Plants sum and subtract stimuli over different timescales.

Mounting evidence suggests that plants engage complex computational processes to quantify and integrate sensory information over time, enabling remarkable adaptive growth strategies. However, quantitative understanding of these computational processes is limited. We report experiments probing the dependence of gravitropic responses of wheat coleoptiles on previous stimuli. First, building on a mathematical model that identifies this dependence as a form of memory, or a filter, we use experimental observations to reveal the mathematical principles of how coleoptiles integrate multiple stimuli over time. Next, we perform two-stimulus experiments, informed by model predictions, to reveal fundamental computational processes. We quantitatively show that coleoptiles respond not only to sums but also to differences between stimuli over different timescales, constituting evidence that plants can compare stimuli-crucial for search and regulation processes. These timescales also coincide with oscillations observed in gravitropic responses of wheat coleoptiles, suggesting shoots may combine memory and movement in order to enhance posture control and sensing capabilities.

A quantitative model for spatio-temporal dynamics of root gravitropism.

Plant organs adapt their morphology according to environmental signals through growth-driven processes called tropisms. While much effort has been directed towards the development of mathematical models describing the tropic dynamics of aerial organs, these cannot provide a good description of roots due to intrinsic physiological differences. Here we present a mathematical model informed by gravitropic experiments on Arabidopsis thaliana roots, assuming a subapical growth profile and apical sensing. The model quantitatively recovers the full spatio-temporal dynamics observed in experiments. An analytical solution of the model enables us to evaluate the gravitropic and proprioceptive sensitivities of roots, while also allowing us to corroborate the requirement for proprioception in describing root dynamics. Lastly, we find that the dynamics are analogous to a damped harmonic oscillator, providing intuition regarding the source of the observed oscillatory behavior and the importance of proprioception for efficient gravitropic control. In all, the model provides not only a quantitative description of root tropic dynamics, but also a mathematical framework for the future investigation of roots in complex media.

The hook shape of growing leaves results from an active regulatory process.

The rachis of most growing compound leaves observed in nature exhibits a stereotypical hook shape. In this study, we focus on the canonical case of Averrhoa carambola. Combining kinematics and mechanical investigation, we characterize this hook shape and shed light on its establishment and maintenance. We show quantitatively that the hook shape is a conserved bent zone propagating at constant velocity and constant distance from the apex throughout development. A simple mechanical test reveals non-zero intrinsic curvature profiles for the rachis during its growth, indicating that the hook shape is actively regulated. We show a robust spatial organization of growth, curvature, rigidity, and lignification, and their interplay. Regulatory processes appear to be specifically localized: in particular, differential growth occurs where the elongation rate drops. Finally, impairing the graviception of the leaf on a clinostat led to reduced hook curvature but not to its loss. Altogether, our results suggest a role for proprioception in the regulation of the leaf hook shape, likely mediated via mechanical strain.

Management in primary care at the time of a suicide attempt and its impact on care post-suicide attempt: an observational study in the French GP sentinel surveillance system.

BACKGROUND: We aimed to describe primary care management at the time of a suicide attempt (SA) and after the SA. METHODS: An observational (cross-sectional) study was conducted among 166 sentinel GPs within France (a non-gatekeeping country) between 2013 and 2017 for all GP's patients who attempted suicide. MEASUREMENTS: frequency of patients 1) managed by the GP at the time of the SA, 2) addressed to an emergency department (ED), 3) without care at the time of the SA, and 4) managed by the GP after the SA and factors associated with GP management at the time of and after the SA. RESULTS: Three hundred twenty-one SAs were reported, of which N = 95 (29.6%) were managed by the GP at the time of the SA, N = (70.5%) were referred to an ED, and N = (27.4%) remained at home. Forty-eight (14.9%) patients did not receive any care at the time of the SA and 178 (55.4%) were managed directly by an ED. GPs were more likely to be involved in management of the patient at the time of the SA if they were younger (39.2% for patients < 34 years old; 22.9% for those 35 to 54 years old, and 30.3% for those more than 55 years old p = 0.02) or the SA involved a firearm or self-cutting (51.9%) versus those involving drugs (23.7%); p = 0.006). After the SA, GPs managed 174 patients (54.2%), more often (60%) when they provided care at home at the time of the SA, p = 0.04; 1.87 [1.07; 3.35]. No other factor was associated with management by GPs after the SA. CONCLUSIONS: The study faced limitations: data were not available for patients managed solely by specialists during their SA and results may not be generalisable to countries with a stronger gatekeeping system. We concluded that GPs are involved in the management of patients at the time of a SA for a third of patients. EDs are the major provider of care at that time. Half patients consulted GPs after the SA and connections between GPs and ED upon discharge should be improved.

