Thrombin regulates the ability of Schwann cells to support neuritogenesis and to maintain the integrity of the nodes of Ranvier

Schwann cells (SC) are characterized by a remarkable plasticity that enables them to promptly respond to nerve injury promoting axonal regeneration. In peripheral nerves after damage SC convert to a repair-promoting phenotype activating a sequence of supportive functions that drive myelin clearance, prevent neuronal death, and help axon growth and guidance. Regeneration of peripheral nerves after damage correlates inversely with thrombin levels. Thrombin is not only the key regulator of the coagulation cascade but also a protease with hormone-like activities that affects various cells of the central and peripheral nervous system mainly through the protease-activated receptor 1 (PAR1). Aim of the present study was to investigate if and how thrombin could affect the axon supportive functions of SC. In particular, our results show that the activation of PAR1 in rat SC cultures with low levels of thrombin or PAR1 agonist peptides induces the release of molecules, which favor neuronal survival and neurite elongation. Conversely, the stimulation of SC with high levels of thrombin or PAR1 agonist peptides drives an opposite effect inducing SC to release factors that inhibit the extension of neurites. Moreover, high levels of thrombin administered to sciatic nerve ex vivo explants induce a dramatic change in SC morphology causing disappearance of the Cajal bands, enlargement of the Schmidt-Lanterman incisures and calcium-mediated demyelination of the paranodes. Our results indicate thrombin as a novel modulator of SC plasticity potentially able to favor or inhibit SC pro-regenerative properties according to its level at the site of lesion

Biomimetic toothpastes: remineralization potential of deciduous teeth

Aim: Primary teeth are subjected to a continuous process of de- and re-mineralization. To prevent loss of dental tissues, fluoride-containing toothpastes have been successfully applied as a global solution to mainly prevent dental caries and promote tooth re-mineralization. However, the swallowing of a high amount of fluoride in younger children would lead to potential risk of fluorosis. Newly developed biomimetic toothpastes have provided promising results in preventive den tistry, therefore, the aim of the present study was to analyse the ability of commercial toothpastes to diffuse into deciduous enamel layer to remineralize the crystal habitat. Materials and Methods: Previously extracted primary teeth (n=8) were manually brushed for 15 days (3 times/day), using 3 different pediatric toothbrushes: (a) commercial toothpaste containing fluorine 500 ppm; (b) commercial toothpaste containing fluorine 1400 ppm; (c) toothpaste containing hydroxyapatite nanocrystal. Elements used as control (n = 2) were subjected to the manual brushing with water. Then, specimens were assessed by means of variable pressure scanning electron microscopy (VP-SEM). Results: Toothpaste containing nanocrystals of hydroxyapatite seemed to better diffuse through the enamel layer of deciduous teeth. This biomimetic toothpaste might contribute to remineralize the loss of the mineral component and play a central role in the prevention of dental caries. Conclusion: Biomimetic toothpastes would be considered a reliable alternative to fluoride-containing toothpaste. These preliminary results not only would improve the synthesis of novel biomaterials for deciduous teeth, but also would represent a positive global economic impact since the wide prevalence of dental caries affecting primary teeth

The effect of postmastectomy radiation therapy on breast implants. Material analysis on silicone and polyurethane prosthesis

The pathogenic mechanism underlying capsular contracture is still unknown. It is certainly a multifactorial process, resulting from human body reaction, biofilm activation, bacteremic seeding, or silicone exposure. The scope of the present article is to investigate the effect of hypofractionated radiotherapy protocol (2.66 Gy × 16 sessions) both on silicone and polyurethane breast implants.Silicone implants and polyurethane underwent irradiation according to a hypofractionated radiotherapy protocol for the treatment of breast cancer. After irradiation implant shells underwent mechanical, chemical, and microstructural evaluation by means of tensile testing, infrared spectra in attenuated total reflectance mode, nuclear magnetic resonance, and field emission scanning electron microscopy.At superficial analysis, irradiated silicone samples show several visible secondary and tertiary blebs. Polyurethane implants showed an open cell structure, which closely resembles a sponge. Morphological observation of struts from treated polyurethane sample shows a more compact structure, with significantly shorter and thicker struts compared with untreated sample. The infrared spectra in attenuated total reflectance mode spectra of irradiated and control samples were compared either for silicon and polyurethane samples. In the case of silicone-based membranes, treated and control specimens showed similar bands, with little differences in the treated one. Nuclear magnetic resonance spectra on the fraction soluble in CDCl3 support these observations. Tensile tests on silicone samples showed a softer behavior of the treated ones. Tensile tests on Polyurethane samples showed no significant differences.Polyurethane implants seem to be more resistant to radiotherapy damage, whereas silicone prosthesis showed more structural, mechanical, and chemical modifications

Nanodiamond-mediated crystallization in fibers of PANI nanocomposites produced by template-free polymerization : conductive and thermal properties of the fibrillar networks

