Multimodal imaging study of the 5-HT1A receptor biased agonist, NLX-112, in a model of L-DOPA-induced dyskinesia

INTRODUCTION

The leading treatment for motor signs of Parkinson's disease is L-DOPA, but, upon extended use, it can lead to levodopa-induced dyskinesia (LID). Serotonergic neurons are involved in LID etiology and previous pre-clinical studies have shown that NLX-112, a 5-HT1A biased agonist, has robust antidyskinetic effects. Here, we investigated its effects in hemiparkinsonian (HPK) rats with a unilateral nigrostriatal 6-OHDA lesion.

METHODS

We compared HPK rats with LID (i.e., sensitized to the dyskinetic effects of chronic L-DOPA) and without LID (HPK-non-LID), using [18F]FDG PET imaging and fMRI functional connectivity following systemic treatment with saline, L-DOPA, NLX-112 or L-DOPA + NLX-112.

RESULTS

In HPK-non-LID rats, [18F]FDG PET experiments showed that L-DOPA led to hypermetabolism in motor areas (cerebellum, brainstem, and mesencephalic locomotor region) and to hypometabolism in cortical regions. L-DOPA effects were also observed in HPK-LID rats, with the additional emergence of hypermetabolism in raphe nuclei and hypometabolism in hippocampus and striatum. NLX-112 attenuated L-DOPA-induced raphe hypermetabolism and cingulate cortex hypometabolism in HPK-LID rats. Moreover, in fMRI experiments NLX-112 partially corrected the altered neural circuit connectivity profile in HPK-LID rats, through activity in regions rich in 5-HT1A receptors.

CONCLUSION

This neuroimaging study sheds light for the first time on the brain activation patterns of HPK-LID rats. The 5-HT1A receptor agonist, NLX-112, prevents occurrence of LID, likely by activating pre-synaptic autoreceptors in the raphe nuclei, resulting in a partial restoration of brain metabolic and connectivity profiles. In addition, NLX-112 also rescues L-DOPA-induced deficits in cortical activation, suggesting potential benefit against non-motor symptoms of Parkinson's disease.

Single subanesthetic dose of ketamine produces delayed impact on brain [18F]FDG PET imaging and metabolic connectivity in rats

Introduction

Ketamine, a glutamate NMDA receptor antagonist, is suggested to act very rapidly and durably on the depressive symptoms including treatment-resistant patients but its mechanisms of action remain unclear. There is a requirement for non-invasive biomarkers, such as imaging techniques, which hold promise in monitoring and elucidating its therapeutic impact.

Methods

We explored the glucose metabolism with [¹⁸F]FDG positron emission tomography (PET) in ten male rats in a longitudinal study designed to compare imaging patterns immediately after acute subanaesthetic ketamine injection (i.p. 10 mg/kg) with its sustained effects, 5 days later. Changes in [¹⁸F]FDG uptake following ketamine administration were estimated using a voxel-based analysis with SPM12 software, and a region of interest (ROI) analysis. A metabolic connectivity analysis was also conducted to estimate the immediate and delayed effects of ketamine on the inter-individual metabolic covariance between the ROIs.

Results

No significant difference was observed in brain glucose metabolism immediately following acute subanaesthetic ketamine injection. However, a significant decrease of glucose uptake appeared 5 days later, reflecting a sustained and delayed effect of ketamine in the frontal and the cingulate cortex. An increase in the raphe, caudate and cerebellum was also measured. Moreover, metabolic connectivity analyses revealed a significant decrease between the hippocampus and the thalamus at day 5 compared to the baseline.

Discussion

This study showed that the differences in metabolic profiles appeared belatedly, 5 days after ketamine administration, particularly in the cortical regions. Finally, this methodology will help to characterize the effects of future molecules for the treatment of treatment resistant depression.

A consensus protocol for functional connectivity analysis in the rat brain

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience.

Risk scores' performance and their impact on operative decision-making in left-sided endocarditis: a cohort study

The accuracy of contemporary risk scores in predicting perioperative mortality in infective endocarditis (IE) remains controversial. The aim is to evaluate the performance of existent mortality risk scores for cardiovascular surgery in IE and the impact on operability at high-risk thresholds. A single-center retrospective review of adult patients diagnosed with acute left-sided IE undergoing surgery from May 2014 to August 2019 (n = 142) was done. Individualized risk calculation was obtained according to the available mortality risk scores: EuroScore I and II, PALSUSE, Risk-E, Costa, De Feo-Cotrufo, AEPEI, STS-risk, STS-IE, APORTEI, and ICE-PCS scores. A cross-validation analysis was performed on the score with the best area under the curve (AUC). The 30-day survival was 96.5% (95%CI 91-98%). The score with worse area under the curve (AUC = 0.6) was the STS-IE score, while the higher was for the RISK-E score (AUC = 0.89). The AUC of the majority of risk scores suggested acceptable performance; however, statistically significant differences in expected versus observed mortalities were common. The cross-validation analysis showed that a large number of survivors (> 75%) would not have been operated if arbitrary high-risk threshold estimates had been used to deny surgery. The observed mortality in our cohort is significantly lower than is predicted by contemporary risk scores. Despite the reasonable numeric performance of the analyzed scores, their utility in judging the operability of a given patient remains questionable, as demonstrated in the cross-validation analysis. Future guidelines may advise that denial of surgery should only follow a highly experienced Endocarditis Team evaluation.

Pharmaco-fUS in cognitive impairment: Lessons from a preclinical model

BACKGROUND

There is an urgent need to understand and reverse cognitive impairment. The lack of appropriate animal models combined with the limited knowledge of pathophysiological mechanisms makes the development of new cognition-enhancing drugs complex. Scopolamine is a pharmacologic agent which impairs cognition and functional imaging in a wide range of animal species, similarly to what is seen in cognitive impairment in humans.

METHODS

In this study, using a functional ultrasound (fUS) neuroimaging technique, we monitored the impact of donepezil (DPZ), a potent acetylcholinesterase inhibitor and first-line treatment in patients with mild to moderate Alzheimer's disease, in a scopolamine-induced mouse model.

