Label-free polarisation-resolved optical imaging of biological samples

Myelin is a biological structure present in all the gnathostomata. It is a highly- ordered structure, in which many lipid-enriched and densely compacted phospho- lipid bilayers are rolled up in a cylindrical symmetry around a subgroup of axons. The myelin sheath increases the electrical transverse resistance and reduces the ca- pacitance making the saltatory conduction of action potentials possible and therefore leading to a critically improved performance in terms of nervous impulse conduc- tion speeds and travel lengths. Myelin pathologies are a large group of neurological diseases that often result in death or disability. In order to investigate the main causes of myelin damage and its temporal progression many microscopy techniques are currently employed, such as electron microscopy and histochemistry or fluorescence imaging. However, electron microscopy and histochemistry imaging require complex sample prepara- tion and are therefore unsuitable for live imaging. Fluorescence imaging, as well as its derivatives, confocal and two-photon imaging, relies on the use of fluorescent probes to generate the image contrast but fluorophores and the associated sample processing, when applicable to living specimens, might nonetheless modify the bi- ological properties of the target molecule and perturb the whole biological process under investigation; moreover, fluorescent immunostaining still requires the fixation of the cells. Coherent anti-Stokes Raman Scattering (CARS) microscopy, on the other hand, is a powerful and innovative imaging modality that permits the study of liv- ing specimens with excellent chemical contrast and spatial resolution and without the confounding and often tedious use of chemical or biological probes. This is par- ticularly important in clinical settings, where the patient biopsy must be explanted in order to stain the tissue. In these cases it may be useful to resort to a set of label-free microscopy techniques. Among these, CARS microscopy is an ideal tool to investigate myelin morphology and structure, thanks to its abundance of CH2 bonds. The chemical selectivity of CARS microscopy is based on the properties of the contrast-generating CARS process. This is a nonlinear process in which the energy difference of a pair of incoming photons (\u201cpump\u201d and \u201cStokes\u201d) matches the energy of one of the vibrational modes of a molecular bond of interest. This vibrational excited state is coherently probed by a third photon (\u201cprobe\u201d) and anti-Stokes radi- ation is emitted. In this thesis I shall discuss the development of a multimodal nonlinear opti- cal setup implementing CARS microscopy together with general Four-Wave Mix- ing, Second Harmonic Generation and Sum Frequency Generation microscopies. Moreover, I shall present a novel polarisation-resolved imaging scheme based on the CARS process, which I named Rotating-Polarisation (RP) CARS microscopy and implemented in the same setup. This technique, using a freely-rotating pump-and- probe-beam-polarisation plane, exploits the CARS polarisation-dependent rules in order to probe the degree of anisotropy of the chemical-bond spatial orientations inside the excitation point-spread function and their average orientation, allowing at the same time the acquisition of large-field-of-view images with minimal polarisa- tion distortions. I shall show that RP-CARS is an ideal tool to investigate the highly- ordered structure of myelinated nervous fibres thanks to the strong anisotropy and symmetry properties of the myelin molecular architecture. I shall also demonstrate that this technique allows the fully label-free assessment of the myelin health status both in a chemical model of myelin damage (lysophos- phatidylcholine-exposed mouse nerve) and in a genetic model (twitcher mouse) of a human leukodystrophy (Krabbe disease) while giving useful insights into the pathogenic mechanisms underlying the demyelination process. I shall also discuss the promises of this technique for applications in optical tractography of the nerve fibres in the central nervous system and for the investigation of the effects of ageing on the peripheral nervous system. Moreover, I shall demonstrate by means of numer- ical simulations that RP-CARS microscopy is extremely robust against the presence of scatterers (such as lipid vesicles, commonly found in the peripheral nervous sys- tem). Finally, I shall discuss the results of the exploitation of my multimodal setup in a different area at the boundary of biophysics and nanomedicine: the observation of the internalization of different kinds of nanoparticles (boron-nitride nanotubes, barium-titanate nanoparticles and barium-titanate-core/gold-shell nanoparticles) by cultured cells and the demonstration of the nanopatterned nature of a structure built with two-photon lithography

Anisakiasis in italy: analysis of hospital discharge records in the years 2005-2015

