Release of VEGF from dental implant improves osteogenetic process: Preliminary in vitro tests

INTRODUCTION: During osseointegration process, the presence of an inflammatory event could negatively influence the proper osteogenetic ability of the implant surface. In order to reduce this possibility, an implementation of angiogenetic event through the release of Vascular Endothelial Growth Factor (VEGF) can be a tool as co-factor for osteoblastic differentiation. In this paper, novel dental implant surfaces enriched with VEGF have been tested. MATERIAL AND METHODS: The ability of VEGF-enriched titanium implants to improve the osteogenetic properties of Mesenchymal stem cells (MSC), also in the presence of an inflammatory environment, have been in vitro tested. Molecular biology, morphological analyses, and biochemical tests have been performed in order to confirm biological properties of these surfaces. RESULTS: Our results confirm that the presence of VEGF onto the implant surface is able not only to protect the cells from in vitro aging and from Reactive Oxygen Species (ROS) damage, but it also improves their osteogenic and endothelial differentiation, even in the presence of inflammatory cytokines. CONCLUSION: This study establishes a biologically powerful novel tool that could enhance bone repair in dental implant integration

Biocompatibility and antibacterial properties of zirconium nitride coating on titanium abutments: An in vitro study

Improving soft tissue attachment and reducing bacterial colonization on titanium abutments are key factors for the long-term maintenance of healthy soft and hard peri-implant tissues. This in vitro study was conducted to compare the biocompatibility and antibacterial activity of four different surfaces: uncoated Ti6Al4V, anodized, and coated with titanium nitride or zirconium nitride. Surface topography was investigated with a high-resolution system for measuring surface finishes. Human gingival fibroblast (HGF) adhesion and proliferation were examined using MTT assay, Scanning Electron Microscopy (SEM) imaging, immunofluorescence analysis and real-time PCR for selected target genes. The hemolysis and AMES tests were performed to assess the chemical compounds' blood compatibility and mutagenic potential, respectively. Antibacterial activity was tested against five bacterial strains isolated from the oral cavity (Streptococcus salivarius, S. sanguinis, S. mutans, S. sobrinus, S. oralis), and the percentage of dead bacteria was calculated. Roughness measurements confirmed a substantial similarity between the surfaces and their compatibility with clinical applications. MTT assay, SEM analysis and immunofluorescence staining showed adhesion and proliferation of HGFs cultured on all the examined surfaces. PCR confirmed that HGFs produced extracellular matrix components efficiently on all the surfaces. No hemolytic activity was detected, and the AMES test confirmed the surfaces' clinical safety. For all tested bacterial strains, biofilms grown on the zirconium nitride surface showed a higher percentage of dead bacteria than on the other disks. The titanium nitride surface inactivated bacterial biofilms, too, but to a lesser extent

L'EDUCAZIONE AMBIENTALE ATTRAVERSO UNA MOSTRA DI INSETTI E FRANCOBOLLI

Prendendo spunto dalla mostra entomologica presentata al centro di divulgazione scientifica “ La Limonaia” e da altre attività, si è cercato di analizzare nei particolari situazioni e punti critici della nostra attività, anche in relazione ai diversi ambienti e contesti in cui abbiamo operato. Preso atto dell’importanza innegabile che si riconosce alla filatelia nella ricostruzione storica, sociale, economica e culturale della storia di un paese, abbiamo pensato di utilizzare il mezzo filatelico per un uso didattico, scientifico e divulgativo nell’insegnamento della disciplina delle Scienze Natural

Bioactive sphene-based ceramic coatings on cpTi substrates for dental implants: An in vitro study