RESULTS

We demonstrated that despite its low impact on the cerebral blood volume (CBV) signal, scopolamine injection produced an overall decrease in functional connectivity between various brain areas. In addition, we revealed that DPZ induced a strong decrease in CBV signal without causing a difference in functional connectivity.

CONCLUSION

Finally, our work highlighted that DPZ counteracted the impact of scopolamine on functional connectivity changes and confirmed the interest of using pharmaco-fUS imaging on cognitive disorders, both in frequent and rare neurological disorders.

Cardiac telerrehabilitation: a safe and effective alternative in patients with coronary artery disease

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): Ferrer Internaciona Groupl, S.A

Background

Center-based cardiac rehabilitation programs (CRP) have shown to reduce morbidity and mortality after an ischemic cardiac event, but their vastly underutilized. Home-based CRP seems to improve patient’s adherence, but there is still scarce evidence, especially in elderly patients and women.

Purpose

To develop a holistic home-based CRP for ischemic heart disease patients and evaluate its safety and impact on functional capacity, adherence to a heart-healthy lifestyle and quality of life.

Methods

The 8-week home-based CRP will include 60 patients (50% women) with no age limit who have suffered an acute myocardial infarction in the previous 3 months, with LVEF ≥40% and a tablet/mobile device. The CRP (Picture 1) includes 3 weekly exercise sessions combining tailored aerobic and strength training and 1 weekly educational session focused on lifestyle habits, therapeutic adherence, and patient empowerment.

Results

Between January and October 2021, 56 patients were included: 2 were rejected for presenting ventricular arrhythmias in the initial stress test and 4 due to technological barrier; 14 patients are currently performing the CRP. The preliminary results from the 36 patients who have completed the CRP show a significant increase in functional capacity, muscle strength, weekly training volume, adherence to Mediterranean diet, emotional state (anxiety) and quality of life (Picture 2). There have been no complications and patient’s adherence has been excellent for both exercise (85%) and educational (80%) sessions.

Conclusion

A holistic telematic CRP dedicated to patients after an ischemic cardiac event, including patients of both gender and of no age-limit, seems to be a feasible, safe and effective in improving maximal aerobic capacity, weekly training volume, muscle strength, quality of life, compliance with the Mediterranean diet and emotional state.

ADENI-UCI study: Analysis of non-income decisions in ICU as a measure of limitation of life support treatments

OBJECTIVE

To analyze the variables associated with ICU refusal decisions as a life support treatment limitation measure.

DESIGN

Prospective, multicentrico.

SCOPE

62 ICU from Spain between February 2018 and March 2019.

PATIENTS

Over 18 years of age who were denied entry into ICU as a life support treatment limitation measure.

INTERVENTIONS

None.

MAIN INTEREST VARIABLES

Patient comorities, functional situation as measured by the KNAUS and Karnosfky scale; predicted scales of Lee and Charlson; severity of the sick person measured by the APACHE II and SOFA scales, which justifies the decision-making, a person to whom the information is transmitted; date of discharge or in-hospital death, destination for hospital discharge.

RESULTS

A total of 2312 non-income decisions were recorded as an LTSV measure of which 2284 were analyzed. The main reason for consultation was respiratory failure (1080 [47.29%]). The poor estimated quality of life of the sick (1417 [62.04%]), the presence of a severe chronic disease (1367 [59.85%]) and the prior functional limitation of patients (1270 [55.60%]) were the main reasons for denying admission. The in-hospital mortality rate was 60.33%. The futility of treatment was found as a risk factor associated with mortality (OR: 3.23; IC95%: 2.62-3.99).

CONCLUSIONS

Decisions to limit ICU entry as an LTSV measure are based on the same reasons as decisions made within the ICU. The futility valued by the intensivist is adequately related to the final result of death.

Impaired Local and Long-Range Brain Connectivity and Visual Response in a Genetic Rat Model of Hyperactivity Revealed by Functional Ultrasound

Attention-Deficit hyperactivity disorder (ADHD) is a central nervous system (CNS) disorder frequently associated with other psychiatric disorders. Pathophysiology processes at stake in ADHD are still under investigation and interestingly neuroimaging data points to modulated brain connectivity in patients. The genetic spontaneously hypertensive rat (SHR) model has been widely used to study pathophysiological underpinnings of ADHD and resting-state brain connectivity using functional magnetic resonance imaging. Here, functional ultrasound imaging, a new technique enabling fast measurement of cerebral blood volume (CBV), was used to further characterize resting-state functional connectivity – at both local and long-range – and visual response in SHR. We demonstrated that response to visual stimulation was increased in SHR in the visual cortex and the superior colliculus. They displayed altered long-range functional connectivity between spatially distinct regions. SHR also displayed modulated local connectivity, with strong increases of regional homogeneity in parts of the motor and visual cortex, along with decreases in the secondary cingulate cortex, the superior colliculus and the pretectal area. As CBV is intricately coupled to cerebral activity, these results suggest an abnormal neural activity in the SHR animal model, consistent with previous clinical studies and demonstrate the potential of functional ultrasound imaging as a translational tool in ADHD.

Long-term cardiac assessment in a sample of adolescent-onset anorexia nervosa

BACKGROUND

High mortality rates have been reported in patients with anorexia nervosa, mainly due to cardiovascular alterations. The purpose of the present study was to assess cardiac structural and functional abnormalities some 20 years after initial treatment in a sample of adolescent-onset anorexia nervosa (A-AN) and to compare them with matched healthy controls (HC).

METHODS

A sample of 29 women diagnosed and treated for AN during adolescence (A-AN) were assessed more than 20 years later. A complete cardiac evaluation was carried out including an electrocardiogram (ECG) and a standard 2D echocardiography. Thirty matched HC were also assessed.