Background Anisakiasis is a fish-borne zoonosis caused by the ingestion of marine food infected with Anisakis third-stage larvae, widespread marine parasitic nematodes. Gastrointestinal and/ or allergic clinical signs and symptoms are not specific. While frequently reported in countries with large raw fish consumption as Japan, the global prevalence of anisakiasis may be severely underestimated due to limitations of available diagnostic tools and to diverse clinical manifestations. Recently, infective larvae were found in the same localization with gastrointestinal tumors. The occurrence of allergic exacerbation upon secondary exposure and the possible occupational exposure, highlight the need to increase scientific evidences on anisakiasis. Methods We performed a retrospective descriptive study using analysis of Hospital Discharge Records (HDRs) from 2005 to 2015 in Italy, with particular attention to allergic manifestations. Descriptive statistics and multivariate analyses were performed using backward step-wise logistic regression models to assess spatial distribution and temporal trend as well as the variables independently associated with the allergic clinical signs and symptoms in Italian cases of anisakiasis. Results HDRs reporting the ICD-9 code for anisakiasis were retrieved (370), with a higher number of cases reported from central and southern regions, with particular regard to populations inhabiting the coastal territories. Around 40% of patients presented allergic manifestations and half of them showed serious allergic reactions. The multivariate analyses showed an independent association between allergic manifestations and features as living in southern regions and female gender, while anaphylactic episodes was independently associated only with female gender. Conclusion The present study is the first attempt to a better understanding of the epidemiological picture of anisakiasis in Italy, mining official data. A common strategy on data collection, monitoring and reporting would favor a more accurate epidemiological scenario in Italy, since the report of the diseases is not mandatory

Effect of Scatterering on Coherent Anti-Stokes Raman Scattering (CARS) signals

We develop a computational framework to examine the factors responsible for scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS) signals in turbid samples. We apply the Huygens-Fresnel Wave-based Electric Field Superposition (HF-WEFS) method combined with the radiating dipole approximation to compute the effects of scattering-induced distortions of focal excitation fields on the far-field CARS signal. We analyze the effect of spherical scatterers, placed in the vicinity of the focal volume, on the CARS signal emitted by different objects (2{\mu}m diameter solid sphere, 2{\mu}m diameter myelin cylinder and 2{\mu}m diameter myelin tube). We find that distortions in the CARS signals arise not only from attenuation of the focal field but also from scattering-induced changes in the spatial phase that modifies the angular distribution of the CARS emission. Our simulations further show that CARS signal attenuation can be minimized by using a high numerical aperture condenser. Moreover, unlike the CARS intensity image, CARS images formed by taking the ratio of CARS signals obtained using x- and y-polarized input fields is relatively insensitive to the effects of spherical scatterers. Our computational framework provide a mechanistic approach to characterizing scattering-induced distortions in coherent imaging of turbid media and may inspire bottom-up approaches for adaptive optical methods for image correction.Comment: 15 pages, 7 figure

The Impact of Exercise Intervention with Rhythmic Auditory Stimulation to Improve Gait and Mobility in Parkinson Disease: An Umbrella Review

Difficulties in walking, controlling balance, and performing activities of daily living are common problems encountered by individuals affected by Parkinson disease. Scientific evidence suggests that exercise performed with music or auditory or rhythmical cues facilitates movement and improves balance, gait, mobility, and activities of daily living (ADL) performance in patients with PD. The aim of this umbrella review was to summarize available high-quality evidence from systematic reviews and meta-analyses on the effectiveness of rhythmically cued exercise to improve gait, mobility, and ADL performance in individuals with PD. PubMed, Cochrane, and Embase databases were searched from January 2010 to October 2020 for systematic reviews and meta-analyses which had to be (1) written in English, (2) include studies on populations of males and females with PD of any age, (3) analyze outcomes related to gait, mobility, and ADL, and (4) apply exercise interventions with music or auditory or rhythmical cues. Two independent authors screened potentially eligible studies and assessed the methodological quality of the studies using the AMSTAR 2 tool. Four studies, two systematic reviews and meta-analyses, one a systematic review, and one a meta-analysis, were selected. Overall results indicated positive effects for gait and mobility of the use of rhythmic auditory cueing with exercise and suggested that it should be incorporated into a regular rehabilitation program for patients affected by PD. Nonetheless, more primary level research is needed to address the identified gaps regarding the application of this method to physical exercise interventions

Utilization of big data to improve management of the emergency departments. Results of a systematic review

Background. The emphasis on using big data is growing exponentially in several sectors including biomedicine, life sciences and scientific research, mainly due to advances in information technologies and data analysis techniques. Actually, medical sciences can rely on a large amount of biomedical information and Big Data can aggregate information around multiple scales, from the DNA to the ecosystems. Given these premises, we wondered if big data could be useful to analyze complex systems such as the Emergency Departments (EDs) to improve their management and eventually patient outcomes. Methods. We performed a systematic review of the literature to identify the studies that implemented the application of big data in EDs and to describe what have already been done and what are the expectations, issues and challenges in this field. Results. Globally, eight studies met our inclusion criteria concerning three main activities: the management of ED visits, the ED process and activities and, finally, the prediction of the outcome of ED patients. Although the results of the studies show good perspectives regarding the use of big data in the management of emergency departments, there are still some issues that make their use still difficult. Most of the predictive models and algorithms have been applied only in retrospective studies, not considering the challenge and the costs of a real-time use of big data. Only few studies highlight the possible usefulness of the large volume of clinical data stored into electronic health records to generate evidence in real time. Conclusion. The proper use of big data in this field still requires a better management information flow to allow real-time application

