Ultra-high density electrodes improve detection, yield, and cell type identification in neuronal recordings

To understand the neural basis of behavior, it is essential to sensitively and accurately measure neural activity at single neuron and single spike resolution. Extracellular electrophysiology delivers this, but it has biases in the neurons it detects and it imperfectly resolves their action potentials. To minimize these limitations, we developed a silicon probe with much smaller and denser recording sites than previous designs, called Neuropixels Ultra (NP Ultra). This device samples neuronal activity at ultra-high spatial density (~10 times higher than previous probes) with low noise levels, while trading off recording span. NP Ultra is effectively an implantable voltage-sensing camera that captures a planar image of a neuron's electrical field. We use a spike sorting algorithm optimized for these probes to demonstrate that the yield of visually-responsive neurons in recordings from mouse visual cortex improves up to ~3-fold. We show that NP Ultra can record from small neuronal structures including axons and dendrites. Recordings across multiple brain regions and four species revealed a subset of extracellular action potentials with unexpectedly small spatial spread and axon-like features. We share a large-scale dataset of these brain-wide recordings in mice as a resource for studies of neuronal biophysics. Finally, using ground-truth identification of three major inhibitory cortical cell types, we found that these cell types were discriminable with approximately 75% success, a significant improvement over lower-resolution recordings. NP Ultra improves spike sorting performance, detection of subcellular compartments, and cell type classification to enable more powerful dissection of neural circuit activity during behavior.

Factors associated with patent foramen ovale-related stroke: SAFAS study

BACKGROUND

Persistent foramen ovale (PFO) contributes to cryptogenic stroke and is associated with stroke recurrence, although the exact mechanism of ischemic events is not fully understood. Several biomarkers have been developed for the prediction of atrial fibrillation after stroke, but there are currently only limited data on their potential value for the diagnosis of PFO-related stroke.

METHODS

This study was a prospective single-center study that included all patients hospitalized between March 31, 2018, and January 18, 2020, in the stroke department of the Dijon University Hospital for ischemic stroke without obvious cause and without a history of atrial fibrillation. PFO was systematically screened by transthoracic echocardiography and images were reviewed by an independent cardiologist blinded from clinical data. PFO was defined according to the CLOSE trial criteria: PFO associated with interatrial septal aneurysm or significant interatrial shunt (> 30 microbubbles in the left atrium within three cardiac cycles after right atrial opacification). The potential association of PFO-related stroke with biomarkers of cardiac fibrosis and inflammation such as galectin-3, GDF-15, ST-2, osteoprotegerin and NT-proBNP was tested using multivariate backward stepwise logistic regression.

RESULTS

Of the 240 patients included in the SAFAS study, 229 had complete echocardiographic data, and 23 (10%) had PFO-related stroke. Patients with PFO-related stroke were significantly younger (58±14 vs. 69±14, P<0.001), had less frequent previous arterial hypertension (30 vs. 60%, P=0.008), and more frequent cerebellar territory involvement (26 vs. 9%, P=0.014) compared to the other patients. In addition, they had less frequently left atrial dilatation (left atrial index volume>34mL/m2 [9 vs. 35%, P=0.009]). After ROC curve analysis for definition of thresholds, PFO-related stroke patients more often had galectin-3<9.5ng/mL (59 vs. 27%, P=0.002), ST2<13380pg/ml (23 vs. 50%, P=0.007), GDF-15<1200ng/mL (59 vs. 27%, P=0.002), osteoprotegerin<1133pg/mL (82 vs. 58%, P=0.033) and NT-proBNP<300pg/mL (88 vs. 55%, P=0.009). After multivariate analysis, only galectin-3<9.5ng/mL (OR [95% CI] 3.4 [1.18; 9.8], P=0.024) and osteoprotegerin<1133pg/L (OR [95% CI] 5.0 [1.1; 22.9], P=0.038) were independently associated with PFO-related stroke.

CONCLUSION

Patients in whom cryptogenic stroke is attributed to a significant PFO have a specific clinical and biological phenotype. Low levels of galectin-3 and osteoprotegerin may help identify patients with PFO-related strokes.

STED microscopy reveals dendrite-specificity of spines in turtle cortex

Dendritic spines are key structures for neural communication, learning and memory. Spine size and shape probably reflect synaptic strength and learning. Imaging with superresolution STED microscopy the detailed shape of the majority of the spines of individual neurons in turtle cortex (Trachemys scripta elegans) revealed several distinguishable shape classes. Dendritic spines of a given class were not distributed randomly, but rather decorated significantly more often some dendrites than others. The individuality of dendrites was corroborated by significant inter-dendrite differences in other parameters such as spine density and length. In addition, many spines were branched or possessed spinules. These findings may have implications for the role of individual dendrites in this cortex.

