Miniature Eye Movements Enhance Fine Spatial Details

Our eyes are constantly in motion. Even during visual fixation, small eye movements continually jitter the location of gaze. It is known that visual percepts tend to fade when retinal image motion is eliminated in the laboratory. However, it has long been debated whether, during natural viewing, fixational eye movements have functions in addition to preventing the visual scene from fading. In this study, we analysed the influence in humans of fixational eye movements on the discrimination of gratings masked by noise that has a power spectrum similar to that of natural images. Using a new method of retinal image stabilization18, we selectively eliminated the motion of the retinal image that normally occurs during the intersaccadic intervals of visual fixation. Here we show that fixational eye movements improve discrimination of high spatial frequency stimuli, but not of low spatial frequency stimuli. This improvement originates from the temporal modulations introduced by fixational eye movements in the visual input to the retina, which emphasize the high spatial frequency harmonics of the stimulus. In a natural visual world dominated by low spatial frequencies, fixational eye movements appear to constitute an effective sampling strategy by which the visual system enhances the processing of spatial detail.National Institutes of Health; National Science Foundatio

Active Vision: Adapting How to Look

SummaryA new study has found that artificial occlusion of central vision leads to rapid emergence, and long-term maintenance of a new preferred retinal locus of fixation. These findings have important implications for the understanding of visual and oculomotor plasticity as well as for the development of rehabilitation techniques

Investigating bifidobacteria-host interactions in the gut using organoid models and network biology approaches

Despite numerous studies indicating that Bifidobacterium species exert beneficial effects a range of diseases, current knowledge about the specific modulating factors is limited. One mechanism is represented by autophagy, mediating key processes in intestinal epithelial cells, and which is often disrupted in gut disorders such as inflammatory bowel disease. In this regard, intestinal organoids represent a useful model to investigate these processes, allowing to study the effect of microbial-derived molecules on host epithelial cell function in a high-throughput and representative manner. The goal of this PhD thesis is to combine experimental and computational approaches, including intestinal organoids and network biology methods, to identify specific mechanisms by which Bifidobacterium-derived metabolites affect intestinal epithelial cell function, exerting a beneficial effect on the host. To achieve these goals, mouse and human intestinal organoid models were developed, and in parallel with existing colon cancer cell lines, their culture conditions were further characterised to allow their co-culture with Bifidobacterium-derived metabolites. Subsequently, downstream applications were optimised to assess modulation of host intestinal barrier, cytokine release, autophagy, and gene expression changes. Host transcriptomics data from organoids was further integrated with a priori knowledge to build regulatory and molecular interaction networks, whose analysis can reveal specific mechanisms modulated by bifidobacteria. This work resulted in the development and further characterisation of novel experimental models to investigate apical host-microbe interactions, including organoids with reversed polarity or organoid-derived monolayers. Furthermore, exposure of epithelial cultures to Bifidobacterium strains highlighted the ability of bifidobacterial metabolites to improve intestinal barrier function and modulate autophagy in epithelial cells. Transcriptomics analysis of human colonic organoids exposed to Bifidobacterium metabolites also revealed positive modulation of the immune response, epithelial differentiation and tight junctions through epigenetics mechanisms, and the downregulation of cholesterol biosynthesis. Overall, this work has increased the understanding of the effects of bifidobacteria on the intestinal epithelium, while showing how a combination of experimental and network biology approaches can be used for these types of studies. Once further validated, results of this thesis will help unravel the beneficial effects of probiotics such as bifidobacteria in the gut, further aiding the development of management strategies for inflammatory diseases of the gut

Mindfulness-based stress reduction in patients with interstitial lung diseases: a pilot, single-centre observational study on safety and efficacy

open11siBackground Chronic, progressive respiratory symptoms are associated with great psychological and emotional impact in patients suffering from interstitial lung disease (ILD). This single-centre pilot study evaluated for the first time the safety, feasibility and efficacy of a Mindfulness Based Stress Reduction Program (MBSR) in a group of patients with ILD. Methods Prospective observational study set in a university hospital ILD outpatient clinic. Nineteen patients with different ILDs were recruited 2 months prior to the start of the 8-week MBSR program and followed up for 12 months. Primary outcomes were program safety and feasibility, while secondary outcomes were changes in moods and stress (assessed by Profile Of Mood State (POMS) and Perceived Stress Scale (PSS) questionnaires), symptoms (Shortness Of Breath (SOB) and Cough And Sputum Assessment (CASA-Q) questionnaires), lung function and exercise tolerance at 12 months. Results Two patients (10.5%) dropped out in the observational period before the start of the MBSR intervention because of non-respiratory causes. All 17 patients who entered the 8-week MBSR program managed to complete it with an adherence average of eight sessions of nine. No adverse events related to the mindfulness training were reported. Statistically significant improvements in the POMS total score and in several individual items of POMS and PSS were observed throughout the study. However, respiratory questionnaire scores, lung function and exercise tolerance did not show a significant difference over time. Conclusions An MBSR program appears to be safe and feasible in patients with ILD, and might affect perceived moods and stress producing a positive and lasting improvement in several stress-related negative domains. These findings pave the way to larger (possibly multicentre), randomised, controlled confirmatory trials.openSgalla, Giacomo; Cerri, Stefania; Ferrari, Roberto; Ricchieri, Maria Pia; Poletti, Stefano; Ori, Margherita; Garuti, Martina; Montanari, Gloria; Luppi, Fabrizio; Petropulacos, Kyriakoula; Richeldi, LucaSgalla, Giacomo; Cerri, Stefania; Ferrari, Roberto; Ricchieri, Maria Pia; Poletti, Stefano; Ori, Margherita; Garuti, Martina; Montanari, Gloria; Luppi, Fabrizio; Petropulacos, Kyriakoula; Richeldi, Luc

