Synthetic non-classical luminescence generation by enhanced silica nanophotonics based on nano-bio-FRET

Fluorescent silica nanoparticles (NPs–(SiO₂–Fluo)) were synthesized based on the classical Störber method for cyanobacteria labelling. Modified mono-coloured SiO₂ NPs with fluorescein (Fl) and rhodamine B (RhB) were obtained (NPs–(SiO₂–Fl) and NPs–(SiO₂–RhB)). Moreover, multi-coloured SiO₂ NPs, via the incorporation of both emitters (NPs–(SiO₂–RhB–Fl)), were tuned for optimal emissions and the biodetection of cyanobacteria. NPs–(SiO₂–Fl) and NPs–(SiO₂–RhB–Fl) were optimized for detection via laser fluorescence microscopy and in-flow cytometry with laser excitation and fluorescence detection. By TEM, homogeneous SiO₂ NPs of 180.0 nm in diameter were recorded. These sizes were slightly increased due to the covalent linking incorporation of fluorescent dye emitters to 210.0 nm with mono-coloured fluorescent modified amine-organosilanes, and to 340.0 nm in diameter with multi-coloured dye incorporation. NPs–(SiO₂–Fluo) showed variable emission depending on the dye emitter concentration, quantum yield and applied luminescent pathway. Thus, mono-coloured NPs–(SiO₂–Fl) and NPs–(SiO₂–RhB) showed diminished emissions in comparison to multi-coloured NPs–(SiO₂–RhB–Fl). This enhancement was explained by fluorescence resonance energy transfer (FRET) between Fl as a fluorescent energy donor and RhB as an energy acceptor produced within the nanoarchitecture, produced only in the presence of both fluorophores with the appropriate laser excitation of the energy donor. The depositions of the nano-emitters on cyanobacteria by non-covalent interactions were observed by TEM and laser fluorescence microscopy. For multi-coloured NPs–(SiO₂–RhB–Fl) labelling, bio-FRET was observed between the emission of the nano-labellers and the natural fluorophores from the cyanobacteria that quenched the emission of the whole nano-biostructure in comparison to mono-coloured NPs–(SiO₂–Fl) labelling. This fact was explained and discussed in terms of different fluorescence energy transfer from the nanolabellers towards different natural chromophore coupling. In the presence of NPs–(SiO₂–RhB–Fl) and NPs–(SiO₂–RhB), the emission was coupled with lower quantum yield chromophores; while upon the application of NPs–(SiO₂–Fl), it was coupled with higher quantum yield chromophores. In this manner, for enhanced luminescent nanoplatform tracking, the multi-coloured NPs–(SiO₂–RhB–Fl) showed improved properties; but more highly luminescent bio-surfaces were generated with mono-coloured NPs–(SiO₂–Fl) that permitted faster cyanobacteria detection and counting by laser fluorescence microscopy, and by in-flow cytometry with laser excitation and fluorescence detection.

Fluorescent silica nanophotonics for cyanobacteria labelling.     

The applause sign in cortical and cortical-subcortical dementia

The “applause sign” is a motor perseveration described in focal and neurodegenerative disorders and characterized by fronto-subcortical dysfunction. Most previous formal investigations focused on Parkinson’s disease or progressive supranuclear palsy. We assessed the prevalence of the applause sign in patients affected by Alzheimer’s disease (AD), Lewy body dementia (LBD), corticobasal syndrome (CBS), and posterior cortical atrophy (PCA), with the aim to verify its contribution to the differential diagnosis. We enrolled 20 patients with AD, 20 with LBD, 16 with CBS, and ten with PCA, and 30 healthy controls. The three clap test (TCT) was used to elicit the applause sign, and was scored by raters blinded to the diagnosis. Correlation with motor (extrapyramidal) and cognitive measures was also performed. A maximum 40 % prevalence of a positive applause sign was found in the two parkinsonian syndromes, which could be discriminated from the two cortical groups with a positive predictive value of 82 % and a negative predictive value of 55 %. According to our findings, a diagnosis of LBD or CBS, rather than of AD or PCA, is highly probable in the presence of an abnormal TCP, but cannot be ruled out based on a negative result. No relevant correlates emerged that could clarify the origin and nature of the applause sign.     

Interaction of child disability and stressful life events in predicting maternal psychological health. Results of an area-based study of very preterm infants at two years corrected age

This study aimed at exploring the relationship between severe neuromotor and/or sensory disability in very preterm infants assessed at 2 years corrected age and their mothers’ psychological health. Data on 581 Italian singletons born at 22–31 weeks of gestation in five Italian regions and their mothers were analyzed. Maternal psychological distress was measured through the General Health Questionnaire short version (GHQ-12). The prevalence of any maternal distress (GHQ scores ≥ 2) and of clinical distress (scores ≥ 5) were 31.3% and 8.1% respectively. At multivariable analysis, we found a statistically significant association between child's disability and mothers’ GHQ scoring ≥5 (OR 3.45, 95% CI 1.07–11.15). Also lower maternal education appeared to increase the likelihood of psychological distress (OR 1.38, 95% CI 1.14–1.66). The impact of child disability was weaker in women who had experienced additional stressful life events since delivery, pointing to the existence of a “ceiling” effect. Maternal psychological assessment and support should be included in follow-up programs targeting very preterm infants.     

Brand new norms for a good old test: Northern Italy normative study of MiniMental State Examination

Neurological Sciences - Mini-Mental State Examination (MMSE) is one of the most used tests for the screening of global cognition in patients with neurological and medical disorders. Norms for the...     

Qualitatively different forms of pure alexia

In this study we investigated two patients with pure alexia, F.C. and L.D.S., in order to make inferences about how processes and levels involved in the early stage of visual word recognition are organized and how they can be selectively damaged. Moreover, we investigated whether pure alexia can be caused by different functional deficits. F.C. and L.D.S. were presented with tasks of letter processing and tasks of orthographic integration. There was a clear double dissociation between the pattern of performance of F.C. and L.D.S. F.C. was able to process single letters rapidly and accurately, but was unable to group together the letters that he had correctly identified. By contrast, L.D.S. was slower and more impaired at letter identification, but she could use letter groups to assist reading. Thus, two different forms of pure alexia emerged: F.C. has a higher level deficit in integrating letters, whereas L.D.S. has a lower level deficit in letter processing. The results support the assumption of a functional organization of the reading process that involves a series of orthographic units (i.e., single letters, sublexical letter groups, and the lexical unit), which can be selectively damaged. Finally, our data present difficulties for models of pure alexia that assume all patients to have a low-level processing deficit.