Biocompatibility of Platinum Nanoparticles in Brain ex vivo Models in Physiological and Pathological Conditions

Platinum nanoparticles (PtNPs) have unique physico-chemical properties that led to their use in many branches of medicine. Recently, PtNPs gathered growing interest as delivery vectors for drugs, biosensors and as surface coating on chronically implanted biomedical devices for improving electrochemical properties. However, there are contradictory statements about their biocompatibility and impact on target organs such as the brain tissue, where these NPs are finding many applications. Furthermore, many of the reported studies are conducted in homeostasis conditions and, consequently, neglect the impact of the pathologic conditions on the tissue response. To expand our knowledge on the effects of PtNPs on neuronal and glial cells, we investigated the acute effects of monodisperse sodium citrate-coated PtNPs on rat organotypic hippocampal cultures in physiological or neuronal excitotoxic conditions induced by kainic acid (KA). The cellular responses of the PtNPs were evaluated through cytotoxic assays and confocal microscopy analysis. To mimic a pathologic scenario, 7-day organotypic hippocampal cultures were exposed to KA for 24 h. Subsequently, PtNPs were added to each slice. We show that incubation of the slices with PtNPs for 24 h, does not severely impact cell viability in normal conditions, with no significant differences when comparing the dentate gyrus (DG), as well as CA3 and CA1 pyramidal cell layers. Such effects are not exacerbated in KA-treated slices, where the presence of PtNPs does not cause additional neuronal propidium iodide (PI) uptake in CA3 and CA1 pyramidal cell layers. However, PtNPs cause microglial cell activation and morphological alterations in CA3 and DG regions indicating the establishment of an inflammatory reaction. Morphological analysis revealed that microglia acquire activated ameboid morphology with loss of ramifications, as a result of their response to PtNPs contact. Surprisingly, this effect is not increased in pathological conditions. Taken together, these results show that PtNPs cause microglia alterations in short-term studies. Additionally, there is no worsening of the tissue response in a neuropathological induced scenario. This work highlights the need of further research to allow for the safe use of PtNPs. Also, it supports the demand of the development of novel and more biocompatible NPs to be applied in the brain.The authors acknowledge the funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No. 764977, in the framework of the mCBEEs project (Advanced integrative solutions to corrosion problems beyond micro-scale: toward long-term durability of miniaturized biomedical, electronic, and energy systems). This work was also financed by Portuguese funds through FCT/MCTES in the framework of the project “Institute for Research and Innovation in Health Sciences”– UIDB/04293/2020. The authors thank the support of the i3S Scientific Platforms Bioimaging and Advanced Light Microscopy (ALM), members of the national infrastructure PPBI–Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122). SS acknowledges FCT for her contract under the Norma Transitória–DL57/2016/CP/CP1360/CT0013

Reed's Syndrome

Multiple cutaneous and uterine leiomyomatosis (MCUL), also known as Reed's syndrome, is a rare genodermatosis, with an autosomal dominant pattern of inheritance. It results from a germline heterozygous mutation of fumarate hydratase gene, that is classified as a tumor suppressor gene. Hereditary leiomyomatosis and renal cell cancer is characterized by the association of MCUL with renal cell carcinoma. We report a case of a 57-year-old woman, with multiple cutaneous leiomyomas as the presenting sign of Reed's syndrome.info:eu-repo/semantics/publishedVersio

Delivering siRNA with dendrimers: In vivo applications

Over the last decades, gene therapy has emerged as a pioneering therapeutic approach to treat or prevent several diseases. Among the explored strategies, the short-term silencing of protein coding genes mediated by siRNAs has a good therapeutic potential in a clinical setting. However, the widespread use of siRNA will require the development of clinically suitable, safe and effective vehicles with the ability to complex and deliver siRNA into target cells with minimal toxicity. Lately, dendrimers have gained considerable attention as non-viral vectors in nucleic acid delivery due to their unique structural characteristics (globular, well defined and highly branched structure, multivalency, low polydispersity and tunable nanosize), along with their relevant capacity to complex and protect nucleic acids in compact nanostructures, which can be functionalized with targeting moieties in order to get cell specificity. Here, we present an overview of the state-of-the-art of the most significant and recent advances on the use of dendrimers as siRNA delivery vectors, with particular focus on the in vivo applications. We will cover the use of different dendrimers, distinct administration routes, toxicity issues, as well as the target tissue or disease, highlighting the potential of dendrimers as nanocarriers for therapeutic and biomedical applications.The authors acknowledge the financial support of the Fundo para a Investigacao em Saude (INFARMED, project reference FIS-2015-01_CCV_20150630-88), as well as the FEDER funds through the Programa Operacional Competitividade e Internacionalizacao - COMPETE 2020 and the Portuguese funds through FCT - Fundacao para a Ciencia e a Tecnologia in the frame of the project POCI-01-0145-FEDER-016639 (reference PTDC/CTM-NAN/3547/2014). V. Leiro is supported by the project NORTE-01-0145-FEDER-000012, financed by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). S.D. Santos is supported by FCT (SFRH/BPD/109297/2015). We thank Joao Pedro Garcia for his contribution to the dendriplex picture