Familial hypercholesterolemia: a systematic review of guidelines on genetic testing and patient management

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal-dominant hereditary disorder of lipid metabolism that causes lifelong exposure to increased LDL levels resulting in premature coronary heart disease and, if untreated, death. Recent studies have shown its prevalence to be higher than previously considered, which has important implications for the mortality and morbidity of associated cardiovascular disease (CVD). Several clinical tools are used worldwide to help physicians diagnose FH, but nevertheless most patients remain undetected. This systematic review of guidelines aims to assess the role of genetic testing in the screening, diagnosis, and management of patients affected by heterozygous or homozygous FH and to identify related health-care pathways. METHODS: We performed a systematic review of the literature; inclusion criteria were English or Italian guidelines focusing on genetic testing. The guidelines were included and evaluated for their content and development process using the Appraisal of Guidelines for Research and Evaluation II instrument. RESULTS: Ten guidelines were considered eligible, and all were judged to be of good quality, with slight differences among them. The most common indications for performing genetic tests were high levels of cholesterol, or physical findings consistent with lipid disorder, in the subject or in the family history. Subsequent screening of family members was indicated when a mutation had been identified in the index patient. Regarding patient management, the various guidelines agreed that intensive treatment with lipid-lowering medications should begin as quickly as possible and that lifestyle modifications should be an integral part of the therapy. CONCLUSION: Since the early detection of affected patients is beneficial for effective prevention of CVD, genetic testing is particularly useful for identifying family members via cascade screening and for distinguishing between heterozygous and homozygous individuals, the latter of which require more extreme therapeutic intervention

Effects of fatigue on muscle stiffness and intermittent sprinting during cycling

Purpose: It was recently demonstrated that musculoarticular (MA) stiffness is related to sprint cycling performance in nonfatigued conditions. This study examined whether relatively stiffer cyclists were more effective at sprinting under fatigued conditions, as occurs during endurance cycling competitions. Methods: MA stiffness of the quadriceps was assessed in 21 trained male cyclists (28.7 ± 9.5 yr, 1.74 ± 0.08 m, 67.5 ± 7.2 kg). Participants also performed a maximal 6-s sprint on a cycle ergometer to assess peak power output (PO peak ), peak crank torque (CT peak ), and peak rate of crank torque development (RCTD peak ). A cycling fatigue protocol then required cyclists to pedal at 30%, 35%, and 40% of PO peak and sprint at the end of each stage. Surface EMG was recorded from vastus lateralis during each sprint and analyzed in the time domain as integrated EMG (iEMG) and in the frequency domain as instantaneous median frequency (MDF) adopting a continuous wavelet transform. Participants were then retested for MA stiffness. Results: MA stiffness (-12%) was significantly reduced after the cycling protocol. Further, PO peak , CT peak , RCTD peak , and iEMG were reduced by 20%, 15%, 13%, and 20%, respectively, after the fatigue protocol (P < 0.05). When the cyclists were divided into relatively stiff (SG) and relatively compliant groups (CG), only SG exhibited significant decreases in MA stiffness, C T peak , RCTD peak (P < 0.05), and instantaneous MDF (R = 0.705). Conclusions: Whereas neuromechanical parameters were generally reduced under conditions of fatigue, stiff and compliant cyclists were affected differently, with the sprint abilities of SG decreased to the level of CG. It seems important for endurance cyclists to incorporate training strategies to maintain MA stiffness during competition to offset declines in sprint performance. © 2011 by the American College of Sports Medicine

Orientarsi nella rete, considerata quale artefatto cognitivo

La logica del Web 2.0 si basa sulla condivisione, partecipazione e interattività, portando l’esperienza di Internet e del suo uso, fino ad integrare e riprodurre schemi analoghi a quelli riscontrabili nelle Reti Sociali reali. A questo punto, sorgono alcune domande: in che modo il Web 2.0 viene utilizzato per la raccolta  di informazioni che possono influenzare le scelte di studio e di vita?Si può pensare che l'utilizzo di piattaforme Web 2.0 modificare le strutture che gli psicologi chiamano meta-cognitive, in grado di modulare la costruzione, la ricerca, catalogazione e utilizzo delle informazioni? Una ricerca, ancora in corso, è stato avviata con lo scopo di rispondere a questi interrogativi, portando alla costruzione di un questionario: NETQRE 2.0, sia in versione cartacea sia in versione on-line. I primi dati sembrano indicare che l'uso di internet in generale e, in particolare per l'orientamento, è fatto in un modo passivo, senza sfruttare appieno tutti gli strumenti che caratterizzano il Web 2.