The dynamics of pattern matching in camouflaging cuttlefish

Many cephalopods escape detection using camouflage¹. This behaviour relies on a visual assessment of the surroundings, on an interpretation of visual-texture statistics^2-4 and on matching these statistics using millions of skin chromatophores that are controlled by motoneurons located in the brain^5-7. Analysis of cuttlefish images proposed that camouflage patterns are low dimensional and categorizable into three pattern classes, built from a small repertoire of components^8-11. Behavioural experiments also indicated that, although camouflage requires vision, its execution does not require feedback^5,12,13, suggesting that motion within skin-pattern space is stereotyped and lacks the possibility of correction. Here, using quantitative methods¹⁴, we studied camouflage in the cuttlefish Sepia officinalis as behavioural motion towards background matching in skin-pattern space. An analysis of hundreds of thousands of images over natural and artificial backgrounds revealed that the space of skin patterns is high-dimensional and that pattern matching is not stereotyped-each search meanders through skin-pattern space, decelerating and accelerating repeatedly before stabilizing. Chromatophores could be grouped into pattern components on the basis of their covariation during camouflaging. These components varied in shapes and sizes, and overlay one another. However, their identities varied even across transitions between identical skin-pattern pairs, indicating flexibility of implementation and absence of stereotypy. Components could also be differentiated by their sensitivity to spatial frequency. Finally, we compared camouflage to blanching, a skin-lightening reaction to threatening stimuli. Pattern motion during blanching was direct and fast, consistent with open-loop motion in low-dimensional pattern space, in contrast to that observed during camouflage.

Interhemispheric competition during sleep

Our understanding of the functions and mechanisms of sleep remains incomplete, reflecting their increasingly evident complexity1-3. Likewise, studies of interhemispheric coordination during sleep4-6 are often hard to connect precisely to known sleep circuits and mechanisms. Here, by recording from the claustra of sleeping bearded dragons (Pogona vitticeps), we show that, although the onsets and offsets of Pogona rapid-eye-movement (REMP) and slow-wave sleep are coordinated bilaterally, these two sleep states differ markedly in their inter-claustral coordination. During slow-wave sleep, the claustra produce sharp-wave ripples independently of one another, showing no coordination. By contrast, during REMP sleep, the potentials produced by the two claustra are precisely coordinated in amplitude and time. These signals, however, are not synchronous: one side leads the other by about 20 ms, with the leading side switching typically once per REMP episode or in between successive episodes. The leading claustrum expresses the stronger activity, suggesting bilateral competition. This competition does not occur directly between the two claustra or telencephalic hemispheres. Rather, it occurs in the midbrain and depends on the integrity of a GABAergic (γ-aminobutyric-acid-producing) nucleus of the isthmic complex, which exists in all vertebrates and is known in birds to underlie bottom-up attention and gaze control. These results reveal that a winner-take-all-type competition exists between the two sides of the brain of Pogona, which originates in the midbrain and has precise consequences for claustrum activity and coordination during REMP sleep.

Single spikes drive sequential propagation and routing of activity in a cortical network

Single spikes can trigger repeatable firing sequences in cortical networks. The mechanisms that support reliable propagation of activity from such small events and their functional consequences remain unclear. By constraining a recurrent network model with experimental statistics from turtle cortex, we generate reliable and temporally precise sequences from single spike triggers. We find that rare strong connections support sequence propagation, while dense weak connections modulate propagation reliability. We identify sections of sequences corresponding to divergent branches of strongly connected neurons which can be selectively gated. Applying external inputs to specific neurons in the sparse backbone of strong connections can effectively control propagation and route activity within the network. Finally, we demonstrate that concurrent sequences interact reliably, generating a highly combinatorial space of sequence activations. Our results reveal the impact of individual spikes in cortical circuits, detailing how repeatable sequences of activity can be triggered, sustained, and controlled during cortical computations.

Molecular diversity and evolution of neuron types in the amniote brain

The existence of evolutionarily conserved regions in the vertebrate brain is well established. The rules and constraints underlying the evolution of neuron types, however, remain poorly understood. To compare neuron types across brain regions and species, we generated a cell type atlas of the brain of a bearded dragon and compared it with mouse datasets. Conserved classes of neurons could be identified from the expression of hundreds of genes, including homeodomain-type transcription factors and genes involved in connectivity. Within these classes, however, there are both conserved and divergent neuron types, precluding a simple categorization of the brain into ancestral and novel areas. In the thalamus, neuronal diversification correlates with the evolution of the cortex, suggesting that developmental origin and circuit allocation are drivers of neuronal identity and evolution.

High prevalence of complex coronary artery lesions in sport-related myocardial infarction. Contemporary data from the RICO survey

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Agence régionale de santé de Bourgogne Franche-Comté

Background

Underlying mechanisms for sport-related acute myocardial infarction (SR-AMI) are only poorly understood. Moreover, their coronary artery disease (CAD) characteristics and lesion complexity are poorly described.

Purpose

To characterize coronary angiographic feature of patients with SR-AMI

Methods

From the RICO database, a large regional acute MI survey, all consecutive patients hospitalized in our University Hospital from 2010 to 2021 who underwent coronary angiography for SR-MI were retrospectively analysed. SR-MI was defined as MI occurring during sport activity or within the first hour of recovery.

Results

Among the 174 patients included, most were male (n=157(91%)). Median (IQR) age was 59 y (48-66), and had ST segment elevation MI (STEMI) (n= 112 (64%)). The SR-MI often occurred while cycling (41%), jogging (23%), hiking (9%) or playing soccer (9%). Patients commonly experienced pre-hospital (PH) sudden cardiac arrest (SCA) (17%). Atherothrombotic risk factors were dyslipidaemia (32%), current smoking (31%) or hypertension (28%). A history of CAD was documented in 31 (18%) patients. Most (n=156(91%)) had significant lesions, of whom 140 (81%) were considered as culprit. Culprit lesions were located on left anterior descending (39%), circumflex (14%) and right coronary artery (33%). Median (IQR) Syntax score was 10.5 (6-15). The vast majority of patients (n=152 (87%)) had at least one complex lesion; 114 of them had several characteristics of complex lesion. Lesions were eccentric in 68 (39%) patients; an intraluminal thrombus was documented in 85 patients (49%), in 55% of STEMI and 37% of non-STEMI (p =0.027). However, 18 subjects (10%) had optically normal coronary angiogram or non-significant lesions, suggesting alternative mechanism such as type 2 MI. Treatment of the lesions was mainly achieved by PCI and/or stenting (n=132(77%)) or coronary artery bypass grafting (n=11(6%)). In-hospital death occurred in 11 patients (6%), of whom 10 experienced a PH-SCA and one was admitted with a cardiogenic shock during the Covid-19 pandemics lockdown. Among the 5 patients treated with extracorporeal membrane oxygenator, only one survived.

