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An overview of basic pathophysiological interactions between gut bacteria and their host
No full textInternational audienceSometimes referred to as a “forgotten organ,” the gut microbiome (GMB) of humans includes hundreds of commensal bacterial species, which carry several million genes and complement our physiology. Commensal bacteria break down indigestible dietary fiber and provide essential metabolites. These often have a dual action: as “stand-alone” chemicals (e.g., combustibles or emulsifiers) and as signaling molecules that influence host gene expression and physiology. A second function of gut bacteria is to help maintain the intestinal barrier, partly by conditioning the host immune system. Alteration and damage to the GMB have been linked to many pathologies. This review provides an introduction to the more basic mechanisms of GMB-host interaction. It focuses on (a) gut bacteria and their metabolites, and (b) the metabolites’ role in host gene regulation and homeostasis. To this end, recent articles were selected, along with some earlier ground-breaking articles. We consider microbiome composition and intestinal homeostasis, microbiome composition and dysbiosis, immune modulation, gut bacteria metabolite chemistry and host gene regulation
Dating a Medieval Tsunami With Uranium‐Series Techniques on Caribbean Corals
No full textInternational audience>Uranium-series dates from coral boulders constrain the timing of a medieval tsunami from the Puerto Rico Trench. Previously reported evidence for this tsunami includes hundreds of coral boulders that came to rest hundreds of meters inland on Anegada, British Virgin Islands. New U-series dates on these coral boulders provide limiting dates for the tsunami. The narrowest limits were by dating interior bands of a coral that retains the hemispherical form of a living coral colony, and which include adjustments for the number of annual density band couplets between the dated samples and the boulder exteriors. By those limits, the tsunami dates between 1381 and 1391 CE, and likely occurred during summer or fall. The tsunami is important as the only reported sign that the eastern Puerto Rico Trench has produced a great earthquake. The dating may aid in defining the earthquake source and in communicating tsunami hazards
Participation complexe des structures d'opération à la gestion durable des réseaux hydroagricoles, cas des plaines d'Andapa et de la basse Mahavavy (Ambilobe)
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Circulation of measles virus genotype B3 in the Republic of the Congo between 2023 and 2024: a molecular characterization study
No full textInternational audienceBackground and aims: the only previous sequence report of measles virus from the Republic of the Congo (RoC) dates back to samples collected in 2000. To update the molecular epidemiology of measles virus in the RoC, our study genotyped measles virus strains circulating in the country from January 2023 to May 2024 Methods: a total of 584 serum or plasma samples were collected by the National Laboratory of Public Health through its nationwide measles surveillance activities. Among these 584 suspected cases, 231 were IgM seropositive, and 170 of them were selected for molecular detection based on their collection date. Results: of these, 20 cases were RT‐qPCR positive, and six sequences were suitable for sequence analysis. Phylogenetic analysis confirmed that the detected measles virus belongs to genotype B3, which is one of the two genotypes currently circulating globally, alongside genotype D8. Genetic comparison revealed three closely related variants, suggesting either ongoing endemic transmission or potential importation. Notably, 45% of PCR‐positive samples had received two vaccine doses, highlighting the need for robust vaccine efficacy evaluation. Conclusion: this study emphasizes the critical role of measles virus surveillance, genotyping capacities, and genetic characterization to strengthen regional disease monitoring and containment strategies
Effects of “Living High‐Training Low and High” on Sleep, Heart Rate Variability, and Psychological Responses in Elite Female Cyclists
No full textInternational audienceABSTRACT “Living High‐Training Low and High” (LHTLH) is an altitude/hypoxic training method used to improve physical performance at sea level. The aim of this exploratory study was to investigate the effects of LHTLH on sleep, heart rate variability (HRV), and psychological stress in 10 elite/international level female cyclists (mean age: 17.3 ± 1.2 years). Participants were monitored for 19 days divided into 3 periods: (i) normoxia (5 days preceding LHTLH), (ii) early acclimatization (day 1–4 of LHTLH), and (iii) middle acclimatization (day 5–14) performed in hypoxic rooms (F i O 2 = 15.09%). Questionnaires of psychological stress and sleep disturbance, sleep architecture (determined through an electroencephalography sleep headband), and HRV (measured at rest with a chest strap) were recorded during the 3 periods. The results found that, compared to normoxia, there was no significant difference in total sleep time, sleep efficiency, latency, or waking during the early acclimatization period. However, a significant increase in sleep disturbance (2.5 ± 1.1 vs. 4.9 ± 2.5 a.u. and p < 0.001), alterations of HRV, and sleep architecture with a significant increase in stages 1 (21.8 ± 3 vs. 25.9 ± 3.6 min and p < 0.007) and 2 (201.2 ± 55 vs. 238.5 ± 55 min and p < 0.008) of sleep was observed. During the middle