Biology subjects

Valente, M.

Publications and source records attributed to Valente, M..

27 records · Page 2Linked to original sources

bioRxiv2019

Fine-mapping of SNCA in REM sleep behavior disorder and overt synucleinopathies

ObjectiveREM-sleep behavior disorder (RBD) is a prodromal synucleinopathy, as >80% will eventually convert to overt synucleinopathy. We performed an in-depth analysis of the SNCA locus to identify RBD-specific risk variants.\n\nMethodsFull sequencing and genotyping of SNCA was performed in isolated/idiopathic RBD (iRBD, n=1,076), Parkinsons disease (PD, n=1,013), and dementia with Lewy bodies (DLB, n=415), and in control subjects (n=6,155). A replication cohort from 23andMe of PD patients with probable RBD (pRBD) was also analyzed (cases n=1,782, controls n=131,250). Adjusted logistic regression models and meta-analyses were performed. Effects on conversion rate were analyzed in 432 RBD patients with available data using Kaplan-Meier survival analysis.\n\nResultsA 5-region SNCA variant (rs10005233) was associated with iRBD (OR=1.43, p=1.1E-08), which was replicated in pRBD. This variant is in linkage disequilibrium (LD) with other 5 risk variants across the different synucleinopathies. An independent iRBD-specific suggestive association (rs11732740) was detected at the 3 of SNCA (OR=1.32, p=4.7E-04, not statistically significant after Bonferroni correction). Homozygous carriers of both iRBD-specific SNPs were at highly increased risk for iRBD (OR=5.74, p=2E-06). The known top PD-associated variant (3 variant rs356182) had an opposite direction of effect in iRBD compared to PD.\n\nInterpretationThere is a distinct pattern of association at the SNCA locus in RBD as compared to PD, with an opposite direction of effect at the 3 of SNCA. Several 5 SNCA variants are associated with iRBD and with pRBD in overt synucleinopathies, and may suggest a cognitive component to this region.

genetics↗

bioRxiv2019

Chronic pain alters microvascular architectural organization of somatosensory cortex

Chronic pain (CP) represents a complex pathology profoundly involving both neural and glial compartments of the central nervous system. While most CP studies have also investigated the macroscopic brain vascular system, its microstructural architecture still remains largely unexplored. Further, the adaptive modifications of the vascular microstructure as consequence of diseases or pathological insults, did not receive adequate attention. Here we show microtomographic signs of diffuse and conspicuous microvascular neogenesis in somatosensory cortex of CP animal models already peaking at 15 days from the model instantiation. Progressive fading of this microvessel neogenesis then ensued in the next six months yet maintaining higher vascular density with a preserved small fraction of them. Due to the important consequences on the neuron-glial-vessel arrangements and on the resulting metabolic and functional disorders of the local networks, novel additional scenarios of CP are thus conceivable with profound consequences of potential future CP diagnostic and therapeutic appraisals.

neuroscience↗

bioRxiv2019

Over-activation of BMP signaling in neural crest cells precipitates heart outflow tract septation

Establishment of separated pulmonary and systemic circulations in vertebrates relies on the key role of neural crest cells (NCC) for the septation of the embryonic cardiac outflow tract (OFT). Absence of NCCs induces OFT septation defects, analogous to a loss of Bone Morphogenetic Proteins (BMPs) activity, though it remains unclear how BMPs control cardiac NCC differentiation and behaviour. To address this question, we monitored cardiac NCC state upon gain in BMP signaling, caused by the deletion of Dullard, using 3D-imaging and single cell transcriptomics. Specific loss of Dullard in the NCC results in premature OFT septation, pulmonary artery obstruction and embryonic death. This is caused by uncontrolled NCC convergence towards the endocardium and asymmetrical myocardial differentiation, promoted by elevated levels of the guiding cue Sema3c and decreased levels in mesenchymal trait markers. Furthermore, we unraveled the molecular basis of the zipper-like OFT septation where graded Sema3c expression follow a gradient of BMP activation in NCC along the OFT length.

developmental biology↗

bioRxiv2019

Functional diversification of hybridoma produced antibodies by CRISPR/HDR genomic engineering

Hybridoma technology is instrumental for the development of novel antibody therapeutics and diagnostics. Recent preclinical and clinical studies highlight the importance of antibody isotype for therapeutic efficacy. However, since the sequence encoding the constant domains is fixed, tuning antibody function in hybridomas has been restricted. Here, we demonstrate a versatile CRISPR/HDR platform to rapidly engineer the constant immunoglobulin domains to obtain recombinant hybridomas which secrete antibodies in the preferred format, species and isotype. Using this platform, we obtained recombinant hybridomas secreting Fab fragments, isotype switched chimeric antibodies, and Fc-silent mutants. These antibody products are stable, retain their antigen specificity, and display their intrinsic Fc-effector functions in vitro and in vivo. Furthermore, we can site-specifically attach cargo to these antibody products via chemo-enzymatic modification. We believe this versatile platform facilitates antibody engineering for the entire scientific community, empowering preclinical antibody research. One Sentence SummaryWe demonstrate a universal CRISPR/HDR based platform for rapid genetic engineering of hybridomas to obtain functionally diverse antibody isotype panels in the species and format of choice.