Conclusion

In our large retrospective study, SR-MI was commonly associated with complex coronary lesions, often characterized by intraluminal thrombus. Our findings suggest that the mechanisms of these events could be mainly related to type 1 MI patterns Moreover, PH-SCA was frequent, thus justifying mass-education to basic life support and deployment of automated external defibrillators, especially in the sport settings.

A novel machine learning algorithm has the potential to reduce by 1/3 the quantity of ILR episodes needing review

Background

Implantable Loop Recorders (ILRs) are increasingly used and generate a high workload for timely adjudication of ECG recordings. In particular, the excessive false positive rate leads to a significant review burden.

Purpose

A novel machine learning algorithm was developed to reclassify ILR episodes in order to decrease by 80% the False Positive rate while maintaining 99% sensitivity.

This study aims to evaluate the impact of this algorithm to reduce the number of abnormal episodes reported in Medtronic ILRs.

Methods

Among 20 European centers, all Medtronic ILR patients were enrolled during the 2nd semester of 2020. Using a remote monitoring platform, every ILR transmitted episode was collected and anonymised.

For every ILR detected episode with a transmitted ECG, the new algorithm reclassified it applying the same labels as the ILR (asystole, brady, AT/AF, VT, artifact, normal). We measured the number of episodes identified as false positive and reclassified as normal by the algorithm, and their proportion among all episodes.

Results

In 370 patients, ILRs recorded 3755 episodes including 305 patient-triggered and 629 with no ECG transmitted. 2821 episodes were analyzed by the novel algorithm, which reclassified 1227 episodes as normal rhythm. These reclassified episodes accounted for 43% of analyzed episodes and 32.6% of all episodes recorded.

Conclusion

A novel machine learning algorithm significantly reduces the quantity of episodes flagged as abnormal and typically reviewed by healthcare professionals.

Funding Acknowledgement

Type of funding sources: None. Figure 1. ILR episodes analysis

Exploring the temporal relationship between atrial fibrillation and heart failure development. Analysis from nationwide database

Background

Atrial fibrillation (AF) and heart failure (HF) often coexist and are closely intertwined, each condition worsening the other. The temporal relationships between these two disorders have not yet been fully explored. We assessed, on a nationwide scale, the prognosis of patients hospitalized with HF and AF, based on the timing of AF and HF development.

Methods

From the administrative database covering hospital care for the whole French population, we identified 1,349,638 patients diagnosed with both AF and HF between 2010 and 2018: 956,086 of these AF patients developed HF first (prevalent HF) and 393,552 developed HF after AF (incident HF). The outcome analysis (all-cause death, cardiovascular [CV] death, ischemic stroke or hospitalization for HF) was performed with follow-up starting at the time of last event between AF or HF in the whole cohort and in 427,848 propensity-score-matched patients (213,924 with incident HF and 213,924 with prevalent HF).

Results

During follow-up (mean follow-up 1.6±1.9 year), matched patients with prevalent HF had a higher risk of all-cause death (21.6 vs 19.2%/year), CV death (7.6 vs 6.5%/year) as well as non-cardiovascular death (13.9 vs 12.7%/year) than those with incident HF. The risk for ischemic stroke was lower in the prevalent HF group (1.2 vs 2.4%/year).

Conclusion

In patients hospitalized with both AF and HF, we identified two distinct clinical entities based on the chronological sequence of the two disorders. Patients in whom HF preceded AF (prevalent HF) had higher mortality and higher risk of rehospitalization for HF.

Funding Acknowledgement

Type of funding sources: None.

Sport-related acute myocardial infarction. Contemporary data from IMACS survey

Background

Sport-related (SR) acute cardiovascular (CV) events are the main cause of sudden cardiac death in the setting of sport activities. However, data are very scarce regarding onset and follow-up of SR acute myocardial infarction (AMI).

Methods

From the prospective study IMACS (Infarctus du Myocarde et Arret Cardiaque au cours du Sport) patients admitted for a SR-AMI in our university hospital from April 2018 to March 2020 were included. A 12 months follow-up (FU) was achieved through telephone interview to address CV outcomes and sport practice information. Information was obtained from relatives in case of out of hospital sudden cardiac arrest (OH-SCA).