SARS-CoV-2 Causes a Different Cytokine Response Compared to Other Cytokine Storm-Causing Respiratory Viruses in Severely Ill Patients

Hyper-induction of pro-inflammatory cytokines, also known as a cytokine storm or cytokine release syndrome (CRS), is one of the key aspects of the currently ongoing SARS-CoV-2 pandemic. This process occurs when a large number of innate and adaptive immune cells activate and start producing pro-inflammatory cytokines, establishing an exacerbated feedback loop of inflammation. It is one of the factors contributing to the mortality observed with coronavirus 2019 (COVID-19) for a subgroup of patients. CRS is not unique to the SARS-CoV-2 infection; it was prevalent in most of the major human coronavirus and influenza A subtype outbreaks of the past two decades (H5N1, SARS-CoV, MERS-CoV, and H7N9). With a comprehensive literature search, we collected changing the cytokine levels from patients upon infection with the viral pathogens mentioned above. We analyzed published patient data to highlight the conserved and unique cytokine responses caused by these viruses. Our curation indicates that the cytokine response induced by SARS-CoV-2 is different compared to other CRS-causing respiratory viruses, as SARS-CoV-2 does not always induce specific cytokines like other coronaviruses or influenza do, such as IL-2, IL-10, IL-4, or IL-5. Comparing the collated cytokine responses caused by the analyzed viruses highlights a SARS-CoV-2-specific dysregulation of the type-I interferon (IFN) response and its downstream cytokine signatures. The map of responses gathered in this study could help specialists identify interventions that alleviate CRS in different diseases and evaluate whether they could be used in the COVID-19 cases.</p

Co-circulation of SARS-CoV-2 Alpha and Gamma variants in Italy, February and March 2021

: BackgroundSeveral SARS-CoV-2 variants of concern (VOC) have emerged through 2020 and 2021. There is need for tools to estimate the relative transmissibility of emerging variants of SARS-CoV-2 with respect to circulating strains.AimWe aimed to assess the prevalence of co-circulating VOC in Italy and estimate their relative transmissibility.MethodsWe conducted two genomic surveillance surveys on 18 February and 18 March 2021 across the whole Italian territory covering 3,243 clinical samples and developed a mathematical model that describes the dynamics of co-circulating strains.ResultsThe Alpha variant was already dominant on 18 February in a majority of regions/autonomous provinces (national prevalence: 54%) and almost completely replaced historical lineages by 18 March (dominant across Italy, national prevalence: 86%). We found a substantial proportion of the Gamma variant on 18 February, almost exclusively in central Italy (prevalence: 19%), which remained similar on 18 March. Nationally, the mean relative transmissibility of Alpha ranged at 1.55-1.57 times the level of historical lineages (95% CrI: 1.45-1.66). The relative transmissibility of Gamma varied according to the assumed degree of cross-protection from infection with other lineages and ranged from 1.12 (95% CrI: 1.03-1.23) with complete immune evasion to 1.39 (95% CrI: 1.26-1.56) for complete cross-protection.ConclusionWe assessed the relative advantage of competing viral strains, using a mathematical model assuming different degrees of cross-protection. We found substantial co-circulation of Alpha and Gamma in Italy. Gamma was not able to outcompete Alpha, probably because of its lower transmissibility

Increasing situational awareness through nowcasting of the reproduction number

The time varying reproduction number R is a critical variable for situational awareness during infectious disease outbreaks, but delays between infection and reporting hinder its accurate estimation in real time. We propose a nowcasting method for improving the timeliness and accuracy of R estimates, based on comparisons of successive versions of surveillance databases. The method was validated against COVID-19 surveillance data collected in Italy over an 18-month period. Compared to traditional methods, the nowcasted reproduction number reduced the estimation delay from 13 to 8 days, while maintaining a better accuracy. Moreover, it allowed anticipating the detection of periods of epidemic growth by between 6 and 23 days. The method offers a simple and generally applicable tool to improve situational awareness during an epidemic outbreak, allowing for informed public health response planning

The ALLgorithMM: How to define the hemodilution of bone marrow samples in lymphoproliferative diseases

IntroductionMinimal residual disease (MRD) is commonly assessed in bone marrow (BM) aspirate. However, sample quality can impair the MRD measurement, leading to underestimated residual cells and to false negative results. To define a reliable and reproducible method for the assessment of BM hemodilution, several flow cytometry (FC) strategies for hemodilution evaluation have been compared. MethodsFor each BM sample, cells populations with a well-known distribution in BM and peripheral blood - e.g., mast cells (MC), immature (IG) and mature granulocytes (N) - have been studied by FC and quantified alongside the BM differential count. ResultsThe frequencies of cells' populations were correlated to the IG/N ratio, highlighting a mild correlation with MCs and erythroblasts (R=0.25 and R=0.38 respectively, with p-value=0.0006 and 0.0000052), whereas no significant correlation was found with B or T-cells. The mild correlation between IG/N, erythroblasts and MCs supported the combined use of these parameters to evaluate BM hemodilution, hence the optimization of the ALLgorithMM. Once validated, the ALLgorithMM was employed to evaluate the dilution status of BM samples in the context of MRD assessment. Overall, we found that 32% of FC and 52% of Next Generation Sequencing (NGS) analyses were MRD negative in samples resulted hemodiluted (HD) or at least mildly hemodiluted (mHD). ConclusionsThe high frequency of MRD-negative results in both HD and mHD samples implies the presence of possible false negative MRD measurements, impairing the correct assessment of patients' response to therapy and highlighs the importance to evaluate BM hemodilution