RESULTS

In the A-AN group, four subjects had a body mass index lower than 18.5 and met full DSM 5 criteria for AN at follow-up (Low-Weight group). They were compared with the rest of the sample (n = 25) who had normalized their weight (Normal-Weight group), though some still showed some eating disorder symptoms. Both groups were compared with the HC group. Subjects in the Low-Weight group presented statistically significant decreases in the left ventricular end-diastolic and left atrium dimensions and left ventricular mass in comparison with the Normal-Weight group and the HC. No other differences in cardiac parameters were found between groups.

CONCLUSIONS

Echocardiographic and ECG parameters of adults who had presented A-AN twenty years earlier and currently maintained normal weight were similar to those of HC who had never been treated or diagnosed with AN. Adult subjects with A-AN who still had low weight in the long term present certain cardiac abnormalities similar to those seen in short-lasting disease. More studies are needed to confirm these results in a larger sample.

Different Alterations of Agonist and Antagonist Binding to 5-HT1A Receptor in a Rat Model of Parkinson’s Disease and Levodopa-Induced Dyskinesia: A MicroPET Study

Background: The gold-standard treatment for Parkinson’s disease is L-DOPA, which in the long term often leads to levodopa-induced dyskinesia. Serotonergic neurons are partially responsible for this, by converting L-DOPA into dopamine leading to its uncontrolled release as a “false neurotransmitter”. The stimulation of 5-HT1A receptors can reduce involuntary movements but this mechanism is poorly understood. Objective: This study aimed to investigate the functionality of 5-HT1A receptors using positron emission tomography in hemiparkinsonian rats with or without dyskinesia induced by 3-weeks daily treatment with L-DOPA. Imaging sessions were performed “off” L-DOPA. Methods: Each rat underwent a positron emission tomography scan with [18F]F13640, a 5-HT1AR agonist which labels receptors in a high affinity state for agonists, or with [18F]MPPF, a 5-HT1AR antagonist which labels all the receptors. Results: There were decreases of [18F]MPPF binding in hemiparkinsonian rats in cortical areas. In dyskinetic animals, changes were slighter but also found in other regions. In hemiparkinsonian rats, [18F]F13640 uptake was decreased bilaterally in the globus pallidus and thalamus. On the non-lesioned side, binding was increased in the insula, the hippocampus and the amygdala. In dyskinetic animals, [18F]F13640 binding was strongly increased in cortical and limbic areas, especially in the non-lesioned side. Conclusion: These data suggest that agonist and antagonist 5-HT1A receptor-binding sites are differently modified in Parkinson’s disease and levodopa-induced dyskinesia. In particular, these observations suggest a substantial involvement of the functional state of 5-HT1AR in levodopa-induced dyskinesia and emphasize the need to characterize this state using agonist radiotracers in physiological and pathological conditions.

Inter-subject registration and application of the SIGMA rat brain atlas for regional labeling in functional ultrasound imaging

BACKGROUND

Recent advances using functional ultrasound (fUS) imaging have opened new avenues to evaluate brain activity through the regional monitoring of cerebral blood volume (CBV) dynamics. In particular, this technology paves the way for understanding physiological or pathological cerebral processes or exploring the pharmacological profiles of new drugs targeting brain disorders. One of the main difficulties of this technology is the lack of standardized and validated tools, in particular relevant brain atlases, to help improving the accuracy, automation and reproducibility of fUS data analysis.

NEW METHOD

Here, we demonstrate the possibility to use the MRI-validated SIGMA brain atlas in rat to perform fast and precise analysis of CBV changes in numerous functionally relevant regions of interest using fUS imaging. We applied this atlas to a dataset obtained in anesthetized rats evaluating the cerebral effects of atomoxetine, a norepinephrine reuptake inhibitor currently marketed in attention-deficit/hyperactivity-disorder.

RESULTS

This approach enabled to show the subregional effects of atomoxetine in the rat with very few inter-individual differences in some areas, such as the dentate gyrus.

CONCLUSIONS

We show the feasibility of inter-individual registration of 2D pharmaco-fUS data and subsequent detailed analysis using the SIGMA atlas.

[18F]F13640, a 5-HT1A Receptor Radiopharmaceutical Sensitive to Brain Serotonin Fluctuations

Introduction

Serotonin is involved in a variety of physiological functions and brain disorders. In this context, efforts have been made to investigate the in vivo fluctuations of this neurotransmitter using positron emission tomography (PET) imaging paradigms. Since serotonin is a full agonist, it binds preferentially to G-protein coupled receptors. In contrast, antagonist PET ligands additionally interact with uncoupled receptors. This could explain the lack of sensitivity to serotonin fluctuations of current 5-HT_1A radiopharmaceuticals which are mainly antagonists and suggests that agonist radiotracers would be more appropriate to measure changes in neurotransmitter release. The present study evaluated the sensitivity to endogenous serotonin release of a recently developed, selective 5-HT_1A receptor PET radiopharmaceutical, the agonist [¹⁸F]F13640 (a.k.a. befiradol or NLX-112).

Materials and Methods

Four cats each underwent three PET scans with [¹⁸F]F13640, i.e., a control PET scan of 90 min, a PET scan preceded 30 min before by an intravenous injection 1 mg/kg of d-fenfluramine, a serotonin releaser (blocking challenge), and a PET scan comprising the intravenous injection of 1 mg/kg of d-fenfluramine 30 min after the radiotracer injection (displacement challenge). Data were analyzed with regions of interest and voxel-based approaches. A lp-ntPET model approach was implemented to determine the dynamic of serotonin release during the challenge study.

Results

D-fenfluramine pretreatment elicited a massive inhibition of [¹⁸F]F13640 labeling in regions known to express 5-HT_1A receptors, e.g., raphe nuclei, hippocampus, thalamus, anterior cingulate cortex, caudate putamen, occipital, frontal and parietal cortices, and gray matter of cerebellum. Administration of d-fenfluramine during PET acquisition indicates changes in occupancy from 10% (thalamus) to 31% (gray matter of cerebellum) even though the dissociation rate of [¹⁸F]F13640 over the 90 min acquisition time was modest. The lp-ntPET simulation succeeded in differentiating the control and challenge conditions.