Results

Among the 55 patients included, all were male, with median (IQR) age at 62 (55–69) y. Most common sports were cycling (n=21), fitness (n=7), swimming (n=5) and hiking (n=5). The SR-AMI occurred during effort for 39 subjects and during recovery for 16. Most SR-AMI occurred in public area (n=24), at home (n=16), or in a specific sport location (n=14). An Automated External Defibrillator (AED) was available in the SR-AMI location in only 10, but was missing in 43 (unknown for 2). In 1 subject with OH-SCA, cardiopulmonary resuscitation (CPR), initiated by witnesses, using a public AED, was unsuccessful. The 4 other patients with OH-SCA underwent successful CPR. Among the 55 subjects, 4 were vapers, of whom 1 was a dual user, 17 were current tobacco smokers, 18 were ex-smokers and 2 experienced cannabis and cocaine use. Among the smokers, most smoked (n=10) or consumed cannabis (n=1) &lt;2h before the event. Strikingly, CV history and/or recent symptoms were present in almost half (n=25). Only 10 felt symptoms exclusively during the sport session. Moreover, a medical advice for recent symptoms was found only for 3 subjects. Three patients who experienced prior AMI have neglected symptoms during the index event. Most were ST segment elevated MI (n=35). Only one patient (with OH-SCA) died &lt;3 days after hospital admission. During hospitalization, most underwent revascularization with coronary stenting (n=44) (drug eluting stent in 43 patients), or coronary artery bypass graft (n=6) and no death nor significant CV event occurred. At 1-FU, most attended a rehabilitation program (n=41) and the majority of smokers quitted (14/17), with 3 persistent smokers starting to vape. Almost half patients (n=23) decreased their physical activity, and 21 increased it. A significant rate of patient (n=9) added fitness in their usual activity, and as a main sport for 4 of them.

Conclusions

In this on-going monocentric prospective survey in SR-AMI, a high proportion of subjects had prodromal symptoms, of whom only few led to sport cessation and medical advices, when requested, failed to prevent the AMI. Our findings highlight that public and medical education are urgently warranted for SR-AMI prevention.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): CHU Dijon Bourgogne Franche Comté et ARS Bourgogne Franche Comté

Pigmentation effects of blue light irradiation on skin and how to protect against them

Background

Visible light, in particular blue light, has been identified as an additional contributor to cutaneous photoageing. However, clinical studies demonstrating the clear effect of blue light on photoageing are still scarce, and so far, most studies have focused on broad‐spectrum visible light. Although there is evidence for increased skin pigmentation, the underlying mechanisms of photoageing in vivo are still unclear. Furthermore, there is still a need for active ingredients to significantly protect against blue light‐induced hyperpigmentation in vivo.

Our study had two aims: to detect visible changes in skin pigmentation following repeated irradiation of the skin with LED‐based blue light and to reduce pigmentation using suitable active ingredients.

Method

We conducted a randomized, double‐blind and placebo‐controlled clinical study on 33 female volunteers with skin phototypes III and IV. We used a repetitive blue light (4 × 60 J cm⁻², 450 nm) irradiation protocol on the volunteers’ inner forearms. Using hyperspectral imaging, we assessed chromophore status. In addition, we took chromameter measurements and photographs to assess visible hyperpigmentation.

Results

We measured significant changes in chromophore status (P < 0.001 vs baseline), that is of melanin, haemoglobin and oxygen saturation, immediately after blue light irradiation. In addition, we found visible skin colour changes which were expressed by a significant decrease in ITA° values (delta ITA° = −16.89, P < 0.001 vs baseline for the placebo group) and an increase in a* (delta a* = +3.37, P < 0.001 vs baseline for the placebo group) 24 h post‐irradiation. Hyperpigmentation and skin reddening were mitigated by both a formulation containing 3% of a microalgal product and a formulation containing 3% niacinamide.

Conclusion

Our study sets out an efficient and robust protocol for investigating both blue light‐induced cutaneous alterations, such as changes in skin chromophores, and signs of photoageing, such as hyperpigmentation. Moreover, we have shown evidence that both an extract of the microalga Scenedesmus rubescens and niacinamide (vitamin B3) have the potential to protect against blue light‐induced hyperpigmentation.

Smoking and associated unhealthy lifestyle behaviours in patients with chronic cardiac diseases during COVID-19 related lockdown

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Dijon University Hospital France

OnBehalf

CLEO-CD

Background

  Lockdown can affect tobacco smoking (TS) behaviours. 

Purpose

To evaluate the impact of lockdown on (TS) and associated lifestyle behaviours in patients with Chronic coronary syndrome (CCS) and congestive heart failure (CHF)

Methods

CCS and CHF patients were invited to answer to a phone-call questionnaire during the 1st COVID-19 lockdown start 

Results

(Table) 343 questionnaires were fit for analysis, 43 (12.5%) were current smokers (CS). CS were younger (p < 0.001), none stopped and 13 increased their consumption (main reasons were stress and boredom). CS felt more often cramped (p = 0.023). CS who increased their TS consumption showed a trend toward a higher rate of unhealthy lifestyle behaviours

Conclusions

During the lockdown, more than ¼ of CS with CCS or CHF increased their TS consumption and none quitted. Moreover, TS was often associated with other deleterious behaviours increasing their risk for short and long term

Impact of lockdown in patients with congestive heart failure during the Covid-19 pandemic

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Dijon Football Côte d"Or

OnBehalf

CLEO-CD

Background

Congestive heart failure (CHF) can be destabilized by Covid-19 (C19) lockdown.

Purpose

To evaluate the impact of lockdown in CHF patients.

Methods

150 out-patients from the HF Clinic of our hospital were invited to answer to a phone-call interview during the 7th week of first C19 lockdown .

Results

From 124 questionnaires, more than 1/5 felt worse and almost 1/4 declared a psychologic distress. CHF medications were modified in 10%. Decrease in physical activity was observed in 2/5. Almost 1/2 declared increased screen time;  smokers often increased consumption. Adherence to dietary counselling was reduced by 1/6, increase in weight and HF symptoms were common. Some patients benefitted from a teleconsultation.