The detonation nanodiamond is a novel versatile nanomaterial with tunable properties and surface chemistry. In this work, we report on a template-free method to synthesize polyaniline based nanocomposite fibers during a chemical oxidative precipitation polymerization where the cooperative interactions between nanodiamond and polyaniline nucleates trigger the final morphology of the nanocomposite. FE–SEM and TEM observations evidence the prominent growth of fibril-like structures assembled in 2-D networks of tightly woven, partially oriented fibers. Optical and Raman spectroscopy and X-ray diffraction analyses reveal that the polymer chains are in a protonated emeraldine form and organize themselves in a highly ordered 3-D spatial arrangement. Conductivity measurements performed on isolated fibers by a conductive tip of an AFM apparatus highlight that the diamond filler does not affect the conductive properties of the polyaniline matrix while increases the thermal stability of the polymer as confirmed by TGA studies

Morpho-chemical observations of human deciduous teeth enamel in response to biomimetic toothpastes treatment

Today, biomaterial research on biomimetic mineralization strategies represents a new challenge in the prevention and cure of enamel mineral loss on delicate deciduous teeth. Distinctive assumptions about the origin, the growth, and the functionalization on the biomimetic materials have been recently proposed by scientific research studies in evaluating the different clinical aspects of treating the deciduous tooth. Therefore, appropriate morpho-chemical observations on delivering specific biomaterials to enamel teeth is the most important factor for controlling biomineralization processes. Detailed morpho-chemical investigations of the treated enamel layer using three commercial toothpastes (Biorepair, F1400, and F500) were performed through variable pressure scanning electron microscopy (VP-SEM) and energy dispersive X-ray spectroscopy (EDS) on deciduous teeth in their native state. A new microscopy methodology allowed us to determine the behaviors of silicate, phosphate, and calcium contents from the early stage, as commercially available toothpastes, to the final stage of delivered diffusion, occurring within the enamel layer together with their penetration depth properties. The reported results represent a valuable background towards full comprehension of the role of organic–inorganic biomaterials for developing a controlled biomimetic toothpaste in biofluid medi

Study of the interaction mechanism between hydrophilic thiol capped gold nanoparticles and melamine in aqueous medium

In the last years, intense efforts have been made in order to obtain colloidal-based systems capable of pointing out the presence of melamine in food samples. In this work, we reported about the recognition of melamine in aqueous solution, using gold nanoparticles stabilized with 3-mercapto-1-propanesulfonate (AuNPs-3MPS), with the aim of deepening how the recognition process works. AuNPs were synthesized using a wet chemical reduction method. The synthesized AuNPs-3MPS probe was fully characterized, before and after the recognition process, by both physicochemical (UV–vis, FT-IR, 1H-NMR, DLS and ζ-potential) and morphostructural techniques (AFM, HR-TEM). The chemical and electronic structure was also investigated by SR-XPS. The sensing method is based on the melamine-induced aggregation of AuNPs; the presence of melamine was successfully detected in the range of 2.5−500 ppm. The results achieved also demonstrate that negatively charged AuNPs-3MPS are potentially useful for determining melamine contents in aqueous solution. SR-XPS measurements allowed to understand interaction mechanism between the probe and the analyte. The presence of sulfonate groups allows a mutual interaction mediated by electrostatic bonds between nanoparticles surface thiols and positively charged amino groups of melamine molecules

Noble Metal Nanoparticles Networks Stabilized by Rod‐Like Organometallic Bifunctional Thiols

od-like organometallic dithiol containing square-planar Pt(II) centers, i. e., trans,trans- [(H3COCS)Pt(PBu3)2(C�C C6H4 C6H4 C�C)(PBu3)2Pt(SCOCH3)] was used as bifunctional stabilizing agent for the synthesis of Pd-, Au-, and AgNPs (MNPs). All the MNPs showed diameters of about 4 nm, which can be controlled by carefully modulating the synthesis parameters. Covalent MNPs stabilization occurred through a single S bridge between Pt(II) and the noble metal nanocluster surfaces, leading to a network of regularly spaced NPs with the formation of dyads, as supported by SR-XPS data and by TEM imaging analysis. The chemical nature of NPs systems was also confirmed by EDS and NMR. Comparison between SR-XPS data of MNPs and self-assembled monolayers and multilayers of pristine rod-like dithiols deposited onto polycrystalline gold surfaces revealed an electronic interaction between Pt(II) centers and biphenyl moieties of adjacent ligands, stabilizing the organic structure of the network. The possibility to obtain networks of regularly spaced MNPs opens outstanding perspectives in optoelectronics

Cholesteatoma affected incus bone surface shows unusual iron-rich crystals, microvesicles and altered bone turnover

