Paulo Loureiro de Sousa

Bio: Paulo Loureiro de Sousa is an academic researcher from University of Strasbourg. The author has contributed to research in topics: Dementia with Lewy bodies & Thought disorder. The author has an hindex of 22, co-authored 62 publications receiving 2518 citations. Previous affiliations of Paulo Loureiro de Sousa include University of Liverpool & Centre national de la recherche scientifique.

Brain dysmyelination and recovery assessment by noninvasive in vivo diffusion tensor magnetic resonance imaging.

Abstract: Diffusion tensor magnetic resonance imaging (DT-MRI) was applied for in vivo quantification of myelin loss and regeneration. A transgenic mouse line (Oligo-TTK) expressing a truncated form of the herpes simplex virus 1 thymidine kinase gene (hsv1-tk) in oligodendrocytes was studied along with two induced phenotypes of myelin pathology. Myelin loss and axonal abnormalities differentially affect values of DT-MRI parameters in the brain of transgenic mice. Changes in the anisotropy of the white matter were assessed by calculating and mapping the radial (D perpendicular) and axial (D parallel) water diffusion to axonal tracts and fractional anisotropy (FA). A significant increase in D perpendicular attributed to the lack of myelin was observed in all selected brain white matter tracts in dysmyelinated mice. Lower D parallel values were consistent with the histological observation of axonal modifications, including reduced axonal caliber and overexpression of neurofilaments and III beta-tubulin. We show clearly that myelination and axonal changes play a role in the degree of diffusion anisotropy, because FA was significantly decreased in dysmyelinated brain. Importantly, myelin reparation during brain postnatal development induced a decrease in the magnitude of D( perpendicular) and an increase in FA compared with the same brain before recovery. The progressive increase in D parallel values was attributed to the gain in normal axonal morphology. This regeneration was confirmed by the detection of enlarged oligodendrocyte population, newly formed myelin sheaths around additional axons, and a gradual increase in axonal caliber.

From adversity to psychosis: pathways and mechanisms from specific adversities to specific symptoms

Abstract: Although there is considerable evidence that adversities in childhood such as social deprivation, sexual abuse, separation from parents, neglect and exposure to deviant parental communication are associated with psychosis in later life, most studies have considered broad diagnoses as outcomes In this review we consider evidence for pathways between specific types of adversity and specific symptoms of psychosis We present theoretical arguments for expecting some degree of specificity (although by no means perfect specificity) between different kinds of adversity and different symptoms of psychosis We review studies that have investigated social–environmental risk factors for thought disorder, auditory–verbal hallucinations and paranoid delusions, and consider how these risk factors may impact on specific psychological and biological mechanisms Communication deviance in parents has been implicated in the development of thought disorder in offspring, childhood sexual abuse has been particularly implicated in auditory–verbal hallucinations, and attachment-disrupting events (eg neglect, being brought up in an institution) may have particular potency for the development of paranoid symptoms Current research on psychological mechanisms underlying these symptoms suggests a number of symptom-specific mechanisms that may explain these associations Few studies have considered symptoms, underlying mechanisms and different kinds of adversity at the same time Future research along these lines will have the potential to elucidate the mechanisms that lead to severe mental illness, and may have considerable clinical implications

Quantitative Muscle MRI as an Assessment Tool for Monitoring Disease Progression in LGMD2I: A Multicentre Longitudinal Study

Abstract: Background: Outcome measures for clinical trials in neuromuscular diseases are typically based on physical assessments which are dependent on patient effort, combine the effort of different muscle groups, and may not be sensitive to progression over short trial periods in slow-progressing diseases. We hypothesised that quantitative fat imaging by MRI (Dixon technique) could provide more discriminating quantitative, patient-independent measurements of the progress of muscle fat replacement within individual muscle groups. Objective: To determine whether quantitative fat imaging could measure disease progression in a cohort of limb-girdle muscular dystrophy 2I (LGMD2I) patients over a 12 month period. Methods: 32 adult patients (17 male;15 female) from 4 European tertiary referral centres with the homozygous c.826C.A mutation in the fukutin-related protein gene (FKRP) completed baseline and follow up measurements 12 months later. Quantitative fat imaging was performed and muscle fat fraction change was compared with (i) muscle strength and function assessed using standardized physical tests and (ii) standard T1-weighted MRI graded on a 6 point scale. Results: There was a significant increase in muscle fat fraction in 9 of the 14 muscles analyzed using the quantitative MRI technique from baseline to 12 months follow up. Changes were not seen in the conventional longitudinal physical assessments or in qualitative scoring of the T1w images. Conclusions: Quantitative muscle MRI, using the Dixon technique, could be used as an important longitudinal outcome measure to assess muscle pathology and monitor therapeutic efficacy in patients with LGMD2I.

Cancer immunotherapy using checkpoint blockade

Abstract: The release of negative regulators of immune activation (immune checkpoints) that limit antitumor responses has resulted in unprecedented rates of long-lasting tumor responses in patients with a variety of cancers. This can be achieved by antibodies blocking the cytotoxic T lymphocyte–associated protein 4 (CTLA-4) or the programmed cell death 1 (PD-1) pathway, either alone or in combination. The main premise for inducing an immune response is the preexistence of antitumor T cells that were limited by specific immune checkpoints. Most patients who have tumor responses maintain long-lasting disease control, yet one-third of patients relapse. Mechanisms of acquired resistance are currently poorly understood, but evidence points to alterations that converge on the antigen presentation and interferon-γ signaling pathways. New-generation combinatorial therapies may overcome resistance mechanisms to immune checkpoint therapy.

Statistical Parametric Mapping The Analysis Of Functional Brain Images

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The evolving landscape of biomarkers for checkpoint inhibitor immunotherapy

Abstract: Checkpoint inhibitor-based immunotherapies that target cytotoxic T lymphocyte antigen 4 (CTLA4) or the programmed cell death 1 (PD1) pathway have achieved impressive success in the treatment of different cancer types. Yet, only a subset of patients derive clinical benefit. It is thus critical to understand the determinants driving response, resistance and adverse effects. In this Review, we discuss recent work demonstrating that immune checkpoint inhibitor efficacy is affected by a combination of factors involving tumour genomics, host germline genetics, PD1 ligand 1 (PDL1) levels and other features of the tumour microenvironment, as well as the gut microbiome. We focus on recently identified molecular and cellular determinants of response. A better understanding of how these variables cooperate to affect tumour-host interactions is needed to optimize the implementation of precision immunotherapy.