Conclusions

Our patients exhibited well-being impairment and unhealthy behaviours. Medication adherence was not diminished and the reduction in care access was counterbalanced by a switch toward telehealth.

Main results

	124 patients	75 Male (M)	49 Female (F)	p value between M and F
Age, years	71.0 ± 14.0	68.9 ± 13.7	74.3 ± 14.0	0.03
Urban/Rural	82/42	49/26	33/16	0.84
HFrEF*	87	62	25	<0.001
Dilated cardiomyopathy	50	37	13	0.02
Ischemic	23	18	5	0.06
Other	51	20	31	<0.0001
Current NYHA class I/II/III/IV	39/48/28/9	29/29/14/3	10/19/14/6	0.66
History of NYHA III-IV class	94	62	32	0.03
Electronic device/Telemonitoring	77/28	54/18	23/10	<0.001/0.66
Increase in dyspnea or edema or fatigue	27	13	14	0.07
Decrease in well-being	27	12	15	0.07
Psychological distress (#)	23	15 (20.0)	8	0.64
Weight gain > 2 kg	34	22 (29.3)	12	0.68
Switch for teleconsultation (##)	16	11 (34.4)	5	1
Teleconsultation (total)	23	14	9	1
Decrease in physical activity	52	25 (33.3)	27	0.02
Increase in screen time	57	31 (41.3)	26	0.27
Increase in cigarette consumption (9 smokers)	4	3	1	1
Decrease in dietary adherence (###)	22 (17.7)	15 (20.0)	7 (14.3)	0.47

*HFrEF; # Kessler-6 score ≥ 5; ## from planned physical examination; ### salt, water, alcohol

Atrial fibrillation with or without structural abnormalities. Analysis from a nationwide database

Background

Atrial Fibrillation (AF) is often associated with underlying heart failure, valvular disease, ischemic heart disease, as well as other structural heart diseases, but can also occur as an independent entity which may be named pure AF or lone AF. Small cohort studies have suggested that lone AF patients may have a favorable prognosis in terms of mortality and ischemic stroke rates. We aimed to assess, at a nationwide scale, the prognosis of patients hospitalized with lone AF and AF associated with cardiac disease.

Methods

From the French administrative hospital-discharge PMSI database (Programme de Médicalisation des Systèmes d'Information) covering hospital care and representative of the whole French population, all consecutive patients with AF diagnosis hospitalized between 2010 and 2018 were included. From this huge database, 2,793,234 patients were included: group lone FA: 665,431, group AF and cardiac disease: 2,727,803. Incidence rates (%/year) for the outcomes (all-cause death, cardiovascular [CV] death, or ischemic stroke) during follow-up were compared between groups using incidence rate ratios (RR) for the whole cohort and also for a subgroup of 539,654 propensity score matched patients for non-cardiovascular conditions (269,827 with AF alone and 269,827 with AF and CD).

Results

The majority of this population had AF associated with a cardiac disease (n=2,127,803; 76.2%). At follow-up (median [IQR] 1.1 [0.1–3.4] years), patients with AF and CD were at higher risk of all-cause mortality (yearly incidence 13.6% vs 9.0%, RR [95% CI] 1.51 [1.50–1.52], p&lt;0.00001) and CV death (4.4% vs 1.9%, RR 2.33 [2.30–2.36], p&lt;0.00001) than those with lone AF. In the propensity score matched population (median follow-up [IQR] 1.9 [0.3–4.4] years), patients with AF and CD also had worse outcomes than patients with lone AF (yearly incidence rates for all-cause mortality: 10.6% vs 7.4%, RR 1.43 [1.42–1.45], p&lt;0.00001; and for CV death: 3.3% vs 2.0%, RR 1.64 [1.61–1.68], p&lt;0.00001). However, lone AF patients were at higher risk of ischemic stroke: yearly incidence rates 2.75% in those with lone AF vs 1.69% in patients with AF and CD (RR 0.62 [0.60–0.63], p&lt;0.00001).

Conclusion

In our large study from a nationwide database about patients hospitalized with AF, two distinct clinical entities were identified, that could explain the results highlighted: 1) the consistently higher mortality in the group associating AF and underlying heart disease (AF may bea marker for poor outcome when there is a structural heart disease; 2) Lone AF group which prognosis may be related to a higher incidence of thromboembolic events. These results could have important implications in terms of thromboembolic prevention but further studies are still needed to investigate the underlying mechanisms of embolic pathophysiology and its specific management.

Funding Acknowledgement

Type of funding source: None

Joint Position Paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology (SFC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) on magnetic resonance imaging in patients with cardiac electronic implantable devices

Magnetic resonance imaging (MRI) has become the reference imaging for the management of a large number of diseases. The number of MR examinations increases every year, simultaneously with the number of patients receiving a cardiac electronic implantable device (CEID). A CEID was considered an absolute contraindication for MRI for years. The progressive replacement of conventional pacemakers and defibrillators by MR-conditional CEIDs and recent data on the safety of MRI in patients with "MR-nonconditional" CEIDs have progressively increased the demand for MRI in patients with a CEID. However, some risks are associated with MRI in CEID carriers, even with "MR-conditional" devices because these devices are not "MR-safe". A specific programing of the device in "MR-mode" and monitoring patients during MRI remain mandatory for all patients with a CEID. A standardized patient workflow based on an institutional protocol should be established in each institution performing such examinations. This joint position paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) describes the effect and risks associated with MRI in CEID carriers. We propose recommendations for patient workflow and monitoring and CEID programming in MR-conditional, "MR-conditional nonguaranteed" and MR-nonconditional devices.