Conclusion

The present findings demonstrate that labeling of 5-HT_1A receptors with [¹⁸F]F13640 is sensitive to serotonin concentration fluctuations in vivo. Although the data underline the need to perform longer PET scan to ensure accurate measure of displacement, they support clinical development of [¹⁸F]F13640 as a tool to explore experimental paradigms involving physiological or pathological (neurological or neuropsychiatric pathologies) fluctuations of extracellular serotonin.

ADENI-UCI Study: Analysis of non-income decisions in ICU as a measure of limitation of life support treatments

OBJECTIVE

To analyze the variables associated with ICU refusal decisions as a life support treatment limitation measure.

DESIGN

Prospective, multicentrico SCOPE: 62 ICU from Spain between February 2018 and March 2019.

PATIENTS

Over 18 years of age who were denied entry into ICU as a life support treatment limitation measure.

INTERVENTIONS

None.

MAIN INTEREST VARIABLES

Patient comorities, functional situation as measured by the KNAUS and Karnosfky scale; predicted scales of Lee and Charlson; severity of the sick person measured by the APACHE II and SOFA scales, which justifies the decision-making, a person to whom the information is transmitted; date of discharge or in-hospital death, destination for hospital discharge.

RESULTS

A total of 2312 non-income decisions were recorded as an LTSV measure of which 2284 were analyzed. The main reason for consultation was respiratory failure (1080 [47.29%]). The poor estimated quality of life of the sick (1417 [62.04%]), the presence of a severe chronic disease (1367 [59.85%]) and the prior functional limitation of patients (1270 [55.60%]) were the main reasons for denying admission. The in-hospital mortality rate was 60.33%. The futility of treatment was found as a risk factor associated with mortality (OR: 3.23; IC95%: 2.62-3.99).

CONCLUSIONS

Decisions to limit ICU entry as an LTSV measure are based on the same reasons as decisions made within the ICU. The futility valued by the intensivist is adequately related to the final result of death.

Aortic stiffness and distensibility in elite athletes: impact of discipline and gender

Background

Aortic remodeling in athletes is variable among sports disciplines with more ascending aorta (Asc Ao) dilatation in endurance (EAs) as compared to power athletes (PAs). Nevertheless, the impact of this differential remodeling on the Asc Ao functional properties is not well established. The aim of this study was to assess the distensibility and stiffness of the ascending aorta in endurance and power elite athletes in order to evaluate if this aortic remodeling implies functional changes.

Methods

119 elite athletes (61 EA and 58 PA, 49% female sex, mean age: 18.7±7.1 years) underwent standardized pre-participation screening with 12 lead ECG, transthoracic echocardiography and maximum stress test. Asc Ao diameter was measured from parasternal long axis views in 2D echocardiography. The aortic distensibility index (ADi) was calculated as 2 × (systolic Asc Ao diameter − diastolic Asc Ao diameter) / (diastolic Asc Ao diameter) × (pulse pressure) (cm–2 dyn–1 10–6). Aortic stiffness (AS) index was defined as Ln (systolic blood pressure/diastolic blood pressure) / (systolic Asc Ao diameter − diastolic Asc Ao diameter)/diastolic proximal Asc Ao diameter.

Results

Globally, EA presented larger AscAO, both in absolute and indexed values, than PA (28±3.0 vs 26±3.0cm, p<0.001 and 16.4±1.5 vs 15.7±1.9cm, p<0.05, while were no differences in AS or ADi) (Figure 1A). Nevertheless, ADi in male EAs was higher than in male PAs (ADi: 4.3±1.7 vs 3.2±1.3 cm2/dyn/10–6, p<0.05) and AS was lower (AS: 4.7±1.7 vs 6.3±3.8, P<0.005) (Figure 1B and 1C). Female athletes presented higher ADi (ADi: 4.7±1.9 vs 4.0±1.6 cm, p<0.05) and a trend towards lower AS (4.8±2.9 vs 5.1±2.6, p: 0.4) than male athletes. There were no differences in AS or ADi between female EAs and PAs.

Conclusion

Male EAs showed an increased aortic distensibility with lower stiffness as compared to that observed in male PAs. This difference was not observed in female EAs and PAs, potentially due to better baseline distensibility with less room for improvement with endurance training.

Funding Acknowledgement

Type of funding source: None

Dynamique de l’excrétion virale chez les patients infectés par le SARS-CoV-2

Introduction

La durée de contagiosité d’un patient infecté par le SARS-CoV-2 n’est à ce jour pas encore clairement définie. Dans l’attente de nouvelles données, des recommandations sur les critères de levées d’isolement (précautions gouttelettes et contact), ont été émises par le Haut Conseil de santé publique. Ces recommandations se basent sur des critères cliniques et temporels et recommandent une durée totale d’isolement d’au moins 14 jours après le début des symptômes en population générale et d’au moins 24 jours chez les patients immunodéprimés. D’autres recommandations internationales (notamment celles de l’eCDC et des Chinoises) associent aux critères de levée d’isolement, une à deux PCR de contrôle sur écouvillons nasopharyngés. Notre établissement centralise depuis le début de l’épidémie les prélèvements pour recherche de SARS-CoV-2 par RT-PCR sur écouvillons nasopharyngés pour 7 établissements de santé. L’objectif de notre étude a été d’évaluer la proportion de patients gardant une PCR positive à SARS-CoV-2 au-delà de 24 jours après la première PCR positive.

Matériels et méthodes

Étude rétrospective incluant l’ensemble des patients ayant eu un dépistage par PCR nasopharyngée (3 mars–10 juin 2020) au sein des 7 établissements. Les données analysées ont inclus l’âge des patients, le délai de réalisation (en jours) entre 2 PCR, le service clinique.