Titanium implant surface modifications have been widely investigated to favor the process of osseointegration. The present work aimed to evaluate the effect of sphene (CaTiSiO5) biocoating, on titanium substrates, on the in vitro osteogenic differentiation of Human Adipose-Derived Stem Cells (hADSCs). Sphene bioceramic coatings were prepared using preceramic polymers and nano-sized active fillers and deposited by spray coating. Scanning Electron Microscopy (SEM) analysis, surface roughness measurements and X-ray diffraction analysis were performed. The chemical stability of the coatings in Tris-HCl solution was investigated. In vitro studies were performed by means of proliferation test of hADSCs seeded on coated and uncoated samples after 21 days. Methyl Thiazolyl-Tetrazolium (MTT) test and immunofluorescent staining with phalloidin confirmed the in vitro biocompatibility of both substrates. In vitro osteogenic differentiation of the cells was evaluated using Alizarin Red S staining and quantification assay and real-time PCR (Polymerase Chain Reaction). When hADSCs were cultured in the presence of Osteogenic Differentiation Medium, a significantly higher accumulation of calcium deposits onto the sphene-coated surfaces than on uncoated controls was detected. Osteogenic differentiation on both samples was confirmed by PCR. The proposed coating seems to be promising for dental and orthopedic implants, in terms of composition and deposition technology

A developmental stage- and Kidins220-dependent switch in astrocyte responsiveness to brain-derived neurotrophic factor

Astroglial cells are key to maintain nervous system homeostasis. Neurotrophins are known for their pleiotropic effects on neuronal physiology but also exert complex functions to glial cells. Here, we investigated (i) the signaling competence of mouse embryonic and postnatal primary cortical astrocytes exposed to brain-derived neurotrophic factor (BDNF) and, (ii) the role of kinase D-interacting substrate of 220 kDa (Kidins220), a transmembrane scaffold protein that mediates neurotrophin signaling in neurons. We found a shift from a kinase-based response in embryonic cells to a response predominantly relying on intracellular Ca2+ transients [Ca2+]i within postnatal cultures, associated with a decrease in the synthesis of full-length BDNF receptor TrkB, with Kidins220 contributing to the BDNF-activated kinase and [Ca2+]i pathways. Finally, Kidins220 participates in the homeostatic function of astrocytes by controlling the expression of the ATP-sensitive inward rectifier potassium channel 10 (Kir4.1) and the metabolic balance of embryonic astrocytes. Overall, our data contribute to the understanding of the complex role played by astrocytes within the central nervous system, and identify Kidins220 as a novel actor in the increasing number of pathologies characterized by astrocytic dysfunctions. This article has an associated First Person interview with the first authors of the paper

In Vitro Evaluation of Cytotoxicity and Proliferative Effects of Lyophilized Porcine Liver Tissue on HepG2 Hepatoma Cells and Adipose-Tissue-Derived Mesenchymal Stromal Cells

In recent years, nutritional supplements from different sources have been widely considered to support medical treatments in patients affected by chronic hepatopathies. Their potential therapeutic benefit has been recognized, but some evidence of safety issues has been reported. Recently it has been hypothesized that the liver could produce various of bioactive factors to maintain organ homeostasis and promote tissue healing. Thus, liver-specific preparations containing bioactive factors could provide a suitable substrate for in vitro study of liver tissue maintenance/healing, as a prospective regenerative medicine approach. Furthermore, they could represent a dietary supplement or nutraceutical for adjuvant therapies when correctly prepared and formulated. This work aims to provide data about the safety and biological activity of a freeze-dried porcine liver preparation. The lyophilized powder obtained from the whole organ has been tested in term of in vitro cell cytotoxicity (MTT assay) and proliferation assays (bromo-deoxyuridine incorporation and direct cell count) in two different cell types: human hepatoma HepG2 cell line and adipose-tissue-derived canine mesenchymal stromal cells (At-MSCs). At concentration levels between 100 to 500 g/mL, the lyophilized liver powder stimulated mitochondrial metabolism as assessed by MTT assay (p 0.001 for HepG2 and for At-MSCs) and induced an increase in bromo-deoxyuridine incorporation in both cell types (p 0.01 for HepG2 and p < 0.001 for At-MSCs). In addition, direct cell count demonstrated a higher proliferative activity in treated At-MSCs (p < 0.001). Although preliminary, these data suggest that the whole-liver powder is noncytotoxic in vitro and may represent a stimulus to cell metabolism and proliferation. Further studies are needed to detect the bioactive components of the supplement and characterize in deeper detail the cellular pathways that they can modulate

