Bioactive glass and glass-ceramic orbital implants

This review focuses on the applications of bioactive glasses and glass-ceramics in the field of orbital implants for ocular surgery. This use is relatively novel and less popular compared to the applications in orthopedics and dentistry for the repair of bone and teeth. Recent studies have shown the suitability of bioactive glasses and glass-ceramics in contact with soft tissues for promoting additional effects associated to the release of therapeutic inorganic ions. Specifically, the angiogenic and antibacterial actions that may be elicited by selected glass compositions are highly appealing for the development of new-generation orbital implants, since improved vascularization and antiseptic properties are the key for a higher success rate of anophthalmic socket procedures. An overall picture of existing orbital implants based on bioactive glasses is here provided, and the further potential and open challenges for future research in this field are highlighted and discussed.     

Pronase-immobilized enzyme reactor: an approach for automation in glycoprotein analysis by LC/LC-ESI/MSn

An automated analytical approach is proposed for simultaneous characterization of glycan and peptide moieties in pronase-generated glycopeptides. The proposed method is based on the use of a new pronase-immobilized enzyme reactor for the on-line rapid digestion of the target glycoprotein. By coupling the bioreactor to a Hypercarb chromatographic trap column, on-line selective glycopeptide enrichment prior to normal-phase liquid chromatography-mass spectrometry was obtained. A detailed study was carried out for integration and automation of each phase of the proposed analytical procedure. On-line digestion allowed extensive cleavage of the model protein (ribonuclease B), yielding to glycopeptides with peptide moieties up to eight amino acids, carrying the Man5-Man9 N-glycans each, selectively resolved on an Amide-80 column. The use of a linear ion trap instrument resulted in efficient ion capture and led to MS3 acquisition times and spectra quality similar to those for MS2, allowing the unambiguous identification of glycan (MS2) and peptide (MS3) sequences. The proposed procedure reduces the glycoprotein analysis time from approximately 3 days, as in most of the traditional off-line methods, to approximately 1 h.     

Disentangling protein-silica interactions

We present the results of modelling studies aimed at the understanding of the interaction of a 7 nm sized water droplet containing a negatively charged globular protein with flat silica surfaces. We show how the droplet interaction with the surface depends on the electrostatic surface charge, and that adhesion of the droplet occurs when the surface is negatively charged as well. The key role of water and of the charge-balancing counter ions in mediating the surface-protein adhesion is highlighted. The relevance of the present results with respect to the production of bioinorganic hybrids via encapsulation of proteins inside mesoporous silica materials is discussed.     

TPA Immobilization on Iron Oxide Nanocubes and Localized Magnetic Hyperthermia Accelerate Blood Clot Lysis

The low specificity and high risk of intracranial hemorrhage associated with currently approved thrombolytic therapies limit their efficacy in recanalizing occluded vessels. Here, a nanoscale thrombolytic agent is demonstrated by immobilizing tissue plasminogen activator molecules (tPA) over 20 nm clustered iron oxide nanocubes (NCs). The resulting nanoconstructs (tPA–NCs) are capable of dissolving clots via both direct interaction of tPA with the fibrin network (chemical lysis) and localized hyperthermia upon stimulation of superparamagnetic NCs with alternating magnetic fields (AMFs) (mechanical lysis). In vitro, as compared to free tPA, the proposed nanoconstructs demonstrate a ≈100‐fold increase in dissolution rate, possibly because of a more intimate interaction of tPA with the fibrin network. The clot dissolution rate is further enhanced (≈10‐fold) by mild, localized heating resulting from the exposure of tPA–NCs to AMF. Intravital microscopy experiments demonstrate blood vessel reperfusion within a few minutes post tail vein injection of tPA–NCs. The proposed nanoconstructs also exhibit high transverse relaxivity (>400 × 10^–3 m ^?1 s^?1) for magnetic resonance imaging. The multifunctional properties and the 3 orders of magnitude enhancement in clot dissolution make tPA–NCs a promising nano‐theranosis agent in thrombotic disease.     