Résultats

À la date du 10 juin, 3603 dépistages (dont 37 non-rendus pour problèmes techniques) ont été réalisés chez 3032 patients ; parmi ces patients, 348 ont eu plusieurs dépistages : 278 ont été dépistés deux fois, 47 trois fois, et 23 quatre fois ou plus. La répartition des patients gardant une PCR positive au moins 24 jours après la première était la suivante :

– 20 patients ont eu un dépistage de contrôle entre 24 et 29 jours après le premier dépistage : 1 patient était encore positif à j27 (5 %) ;

– 42 patients ont eu un dépistage de contrôle entre 30 et 41 jours : 8 étaient encore positifs (19 %) ;

– 34 patients ont eu un dépistage de contrôle après 42 jours : 3 étaient encore positifs (9 %).

Les 12 patients gardant une PCR positive au moins 24 jours après la première, avaient été hospitalisés, avaient une moyenne d’âge de 66 ans et 7 d’entre eux avaient un cancer sous-jacent ou avaient nécessité une prise en charge en réanimation.

Conclusion

Plus de 10 % des patients dépistés au moins 24 jours après le diagnostic microbiologique gardait une PCR nasopharyngée positive. Même si l’excrétion d’ARN viral n’équivaut pas directement à l’infectiosité, au vu des inconnues encore importantes sur le SARS-CoV-2, la levée précoce de l’isolement doit être réfléchie au cas par cas, en particulier pour les formes graves et les patients immunodéprimés.

Pharmaco-fUS for Characterizing Drugs for Alzheimer's Disease - The Case of THN201, a Drug Combination of Donepezil Plus Mefloquine

Donepezil is a potent acetylcholinesterase inhibitor, largely used worldwide to alleviate cognitive symptoms in Alzheimer’s disease (AD). Beyond the widely described neuronal impact of donepezil, it was recently shown that targeting connexins, the proteins involved in astrocyte network organization, potentiates donepezil efficacy profile using behavioral tests in AD rodent models. We herein present data demonstrating the potential of functional ultrasound imaging to monitor cerebral activity changes after pharmacological challenge in mice. As an example, we showed that although administration of donepezil or mefloquine alone at low dose had only very limited effects on the signal compared to the baseline, their combination produced marked hemodynamic effects in the hippocampus, in line with previously published behavioral data demonstrating a synergic interaction between both drugs. Thus, the present study provides new perspectives, (i) through the use of pharmaco-fUS, a new non-clinical imaging modality, to move forward drug discovery in AD and (ii) by the profiling of two drug treatments on brain dynamics, one used in AD: donepezil, and the other in development: donepezil combined with mefloquine (THN201) as a modulator of astrocyte network.

Bayesian Estimation of the ntPET Model in Single-Scan Competition PET Studies

This paper proposes an innovative method, named b-ntPET, for solving a competition model in PET. The model is built upon the state-of-the-art method called lp-ntPET. It consists in identifying the parameters of the PET kinetic model relative to a reference region that rule the steady state exchanges, together with the identification of four additional parameters defining a displacement curve caused by an endogenous neurotransmitter discharge, or by a competing injected drug targeting the same receptors as the PET tracer. The resolution process of lp-ntPET is however suboptimal due to the use of discretized basis functions, and is very sensitive to noise, limiting its sensitivity and accuracy. Contrary to the original method, our proposed resolution approach first estimates the probability distribution of the unknown parameters using Markov-Chain Monte-Carlo sampling, distributions from which the estimates are then inferred. In addition, and for increased robustness, the noise level is jointly estimated with the parameters of the model. Finally, the resolution is formulated in a Bayesian framework, allowing the introduction of prior knowledge on the parameters to guide the estimation process toward realistic solutions. The performance of our method was first assessed and compared head-to-head with the reference method lp-ntPET using well-controlled realistic simulated data. The results showed that the b-ntPET method is substantially more robust to noise and much more sensitive and accurate than lp-ntPET. We then applied the model to experimental animal data acquired in pharmacological challenge studies and human data with endogenous releases induced by transcranial direct current stimulation. In the drug challenge experiment on cats using [¹⁸F]MPPF, a serotoninergic 1A antagonist radioligand, b-ntPET measured a dose response associated with the amount of the challenged injected concurrent 5-HT1A agonist, where lp-ntPET failed. In human [¹¹C]raclopride experiment, contrary to lp-ntPET, b-ntPET successfully detected significant endogenous dopamine releases induced by the stimulation. In conclusion, our results showed that the proposed method b-ntPET has similar performance to lp-ntPET for detecting displacements, but with higher resistance to noise and better robustness to various experimental contexts. These improvements lead to the possibility of detecting and characterizing dynamic drug occupancy from a single PET scan more efficiently.

Preclinical validation of [18F]2FNQ1P as a specific PET radiotracer of 5-HT6 receptors in rat, pig, non-human primate and human brain tissue

INTRODUCTION

The aim of this study was to perform in-vitro and in-vivo radiopharmacological characterizations of [¹⁸F]2FNQ1P, a new PET radiotracer of 5-HT₆ receptors, in rat, pig, non-human primate and human tissues. The 5-HT₆ receptor is one of the more recently identified serotonin receptors in central nervous system and, because of its role in memory and cognitive processes, is considered as a promising therapeutic target.

METHODS

In-vitro autoradiography and saturation binding assays were performed in postmortem brain tissues from rat, pig, non-human primate and human caudate nucleus, completed by serum stability assessment in all species and cerebral radiometabolite and biodistribution studies in rat.

RESULTS

In all species, autoradiography data revealed high binding levels of [¹⁸F]2FNQ1P in cerebral regions with high 5-HT₆ receptor density. Binding was blocked by addition of SB258585 as a specific antagonist. Binding assays provided K_D and B_max values of respectively 1.34 nM and 0.03 pmol·mg^-1 in rat, 0.60 nM and 0.04 pmol·mg^-1 in pig, 1.38 nM and 0.07 pmol·mg^-1 in non-human primate, and 1.39 nM and 0.15 pmol·mg^-1 in human caudate nucleus. In rat brain, the proportion of unmetabolized [¹⁸F]2FNQ1P was >99% 5 min after iv injection and 89% at 40 min. The biodistribution studies found maximal radioactivity in lungs and kidneys (3.5 ± 1.2% ID/g and 2.0 ± 0.7% ID/g, respectively, 15 min post-injection).

