red and oxyfuel operation in a pilot-scale 250 kWth furnace. The furnace is part of the UKCCSRC Pilot-scale Advanced Capture Technology (PACT) facilities and was designed for detailed analysis of the combustion process. Two radiation models were evaluated during the RANS calculations, the widely used weighted sum of grey gases (WSGG) andthe full-spectrum correlated k (FSCK) model, while the LES case was calculated using the FSCK radiation model. The results show that the LES solutions are in better agreement with measured values than the RANS predictions for both air- red and oxyfuel coal combustion, however LES demands considerably more computational resources

Sequence-selective DNA recognition and enhanced cellular up-take by peptide–steroid conjugates

Several GCN4 bZIP TF models have previously been designed and synthesized. However, the synthetic routes towards these constructs are typically tedious and difficult. We here describe the substitution of the Leucine zipper domain of the protein by a deoxycholic acid derivative appending the two GCN4 binding region peptides through an optimized double azide–alkyne cycloaddition click reaction. In addition to achieving sequence specific dsDNA binding, we have investigated the potential of these compounds to enter cells. Confocal microscopy and flow cytometry show the beneficial influence of the steroid on cell uptake. This unique synthetic model of the bZIP TF thus combines sequence specific dsDNA binding properties with enhanced cell-uptake. Given the unique properties of deoxycholic acid and the convergent nature of the synthesis, we believe this work represents a key achievement in the field of TF mimicry

A synthetic snRNA m3G-CAP enhances nuclear delivery of exogenous proteins and nucleic acids

Accessing the nucleus through the surrounding membrane poses one of the major obstacles for therapeutic molecules large enough to be excluded due to nuclear pore size limits. In some therapeutic applications the large size of some nucleic acids, like plasmid DNA, hampers their access to the nuclear compartment. However, also for small oligonucleotides, achieving higher nuclear concentrations could be of great benefit. We report on the synthesis and possible applications of a natural RNA 5′-end nuclear localization signal composed of a 2,2,7-trimethylguanosine cap (m3G-CAP). The cap is found in the small nuclear RNAs that are constitutive part of the small nuclear ribonucleoprotein complexes involved in nuclear splicing. We demonstrate the use of the m3G signal as an adaptor that can be attached to different oligonucleotides, thereby conferring nuclear targeting capabilities with capacity to transport large-size cargo molecules. The synthetic capping of oligos interfering with splicing may have immediate clinical applications