New heparinizable modified poly(carbonate urethane) surfaces diminishing bacterial colonization

Percutaneous devices are extensively used in modern medicine therapies, even in long term applications. Complications from their use, related to bacterial colonization and/or to materials thrombogenicity, may result in a significant morbidity and mortality incidence. In this study, a novel polycarbonate-urethane (PCU), incorporating a tailor-made diamino-diamide-diol (PIME) showing the ability to bind heparin at physiological pH, was compared to commercial medical-grade PCUs (Carbothane and Bionate). Mechanical and thermal properties were evaluated by tensile tests, dynamic mechanical analysis and differential scanning calorimetry. The presence of a low amount of PIME chain extender in Bionate polyurethanes (Bionate-PIME) slightly affects the mechanical properties, remaining however comparable with the medical grade PCUs used for the fabrication of cardiovascular devices. To verify thereof heparin surface adsorbed in disfavouring bacterial colonization, heparinized Bionate-PIME was tested for bacterial adhesion, using Bionate and Carbothane as reference. In vitro bacterial interaction tests were performed with the strains mainly involved in the pathogenesis of device-related infections (S. epidermidis and S. aureus). MTT tests and SEM observations showed a decrease in colonization of the different strains on the heparinized Bionate-PIME surfaces, confirming that preadsorbed heparin plays a role in mediating the biomaterial surface/bacterial cells interactions.     

Magnetic Characterization of MgB2 Bulk Superconductor for Magnetic Field Mitigation Solutions

Magnetic shielding properties of MgB₂ bulk samples synthesized by the SPS (Spark?CPlasma?CSintering) technique were characterized in low applied magnetic fields at temperatures ranging from 20 to 37 K. The used growth technique allows one to produce this compound in different shapes and sizes required for shielding applications. In this framework, shielding magnetic-induction field profiles generated by MgB₂-based shield components, shaped as planar thick disks, were measured by means of a suitable Hall probe in-plane array. The magnetic field distribution at different vertical distances above the sample was also obtained by a micrometric motion of the probe ensemble. Magnetic field profiles were then analyzed in the framework of the critical state model and the critical current density, J _c , was evaluated. The J _c magnitude indicates that the material under test is a good candidate for passive magnetic shield manufacturing up to temperatures close to the transition one.     

Oxidative biodegradation of single- and multi-walled carbon nanotubes

In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide.     

Food risk characterization from exposure to persistent organic pollutants and metals contaminating eels from an Italian lake

Monitoring environmental contaminants in edible animal species is important for the assessment of environmental quality and for food safety as well. In this study, the occurrence of 2,3,7,8 dioxins, and furans, dioxin-like polychlorinated biphenyls, six non-dioxin-like polychlorinated biphenyl indicators (ndl-PCBs), seven polybrominated diphenylethers (PBDEs), four polycyclic aromatic hydrocarbons (PAHs) and four metals (As, Hg, Ni, Pb) was evaluated in 90 European eels (Anguilla anguilla) from Lake Garda. The results on eel samples showed a frequent contamination of dl-PCBs, found at concentrations higher than the maximum limit (ML) provided by European Union in 41 % of the eels. Two PBDE congeners (BDE 47 and BDE 99) were detected in almost all the samples. The contamination by PAHs was found negligible; only one sample had a high concentration of benzo[a]pyrene. Concerning metals, Pb showed concentrations higher than the maximum level (ML) in 77% of the samples, while Ni content could be a cause of acute toxicity due to dermatitis. Extreme consumers (95th percentile) are subjected to an actual risk attributable to dioxins, furans, and mainly dl-PCBs and PBDEs. The contamination of Lake Garda eels is therefore a matter of concern and a constant monitoring of the pollution levels of its freshwater is mandatory.     

Evaluation of milk components during whole lactation in healthy quarters

Several milk components related to immune defences (lysozyme, lactoferrin and gamma-globulins, gamma-G) and to inflammation (somatic cell counts, SCC; N-acetyl-beta-glucosaminidase, NAGase; albumin) were considered. Forty-one quarters and 685 samples of 24 cows were included in the study; among them 534 samples were defined as negative (78.0%), 93 as diseased (13.5%) and 58 (8.5%) as subclinical. The pattern of each milk component in quarters always negative during the follow-up period was evaluated by a mixed model. Statistical analysis showed that days in milk (DIM), age (primiparous, pluriparous), herd and the interaction between herd and days in milk significantly influenced all the markers, with very few exceptions. A subset of samples including the negative quarters before the first outcome of an infection or a subclinical mastitis and the samples from quarters always negative was also selected. The analysis showed that herd, DIM and health status had a significant influence on most markers. Overall, primiparous cows were confirmed to have higher levels of most of the markers than pluriparous cows. The presence of a herd effect on non specific immune defences in fully negative quarters implies that when the mechanisms behind their release are fully elucidated, it might be possible to modulate them. Udder tissues were confirmed as an important source of some immune components, as supported by the inconsistency between SCC mean values and NAGase, lysozyme and lactoferrin values. Overall, quarters with high levels of NAGase, lysozyme and gamma-G, exposed to bacteria, did not develop subclinical mastitis. Hence, invading pathogens could induce the development of subclinical IMI when these components and gammaG are in low concentration.