Modulation of junction tension by tumor suppressors and proto-oncogenes regulates cell-cell contacts.

Tumor suppressors and proto-oncogenes play crucial roles in tissue proliferation. Furthermore, de-regulation of their functions is deleterious to tissue architecture and can result in the sorting of somatic rounded clones minimizing their contact with surrounding wild-type (wt) cells. Defects in the shape of somatic clones correlate with defects in proliferation, cell affinity, cell-cell adhesion, oriented cell division and cortical contractility. Combining genetics, live-imaging, laser ablation and computer simulations, we aim to analyze whether distinct or similar mechanisms can account for the common role of tumor suppressors and proto-oncogenes in cell-cell contact regulation. In Drosophila epithelia, the tumor suppressors Fat (Ft) and Dachsous (Ds) regulate cell proliferation, tissue morphogenesis, planar cell polarity and junction tension. By analyzing the evolution over time of ft mutant cells and clones, we show that ft clones reduce their cell-cell contacts with the surrounding wt tissue in the absence of concomitant cell divisions and over-proliferation. This contact reduction depends on opposed changes of junction tensions in the clone bulk and its boundary with neighboring wt tissue. More generally, either clone bulk or boundary junction tension is modulated by the activation of Yorkie, Myc and Ras, yielding similar contact reductions with wt cells. Together, our data highlight mechanical roles for proto-oncogene and tumor suppressor pathways in cell-cell interactions.

Motions of leaves and stems, from growth to potential use.

The study on aerial plant organs (leaves and stems) motions is reviewed. The history of observations and studies is put in the perspective of the ideas surrounding them, leading to a presentation of the current classification of these motions. After showing the shortcomings of such a classification, we present, following an idea of Darwin's, the various movements in a renewed and observation-based perspective of the plant development. With this perspective, the different movements fit together logically, and in particular we point out that the mature reversible movements, such as the sensitive or circadian movements, are just partial regressions of the developmental ones.

Secular trends in incidence of acute gastroenteritis in general practice, France, 1991 to 2015.

We analysed 25 years of general practitioner (GP) visits for acute gastroenteritis (AG) surveillance in France, by the GP Sentinelles network. We searched for time trends of acute gastroenteritis incidence during winter periods. Data from emergency departments and drug reimbursement were additional data sources. A time-series analysis was performed using a generalised additive model for all data sources for the winter period. Virological data were incorporated and compared with the three data sources. The cumulative incidence of GP visits for winter AG exhibited an increasing trend from 1991 until 2008, when it reached 6,466 per 100,000 inhabitants. It decreased thereafter to 3,918 per 100,000 inhabitants in 2015. This decreasing trend was observed for all age groups and confirmed by the generalised additive model. For emergency department visits a decreasing trend was observed from 2004. Drug reimbursement data analyses demonstrated a decreasing trend from when data began in 2009. The incidence reported by GPs and emergency departments was lower following the emergence of norovirus GII.4 2012 (p < 0.0001). Winter AG incidences seem to follow long-term rising and decreasing trends that are important to monitor through continuous surveillance to evaluate the impact of prevention strategies, such as future immunisation against acute viral gastroenteritis.

Trends and characteristics of attempted and completed suicides reported to general practitioners before vs during the COVID-19 pandemic in France: Data from a nationwide monitoring system, 2010-2022.