bioengineering↗

bioRxiv2019

Removal of behavioural and electrophysiological signs of chronic pain by in vivo microsections of rat somatosensory cortex with parallel X-ray microbeams

Chronic pain (CP) is a condition characterized by a wide spectrum of clinical signs and symptoms, missing a sound modelling at the neuronal network scale. Recently, we presented a general theory showing common electrophysiological traits in different CP rat models, i.e. a collapse of relevant functional connectivity network properties, such as modularity, in the somatosensory thalamo-cortical (TC) network. In this work, we preliminary investigated by an in silico accurate simulator of the six-layer mammalian cortical networks that evidenced the crucial collapse of network modularity in CP simulated conditions and the consequent reduction of network adaptive processes. On this track, in studies on CP experimental animals affected by sciatic nerve multiple ligature (Bennett-Xie model), by synchrotron-generated X-ray microbeam (MB) irradiations (7 parallel beams, 100um width), we targeted in vivo the CP involved hindlimb somatosensory projection cortex that, because of the doses radiation (360 Gy, peak at each beam), non-invasively produced fast and precise tissue destruction along the 7 beam projections. These parcellated the cortical tissue and restored the cortical network statistics related to modularity and information processing efficiency as evidenced from post irradiation in vivo electrophysiological recordings. In addition, by MB treatment there was an ensuing removal of behavioral signs of allodynia and hyperalgesia accompanied by recovered normal gait schemes yet preserving the normal sensory thresholds of the experimental rats up to three months after the MB irradiation. Finally, novel and unprecedented therapeutic appraisals for CP are devised. Significance StatementChronic pain (CP) is an excruciating condition with severe effects on patients life. Apart from many clinical and experimental studies no current theory on CP is generally accepted. Recently, we proposed a general theory of CP in experimental animals as characterized by strong alteration of the connections among neurons in different brain regions. We show here on in silico simulations that specific connectivity changes in the somatosensory cortex recover the lost functional integrity. Concurrently, in experimental animals, we re-modulated, in vivo, some anatomical connections of the somatosensory cortex by extremely thin synchrotron generated X-ray microbeam irradiations. The resulting behavioral and electrophysiological signs of CP disappeared yet maintaining normal sensory responses. No adverse or pathological effects on blank animals were observable.

neuroscience↗

bioRxiv2019

HSA+ immature cardiomyocytes persist in the adult heart and expand after ischemic injury

The assessment of the regenerative capacity of the heart has been compromised by the lack of surface signatures to characterize cardiomyocytes. Here, combined multiparametric surface marker analysis with single cell transcriptional profiling and in vivo transplantation, identify the main fetal cardiac populations and their progenitors. We found that cardiomyocytes at different stages of differentiation co-exist during development. We identified a population of immature HSA/CD24+ cardiomyocytes that persists throughout life and that, unlike other cardiomyocyte subsets, actively proliferates up to one week of age and engraft cardiac tissue upon transplantation. In adult heart HSA/CD24+ cardiomyocytes appear as mononucleated cells that cycle and increase in frequency after infarction. Our work identified cell surface signatures that allow the prospective isolation of cardiomyocytes at any developmental stage and the detection of adult cardiomyocytes poised for activation in response to ischemic stimuli. This work opens new perspectives in the understanding and treatment of heart pathologies.

developmental biology↗

bioRxiv2018

State-dependent geometry of population activity in rat auditory cortex

The accuracy of the sensory neural code depends on the relationship between variability in population activity caused by the stimuli versus variability caused by noise. Whereas a large body of work has addressed this issue at a theoretical level, there have been few systematic empirical investigations using large-scale simultaneous recordings. We studied the geometry of the population code in the rat auditory cortex using sound stimuli varying across two orthogonal dimensions: the difference in sound level between the two ears, and the average level across the ears. We quantified the structure of the code across recordings spanning a wide range of brain states along the activation/inactivation continuum. We found that the nature of the code, both in terms of the stimulus and the noise subspaces, depends strongly on the degree of cortical activation. During the inactive (or synchronized) state, the code is characterized by a prevalence of contra-lateral tuning, a preference for loud sounds, gain-modulated tuning curves and coherent global noise fluctuations overlapping with the signal subspace. In contrast, in the most active (or desynchronized) recordings, there is an approximately symmetric preference between contra-, ipsi-, quiet and loud sounds, no systematic changes in the gain of lateralization tuning curves by sound intensity, and noise fluctuations span dimensions orthogonal to those evoked by the stimuli. Logistic regression could predict the sound lateralization with accuracy similar to the behaving rats, but only during cortical activation. Furthermore, also exclusively during the active state, the lateralization of sounds of different overall level could be decoded with the same accuracy, even by the same decoder, due to an orthogonal representation of level-differences and overall level across the population. Decoding accuracy from surrogate datasets with independent noise across neurons still displays strong state-dependence, suggesting that tuning curve reorganization plays a critical role in the overall effect of brain state on the population code. Our results provide an empirical foundation for the geometry and state dependence of cortical population codes.

