Laser-light scattering approach to peptide–membrane interaction

© International University Line, 2010Membrane-active peptides are becoming widely used, mainly due to their high therapeutic potential. Although the therapeutic action is characterized, the mechanisms of interaction are often unclear or controversial. In biophysical studies, non-invasive techniques are overlooked when studying the effect of peptides on membranes. Light scattering techniques, such as dynamic light scattering and static light scattering, can be used as tools to determine whether promotion of membrane aggregation in the presence of peptides and of self-peptide aggregation in solution occurs. More recently, light scattering has been used for evaluating the alteration on membrane surface charge (ζ-potential) promoted by membrane–peptide interactions. The data obtained by these techniques (either by themselves or combined with complementary experimental approaches) therefore yield valuable elucidations of membrane-active peptides’ mechanisms of action at the molecular level.This work was partially supported by the Fundação para a Ciência e Tecnologia (FCT) of the Portuguese Ministry of Science, Technology and Higher Education. M.M.D. acknowledges the grant SFRH/BD/41750/2007 from FCT

Computational Intelligence in Serious Games: a case study to identify patterns in a game for children with learning disabilities

This work explores the application of computational intelligence techniques in a serious game (SG) for children with learning disabilities. Specifically, we apply Data Mining (DM) techniques such as Decision Tree and Apriori algorithms aiming to identify the existence of patterns that would allow a better understanding on the profiles of children involved in the game. The data analyzed are related to the interaction of twenty children with the considered SG, which consists of a three dimensional virtual zoo, developed with features that appeal to the preferences of children about nine years old in order to assist and motivate their learning. The results obtained in the conducted experiments revealed patterns in the profiles of the game's players under analysis, allowing to identify some characteristics that can help the psychopedagogical team. These findings can also enable the improvement of the game making it adaptable to different player profiles.info:eu-repo/semantics/publishedVersio

Artificial Intelligence identifying patterns in the social interaction of senior individuals through online activities at Virtual Senior University in Pandemic

Objectives: Data Mining techniques applied to observe patterns in the social interaction of senior individuals during their participation in the online activities that were proposed by the Virtual Senior University during the pandemic. Methodology: Zoom and Facebook platforms were used to streamline conversations, videos with student performances and homework during the COVID-19 pandemic. The experiments conducted enabled the application of the Artificial Intelligence technique called Data Mining to perform statistical analyses and identify profiles based on the social interaction of the individuals who participated in the online activities. Participants answered about Gender, Age (years), Marital Status, Time attending Senior University and Participation in online activities. They also answered about their participation in these activities, informing if it increased, decreased, remained unchanged or if they did not participate. To carry out the analyses of the collected data, age groups were organized, being 50 to 64 years, 65 to 74 years and 75 or more years. Results and Discussion: It was observed that the majority of seniors who had been attending the Virtual Senior University since before 2020, aged between 50 and 64 years, reported that their participation in online activities had increased. According to the analysis that was carried out, it was possible to correctly classify 76.087% of the data. The accuracy described through the Kappa statistic coefficient showed reliability in the data showing a score of 0.6383 and corresponding to a substantial agreement (range between 0.61 and 0.80). Conclusions: The Data Mining technique applied in this study suggests that there was statistical significance for the analyses carried out based on the social interaction of senior individuals, in the age group between 50 and 64 years old, who participated in the online activities proposed by the Virtual Senior University during the pandemic. Different activities are suggested for the other age groups.info:eu-repo/semantics/publishedVersio

Peptide-Phospholipid Cross-Linking Reactions: Identification of Leucine Enkephalin-Alka(e)nal-Glycerophosphatidylcholine Adducts by Tandem Mass Spectrometry

The covalent interactions between peptides and lipid oxidation products, with formation of Schiff and Michael adducts, are known to occur during free radical oxidative damage. In this study, leucine-enkephalin-glycerophosphatidylcholine alka(e)nal adducts were analyzed by electrospray tandem mass spectrometry (MS/MS). Upon collision-induced dissociation of the Leucine enkephalin-2-(9-oxo-nonanoyl)-1-palmitoyl-3-glycerophosphatidylcholine, an alkanal Schiff adduct observed at m/z 1187.7, the main product ions were attributed to the phosphocholine polar head and loss of the peptide. Also, product ions resulting from characteristic losses of phosphatidylcholines and cleavages of the peptide chain (mainly b-type) were observed. Additional product ions formed by combined peptide and phosphatidylcholine fragmentations were identified. The fragmentation pattern of the leucine enkephalin-alkanal Schiff adduct and the leucine enkephalin-alkenal phosphatidylcholine Schiff and Michael adducts were similar, although the loss of the peptide for the Michael adduct should occur through a distinct mechanism. These fragmentation pathways differ greatly from those described for peptide-lipid Schiff and Michael adducts, in which only peptide chain cleavages are reported, probably due to charge retention in the glycerophosphatidylcholine polar head in peptide-glycerophosphatidylcholine adducts

Halophyte plants from sustainable marine aquaponics are a valuable source of omega-3 polar lipids