Estimation from cross-sectional data under a semiparametric truncation model

Cross-sectional sampling is often used when investigating inter-event times, resulting in left-truncated and right-censored data. In this paper, we consider a semiparametric truncation model in which the truncating variable is assumed to belong to a certain parametric family. We examine two methods of estimating both the truncation and the lifetime distributions. We obtain asymptotic representations of the estimators for the lifetime distribution and establish their weak convergence. Both of the proposed estimators perform better than Wang’s (1991) nonparametric maximum likelihood estimator in terms of the integrated mean squared error, when the parametric family for the truncation is sufficiently close to its true distribution. The full likelihood approach is preferable to the conditional likelihood approach in estimating the lifetime distribution, though not necessarily the truncation distribution. In an application to Alzheimer’s disease data, hypothesis tests reject the uniform truncation distribution, but several other parametric models lead to similar behaviour of the truncation and lifetime distributions after disease onset.

AMAFRICA, a patient-navigator program for accompanying lymphoma patients during chemotherapy in Ivory Coast: a prospective randomized study

Background

Previous studies have indicated that accompanying socially underserved cancer patients through Patient Navigator (PN) or PN-derived procedures improves therapy management and reassurance. At the Cancer Institute of Toulouse-Oncopole (France), we have implemented AMA (Ambulatory Medical Assistance), a PN-based procedure adapted for malignant lymphoma (ML) patients under therapy. We found that AMA improves adherence to chemotherapy and safety. In low-middle income countries (LMIC), refusal and abandonment were documented as major adverse factors for cancer therapy. We reasoned that AMA could improve clinical management of ML patients in LMIC.

Methods

This study was set up in the Abidjan University Medical Center (Ivory Coast) in collaboration with Toulouse. One hundred African patients were randomly assigned to either an AMA or control group. Main criteria of judgment were refusal and abandonment of CHOP or ABVD chemotherapy.

Results

We found that AMA was feasible and had significant impact on refusal and abandonment. However, only one third of patients completed their therapy in both groups. No differences were noted in terms of complete response rate (CR) (16% based on intent-to-treat) and median overall survival (OS) (6 months). The main reason for refusal and abandonment was limitation of financial resources.

Conclusion

Altogether, this study showed that PN may reduce refusal and abandonment of treatment. However, due to insufficient health care coverage, its ultimate impact on OS remains limited.

Visual perception and cuttlefish camouflage

Visual perception is inherently statistical: brains exploit repeating features of natural scenes to disambiguate images that could, in principle, have many causes. A clear case for the relevance of statistical inference in vision is animal camouflage. Although visual scenes are each composed of unique arrangements of pixels, they are usually perceived mainly as groupings of statistically defined patches (sandy/leafy/smooth etc…); this fact is exploited by camouflaging animals. The unique ability of certain cephalopods to camouflage actively within many different surroundings provides a rare and direct behavioral readout for texture perception. In addition, because cephalopods and chordates each arose after a phylogenetic split that occurred some 600M years ago, the apparent convergence of texture perception across these groups suggests common principles. Studying cephalopod camouflage may thus help us resolve general problems of visual perception.

Reliable Sequential Activation of Neural Assemblies by Single Pyramidal Cells in a Three-Layered Cortex

Recent studies reveal the occasional impact of single neurons on surround firing statistics and even simple behaviors. Exploiting the advantages of a simple cortex, we examined the influence of single pyramidal neurons on surrounding cortical circuits. Brief activation of single neurons triggered reliable sequences of firing in tens of other excitatory and inhibitory cortical neurons, reflecting cascading activity through local networks, as indicated by delayed yet precisely timed polysynaptic subthreshold potentials. The evoked patterns were specific to the pyramidal cell of origin, extended over hundreds of micrometers from their source, and unfolded over up to 200 ms. Simultaneous activation of pyramidal cell pairs indicated balanced control of population activity, preventing paroxysmal amplification. Single cortical pyramidal neurons can thus trigger reliable postsynaptic activity that can propagate in a reliable fashion through cortex, generating rapidly evolving and non-random firing sequences reminiscent of those observed in mammalian hippocampus during "replay" and in avian song circuits.

[Interventional management of atrial fibrillation]

In 2030, the European Union will include 14 to 17 million atrial fibrillation (AF) patients, with 120,000 to 215,000 new cases each year. The increase in the prevalence of this arrhythmia has led to the development of new therapeutic intervention strategies to manage the different aspects of this disease. Thus, endocavitary or epicardial ablation of AF, by radiofrequency or cryoablation, provides superior results to antiarrhythmic therapy in controlling symptoms and preventing heart failure in paroxysmal or persistent AF. In heart failure patients with advanced AF, the ablation of the atrioventricular junction associated with the implantation of a bi-ventricular pacemaker has just demonstrated its clear superiority, bringing this technique up to date. Finally, in the event of a major bleeding risk and contraindication to anticoagulants, percutaneous occlusion of the left atrium has proven its value in preventing AF-related embolic events. The future will certainly see the emergence of new technologies but also personalized strategies based on an optimal selection of the right candidates for these interventions, thanks in particular to the contribution of imaging before the procedure.

Evolution of neuronal identity in the cerebral cortex

To understand neocortex evolution, we must define a theory for the elaboration of cell types, circuits, and architectonics from an ancestral structure that is consistent with developmental, molecular, and genetic data. To this end, cross-species comparison of cortical cell types emerges as a very informative approach. We review recent results that illustrate the contribution of molecular and transcriptomic data to the construction of plausible models of cortical cell-type evolution.