acclimatization period, the athletes had restorative sleep but HRV remained altered, with a significant increase in external tension (1.24 ± 0.4 vs. 2.83 ± 1.8 a.u. and p < 0.05). All these findings suggest that an acclimatization period of at least 4 days is required to recover restorative sleep during LHTLH intervention. This article provides the first insights on the understanding of psychophysiological stress induced using the “Live High‐Training Low and High” paradigm, particularly in elite/international level female athletes. Results indicate that: during the early acclimatization period, sleep disturbances are observed, with an alteration in heart rate variability. After this period, the athletes return to restful sleep, enabling them to increase their training load. However, heart rate variability and psychological stress remain impaired for at least 10 days
Épidémiologie et parcours de soins des cas de syphilis diagnostiqués en CDPS et hôpitaux de proximité de Guyane de 2020 à 2023
No full textBackground: French Guiana have experienced a resurgence of syphilis cases since 2020, which also affects the territories of screening, prevention, and care centers (SPCC). The aim of this study was to describe the evolution of the incidence rate of syphilis in this territory, as well as the patients’ care pathways and the risk factors associated with incomplete follow-up.Method: This was a retrospective descriptive study that included all patients diagnosed with syphilis at one of the 13 CDPS and 3 local hospitals in French Guiana between January 1, 2020, and December 31, 2023.Results: A total of 199 patients were included, with 209 episodes of syphilitic infections, consisting of 72 men and 127 women, including 44 pregnant women. The median age was 25 years (CI: 20-33). The incidence rate of syphilis within the CDPS of French Guiana rose from 24 to 200 per 100,000 inhabitants between 2020 and 2023. The diagnosis was made at an early stage for 86 patients (41%) and late for 123 (59%), with only 49 patients (23%) showing clinical signs of syphilis. Fourteen pregnancies (31%) had unfavorable outcomes and 9 newborns (23%) had confirmed or highly probable congenital syphilis. Regarding follow-up, 69 patients (33%) did not receive complete treatment and 90 (44%) were lost to follow-up. Male gender, patients born in Brazil, and lack of health assurance were associated with an increased risk of being lost to follow-up.Conclusion: The incidence of syphilis increased eightfold over four years in the screening, prevention, and care centers (SPCC). The use of rapid diagnostic tests, the provision of health mediation to trace lost patients, and the improvement of sexual healIntroduction : Depuis 2020, la Guyane connaît une recrudescence des cas de syphilis touchant notamment les centres de dépistage, de prévention et de soins (CDPS). Cette étude avait pour objectif de décrire l’évolution de l’incidence de la syphilis, le parcours de soins des patients et les facteurs associés à un suivi incomplet.Méthode : Il s’agissait d’une étude descriptive rétrospective incluant tous les patients diagnostiqués avec une syphilis dans l’un des 13 CDPS et 3 hôpitaux de proximité de Guyane entre le 01/01/2020 et le 31/12/2023.Résultats : Au total, 199 patients ont été inclus, représentant 209 épisodes de syphilis, dont 72 hommes et 127 femmes, parmi lesquelles 44 femmes enceintes. L’âge médian était de 25 ans (IQR : 20–33). L’incidence est passée de 24 à 200 pour 100 000 habitants entre 2020 et 2023. Le diagnostic était précoce pour 41 % des patients et tardif pour 59 %. Seuls 23 % présentaient des signes cliniques. Parmi les grossesses, 31 % ont eu une évolution défavorable et 23 % des nouveau-nés présentaient une syphilis congénitale confirmée ou probable. Concernant le suivi, 33 % des patients n’ont pas reçu un traitement complet et 44 % ont été perdus de vue. Le sexe masculin, la naissance au Brésil et l’absence de droits sociaux étaient associés à un risque accru de perte de suivi.Conclusion : L’incidence de la syphilis a été multipliée par huit en quatre ans dans les CDPS. Le recours aux TROD, la médiation en santé et le renforcement de l’éducation en santé sexuelle apparaissent essentiels pour contrôler cette épidémie
The February–April 2021 sequence of lava fountain paroxysms on Mt Etna: source mechanism deciphered from ground-based and satellite survey of volcanic gas emissions
No full textInternational audienceAbstract Between 16 February and 1 April 2021, the Southeast Crater (SEC) of Mt Etna produced a spectacular sequence of 17 lava fountain paroxysms, separated by 2.5 days on average, which generated ≥ 10 km high eruptive columns and heavy tephra fallout over populated surroundings. We examine the magmatic processes responsible for these events based on pre- and syn-eruptive data for the mass flux and chemistry of Etna gas emissions, surveyed both from the ground (scanning DOAS, OP-FTIR spectroscopy) and from space (TROPOMI, SEVIRI), and comparing with the seismic tremor. Bulk plume SO 2 emission rates determined from the ground and from space are consistent with one another. We show that after several months of background summit activity, sustained since June 2020 by open-system degassing of ~ 29 × 10 6 m 3 (DRE) of magma through the central volcano conduits, an influx of deeply derived primitive magma led to a pressure build-up phase from early December 2020 to 13 February 2021, marked by a rapid increase in the SO 2 flux and tremor (the former interpreted to represent an ~ 3 times higher magma degassing