Marine aquaponics is a promising sustainable approach for the production of profitable crops such as halophytes. However, the effect of this culture approach on the lipid composition of halophytes remains unknown. In this work, we contrasted the polar lipidome of Salicornia ramosissima and Halimione portulacoides when produced in marine aquaponics (effluent from a super-intensive flatfish aquaculture production), with that of conspecifics from donor wild populations. Phospholipids and glycolipids were identified and quantified by LC-MS and MS/MS and their profile statistically analysed. Halophytes produced in aquaponics have higher levels of glycolipids with n-3 fatty acids (DGDG 36:3; SQDG 36:3; MGDG 36:6) compared with the donor wild populations. In the case of H. portulacoides, a significant increase of phospholipids bearing n-3 fatty acids (most in PC and PE) was also recorded. These lipids have potential applications in food, feed and pharmaceutical industries, contributing to the valorization of halophytes produced under sustainable aquaculture practices.publishe

Translocating the blood-brain barrier using electrostatics

Copyright © 2012 Ribeiro,Domingues, Freire,Santos and Castanho. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.Mammalian cell membranes regulate homeostasis, protein activity, and cell signaling. The charge at the membrane surface has been correlated with these key events. Although mammalian cells are known to be slightly anionic, quantitative information on the membrane charge and the importance of electrostatic interactions in pharmacokinetics and pharmacodynamics remain elusive. Recently, we reported for the first time that brain endothelial cells (EC) are more negatively charged than human umbilical cord cells, using zeta-potential measurements by dynamic light scattering. Here, we hypothesize that anionicity is a key feature of the blood-brain barrier (BBB) and contributes to select which compounds cross into the brain. For the sake of comparison, we also studied the membrane surface charge of blood components—red blood cells (RBC), platelets, and peripheral blood mononuclear cells (PBMC).To further quantitatively correlate the negative zeta-potential values with membrane charge density, model membranes with different percentages of anionic lipids were also evaluated. From all the cells tested, brain cell membranes are the most anionic and those having their lipids mostly exposed, which explains why lipophilic cationic compounds are more prone to cross the blood-brain barrier.Fundação para a Ciência e Tecnologia — Ministério da Educação e Ciência (FCT-MEC, Portugal) is acknowledged for funding (including fellowships SFRH/BD/42158/2007 to Marta M.B. Ribeiro, SFRH/BD/41750/2007 to Marco M. Domingues and SFRH/BD/70423/2010 to João M. Freire) and project PTDC/QUI-BIQ/119509/2010. Marie Curie Industry-Academia Partnerships and Pathways (European Commission) is also acknowledged for funding (FP7-PEOPLE-2007-3-1-IAPP, Project 230654)

Liquid chromatography/tandem mass spectrometry characterization of nitroso, nitrated and nitroxidized cardiolipin products

Cardiolipins (CL) are anionic dimeric phospholipids bearing four fatty acids, found in inner mitochondrial membrane as structural components and are involved in several processes as oxidative phosphorylation or apoptotic signalling. As other phospholipids, CL can be modified by reactive oxygen species (ROS) and reactive nitrogen species (RNS), which can modulate various cellular functions. Modifications of CL by RNS remain largely unstudied although other nitrated lipids are emerging as bioactive molecules. In this work, we developed a C30-LC-HRMS/MS methodology to identify the nitrated and nitroxidized tetralinoleoyl-cardiolipin (TLCL), using a biomimetic model of nitration, and to disclose specific fragmentation pathways under HCD MS/MS. Using this lipidomics approach, we were able to separate and identify nitro, nitroso, nitronitroso, and nitroxidized TLCL derivatives, comprising 11 different nitrated compounds. These products were identified using accurate mass measurements and the fragmentation pattern acquired in higher-energy collision dissociation (HCD)-tandem MS/MS experiments. These spectra showed classifying fragmentation pathways, yielding phosphatidic acid (PA-), lysophosphatidic acid (LPA-), and carboxylate fragment ions with the modifying moiety. Remarkably, the typical neutral losses associated with the added moieties were not observed. In conclusion, this work has developed a new method for the identification of nitroso, nitrated and nitroxidized cardiolipin products by using a C30LC-MS platform method, potentially allowing their detection in biological samples.publishe

Analysis of project management tools to support knowledge management

Knowledge Management is an essential element for the successful implementation of projects. Due to the temporary nature of the projects and the teams that participate in them, the transfer, integration, and management of knowledge among projects is vital to promote sharing best practices, and to avoid the repetition of previous mistakes, in order to increase the probability of success for the projects and the organization. For this reason, Project Management tools can play a significant role in supporting Knowledge Management. The goal of this paper is to analyze and evaluate the project management tools of the Gartner Leader quadrant (2019 Gartner Magic Quadrant) regarding their potential for the Capture, Storage, Sharing and Application of knowledge, according to the artifacts in the PMBOK [1], and determine which are the best options. Gartner's leader tools were compared to Confluence, referenced as a great choice for knowledge and project document management. For the development of the artifact was used the Design Science Research (DSR) methodology. The application that obtained the highest score was Targetprocess.info:eu-repo/semantics/publishedVersio

Cleavages of photochromic compounds derived from heterocycles under electrospray tandem mass spectrometry : study of the influence of the heteroatom in fragmentation mechanisms

In this paper we report the fragmentation pathways of chromenes derived from carbazole, dibenzofuran and dibenzothiophene, under ESI-MS/MS experimental conditions, and their relationship with structural features, specially focused on the heteroatom’s effect on the fragmentation mechanisms.Fundação para a Ciência e Tecnologia (FCT