Fear of cancer recurrence in Non- and Hodgkin lymphoma survivors during their first three years of survivorship among French patients

The aim of this study was to measure the prevalence of FCR among a sample of French lymphoma survivors and to determine factors associated with clinical levels of FCR. The study was conducted with two cross-sectional measures: sociodemographic and anxiety, depression as well as health-related quality of life (HRQoL) scores were measured at the baseline of the post-cancer period and FCR was evaluated during the first 3 years of survivorship. The prevalence of clinical levels of FCR (≥13) was evaluated by the Fear of Cancer Recurrence Inventory - Short Form (FCRI-SF) among non- and Hodgkin lymphoma survivors undergoing prior first-line chemotherapy. Among 108 lymphoma survivors with an average follow-up of 1.6 years (range 0.3-3.0 years), clinical levels of FCR (≥13) were observed for 44.4% (n = 48). Multivariate analysis indicated that baseline anxiety and low quality of life were related to clinically significant FCR levels.

Temperature-dependent transport measurements with Arduino

The current performances of single-board microcontrollers render them attractive, not only for basic applications, but also for more elaborate projects, amongst which are physics teaching or research. In this article, we show how temperature-dependent transport measurements can be performed by using an Arduino board, from cryogenic temperatures up to room temperature or above. We focus on two of the main issues for this type of experiments: the determination of the sample temperature and the measurement of its resistance. We also detail two student-led experiments: evidencing the magnetocaloric effect in Gadolinium and measuring the resistive transition of a high critical temperature superconductor. Received: 7 July 2018,  Accepted: 27 September 2018; Edited by: A. Marti,  M. Monteiro;  Reviewed by: R. Marotti, Instituto de Física, Facultad de Ingeniería - Universidad de la República, Uruguay; DOI: http://dx.doi.org/10.4279/PIP.100007 Cite as: A Hilberer, G Laurent, A Lorin, A Partier, J Bobroff, F Bouquet, C Even, J M Fischbach, C A Marrache Kikuchi, M Monteverde, B Pilette, Q Quay,  Papers in Physics 10, 100007(2018) This paper, by A Hilberer, G Laurent, A Lorin, A Partier, J Bobroff, F Bouquet, C Even, J M Fischbach, C A Marrache Kikuchi, M Monteverde, B Pilette, Q Quay, is licensed under the Creative Commons Attribution License 4.0.    

Elucidating the control and development of skin patterning in cuttlefish

Few animals provide as objective a readout of their perceptual state as camouflaging cephalopods. Their skin display system includes an extensive array of pigment cells (chromatophores), each activated by radial muscles controlled by motoneurons. If one could track the individual expansion states of the chromatophores, one would obtain a quantitative description—and potentially even, a neural description by proxy— of the perceptual state of the animal in real time. We developed computational and analytical methods to achieve this in behaving animals, quantifying the state of tens of thousands of chromatophores at sixty frames per second, single-cell resolution, and over weeks. We could infer a statistical hierarchy of motor control, reveal an underlying low-dimensional structure to pattern dynamics, and uncover rules governing skin pattern development. This approach provides an objective description of complex perceptual behaviour, and powerful means to uncover organizational principles underlying neural systems function, dynamics, and morphogenesis.

Comparative photophysical investigation of doubly-emissive photochromic-fluorescent diarylethenes

Diarylethene molecules showing photochromism and fluorescence properties in both open and closed forms, associated with two different emission colors, are very promising for applications involving ratiometric emissive photoswitches. We report here a complete study on the competition between the multiple photophysical processes involved in the excited states for two sulfone derivatives of benzothiophene-based diarylethene molecules, only differing by the substituent groups on their reactive carbon (methyl for DAE-Me and ethyl for DAE-Et). Steady-state and time-resolved spectroscopy, combined with DFT and TD-DFT calculations, allow a complete determination of the kinetic constants leading to fluorescence and photoreaction pathways in different solvents, and enlighten the specific role of the substituent group in the photophysical properties due to a shielding effect against the solvation environment. The predominant role of the non-radiative deactivation processes in such a family of molecules is shown, and a tentative excited state mechanistic scheme is proposed based on femtosecond transient absorption experiments performed on the closed forms.

On the Value of Reptilian Brains to Map the Evolution of the Hippocampal Formation

Our ability to navigate through the world depends on the function of the hippocampus. This old cortical structure plays a critical role in spatial navigation in mammals and in a variety of processes, including declarative and episodic memory and social behavior. Intense research has revealed much about hippocampal anatomy, physiology, and computation; yet, even intensely studied phenomena such as the shaping of place cell activity or the function of hippocampal firing patterns during sleep remain incompletely understood. Interestingly, while the hippocampus may be a 'higher order' area linked to a complex cortical hierarchy in mammals, it is an old cortical structure in evolutionary terms. The reptilian cortex, structurally much simpler than the mammalian cortex and hippocampus, therefore presents a good alternative model for exploring hippocampal function. Here, we trace common patterns in the evolution of the hippocampus of reptiles and mammals and ask which parts can be profitably compared to understand functional principles. In addition, we describe a selection of the highly diverse repertoire of reptilian behaviors to illustrate the value of a comparative approach towards understanding hippocampal function.

