Quantitative characterization of the influence of the nanoscale morphology of nanostructured surfaces on bacterial adhesion and biofilm formation

Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological features. The quantitative information, provided by this study about the relation between surface nanoscale morphology and bacterial adhesion points towards the rational design of implant surfaces that control or inhibit bacterial adhesion and biofilm formation

Multidisciplinary studies on a sick-leader syndrome-associated mass stranding of sperm whales (Physeter macrocephalus) along the Adriatic coast of Italy

Mass strandings of sperm whales (Physeter macrocephalus) are rare in the Mediterranean Sea. Nevertheless, in 2014 a pod of 7 specimens stranded alive along the Italian coast of the Central Adriatic Sea: 3 individuals died on the beach after a few hours due to internal damages induced by prolonged recumbency; the remaining 4 whales were refloated after great efforts. All the dead animals were genetically related females; one was pregnant. All the animals were infected by dolphin morbillivirus (DMV) and the pregnant whale was also affected by a severe nephropathy due to a large kidney stone. Other analyses ruled out other possible relevant factors related to weather conditions or human activities. The results of multidisciplinary post-mortem analyses revealed that the 7 sperm whales entered the Adriatic Sea encountering adverse weather conditions and then kept heading northward following the pregnant but sick leader of the pod, thereby reaching the stranding site. DMV infection most likely played a crucial role in impairing the health condition and orientation abilities of the whales. They did not steer back towards deeper waters, but eventually stranded along the Central Adriatic Sea coastline, a real trap for sperm whales

Probing nanoscale interactions on biocompatible cluster-assembled titanium oxide surfaces by atomic force microscopy

We report on the investigation of the adhesive properties of cluster-assembled nanostructured TiOx (ns-TiOx) films against a Si3N4 AFM tip, in air and in water. The interacting AFM tip apex represents a model nanometer-sized probe, carrying both silanol (Si-OH) and silamine (Si2-NH) groups: it is therefore well suited to investigate biologically relevant molecular interactions with the biocompatible ns-TiOx surface. Coupling nanosphere lithography with supersonic cluster beam deposition we produced sub-micrometer patterns of ns-TiOx on a reference amorphous silica surface. These devices are ideal platforms for conducting comparative nanoscale investigations of molecular interactions between surfaces and specific groups. We have found that in the aqueous medium the adhesion is enhanced on ns-TiOx with respect to amorphous silica, opposed to the case of humid air. A comparative analysis of the different interactions channels (van der Waals, electrostatic, chemical bonding) led to the conclusion that the key for understanding this behavior can be the ability of incoming nucleophiles like nitrogen or oxygen on the Si3N4 tip to displace adsorbed molecules on ns-TiOx and link to Ti atoms via co-ordinate (dative covalent) bonding. This effect is likely enhanced on nanostructured TiOx with respect to crystalline or micro-porous TiO2, due to the greatly increased effective area and porosity. This study provides a clue for the understanding of interaction mechanisms of proteins with biocompatible ns-TiOx, and in general with metal-oxide surfaces

Influence of surface morphology on the wettability of cluster-assembled carbon films

We have evaluated the surface energy and characterized the wettability of cluster-assembled carbon films deposited on polyethylene, Si and Al substrates by a sessile-drop method using water and glycerol. The effective surface energy of nanostructured carbon is of the order of 30 mJ/m(2) as calculated using the Fowkes approach. The advancing contact angle (66-83degrees) is found to increase with surface roughness, i.e. the surface becomes more hydrophobic as the roughness increases. This behavior is ascribed to gas trapping in pores of the film with a self-affine surface. It is argued that the wettability of nanostructured carbon and other cluster-assembled coatings can be tuned simply by controlling the surface topography, through a suitable control of the deposition parameters, such as the cluster size distribution

Giustizia, famiglia e cultura giuridica

La costruzione della cultura giuridica vista con il punto di osservazione degli operatori e dei giudici minorili, togati e non

Minimally invasive thoracotomy for myocardial revascularisation. A study of 32 cases

