Optimality in self-organized molecular sorting

We introduce a simple physical picture to explain the process of molecular sorting, whereby specific proteins are concentrated and distilled into submicrometric lipid vesicles in eukaryotic cells. To this purpose, we formulate a model based on the coupling of spontaneous molecular aggregation with vesicle nucleation. Its implications are studied by means of a phenomenological theory describing the diffusion of molecules towards multiple sorting centers that grow due to molecule absorption and are extracted when they reach a sufficiently large size. The predictions of the theory are compared with numerical simulations of a lattice-gas realization of the model and with experimental observations. The efficiency of the distillation process is found to be optimal for intermediate aggregation rates, where the density of sorted molecules is minimal and the process obeys simple scaling laws. Quantitative measures of endocytic sorting performed in primary endothelial cells are compatible with the hypothesis that these optimal conditions are realized in living cells

Association between high dietary intake of the n-3 polyunsaturated fatty acid docosahexaenoic acid and reduced risk of Crohn's disease

Background: There are plausible mechanisms for how dietary docosahexaenoic acid (DHA), an n−3 polyunsaturated fatty acid, could prevent Crohn's disease (CD). Aim: To conduct a prospective study to investigate the association between increased intake of DHA and risk of CD. Methods: Overall, 229 702 participants were recruited from nine European centres between 1991 and 1998. At recruitment, dietary intakes of DHA and fatty acids were measured using validated food frequency questionnaires. The cohort was monitored through to June 2004 to identify participants who developed incident CD. In a nested case–control analysis, each case was matched with four controls; odds ratios (ORs) were calculated for quintiles of DHA intake, adjusted for total energy intake, smoking, other dietary fatty acids, dietary vitamin D and body mass index. Results: Seventy-three participants developed incident CD. All higher quintiles of DHA intake were inversely associated with development of CD; the highest quintile had the greatest effect size (OR = 0.07; 95% CI = 0.02–0.81). The OR trend across quintiles of DHA was 0.54 (95% CI = 0.30–0.99, Ptrend = 0.04). Including BMI in the multivariate analysis, due to its correlation with dietary fat showed similar associations. There were no associations with the other dietary fatty acids studied. Conclusion: There were inverse associations, with a biological gradient between increasing dietary docosahexaenoic acid intakes and incident Crohn's disease. Further studies in other populations should measure docosahexaenoic acid to determine if the association is consistent and the hypothesis tested in randomised controlled trials of purely docosahexaenoic acid supplementation

Interactions between endothelial cells and HIV-1.

Endothelial cells (EC) participate in inflammatory and immune reactions by producing and responding to soluble mediators. Human immunodeficiency virus (HIV)-1 profoundly alters the features of EC. In some anatomical districts, they are infected by the virus and may represent a relevant reservoir. During lymphomononuclear cell diapedesis, EC activate virus replication in crossing cells. Direct or indirect damage of EC is particularly relevant in central nervous system, where blood-brain barrier perturbation is pivotal in neuronal degeneration. The observed alterations of EC adhesive properties contribute in altered leukocyte traffic from blood to lymphoid organs and tissues and play a role in the onset of immune surveillance alteration. These alterations of EC functions are relevant for the general vasculopathy, which marks the acquired immunodeficiency syndrome, and in particular are instrumental in the pathogenesis of Kaposi's sarcoma. Here we discuss the biological and molecular activation of EC in HIV-1 infection that represents the basis to understand the pathogenesis of HIV-1 associated vascular diseases

Gravitational Geons in 1+1 Dimensions

It is well known that general relativity does not admit gravitational geons that are stationary, asymptotically flat, singularity free and topologically trivial. However, it is likely that general relativity will receive corrections at large curvatures and the modified field equations may admit solutions corresponding to this type of geon. If geons are produced in the early universe and survive until today they could account for some of the dark matter that has been "observed" in galaxies and galactic clusters. In this paper I consider gravitational geons in 1+1 dimensional theories of gravity. I show that the Jackiw-Teitelboim theory with corrections proportional to $R^2$ and $\Box R$ admits gravitational geons. I also show that gravitational geons exist in a class of theories that includes Lagrangians proportional to $R^{2/3}$.Comment: 8 pages, a comment added, two references corrected, to appear in Classical and Quantum Gravit

Integrins: A flexible platform for endothelial vascular tyrosine kinase receptors.