Consensus-Based Sorting of Neuronal Spike Waveforms

Optimizing spike-sorting algorithms is difficult because sorted clusters can rarely be checked against independently obtained “ground truth” data. In most spike-sorting algorithms in use today, the optimality of a clustering solution is assessed relative to some assumption on the distribution of the spike shapes associated with a particular single unit (e.g., Gaussianity) and by visual inspection of the clustering solution followed by manual validation. When the spatiotemporal waveforms of spikes from different cells overlap, the decision as to whether two spikes should be assigned to the same source can be quite subjective, if it is not based on reliable quantitative measures. We propose a new approach, whereby spike clusters are identified from the most consensual partition across an ensemble of clustering solutions. Using the variability of the clustering solutions across successive iterations of the same clustering algorithm (template matching based on K-means clusters), we estimate the probability of spikes being clustered together and identify groups of spikes that are not statistically distinguishable from one another. Thus, we identify spikes that are most likely to be clustered together and therefore correspond to consistent spike clusters. This method has the potential advantage that it does not rely on any model of the spike shapes. It also provides estimates of the proportion of misclassified spikes for each of the identified clusters. We tested our algorithm on several datasets for which there exists a ground truth (simultaneous intracellular data), and show that it performs close to the optimum reached by a support vector machine trained on the ground truth. We also show that the estimated rate of misclassification matches the proportion of misclassified spikes measured from the ground truth data.

The care center influences the management of lymphoma patients in a universal health care system: an observational cohort study

Background

Healthcare providers-related disparities in adherence to the treatment plan among lymphoma patients are found even in a universal healthcare system, but the mechanism remains unclear. We investigated the association between the type of care center and the relative dose intensity and determined whether it persists after adjustment for patients’ recruitment differences.

Methods

Prospective observational cohort study of 294 patients treated with standard protocols for diffuse large B-cell lymphoma (DLBCL) in teaching or community public hospitals or in private centers in the French Midi-Pyrénées region from 2006–2013. To test our assumptions, we used multinomial and mixed-effect logistic models progressively adjusted for patients’ biomedical characteristics, socio-spatial characteristics and treatment-related toxicity events.

Results

Patients treated using standard protocols in the teaching hospital had more advanced stage and poorer initial prognosis without limitation regarding the distance from the residence to the care center. Patients’ recruitment profile across the different types of care center failed to explain the difference in relative dose intensity. Low relative dose intensity was less often observed in teaching hospital than elsewhere.

Conclusion

We showed that even in a universal healthcare system, disparities in the management of DLBCL patients’ do exist according to the types of care center. A main issue may be to find and diffuse the reasons of this benefit in cancer management in the teaching hospital to the other centers.

Y a-t-il un euroconsommateur du luxe? Une analyse comparative des profils sociodémographiques des acheteurs européens

A partir d'une étude paneuropéenne portant sur 12 500 consommateurs et leurs attitudes vis-à-vis de 30 marques internationales, le présent article compare le pouvoir segmentant d'un ensemble d'indicateurs géographiques et socio-économiques susceptibles d'éclairer l'achat de marques de luxe. Bien que certaines différences entre les pays européens soient observées, les résultats obtenus révèlent que le revenu, le niveau d'éducation et la catégorie professionnelle différencient les consommateurs mieux que leur affiliation nationale. Dans cette mesure, on doit conclure à l'existence d'un euroconsommateur du luxe dont le portrait robot peut être dressé avec une relative précision

Les profils d'implication

On parle beaucoup d'implication du consommateur dans un produit. Il y a en fait plusieurs sortes d'implications. Nous présentons des résultats empiriques fondés sur l'analyse de plus de y 500 interviews, à propos de 37 catégories de produit. Selon la source de l'implication (la valeur de plaisir du produit, sa valeur de signe, les risques qu'il entraîne ou l'intérêt qu'on lui porte), les conséquences sur le comportement du consommateur seront différentes. C'est pourquoi nous recommandons de mesurer un profil d'implication du consommateur dans un produit, plutôt qu'un niveau d'implication unidimensionnel. Cette approche est plus riche en termes de compréhension du phénomène de l'implication, de prévision de ses conséquences et de diagnostic de gestion.

Minor changes in the macrocyclic ligands but major consequences on the efficiency of gold nanoparticles designed for radiosensitization

Many studies have been devoted to adapting the design of gold nanoparticles to efficiently exploit their promising capability to enhance the effects of radiotherapy. In particular, the addition of magnetic resonance imaging modality constitutes an attractive strategy for enhancing the selectivity of radiotherapy since it allows the determination of the most suited delay between the injection of nanoparticles and irradiation. This requires the functionalization of the gold core by an organic shell composed of thiolated gadolinium chelates. The risk of nephrogenic systemic fibrosis induced by the release of gadolinium ions should encourage the use of macrocyclic chelators which form highly stable and inert complexes with gadolinium ions. In this context, three types of gold nanoparticles (Au@DTDOTA, Au@TADOTA and Au@TADOTAGA) combining MRI, nuclear imaging and radiosensitization have been developed with different macrocyclic ligands anchored onto the gold cores. Despite similarities in size and organic shell composition, the distribution of gadolinium chelate-coated gold nanoparticles (Au@TADOTA-Gd and Au@TADOTAGA-Gd) in the tumor zone is clearly different. As a result, the intravenous injection of Au@TADOTAGA-Gd prior to the irradiation of 9L gliosarcoma bearing rats leads to the highest increase in lifespan whereas the radiophysical effects of Au@TADOTAGA-Gd and Au@TADOTA-Gd are very similar.