BACKGROUND: This study aimed to evaluate the advantages offered by a myocardial revascularisation technique proposed by Kolessov in 1967: minimally invasive thoracotomy for myocardial revascularisation. The aim was to assess its short and medium-term benefits. During the course of the 1980s, the problems linked to extracorporeal circulation (ECC) and the contraindications for traditional myocardial revascularisation led to a renewed popularity of "beating heart" revascularisation techniques. METHODS: The largest and most extensive series of patients in the literature undergoing myocardial revascularisation during left mini-thoracotomy was reported by Calafiore et al. In this study we report the series treated by our centre which, albeit involving only 32 cases, obtained good results in the short and medium term. This surgical procedure can only be applied to patients presenting monovasal obstructive coronary disease affecting the anterior interventricular artery (IVA) which must not present small calibre, calcified walls or a lateralised or intramyocardial anatomic position. RESULTS: Invasive and non-invasive instrumental tests carried out to control the distal anastomoses of the left internal mammary artery (IMA) did not reveal angulations and/or stenosing tractions before the anastomosis of IMA to a significant extent also for treatment, when isolating IMA, able to obtain the longest possible length and the best mobility. No infection of surgical wounds was reported postoperatively, as sometimes occurs in median longitudinal sternotomy. CONCLUSIONS: The 2-year follow-up showed the resolution of angina in 100% of the patients studied, as well as a satisfactory and rapid renewal of social relations

Investigation of adhesion mechanisms of proteins on nanostructured surfaces by a combined local approach based on Atomic Force Microscopy and Fluorescence Microscopy

Protein adsorption is the triggering event for a variety of complex phenomena occurring at the nanoscale and determining cell adhesion, proliferation and differentiation. Biomaterials surfaces are rapidly coated by proteins that mediate the cell/substrate interactions, regulating the cell behavior through complex signaling pathways. A quantitative characterization of surface nanoscale properties and interactions influencing protein adsorption is therefore strategic for the understanding of the overall biocompatibility of surfaces. We present the results of an experimental study of the local morphological and physico-chemical properties of cluster-assembled nanostructured (ns) biocompatible TiO2 films, and of their role in protein (BSA) adsorption. In particular, we highlight the peculiar role of nanoscale surface morphology and surface charge distribution (in particular the IsoElectric Point correlated to different roughness) in determining the optimal conditions for protein condensation into nanopores, which enhances protein coverage beyond the limits of classical Langmuir isotherm model. As a result of our work, we propose a preliminary simplified model of the protein/surface adsorption based on the interplay of subtle morphological parameters (local aspect ratio, pore volume) and electrostatic interactions. Beside improving our understanding of the basic mechanisms of biocompatibility, the results of this study suggest that suitable nanostructured platforms, where nanoscale chemistry and morphology can be independently controlled, could be employed for detecting and controlling specific biological interactions for the investigation of surface-induced phenomena, such as protein competitive adsorption, aggregation and crystallization, and hydrophobic interactions

Intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade vesicoureteral reflux.

To present a preliminary experience with the modified technique of extravesical intraureteral injection of non-animal-stabilized hyaluronic acid/dextranomer (NASHA/Dx) gel under direct ureteroscopic visualization for the treatment of primary high-grade vesicoureteral reflux (VUR).The medical records of all pediatric patients (age range, 0-14 years) who underwent intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade VUR during the period June 2006-June 2010 were reviewed.Eighty-nine children (61 boys, 28 girls; M:F ratio, 2.1) underwent intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade VUR during the study period. VUR completely disappeared after the injection of NASHA/Dx gel into 105 (73\%) of 144 ureters, with no further treatment required. Thirty-five (24.3\%) required a second injection, and 2 (1.4\%) required a third injection for resolution of their VUR. No intraoperative complications were observed. No ureteral obstruction during follow-up was observed using ultrasound or micturition studies.Intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization is safe and effective in the treatment of primary high-grade VUR, including cases with ureteral duplication, if the ureteral meatus is easy to pass through without mechanical dilation. This approach represents an effective and safe alternative to antibiotic prophylaxis alone and open surgery