Non-adiabatic radiative collapse of a relativistic star under different initial conditions

We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star with interior comprising of a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the configurations are spherically symmetric, however, in the latter case, the physical space $t= constant$ of the configurations is assumed to be inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is observed that as long as the collapse is shear-free, its evolution depends only on the mass and size of the star at the onset of collapse.Comment: To appear in Pramana- j. of physic

Dendrimers as Powerful Building Blocks in Central Nervous System Disease: Headed for Successful Nanomedicine

Dendrimers have emerged as a powerful class of nanomaterials in the nanomedicine field due to their unique structural features: globular, well-defined, highly branched and controllable structure, nanosize-scale, low polydispersity, and the presence of several terminal groups that can be functionalized with different ligands simulating the multivalency present in different biological systems. Although in its infancy, the application of dendrimers as therapeutics or theranostic tools in central nervous system (CNS) disorders is already significant and has opened promising avenues in the treatment of many conditions where the inherent "smartness" of the dendritic structures is being explored to effectively target the CNS. Here we present an overview of the past and future challenges of the use of dendrimers to respond to one of the ultimate challenges in the (nano)medicine field: to attain CNS repair and regeneration.V Leiro, SD Santos, and CDF Lopes contributed equally to this work. The authors would like to acknowledge the financial support of the Fundo para a Investigação em Saúde (INFARMED, project reference FIS-2015-01_CCV_20150630-88), as well as the FEDER funds through the Programa Operacional Competitividade e Internacionalização – COMPETE 2020 and the Portuguese funds through FCT − Fundação para a Ciência e a Tecnologia in the frame of the project POCI-01-0145-FEDER-016639 (reference PTDC/CTM-NAN/3547/2014). SD Santos is supported by FCT funds (SFRH/BPD/109297/2015). V Leiro is supported by the project NORTE-01-0145-FEDER-000012, financed by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)

Three-body interactions with cold polar molecules

We show that polar molecules driven by microwave fields give naturally rise to strong three-body interactions, while the two-particle interaction can be independently controlled and even switched off. The derivation of these effective interaction potentials is based on a microscopic understanding of the underlying molecular physics, and follows from a well controlled and systematic expansion into many-body interaction terms. For molecules trapped in an optical lattice, we show that these interaction potentials give rise to Hubbard models with strong nearest-neighbor two-body and three-body interaction. As an illustration, we study the one-dimensional Bose-Hubbard model with dominant three-body interaction and derive its phase diagram.Comment: 8 pages, 4 figure

Computational modelling of cancerous mutations in the EGFR/ERK signalling pathway

