La géo-ingénierie climatique : approche complémentaire ou contradictoire aux efforts d'atténuation des émissions de gaz à effet de serre?

Le réchauffement climatique est un processus global de modification du climat causé par les émissions importantes de gaz à effet de serre d’origine anthropique dans l’atmosphère. La géo-ingénierie figure parmi les solutions explorées pour contrer ce problème. Elle comprend plusieurs technologies qui se distinguent par leur maturité, leur potentiel d’atténuation du réchauffement planétaire, leurs risques éventuels, et leur acceptabilité sociale. L’objectif de cet essai consiste donc à évaluer l’état d’avancement, l’efficacité et les effets secondaires de ces approches pour leur déploiement à grande échelle. Le premier chapitre présente un résumé des efforts utilisés par le gouvernement québécois et fédéral pour réduire leur émission de gaz à effets de serre. Le deuxième chapitre quant à lui comprend une revue des informations sur les principales technologies de géo-ingénierie. Les enjeux éthiques, la gouvernance et l’acceptabilité sociale de la géo-ingénierie sont discutés dans le troisième chapitre. Pour réaliser l’objectif global de l’essai, une analyse multicritère a été menée dans le chapitre quatre. La première étape de cette dernière a permis d’identifier les technologies qui sont les plus avancées. Lors de la deuxième étape de l’analyse, quatre technologies ont été sélectionnées pour leur comparaison détaillée dans la troisième étape. Elles concernent la capture directe du dioxyde de carbone de l’atmosphère, le biochar, la bioénergie et le boisement/reboisement. Le biochar est un charbon riche en carbone généré par pyrolyse d’une variété de résidus de biomasse végétale, et qui peut séquestrer le carbone dans le sol pendant une très longue période. La comparaison de ces quatre approches précitées a été basée sur certains critères choisis selon leur importance vis-à-vis de l’atténuation des gaz à effet de serre. Grâce à cette analyse, les technologies qui auraient moins d’impacts négatifs ont été mises en évidence. Les résultats ont montré que le biochar se place en première position, car il présente un impact global positif le plus élevé au niveau des trois volets : environnement, économie et social. Il est suivi par la capture directe du dioxyde de carbone, le boisement/reboisement et en dernier lieu par la bioénergie. Plusieurs recommandations sont indiquées au chapitre cinq quant à l’utilisation de ces approches comme mesures d’atténuation des changements climatiques. Par exemple, pour le biochar, une évaluation de son effet potentiel sur l’albédo des surfaces terrestres est essentielle avant sa mise en œuvre. La technologie de capture directe du dioxyde de carbone est très énergivore. Pour cela, elle nécessiterait l’emploi d’une énergie renouvelable pour diminuer ses coûts. En conclusion, les technologies de géo-ingénieries qui ont moins d’impacts négatifs sont le biochar et la capture directe du dioxyde de carbone de l’atmosphère. Ces approches pourraient être déployées comme mesures complémentaires aux efforts de réduction des gaz à effet de serre. Par contre, elles ne devraient pas être considérées comme une substitution à ces efforts

Étude des mécanismes d'inhibition du transport des électrons photosynthétiques induite par les xénobiotiques affectant les réactions photochimiques du photosystème II