Silver Nanoparticles in Alveolar Bone Surgery Devices

Silver (Ag) ions have well-known antimicrobial properties and have been applied as nanostrategies in many medical and surgical fields, including dentistry. The use of silver nanoparticles (Ag NPs) may be an option for reducing bacterial adhesion to dental implant surfaces and preventing biofilm formation, containing the risk of peri-implant infections. Modifying the structure or surface of bone grafts and membranes with Ag NPs may also prevent the risk of contamination and infection that are common when alveolar bone augmentation techniques are used. On the other hand, Ag NPs have revealed some toxic effects on cellsin vitroandin vivoin animal studies. In this setting, the aim of the present paper is to summarize the principle behind Ag NP-based devices and their clinical applications in alveolar bone and dental implant surgery

Alginate-Derived Active Blend Enhances Adsorption and Photocatalytic Removal of Organic Pollutants in Water

The ever-increasing need for clean water is one of the most urgent sustainable development goals, which requires environmentally-friendly strategies for water remediation against different types of pollutants. In this work, the possibility of using alginate, a biocompatible and natural polysaccharide, is explored for the preparation of both oxide (TiO2, Al2O3, and yttria-stabilized ZrO2 (YSZ)) macrobeads and an active blend of rich carbon nanoparticles, depolymerized alginate, formic acid, and a complex mixture of other organic acids. In particular, the active blend is obtained through low-energy-demanding microwave assisted digestion of sodium alginate solution, and it is used to enhance the decontamination activity of oxide macrobeads in mild conditions (e.g., low temperature, no pH buffers, and visible illumination). It is demonstrated that the alginate-derived active blend obtained without the addition of any other chemicals increases primarily the adsorption capability of oxide macrobeads toward positively charged pollutants (methylene blue, crystal violet, and tetracaine) and, also, the photocatalytic activity of TiO2 during their degradation. Interestingly, functionalization with the obtained alginate-derived active blend enables better performance in comparison with functionalization of its single components or with carbon-dots (C-Dots) obtained with conventional and more energy-demanding hydrothermal methods, enabling them to obtain a fully sustainable, environmentally-friendly system for water remediation

Fundamental shock selection in DSGE models

DSGE models are typically estimated assuming the existence of certain structural shocks that drive macroeconomic fluctuations. We analyze the consequences of introducing nonfundamental shocks for the estimation of DSGE model parameters and propose a method to select the structural shocks driving uncertainty. We show that forcing the existence of non-fundamental structural shocks produces a downward bias in the estimated internal persistence of the model. We then show how these distortions can be reduced by allowing the covariance matrix of the structural shocks to be rank deficient using priors for standard deviations whose support includes zero. The method allows us to accurately select fundamental shocks and estimate model parameters with precision. Finally, we revisit the empirical evidence on an industry standard medium-scale DSGE model and find that government, price, and wage markup shocks are non-fundamental

Selecting structural innovations in DSGE models

Dynamic stochastic general equilibrium (DSGE) models are typically estimated assuming the existence of certain structural shocks that drive macroeconomic fluctuations. We analyze the consequences of estimating shocks that are “nonexistent” and propose a method to select the economic shocks driving macroeconomic uncertainty. Forcing these nonexisting shocks in estimation produces a downward bias in the estimated internal persistence of the model. We show how these distortions can be reduced by using priors for standard deviations whose support includes zero. The method allows us to accurately select shocks and estimate model parameters with high precision. We revisit the empirical evidence on an industry standard medium‐scale DSGE model and find that government and price markup shocks are innovations that do not generate statistically significant dynamics