BACKGROUND: Most studies published to date have investigated the impact of the COVID-19 pandemic on suicidal acts using hospital data. Trends from primary care in a country such as France are crucial, as individuals may not consult hospital services after suicide attempts (SAs) but rather see their general practitioner (GP). OBJECTIVES: We aimed to evaluate whether the incidence and characteristics of SAs and completed suicides (CSs) reported to French GPs were different during the COVID-19 pandemic than those of before. METHODS AND FINDINGS: We conducted a retrospective observational study using data from a nationwide monitoring system, the French Sentinel Network (FSN). All SAs and CSs reported by GPs to the FSN from January 1, 2010, to March 10, 2022 were included. The annual incidence rates (IRs) and the characteristics of SAs and CSs during the pandemic (March 11, 2020, to March 10, 2022) were compared to those of before. In total, 687 SAs and 169 CSs were included. The IRs remained stable for SAs and CSs before and during the pandemic (overlap in confidence intervals). The mean IRs were 52 (95%CI = 44; 57) per 100,000 inhabitants for SAs during the pandemic versus 47 [36; 57] during the pre-pandemic period (p = 0.49), and 5 (95%CI = 2; 9) for CSs versus 11 [6; 16] (p = 0.30). During the pandemic, SA were slightly different from those before in terms of age and occupational status (young/students and older/retirees over-represented), history of consultation and expression of suicidal ideas to GP (more frequent), and CS in terms of occupational status (students over-represented) (p<0.05). CONCLUSION: The COVID-19 pandemic had no major effect on the overall incidence of SAs and CSs reported to French GPs. However, more suicidal acts were reported among younger and older individuals. Suicidal patients and GPs have adapted by improving the expression of suicidal ideas.

Long-term occupational trajectories and suicide: a 22-year follow-up of the GAZEL cohort study.

Objective Most suicides occur among individuals of working age. Risk is elevated in some occupational groups, however relations between long-term occupational trajectories and suicide are not well known. We describe career-long occupational trajectories and examine their influence on suicide. Methods Data come from GAZEL, a French cohort study set among employees of a large national utilities company. Occupational grade was obtained from company records from the time of hiring (1953‒1988). Group-based trajectory models were used to define occupational trajectories over a mean time period of 25.0 (standard deviation 6.5) years. Causes of mortality, coded using the International Classification of Diseases, were recorded from 1993‒2014 and studied using Cox regression models. Results Of the 20 452 participants included in the study, 73 died by suicide between 1993‒2014. Results suggested an increased risk of suicide [hazard ratio (HR) 2.57, 95% confidence interval (CI) 1.08-6.15] among participants with persistently low occupational grade compared to those with higher occupational grade and career development. After adjustment for all covariates, especially psychological factors, this association was reduced and no longer statistically significant (HR 2.02, 95% CI 0.82-4.95). Conclusions Persistently low occupational grade could be related to an elevated risk of suicide. This association partly reflects psychological and health characteristics, which can influence occupational trajectories and be reinforced by unfavorable work conditions.

Which work-related characteristics are most strongly associated with common mental disorders? A cross-sectional study.

OBJECTIVES: Studies exploring work-related risk factors of common mental disorders (CMDs), such as major depressive disorder (MDD), generalised anxiety disorder (GAD) or alcohol abuse, have generally focused on a limited set of work characteristics. For the first time in a primary care setting, we examine simultaneously multiple work-related risk factors in relation to CMDs. METHOD: We use data from a study of working individuals recruited among 2027 patients of 121 general practitioners (GPs) representative of the Nord-Pas-de-Calais region in the North of France (April-August 2014). CMDs (MDD; GAD; alcohol abuse) were assessed using the Mini-International Neuropsychiatric Interview. Six worked-related factors were examined (work intensity, emotional demands, autonomy, social relations at work, conflict in values and job insecurity). Several covariates were considered (patient, GP and contextual characteristics). To study the association between workplace risk factors and CMDs, we used multilevel Poisson regression models adjusted for covariates. RESULTS: Among study participants, 389 (19.1%) met criteria for MDD, 522 (25.8%) for GAD and 196 (9.7%) for alcohol abuse. In multivariable analyses adjusted for covariates, MDD/GAD was significantly associated with work intensity (RR 1.16, 95% CI 1.06 to 1.27) (absolute risk=52.8%), emotional demands (RR 1.24, 95% CI 1.13 to 1.35) (absolute risk=54.9%) and social relations at work (RR 0.78, 95% CI 0.70 to 0.87) (absolute risk=15.0%); alcohol abuse was associated with social relations at work (RR 1.25, 95% CI 1.01 to 1.53) (absolute risk=7.6%) and autonomy (OR 0.82, 95% CI 0.67 to 0.99) (absolute risk=8.9%). CONCLUSIONS: Several workplace factors are associated with CMDs among working individuals seen by a GP. These findings confirm the role of organisational characteristics of work as a correlate of psychological difficulties above and beyond other sources of risk.