Compared to lower metazoans, vertebrates built up an exclusively new set of adhesion-related genes involved in the tissue development and in their functions. They include a large variety of extracellular matrix proteins and their heterodimeric integrin adhesive receptors. Integrins control the adhesive state of the cell through complex molecular mechanisms. Outside-in signalling informs the cell about the extracellular matrix environment, while Inside-out signalling results in changes in integrin functional activity. In the last 10 years it has well established a reciprocal integration of signals originating from integrins and receptors for soluble growth factors. This review summarizes the current understanding of this connection in vascular endothelial cells and highlights how integrins regulate a genetic program triggered by angiogenic inducers during embryo development and in adult life

Percolation, Morphogenesis, and Burgers Dynamics in Blood Vessels Formation

Experiments of in vitro formation of blood vessels show that cells randomly spread on a gel matrix autonomously organize to form a connected vascular network. We propose a simple model which reproduces many features of the biological system. We show that both the model and the real system exhibit a fractal behavior at small scales, due to the process of migration and dynamical aggregation, followed at large scale by a random percolation behavior due to the coalescence of aggregates. The results are in good agreement with the analysis performed on the experimental data.Comment: 4 pages, 11 eps figure

Gravitational Geons on the Brane

In this paper, we examine the possibility of static, spherically symmetric gravitational geons on a 3 dimensional brane embedded in a 4+1 dimensional space-time. We choose a specific g_tt for the brane-world space-time metric. We then calculate g_rr analytically in the weak field limit and numerically for stronger fields. We show that the induced field equations on the brane do admit gravitational geon solutions.Comment: 14 pages with 9 figures. To appear in General Relativity and Gravitatio

Collective cyber situational awareness in EU. A political project of difficult legal realisation?

From 2020 onward, the European cybersecurity strategy has seen a major reformulation of its objectives given the changed international environment. The policy documents reveal an interest in the establishment of an increasingly integrated overall security system, in which the relevant institutions of the Union have a central role. Among the various aspects considered is the establishment of a “collective situational awareness” based on the exchange of security information between Member States and European authorities, as well as between the Union authorities themselves. The sharing of security information is certainly an expression of the capacity for cooperation among Member States in the “Area of Freedom, Security and Justice” of the European Union. The analysis proposed in this contribution aims to study the organisation and procedures of information exchange to counter cyber threats (cybersecurity information sharing) in light of recent legislative interventions in the field of cybersecurity. After analysing the evolution of European administrations, and the tools employed in cybersecurity information sharing practices, the investigation focuses on the dynamic profiles related to the treatment of personal data and sensitive and classified information contained in said information by the different actors involved in the sharing process (private entities, single points of contact, law enforcement agencies, European institutions). The conclusions aim to formulate some considerations on the current state of the art in cybersecurity information sharing practices

First evidence of resistance to pyrethroid insecticides in Italian Aedes albopictus populations after 26 years since invasion

Aedes albopictus has spread during the last decades all over the world. This has increased significantly the risk of exotic arbovirus transmission (e.g. Chikungunya, Dengue, and Zika) also in temperate areas, as testified by the Chikungunya 2007- and 2017-outbreaks in north-east and central Italy. Insecticides represent a main tool for limiting the circulation of these mosquito-borne viruses. The aim of the present study is to start filling the current gap of knowledge on pyrethroid insecticide resistance of European Ae. albopictus populations focusing on populations from Italy, Albania and Greece