CONCLUSION

These radiopharmacological data confirm that [¹⁸F]2FNQ1P is a specific radiotracer for molecular imaging of 5-HT₆ receptors and suggest that it could be used as a radiopharmaceutical in humans.

P754 Severe aortic stenosis with preserved ejection prognostic differences according to flow status and gradient fraction: a Spanish multicentre study

Background and objectives

Low-flow low-gradient (LFLG) aortic stenosis portends bad prognosis in different series. The objective of this study was to evaluate the evolution of this entity in our country.

Methods

We included 1394 consecutive patients evaluated between 2008-2016 with severe AS (AVA <1 cm²) and ejection fraction> 50% from 14 Spanish centres. The results (aortic valve intervention and mortality) were compared using the Kaplan-Meier survival analysis.

Results

Three groups based on gradient and flow status were established (high gradient: HG, normal flow under gradient: NFLG, low gradient low flow: LFLG). No significant demographic or clinical differences between groups were observed. After a follow-up of 61.52 months (IQR 43.5-86.5), 551 (73.8%) HG, 268 (35.4%) with NFLG and 81 (57.9%) LFLG received intervention, with a later surgery/TAVI indication in the LFLG group compared with HG group (p = 0.001) (Figure 1). The analysis of the Kaplan-Meier mortality curves showed no significant differences.

Conclusions

Patients with LFLG aortic stenosis with normal ejection fraction received less and later aortic valve intervention than the HG group with no significant differences in mortality.

Abstract P754 Figure. Time to surgery

474 Isolated pulmonary endocarditis

INTRODUCTION

Isolated pulmonary endocarditis is a rare entity, especially in patients without predisposing factors, being its current incidence less than 1% of the total cases of infectious endocarditis. This is due to the lower right heart pressures and a decrease of intravenous drug-consum, being most of the cases nowadays, related to congenital right-heart diseases or pacemakers and defibrillators implants.

CLINICAL CASE

A 35 year-old man, tobacco smoker and intravenous cocaine consumer since he was 25, was admitted to our Emergency Department for fever up to 40ºC, cough and dyspnea started three days before admission. In the anamnesis he refereed intravenous consum of cocaine and sharing of syringes the last week. On physical examination he was tachycardic and signs of heart right failure were present such as jugular ingurgitation and peripheral edema. No murmurs were heard. No respiratory failure was detected at any time. Blood test analysis showed high levels of protein C reactive and leukocytosis. Blood cultures were positive for S. aureus (OXA-S) in the first 24h. Chest X-ray (image 1) showed a necrotizing bilateral pneumonia that was confirmed with the presence of cavitated images in the pulmonary CT (image 2). Antibiotic treatment was started with daptomicine + cloxaciline. With the suspicion of right endocarditis a transthoracic echocardiography was performed, showing the presence of a big vegetation (4x1cm) on the pulmonary valve that caused moderate pulmonary insufficiency (images 3, 4). Neither tricuspid nor left side valves were involved. Biventricular function was conserved and hyperdynamic. Endocarditis diagnosis was definitive and due to the presence of multiple right embolisms and the big size of the vegetation, the patient underwent cardiac surgery. Intra-surgical finding demonstrated a big vegetation of almost 5 cm (image 5) depending of the posterior pulmonary valve that was removed; the posterior valve needed to be repaired. Posterior clinical evolution was correct without complications, completing 17 days of i.v. antibiotics (cloxaciline) before discharge.

CONCLUSIONS

Right endocarditis is a rapidly progressive disease due to the fact that staphylococcus are the most frequent microorganisms involved. Valvular destruction and secondary embolic phenomena are the rule. Tricuspid valve is involved most of the times being the isolated pulmonary valve affection very uncommon.

Abstract 474 Figure. CT, Echo and surgical images

P632 Apical mass after acute myocardial infarction

Funding Acknowledgements

No financial support

53-year-old male, with a personal history of high blood pressure and current smoking.

He presented in the emergency department with typical chest pain. The initial electrocardiogram showed a ST segment elevation in DI and AVL leads. An emergency coronariography was performed showing a single vessel disease with two tandem lesions on the first diagonal, which were treated with pharmacoactive stents.

An echocardiography was performed, showing a mild apicolateral hypokinesia, with good contractility of the remaing segments. In addition, a rounded, pediculated and mobile mass in the apex was observed; the mass was hyperechogenic compared to the myocardium. In this setting, the differential diagnosis should include thrombus in context of acute coronary syndrome (despite a small infarction with early revascularization and good contractility of the segments involved) vs. tumoral mass. Anticoagulant treatment was maintained and a cardiac magnetic resonance (MR) was performed. The MR showed an apical round mass of 11 mm, with hyperintense signal in both T1- and T2-enhanced sequences in comparison to normal myocardium; although no contrast uptake was observed in early gadolinium enhancement sequence, the mass showed homogeneous enhancement in the late enhancement images, both with optimal TI and with long T1. These findings were suggestive of a benign tumoral mass of atypical location. In addition, a small anterior subendocardial enhancement with preserved ejection fraction was observed.

A control echocardiogram after 5 weeks of anticoagulant treatment showed no changes in either size or characteristics of the mass. After risk-benefit assessment and according to patient preferences, surgical resection of the mass was decided by a mini-thoracotomy approach. A surgical piece was obtained, described as a mobile pediculated tumour with a granulated surface and mucinous aspect. The postoperative period was uneventful. Subsequently, the pathological study confirmed the diagnosis of papillary fibroelastoma of atypical location.

This case summarizes the usefulness of MR to characterize cardiac masses and, in particular, to differentiate tumours from thrombus. Although in this setting (recent myocardial infarction) an apical thrombus was initially suspected, the MR exam correctly identified a contrast enhanced mass, which ruled out acute thrombus and suggested benign tumour.

Abstract P632 Figure.

