Design of a custom-made device for real-time optical measurement of differential mineral concentrations in three-dimensional scaffolds for bone tissue engineering.

Monitoring bone tissue engineered (TEed) constructs during their maturation is important to ensure the quality of applied protocols. Several destructive, mainly histochemical, methods are conventionally used to this aim, requiring the sacrifice of the investigated samples. This implies (i) to plan several scaffold replicates, (ii) expensive and time consuming procedures and (iii) to infer the maturity level of a given tissue construct from a cognate replica. To solve these issues, non-destructive techniques such as light spectroscopy-based methods have been reported to be useful. Here, a miniaturized and inexpensive custom-made spectrometer device is proposed to enable the non-destructive analysis of hydrogel scaffolds. Testing involved samples with a differential amount of calcium salt. When compared to a reference standard device, this custom-made spectrometer demonstrates the ability to perform measurements without requiring elaborate sample preparation and/or a complex instrumentation. This preliminary study shows the feasibility of light spectroscopy-based methods as useful for the non-destructive analysis of TEed constructs. Based on these results, this custom-made spectrometer device appears as a useful option to perform real-time/in-line analysis. Finally, this device can be considered as a component that can be easily integrated on board of recently prototyped bioreactor systems, for the monitoring of TEed constructs during their conditioning.

Temporal modes of hub synchronization at rest.

The brain is a dynamic system that generates a broad repertoire of perceptual, motor, and cognitive states by the integration and segregation of different functional domains represented in large-scale brain networks. However, the fundamental mechanisms underlying brain network integration remain elusive. Here, for the first time to our knowledge, we found that in the resting state the brain visits few synchronization modes defined as clusters of temporally aligned functional hubs. These modes alternate over time and their probability of switching leads to specific temporal loops among them. Notably, although each mode involves a small set of nodes, the brain integration seems highly vulnerable to a simulated attack on this temporal synchronization mechanism. In line with the hypothesis that the resting state represents a prior sculpted by the task activity, the observed synchronization modes might be interpreted as a temporal brain template needed to respond to task/environmental demands .

Cortical cores in network dynamics.

Spontaneous brain activity at rest is spatially and temporally organized in networks of cortical and subcortical regions specialized for different functional domains. Even though brain networks were first studied individually through functional Magnetic Resonance Imaging, more recent studies focused on their dynamic 'integration'. Integration depends on two fundamental properties: the structural topology of brain networks and the dynamics of functional connectivity. In this scenario, cortical hub regions, that are central regions highly connected with other areas of the brain, play a fundamental role in serving as way stations for network traffic. In this review, we focus on the functional organization of a set of hub areas that we define as the 'dynamic core'. In the resting state, these regions dynamically interact with other regions of the brain linking multiple networks. First, we introduce and compare the statistical measures used for detecting hubs. Second, we discuss their identification based on different methods (functional Magnetic Resonance Imaging, Diffusion Weighted Imaging, Electro/Magneto Encephalography). Third, we show that the degree of interaction between these core regions and the rest of the brain varies over time, indicating that their centrality is not stationary. Moreover, alternating periods of strong and weak centrality of the core relate to periods of strong and weak global efficiency in the brain. These results indicate that information processing in the brain is not stable, but fluctuates and its temporal and spectral properties are discussed. In particular, the hypothesis of 'pulsed' information processing, discovered in the slow temporal scale, is explored for signals at higher temporal resolution.

[Evaluation of the biocompatibility of grafts for bone defects]. / Valutazione della biocompatibilità del fisiograft per difetti ossei.

BACKGROUND: This paper examines a new material composed of polylactic and polyglycolic acids mixed with destrane easy to handle in bone defect reconstruction in periodontology and implantology: its name is fisiograft. METHODS: According to the European directives, fisiograft was checked for some biological tests selected for its specific use. In particular, tests of cytotoxicity, genotoxicity, sensitization and implantation in rabbit's femurs were carried out. RESULTS: The results show that the composite material is not cytotoxic when it is in direct and indirect contact with murine fibroblasts. It is not genotoxic and not allergenic. The implantation in rabbit, already after 30 days, shows that around the material there is a rapid bone growth and the material is reabsorbing. The degradation is suitable for its clinical use. CONCLUSIONS: Fisiograft showed to be biocompatible, easy to handle and its degradation kinetics in bone is appropriate.

Study of the hemocoagulative parameters in hemoperfusion on polymer coated resins.

A hemoperfusion column containing anionic exchange resin coated with a new polymer has been tested in vivo for blood compatibility. The hemocoagulative parameters, evaluated before and after the cartridge during hemoperfusion, did not show any significant alteration even as regards the number and the functionality of the platelets nor as regards a possible activation of the fibrinolysis process. On the basis of these results, the hemoperfusion system examined can be regarded as hemocompatible from the hemocoagulative standpoint.