rate) and decreasing SO 2 /HCl plume ratio. A series of 17 lava fountains began immediately after a shallow seismic cluster and a sharp drop in the SO 2 emission rate from the summit craters, reflecting the lateral transfer of pressurized primitive magma to beneath the SEC. The fountain paroxysms were characterized by sharp increases in tremor amplitude, intense SO 2 release, and higher volcanic gas SO 2 /HCl ratios. The magnitude of SO 2 emission rate correlates with the proportion of primitive magma in co-erupted products during the first half of the sequence. The estimated total gas discharge, compared to the co-erupted tephra mass, suggests a large excess gas release for most events, which is proportional to the length of the repose interval. Combining these observations with models of S and Cl degassing from Etna trachybasalt, we infer that the February–April 2021 lava fountain series resulted from the recurrent accumulation of H 2 O-CO 2 -rich bubble foams at ~ 2–3 km depth beneath SEC, whose periodic collapse promoted fast magma ascent and fragmentation associated with essentially syn-eruptive degassing of S and Cl. Our study thus provides further insight into the complexity of magmatic processes determining lava fountain paroxysms at Mt Etna and, possibly, other basaltic volcanoes
Coral Venom and Toxins as Protection Against Crown‐of‐Thorns Sea Star Attack
No full textInternational audienceCrown‐of‐thorns sea star (CoTS) outbreaks are a main cause of hard coral cover decline across the Indo‐Pacific, posing a major threat to the resilience of coral reefs. However, the drivers underlying CoTS feeding on preferred (e.g., Acropora species) versus non‐preferred (e.g., Porites species) are poorly understood. We hypothesised that coral venom may influence CoTS prey preferences. To investigate this hypothesis, we compared the coral venom toxin families across the genomes of preferred ( A. digitifera , A. hyacinthus , A. millepora and A. tenuis ) and non‐preferred ( P. australiensis , P. compressa , P. lutea and P. rus ) prey species of CoTS. We also included one species from each genus inhabiting the Caribbean, where CoTS are absent ( A. cervicornis and P. astreoides ), to broaden our identification of venom constituents shared within each genus and investigate geographic differences. We collected known cnidarian toxins, and along with the cnidarian Tox‐Prot database, used these to identify putative toxins and investigate their phylogeny. The most abundant toxins across all coral species included neurotoxins (kunitz‐type and SCRiPS) and pore‐forming toxins (actinoporins and MAC‐PFs). We found genera‐specific differences with jellyfish toxins (CFXs) only present in Porites species. Similarly, only Acropora species harboured pore‐forming toxins with the aerolysin domain. Two toxin homologues only present in Indo‐Pacific corals (CFX and MAC‐PF homologues) showed evidence of positive selection, suggesting their evolution is shaped by environmental pressures, including exposure to CoTS. These findings provide a foundation for future studies of scleractinian venoms, which have direct applications to assessing reef coral's susceptibility to future CoTS outbreaks and active reef management
Automated Theorem Proving for Prolog Verification
No full textInternational audienceLPTP (Logic Program Theorem Prover) is an interactive natural-deduction-based theorem prover for pure Prolog programs with negation as failure, unification with the occurs check, and a restricted but extensible set of built-in predicates. With LPTP, one can formally prove termination and partial correctness of such Prolog programs. LPTP was designed in the mid-1990's by Robert F. Staerk. It is written in ISO-Prolog and comes with an Emacs user-interface.From a theoretical point of view, in his publications about LPTP, Staerk associates a set of first-order axioms IND(P) to the considered Prolog program P. IND(P) contains the Clark's equality theory for P, definitions of success, failure and termination for each user-defined logic procedure in P, axioms relating these three points of view, and an axiom schema for proving inductive properties. LPTP is thus a dedicated proof editor where these axioms are hard-wired.We propose to translate these axioms as first-order formulas (FOFs), and apply automated theorem provers to check the property of interest. Using FOF as an intermediary language, we experiment the use of automated theorem provers for Prolog program verification. We evaluate the approach over a benchmark of about 400 properties of Prolog programs from the library available with LPTP. Both the compiler which generates a set of FOF files from a given input Prolog program together with its properties and the benchmark are publicly available
The Palms of South-east Madagascar: Fort Dauphin as a Ravenea Hotspot
No full textInternational audienceSoutheast Madagascar, especially the Fort Dauphin (Taolagnaro) district, represents one of the last remnants of the original rainforest along the island's eastern coast and marks the transition between humid and arid climatic zones. Here, we report findings from an expedition in March and April 2024, which demonstrate that the southern part of Fort Dauphin seems to be a significant “hotspot” for the genus Ravenea. Its location in the southern half of the region, previous biogeographic events and distinct, stable climate patterns may all contribute to this particular richness. Surprisingly, the taxonomy of palm species in this area is still not well understood, even though it is reasonably accessible