Cholesteatoma is a noncancerous cystic lesion consisting in an abnormal growth of keratinizing squamous epithelium that invades the middle ear cavity. Due to its capacity of intracranial complications, cholesteatoma is cause of pediatric morbidity and death in countries with scarce hygiene and low possibility to access to advanced medical care (1). In order to understand cholesteatoma etiopathogenesis, we performed a SEM morphological analysis of 11 incus bones affected by cholesteatoma. Samples were fixed immediately upon recovery in 2.5% glutaraldehyde in PBS at 4°C for 48 h, then they were gently sonicated (to remove excess of keratinizing squamous epithelium, that would have prevented surface observation) and finally they were prepared with standard method for scanning electron microscopy observation. Five consecutive fields at 100X magnification aligned in 3 raws, the first one proximal and the last one distal to surgical removal point were analized. Images were obtained in secondary electron mode and in backscattering, bidimensional EDX analysis and mapping was also carried on. Incus bone surface analysis reveals the existence of an environment in which abnormal bone turnover takes place, in fact area of marked erosion were present together with areas of new bone formation. Resorbing bone surfaces with their characteristic lacunae were observed, resting surfaces (smooth and with collagen fibre bundles evident) were found and forming bone surface (collagen bundles in which calcium salts were just deposited) were also observed. Unusual flower-like apatite crystals rich in iron were uncovered in one sample. Iron presence may be due to cholesteatoma itself, being it made up of corneocytes that are iron-rich cells (2). Microvesicles of cellular origin, alone or clustered in groups or in about to fusing together, were found. Macrophages, lymphocytes osteoblast and osteoclast were observed in fully activated stage. The picture of these cell near to each other is the morphological representation of the complex cytochemical dialog existing among them. Taken all together our morphological results let us hypothesize that cholesteatoma creates an environment of chronic infection with peculiar biochemical characteristics that alters normal bone turnover on incus bone.This work was supported by grants from MIUR

FE-SEM and VP-SEM imaging of human calcified aortic valves: conventional vs Ionic Liquid innovative techniques

Conventional FE-SEM protocol for calcified aortic valves (CAVs) consist of following steps: glutaraldehyde fixation, OsO4 post-fixation, dehydration in alcohol series, critical point drying and finally sputter coating. CAVs can be observed in their native state (fixed in glutaraldehyde with and without post-fixation in OsO4) by Variable Pressure-SEM (range 6- 650 Pa). Gas presence allows an inferior resolution (low signal to noise ratio), however there is the possibility to perform EDS elemental analysis without background noise due to sputter coating. Recently Ionic liquids (IL, salts in the liquid state at room temperature) were used as suppliers of electronic conductivity with insulating properties, so we have tested their ability to replace sputter coating on CAVs in high vacuum condition. Samples fixed in glutharaldehyde 2,5% in PBS with and without OsO4 post-fixation treated with ionic liquid (Hitachi HILEM® IL 1000) were compared with samples treated with conventional FE-SEM procedures. Several IL concentration (range from 5% to 20%) were tested, different operating voltages (range from 3 to 20Kv) were used. This novel technology requires a high degree of customization for each sample type. In our opinion fixation in glutaraldehyde with OsO4 post-fixation is recommended to preserve finest details, moreover residual liquid elimination is important to increase resolution and avoid beam interference as linear markings. Setting of a proper accelerating voltage allows to correctly visualize the surface topography. Processing CAVs with IL with respect to conventional FE-SEM is useful for several reasons. Mainly this method is time saving (and cost saving), secondary the same sample can be processed for transmission electron microscopy after SEM observations (allowing correlative microscopy), finally EDS can be performed without background noise due to sputter coating. Perhaps now this technique can not completely replaces the conventional SEM in terms of resolution but in our opinion rapid technical improvement can further reduce this gap

Aberrant Crosstalk between Insulin Signaling and mTOR in Young Down Syndrome Individuals Revealed by Neuronal-Derived Extracellular Vesicles

INTRODUCTION: Intellectual disability, accelerated aging, and early-onset Alzheimer-like neurodegeneration are key brain pathological features of Down syndrome (DS). Although growing research aims at the identification of molecular pathways underlying the aging trajectory of DS population, data on infants and adolescents with DS are missing. METHODS: Neuronal-derived extracellular vesicles (nEVs) were isolated form healthy donors (HDs, n = 17) and DS children (n = 18) from 2 to 17 years of age and nEV content was interrogated for markers of insulin/mTOR pathways. RESULTS: nEVs isolated from DS children were characterized by a significant increase in pIRS1Ser636, a marker of insulin resistance, and the hyperactivation of the Akt/mTOR/p70S6K axis downstream from IRS1, likely driven by the higher inhibition of Phosphatase and tensin homolog (PTEN). High levels of pGSK3βSer9 were also found. CONCLUSIONS: The alteration of the insulin-signaling/mTOR pathways represents an early event in DS brain and likely contributes to the cerebral dysfunction and intellectual disability observed in this unique population