This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2009 Orton et al.BACKGROUND: The Epidermal Growth Factor Receptor (EGFR) activated Extracellular-signal Regulated Kinase (ERK) pathway is a critical cell signalling pathway that relays the signal for a cell to proliferate from the plasma membrane to the nucleus. Deregulation of the EGFR/ERK pathway due to alterations affecting the expression or function of a number of pathway components has long been associated with numerous forms of cancer. Under normal conditions, Epidermal Growth Factor (EGF) stimulates a rapid but transient activation of ERK as the signal is rapidly shutdown. Whereas, under cancerous mutation conditions the ERK signal cannot be shutdown and is sustained resulting in the constitutive activation of ERK and continual cell proliferation. In this study, we have used computational modelling techniques to investigate what effects various cancerous alterations have on the signalling flow through the ERK pathway. RESULTS: We have generated a new model of the EGFR activated ERK pathway, which was verified by our own experimental data. We then altered our model to represent various cancerous situations such as Ras, B-Raf and EGFR mutations, as well as EGFR overexpression. Analysis of the models showed that different cancerous situations resulted in different signalling patterns through the ERK pathway, especially when compared to the normal EGF signal pattern. Our model predicts that cancerous EGFR mutation and overexpression signals almost exclusively via the Rap1 pathway, predicting that this pathway is the best target for drugs. Furthermore, our model also highlights the importance of receptor degradation in normal and cancerous EGFR signalling, and suggests that receptor degradation is a key difference between the signalling from the EGF and Nerve Growth Factor (NGF) receptors. CONCLUSION: Our results suggest that different routes to ERK activation are being utilised in different cancerous situations which therefore has interesting implications for drug selection strategies. We also conducted a comparison of the critical differences between signalling from different growth factor receptors (namely EGFR, mutated EGFR, NGF, and Insulin) with our results suggesting the difference between the systems are large scale and can be attributed to the presence/absence of entire pathways rather than subtle difference in individual rate constants between the systems.This work was funded by the Department of Trade and Industry (DTI), under their Bioscience Beacon project programme. AG was funded by an industrial PhD studentship from Scottish Enterprise and Cyclacel

Are isomeric alkenes used in species recognition among neo-tropical stingless bees (Melipona spp)

The majority of our understanding of the role of cuticular hydrocarbons (CHC) in recognition is based largely on temperate ant species and honey bees. The stingless bees remain relatively poorly studied, despite being the largest group of eusocial bees, comprising more than 400 species in some 60 genera. The Meliponini and Apini diverged between 80-130 Myr B.P. so the evolutionary trajectories that shaped the chemical communication systems in ants, honeybees and stingless bees may be very different. Therefore, the main aim of this study was to study if a unique species CHC signal existed in Neotropical stingless bees, as shown for many temperate species, and if so what compounds are involved. This was achieved by collecting CHC data from 24 colonies belonging to six species of Melipona from North-eastern Brazil and comparing this new data with all previously published CHC studies on Melipona. We found that each of the eleven Melipona species studied so far each produced a unique species CHC signal based around their alkene isomer production. A remarkable number of alkene isomers, up to 25 in M. asilvai, indicated the diversification of alkene positional isomers among the stingless bees. The only other group to have really diversified in alkene isomer production are the primitively eusocial Bumblebees (Bombus spp), which are the sister group of the stingless bees. Furthermore, among the eleven Neotropical Melipona species we could detect no effect of the environment on the proportion of alkane production as has been suggested for some other species

Enrichment analysis of Alu elements with different spatial chromatin proximity in the human genome

Transposable elements (TEs) have no longer been totally considered as “junk DNA” for quite a time since the continual discoveries of their multifunctional roles in eukaryote genomes. As one of the most important and abundant TEs that still active in human genome, Alu, a SINE family, has demonstrated its indispensable regulatory functions at sequence level, but its spatial roles are still unclear. Technologies based on 3C(chromosomeconformation capture) have revealed the mysterious three-dimensional structure of chromatin, and make it possible to study the distal chromatin interaction in the genome. To find the role TE playing in distal regulation in human genome, we compiled the new released Hi-C data, TE annotation, histone marker annotations, and the genome-wide methylation data to operate correlation analysis, and found that the density of Alu elements showed a strong positive correlation with the level of chromatin interactions (hESC: r=0.9, P<2.2×1016; IMR90 fibroblasts: r = 0.94, P < 2.2 × 1016) and also have a significant positive correlation withsomeremote functional DNA elements like enhancers and promoters (Enhancer: hESC: r=0.997, P=2.3×10−4; IMR90: r=0.934, P=2×10−2; Promoter: hESC: r = 0.995, P = 3.8 × 10−4; IMR90: r = 0.996, P = 3.2 × 10−4). Further investigation involving GC content and methylation status showed the GC content of Alu covered sequences shared a similar pattern with that of the overall sequence, suggesting that Alu elements also function as the GC nucleotide and CpG site provider. In all, our results suggest that the Alu elements may act as an alternative parameter to evaluate the Hi-C data, which is confirmed by the correlation analysis of Alu elements and histone markers. Moreover, the GC-rich Alu sequence can bring high GC content and methylation flexibility to the regions with more distal chromatin contact, regulating the transcription of tissue-specific genes