1094 Exercise syncope as initial symptom of constrictive pericarditis in a young patient

Introduction

Constrictive pericarditis is a form of diastolic heart failure that arises because an inelastic pericardium inhibits cardiac filling. Syncope is a rare initial symptom of constrictive pericarditis.

Clinical case

A 22-year-old man with previous medical history of viral meningitis when he was 3 months-old but without any family history of cardiac disease or sudden cardiac death, was admitted to the Emergency Department for syncope. During the last year, he had suffered several episodes of intense exercise-related syncope. The patient denied having prodromes, chest pain, palpitations or any other symptoms. The physical exam of the patient was normal with stable vital signs. Normal S1 and S2 heart sounds were present, no murmurs or gallop. There were no signs of heart failure, only a minimal jugular ingurgitation. An electrocardiogram (ECG) revealed sinus rhythm, signs of bi-atrial enlargement (prominent P-wave with P mitral morphology in DI-II leads, with enhanced negative deflection in V1), and negative asymmetric T-waves in inferior (DII-III-aVF) and V6 leads. Chest X-ray showed minimal calcium density in the inferior pericardial silhouette. The patient was admitted in the Cardiology Department for aetiological study. A transthoracic echocardiogram revealed a marked protodiastolic cleft in the interventricular septum, with 40% variations of the transmitral flow with the respiratory changes and dilation of the cava vein, with absent respiratory collapse. A marked thickening and calcification of the inferoposterior pericardium was also seen. Considering these results, the diagnosis of constrictive pericarditis was suggested (Fig. A, B, C). Blood tests for autoimmune disease screening, as well as infectious diseases, including Quantiferon test, HIV, HVC, HVB and other viral serologies were done, with negative results. A cardiac magnetic resonance was requested, which confirmed the echocardiographic findings, with bi-atrial enlargement and markedly thickened pericardium with loss of signal, suggestive of calcification. Left and right ventricle had normal dimensions and contractility. The CT coronary angiography revealed normal coronary anatomy. Extensive calcification and pericardial thickening were shown, with myocardial infiltration in the lateral-basal area (Fig D). It was considered important to rule out any additional arrhythmic aetiology of the exercise syncope. Therefore, a stress test and, an electrophysiologic study were done, both with normal results. The patient remained asymptomatic and a pericardiectomy was indicated given the severe thickening and calcification of the pericardium and frequent syncopal episodes that our patient suffered.

Conclusions

Syncope as the initial symptom in the absence of significant right heart failure signs is a very unusual form of presentation of idiopathic constrictive pericarditis given the severe thickening and calcification of the pericardium of our patient.

Abstract 1094 Figure.

Pharmacological MRI to investigate the functional selectivity of 5-HT1A receptor biased agonists

The emerging concept of "biased agonism" denotes the phenomenon whereby agonists can preferentially direct receptor signalling to specific intracellular responses among the different transduction pathways, thus potentially avoiding side effects and improving therapeutic effects. The aim of this study was to investigate biased agonism by using pharmacological magnetic resonance imaging (phMRI). The cerebral blood oxygen level dependent (BOLD) signal changes induced by increasing doses of two serotonin 5-HT_1A receptor biased agonists, NLX-112 and NLX-101, were mapped in anaesthetized rats. Although both compounds display high affinity, selectivity and agonist efficacy for 5-HT_1A receptors, NLX-101 is known to preferentially activate post-synaptic receptors, whereas NLX-112 targets both pre- and post-synaptic receptors. We used several doses of agonists in order to determine if the regional selectivity of NLX-101 was dose-dependent. NLX-112 and NLX-101 induced different positive and negative hemodynamic changes patterns at equal doses. Importantly, NLX-101 had no significant effect in regions expressing pre-synaptic receptors contrary to NLX-112. NLX-112 also produced higher BOLD changes than NLX-101 in the orbital cortex, the somatosensory cortex, and the magnocellular preoptic nuclei. In other regions such as the retrosplenial cortex and the dorsal thalamus, the drugs had similar effects. In terms of functional connectivity, NLX-112 induced more widespread changes than NLX-101. The present phMRI study demonstrates that two closely-related agonists display notable differences in their hemodynamic "fingerprints". These data support the concept of biased agonism at 5-HT_1A receptors and raise the prospect of identifying novel therapeutics which exhibit improved targeting of brain regions implicated in neuropsychiatric disorders. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Is There a Role for GPCR Agonist Radiotracers in PET Neuroimaging?

Positron emission tomography (PET) is a molecular imaging modality that enables in vivo exploration of metabolic processes and especially the pharmacology of neuroreceptors. G protein-coupled receptors (GPCRs) play an important role in numerous pathophysiologic disorders of the central nervous system. Thus, they are targets of choice in PET imaging to bring proof concept of change in density in pathological conditions or in pharmacological challenge. At present, most radiotracers are antagonist ligands. In vitro data suggest that properties differ between GPCR agonists and antagonists: antagonists bind to receptors with a single affinity, whereas agonists are characterized by two different affinities: high affinity for receptors that undergo functional coupling to G-proteins, and low affinity for those that are not coupled. In this context, agonist radiotracers may be useful tools to give functional images of GPCRs in the brain, with high sensitivity to neurotransmitter release. Here, we review all existing PET radiotracers used from animals to humans and their role for understanding the ligand-receptor paradigm of GPCR in comparison with corresponding antagonist radiotracers.

