Main-duct intraductal papillary mucinous neoplasm of the pancreas: a case report

Three distinct entities among non-inflammatory cystic lesions of the pancreas have been defined: intraductal papillary mucinous neoplasm (IPMN), serous cystic neoplasm (SCN) and mucinous cystic neoplasm (MCN). IPMN is characterized by intraductal papillary growth and thick mucus secretion: its incidence has dramatically increased since its initial description. These lesions probably can progress towards invasive carcinoma. IPMNs are symptomatic in most cases: the typical presentation is a recurrent acute pancreatitis, without evident cause, of low or moderate severity. The diagnosis is usually based upon the imaging (CT/cholangio-MRI) demonstrating a pancreatic cystic mass, involving a dilated main duct, eventually associated to some filling defects, or a normal Wirsung duct communicating with the cyst lesion. Surgical treatment is generally indicated for main duct IPMN and branch duct IPMN with suspected malignancy (tumour size ≥ 30 mm, mural nodules, dilated main pancreatic duct, or positive cytology) or prominent symptoms. Herein we present a case of IPMN of the main duct which occurred with abdominal and back pain associated with weight loss. After the diagnosis, she successfully underwent surgery and is now in a follow-up program

Sarcoidosis presenting with splenomegaly and abdominal pain: a case report

Sarcoidosis is a multisystemic disease of unknown aetiology characterized by proliferation of noncaseating granulomas at disease sites. It commonly affects young and middle-age adults and frequently presents with pulmonary infiltration, bilateral hilar lymphadenopathy, ocular and skin lesions. The liver, spleen, lymph nodes, salivary glands, heart, nervous system, muscles, bones, and other organs may also be involved. A diagnosis of the disorder usually requires the demonstration of typical lesions in more than one organ system and exclusion of other disorder known to cause granulomatous inflammation. We present the case of a young woman with abdominal pain and weight loss. The finding of splenomegaly by abdominal ultrasound and the presence of hypercalciuria, hypercalcemia and mild renal impairment led us to include sarcoidosis in the differential diagnosis. The final diagnosis was established by demonstration of involvement of lymph nodes and lung parenchyma on CT scan, and typical histology in bioptic specimens collected from bronchial mucosa

Perineuronal nets control visual input via thalamic recruitment of cortical PV interneurons

In the neocortex, critical periods (CPs) of plasticity are closed following the accumulation of perineuronal nets (PNNs) around parvalbumin (PV)-positive inhibitory interneurons. However, how PNNs tune cortical function and plasticity is unknown. We found that PNNs modulated the gain of visual responses and \u3b3-oscillations in the adult mouse visual cortex in vivo, consistent with increased interneuron function. Removal of PNNs in adult V1 did not affect GABAergic neurotransmission from PV cells, nor neuronal excitability in layer 4. Importantly, PNN degradation coupled to sensory input potentiated glutamatergic thalamic synapses selectively onto PV cells. In the absence of PNNs, increased thalamic PV-cell recruitment modulated feed-forward inhibition differently on PV cells and pyramidal neurons. These effects depended on visual input, as they were strongly attenuated by monocular deprivation in PNN-depleted adult mice. Thus, PNNs control visual processing and plasticity by selectively setting the strength of thalamic recruitment of PV cells

Modifications synaptiques suite à la dégradation du réseau péri-neuronal extracellulaire dans le cortex visuel de souris adulte

The maturation of sensory processing undergoes a critical period (CP), during which cortical neural circuits are sculpted and changed by experience. The closure of CP is paralleled by the accumulation of extracellular perineuronal nets (PNN) around parvalbumin (PV)-positive interneurons. The degradation of PNNs in adult animals was shown to re-open the structural plasticity typical of the CP. We aimed at defining i) the neurophysiological properties of PV cells and principal neurons in layer 4 of primary visual cortex (V1) during the establishment of the CP ii) how these properties are altered by PNN accumulation. We found a robust age-dependent increase of input-output firing relationships in both cell types. Importantly, in vivo PNN removal in adult V1 increased both excitatory and inhibitory transmission selectively onto PV, leaving their excitability intact, and recapitulating younger states. In addition, triggering plasticity in vivo by monocular deprivation did not boost the increased activity onto PV cells. Interestingly, paired recordings in layer 4 showed no changes of inhibitory unitary connections, with or without PNNs. In order to understand the circuit mechanisms underlined, we expressed the light-sensitive opsin ChR2 in the visual thalamus. We found that PNN removal increases the recruitment of PV cells by thalamocortical fibers leading to an increase of feedforward inhibition. These results are in agreement with V1 recordings in vivo of visually evoked potentials in response of increasing contrast. Indeed, PNN disruption caused a reduction of the slope of the contrast sensitivity curve, indicating a higher recruitment of inhibition.Les réseaux neuronaux sont hautement sensibles aux stimuli sensoriels pendant une fenêtre temporelle dite période critique (PC). Un des acteurs clé de la consolidation de ces réseaux est le Perineuronal Net (PNN), une matrice extracellulaire qui s’accumule au cours de la PC majoritairement autour des interneurones parvalbumin-positifs (PV). La dégradation des PNNs chez l’adulte restaure une plasticité structurale, typique de la PC. Ce projet de recherche vise à déterminer i) les propriétés neurophysiologiques des neurones PV et glutamatergiques dans la couche 4 du cortex visuel primaire de souris au cours du développement ii) de quelle façon ces propriétés sont altérées par l’accumulation des PNN. Nous avons montré, au cours du développement, une augmentation de l’excitabilité des deux types de neurones. La dégradation in vivo des PNN augmente la transmission glutamatergique et GABAergique spécifiquement sur les PV, récapitulant un état juvénile. Dégrader les PNN chez l’adulte n’affecte pas les connections unitaires inhibitrices en couche 4. Afin de comprendre les mécanismes impliqués au niveau du circuit, nous avons exprimé l’opsine sensible à la lumière ChR2 dans les neurones glutamatergiques du thalamus visuel projetant sur la couche 4 du cortex. Ainsi, une absence de PNN augmente le recrutement spécifique des PV par le thalamus, entrainant une augmentation de l’inhibition feedforward. Ces résultats sont en accord avec des expériences réalisées in vivo, au cours desquelles nous avons mesuré les potentiels évoqués en réponse à des stimuli visuels suite à une dégradation des PNN et qui indiquent une augmentation du recrutement de l’inhibition