neuroscience↗

bioRxiv2018

\"DoC-feeling\": a new behavioural tool to help diagnose the Minimally Conscious State.

ObjectivesThe clinical distinction between vegetative state/unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) is a key step to elaborate a prognosis and formulate an appropriate medical plan for any patient suffering from disorders of consciousness (DoC). However, this assessment is often challenging and may require specialized expertise. In this study, we hypothesized that pooling subjective reports of the level of consciousness of a given patient across several nursing staff members can be used to clinically detect MCS.\n\nSetting and ParticipantsPatients referred for consciousness assessment were prospectively screened. MCS (target condition) was defined according to the best Coma Recovery Scale-Revised score (CRS-R) obtained from expert physicians (reference standard). \"DoC-feeling\" score consisted in the median value of multiple ratings of patients behavior observation pooled from multiple staff members during a week of hospitalisation (index test). Individual ratings were collected at the end of each shift using a 100mm visual analog scale, blinded from the reference standard. Diagnostic accuracy was evaluated using area under the receiver operating characteristic curve (AUC), sensitivity and specificity metrics.\n\nResults692 ratings performed by 83 nursing staff members were collected from 47 patients. Twenty patients were in a UWS and 27 in a MCS. DoC-feeling scores obtained by pooling all individual ratings obtained for a given patient were significantly greater in MCS than in UWS patients (59.2 mm [IQR: 27.3-77.3] vs. 7.2 mm [IQR: 2.4-11.4]; p<0.001) yielding an AUC of 0.92 (95%CI: 0.84-0.99).\n\nConclusionsDoC-feeling capitalizes on the expertise of nursing staff to evaluate patients consciousness. Together with the CRS-R as well as with brain imaging, DoC-feeling might improve diagnostic and prognostic accuracy of DoC patients.\n\nStrengths and limitations of this studyO_LIWe designed a new behavioural tool called \"DoC-feeling\" to help face the clinical challenge of the detection of Minimally Conscious State in patients suffering from disorders of consciousness (DoC)\nC_LIO_LI\"DoC-feeling score\" quantifies nursing staffs subjective perception of patients consciousness by pooling multiple assessments obtained from multiple caregivers (\"wisdom of the crowds\")\nC_LIO_LIThis score which requires no particular training showed a very good accuracy when compared to the gold standard (repeated expert clinical assessment using the Coma Recovery Scale - Revised (CRS-R))\nC_LIO_LIA validation in a separate cohort would help to determine its place in consciousness assessment\nC_LIO_LIThis score should be tested not only against the CRS-R but also against brain-imaging techniques to test for its capacity to detect covert signs of consciousness\nC_LI

neuroscience↗

bioRxiv2018

Weber’s law is the result of exact temporal accumulation of evidence

Webers law states that the discriminability between two stimulus intensities depends only on their ratio. Despite its status as the cornerstone of psychophysics, the mecha-nisms underlying Webers law are still debated, as no principled way exists to choose between its many proposed alternative explanations. We studied this problem training rats to discriminate the lateralization of sounds of different overall level. We found that the rats discrimination accuracy in this task is level-invariant, consistent with Webers law. Surprisingly, the shape of the reaction time distributions is also level-invariant, implying that the only behavioral effect of changes in the overall level of the sounds is a uniform scaling of time. Furthermore, we demonstrate that Webers law breaks down if the stimulus duration is capped at values shorter than the typical reaction time. Together, these facts suggest that Webers law is associated to a process of bounded evidence accumulation. Consistent with this hypothesis, we show that, among a broad class of sequential sampling models, the only robust mechanism consistent with reaction time scale-invariance is based on perfect accumulation of evidence up to a constant bound, Poisson-like statistics, and a power-law encoding of stimulus intensity. Fits of a minimal diffusion model with these characteristics describe the rats performance and reaction time distributions with virtually no error. Various manipulations of motivation were unable to alter the rats psychometric function, demonstrating the stability of the just-noticeable-difference and suggesting that, at least under some conditions, the bound for evidence accumulation can set a hard limit on discrimination accuracy. Our results establish the mechanistic foundation of the process of intensity discrimination and clarify the factors that limit the precision of sensory systems.

neuroscience↗