Serotonin 5-HT1A Receptor Biased Agonists Induce Different Cerebral Metabolic Responses: A [18F]-Fluorodesoxyglucose Positron Emission Tomography Study in Conscious and Anesthetized Rats

Serotonin 5-HT_1A receptors constitute an attractive therapeutic target for various psychiatric or neurodegenerative disorders. These receptors are expressed in multiple brain regions on different neuronal populations and can be coupled with distinct G-protein subtypes; such functional diversity complicates the use of 5-HT_1A ligands in several pathologies where it would be desirable to stimulate the receptors in a precise region. Therefore, using "biased agonists" able to target specifically certain subpopulations of 5-HT_1A receptors would enable achievement of better therapeutic benefit. Several 5-HT_1A receptor biased agonists are currently in development, including NLX-101 (aka F15599) and NLX-112 (aka F13640, befiradol), with preclinical data suggesting that they preferentially target different populations of 5-HT_1A receptors. However, most previous studies used invasive and regionally limited approaches. In this context, [¹⁸F]-fluorodesoxyglucose (FDG)-positron emission tomography (PET) imaging constitutes an interesting technique as it enables noninvasive mapping of the regional brain activity changes following a pharmacological challenge in conscious animals. We report here the evaluation of cerebral glucose metabolism following intraperitoneal injection of different doses of NLX-112 or NLX-101 in conscious or isoflurane-anesthetized rats. The biased agonists produced different metabolic "fingerprints" with distinct regional preferences, consistent with previous studies. At equal doses, the effect of NLX-101 was less marked than NLX-112 in the piriform cortex, in the striatum (in terms of inhibition), and in the pontine nuclei and the cerebellum (in terms of activation); furthermore, only NLX-112 increased the glucose metabolism in the parietal cortex, whereas only NLX-101 induced a clear activation in the colliculi and the frontal cortex, which may be related to its distinctive procognitive profile. Both agonist effects were almost completely unapparent in anesthetized animals, underlining the importance of studying serotonergic neurotransmission in the conscious state. In this regard, [¹⁸F]FDG-PET imaging seems very complementary with other functional imaging techniques such as pharmacological MRI.

Implementation of Alere i Influenza A & B point of care test for the diagnosis of influenza in an ED

STUDY OBJECTIVE

This study aimed to evaluate the impact of implementing rapid point-of-care testing (POCT) with the Alere i Influenza A & B in an emergency department (ED) during an influenza epidemic.

METHODS

Direct nasal swabs were prospectively collected following the physical examination of patients aged >18years who presented to the ED of a tertiary hospital in France with influenza-like illness (ILI) symptoms (N=301) between February 1st and March 31st, 2016, which coincided with an influenza epidemic. Laboratory-based testing (standard of care) was used to obtain a diagnosis in February 2016 (pre-POCT cohort) and positive results were confirmed using polymerase chain reaction. The primary endpoint was patient time in the ED.

RESULTS

A total of 169 and 132 patients participated in the pre-POCT phase and POCT phase respectively. A significantly higher proportion of patients received a positive diagnosis in the POCT cohort compared with the pre-POCT cohort (31% versus 5.3%, P<0.01). Mean time spent in the ED and hospitalization rate were significantly lower in the POCT cohort (6.06h versus 4.15h, P=0.03, and 44.4% versus 9.7%, P=0.02, respectively). Despite similar rates in the prescription of antibiotics and antiviral therapies, the proportion of patients who were referred for additional tests was significantly lower in the POCT cohort (78.1% versus 62.1%, P=0.003, and 80.5% versus 63.6%, P=0.01, respectively).

CONCLUSIONS

The Alere i Influenza A & B POCT reduced the length of stay in ED, the hospitalization rates, and the number of additional diagnostic tests compared with standard of care testing.

Fibroma sinovial como causa atípica de síndrome de túnel del carpo: presentación de 2 casos clínicos

El fibroma sinovial (FS) es una tumoración benigna que puede encontrarse en la mano, teniendo predilección por las vainas flexoras. Esta lesión puede comportarse como una lesión ocupante de espacio (LOE), la cual puede llegar a comprimir nervios, como en el túnel del carpo, provocando un síndrome del túnel del carpo (STC). Este hecho solo ha sido descrito en 9 ocasiones. Cuando el STC se presenta de manera unilateral debemos descartar una LOE, entre las cuales el FS debería ser considerado como diagnóstico diferencial, especialmente frente al tumor de células gigantes, del cual solo es diferenciable microscópicamente, por lo que la resección de la masa es imprescindible. Los 2 casos aquí descritos tuvieron diferentes presentaciones clínicas pero sin complicaciones tras la resección.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Agonist and antagonist bind differently to 5-HT1A receptors during Alzheimer's disease: A post-mortem study with PET radiopharmaceuticals

PET imaging studies using 5-HT1A receptor radiotracers show a decreased density of this receptor in hippocampi of patients with Alzheimer's disease (AD) at advanced stages. However, current 5-HT1A receptor radiopharmaceuticals used in neuroimaging are antagonists, thought to bind to 5-HT1A receptors in different functional states (i.e., both the one which displays high affinity for agonists and is thought to mediate receptor activation, as well as the state which has low affinity for agonists). Comparing the PET imaging obtained using an agonist radiotracer, which binds selectively to functional receptors, with the PET imaging obtained using an antagonist radiotracer would therefore provide original information on 5-HT1A receptor impairment during AD. Quantitative autoradiography using [(18)F]F13640 and [(18)F]MPPF, a 5-HT1A agonist and antagonist, respectively, was measured in hippocampi of patients with AD (n = 25, at different Braak stages) and control subjects (n = 9). The neuronal density was measured in the same tissues by NeuN immunohistochemistry. The specific binding of both radiotracers was determined by addition of WAY-100635, a selective 5-HT1A receptor antagonist. The autoradiography distribution of both 5-HT1A PET radiotracers varied across hippocampus regions. The highest binding density was in the pyramidal layer of CA1. Incubation with Gpp(NH)p, a non-hydrolysable analogue of GTP, reduced significantly [(18)F]F13640 binding in hippocampal regions, confirming its preferential interaction with G-coupled receptors, and slightly increased [(18)F]MPPF binding. In the CA1 subfield, [(18)F]F13640 binding was significantly decreased at Braak stages I/II (-19%), Braak stages III/IV (-23%), and Braak stages V/VI (-36%) versus control. In contrast, [(18)F]MPPF binding was statistically reduced only at the most advanced Braak stages V/VI compared to control (-33%). Since [(18)F]F13640 and [(18)F]MPPF can be used in vivo in humans, this neuropharmacological paradigm supports testing the concept of functional imaging using agonist radiopharmaceuticals in future clinical studies.