Le cerveau holographique : mise en forme de la lumière pour activer les neurones

International audienceComprendre l'étroite relation entre l'activité corticale, la perception, la cognition et le comportement résultant est une des questions fondamentales en Neuroscience. Les récents outils optogénétiques, qui rendent les neurones activables par la lumière, couplés avec des techniques optiques de pointe, capables de cibler précisément l'illumination sur des neurones uniques ou des ensembles de neurones, ouvrent la voie vers une investigation tout-optique de l'activité cérébrale

Reelin functions beyond neuronal migration: from synaptogenesis to network activity modulation

International audienceReelin, a glycoprotein of the extracellular matrix, has been the focus of several studies over the years, mostly for its role in cell migration. Here we report the role of this molecule and of its downstream pathways in post-mitotic neurons and how they contribute to neural circuit assembly, refinement and function. Accumulating evidence has pointed at a major role for Reelin in axonal guidance, synaptogenesis and dendritic spine formation. In particular new evidence points at a direct role in axonal targeting and refinement at the target site. In addition, recent advances highlight new functions of Reelin in the modulation of synaptic activity, plasticity and behavior and it directly regulates GABA receptors expression and stability. We discuss these findings in the context of neurodevelopmental disorders. Highlights Reelin signaling is required for axonal targeting and refinement at the target site. Reelin signaling regulates dendritogenesis and spine formation in mature neurons. Reelin modulates GABA receptors expression and stability, pre-and-post-synaptically. Reelin is important for hippocampal integrity, synaptic plasticity and behavior

Influence of carotid atherosclerotic plaques on pulse wave assessment with arterial tonometry

OBJECTIVE: Aortic stiffness and central pressure measurements have become increasingly important for the overall estimation of cardiovascular risk. The aim of this study is to verify whether the presence of stenosis in the carotid arteries due to atherosclerotic plaques may induce a bias in the measurement of carotid-femoral pulse wave velocity (PWV) and in the analysis of central pulse waveform variables assessed by carotid tonometry. METHODS: Eighty-four patients (age: 67.1\u200a\ub1\u200a12.4 years) undergoing screening for carotid atherosclerosis were enrolled, divided into three groups according to carotid ultrasound findings (NASCET criteria): 28 patients without significant stenosis, 30 patients with bilateral plaques, and 26 patients with right or left monolateral stenosis. PWV and other variables derived from the central pulse waveform analysis (central blood pressure, augmentation index and forward and backward waves) were measured at both right and left carotid arteries by a validated PulsePen tonometer. A repeatability study was performed in 28 young healthy patients (age: 25.4\u200a\ub1\u200a2.9 years). RESULTS: A high degree of correlation was found between bilateral measurements in all groups, and particularly in groups with monolateral carotid stenosis, with no significant difference attributable to lateralized stenosis. Right-left differences in asymmetric groups were 0.35\u200a\ub1\u200a5.12\u200ammHg (R\u200a=\u200a0.960) for central blood pressure, -2.12\u200a\ub1\u200a7.39% (R\u200a=\u200a0.743) for augmentation index, 0.64\u200a\ub1\u200a1.56\u200am/s (R\u200a=\u200a0.947) for PWV, 0.08\u200a\ub1\u200a8.48\u200ammHg for forward wave (R\u200a=\u200a0.742) and 0.35\u200a\ub1\u200a2.35\u200ammHg for backward wave (R\u200a=\u200a0.907). CONCLUSION: Measurement of PWV and of variables derived from the central pulse waveform analysis by carotid tonometry is not biased by the presence of local atherosclerotic plaques

Ultrafast light targeting for high-throughput precise control of neuronal networks

Current holographic approaches for neuronal stimulation have limitations in their temporal resolution and the number of targeted neurons. Here, the authors demonstrate an approach for ultra-fast holographic light targeting which, combined with optogenetics, enables sub-millisecond control of sequential neuronal activation and high throughput simultaneous multicell illumination

Robot assisted surgery in space: Pros and Cons. A review from the surgeon’s point of view.

The target of human flight in space has changed from permanence on the International Space Station to missions beyond low earth orbit and the Lunar Gateway for deep space exploration and Missions to Mars. Several conditions affecting space missions had to be considered: for example the effect of weightlessness and radiations on the human body, behavioral health decrements or communication latency, and consumable resupply. Telemedicine and telerobotic applications, robot-assisted surgery with some hints on experimental surgical procedures carried out in previous missions, had to be considered as well. The need for greater crew autonomy in health issues is related to the increasing severity of medical and surgical interventions that could occur in these missions, and the presence of a highly trained surgeon on board would be recommended. A surgical robot could be a valuable aid but only inasfar as it is provided with multiple functions, including the capability to perform certain procedures autonomously. Space missions in deep space or on other planets present new challenges for crew health. Providing a multi-function surgical robot is the new frontier. Research in this field shall be paving the way for the development of new structured plans for human health in space, as well as providing new suggestions for clinical applications on Earth