Le projet de recherche de cette thèse consiste à investiguer les mécanismes d'inhibition du transport d'électrons photosynthétiques induite par les xénobiotiques qui affectent les réactions photochimiques du photosystème II (PSII). Des méthodes fluorimétriques et biochimiques ont été utilisées pour étudier les effets de xénobiotiques sur les réactions photochimiques et le transport des électrons photosynthétiques. Le changement des différents paramètres de fluorescence chlorophyllienne, indiquant la dissipation de l'énergie via le transport d'électrons ou via les voies non photochimiques, a été utilisé comme indicateur de toxicité de xénobiotiques. L'induction du stress oxydatif a été analysée par l'investigation de la teneur en espèces réactives de l'oxygène. Nous avons utilisé les plantes Lemna gibba et Lactuca sativa ainsi que l'algue Chlamydomonas reinhhardtii comme matériel pour les expériences.\ud Dans la partie concernant l'étude des mécanismes de toxicité du dichromate chez L. gibba, nous avons démontré que ce xénobiotique inhibe le transport d'électrons du PSII et induit la dissipation d'énergie sous forme non photochimique. Sous ces conditions, une inhibition de l'activité photochimique du PSII et une diminution de la proportion des centres réactionnels en état fonctionnel ont été obtenues. Le changement du rendement et de la cinétique rapide de fluorescence montre que le dichromate induit une inhibition du complexe de la photolyse de l'eau et de la réduction de l'accepteur primaire d'électrons (QA). Ces effets ont été associés à l'altération de la protéine Dl du centre réactionnel du PSII, ainsi que la protéine 33 kDa constituant le complexe de photolyse de l'eau. L'induction d'un stress oxydatif a été démontrée par l'augmentation de la teneur en espèces réactives de l'oxygène chez les plantes exposées au dichromate. La diminution de la proportion des PSII en état fonctionnel et la formation des espèces réactives de l'oxygène induites par le dichromate ont été corrélées avec le changement des polypeptides Dl. On a pu établir que l'altération fonctionnelle de l'activité du PSII par le dichromate est étroitement associée au changement structurel se produisant dans le complexe PSII. Nous avons également investigué les effets toxiques du dichromate sur l'activité du PSII chez des algues ayant une faible capacité de dissipation de l'énergie sous forme non photochimique. On a utilisé deux algues mutantes de C. reinhardtii qui ont une altération de la biosynthèse de pigments xanthophylles: le premier mutant, npq1, est déficient en zéaxanthine et le deuxième, npq2, est déficient en violaxanthine et accumule la zéaxanthine. On a étudié l'effet du dichromate sur l'activité du PSII sous des conditions lumineuses favorisant la photoinhibition. Après exposition au dichromate, ces algues ont été illuminées par différentes intensités lumineuses pour mesurer le changement du rendement photochimique opérationnel du PSII et la dissipation de l'énergie sous forme non photochimique. L'exposition aux dichromate des mutants npq1 et npq2 a induit une inhibition de transport d'électrons de PSII à faible intensité lumineuse, indiquant une accélération de la photoinhibition par le dichromate. Lorsque ces mutants d'algues ont été exposés aux dichromate et à une intensité lumineuse élevée, la dissipation d'énergie sous forme non photochimique, impliquant des processus non régulateurs, est devenue majoritaire, atteignant la valeur de 80 %. Par conséquent, les mutants d'algues npq1 et npq2 ayant le cycle de xanthophylles non fonctionnel étaient plus sensibles aux effets toxiques du dichromate. Ces résultats ont permis l'élaboration d'un modèle des effets du dichromate sur l'activité du PSII chez les algues ayant un cycle de xanthophylles non fonctionnel. Dans la troisième partie, on a analysé les effets toxiques du trinitrotoluène sur le changement des paramètres de fluorescence utilisés comme indicateurs de toxicité sur la photosynthèse et l'état physiologique de Lactuca sativa. L'activité photosynthétique a été mesurée en utilisant la cinétique rapide de la fluorescence chlorophyllienne et la fluorimétrie modulée. Nos résultats ont montré une diminution de la fluorescence variable provoquée par la désactivation des centres réactionnels PSII. En plus de cet effet, les paramètres de fluorescence indiquant l'état de réduction du PSII et la dissipation d'énergie sous forme non photochimique ont été les indicateurs les plus sensibles de la toxicité du trinitrotoluène. Ces paramètres ont montré une dépendance entre l'inhibition de l'activité du PSII et la concentration du trinitrotoluène. Le changement des paramètres photosynthétiques de fluorescence était une indication fiable de l'état physiologique des plantes exposées à ce polluant. Nous avons proposé que l'état de réduction du PSII et la dissipation non photochimique de l'énergie représentent des indicateurs utiles dans les bioessais. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Xénobiotiques, Bioessais, Fluorescence chlorophyllienne, Réactions photochimiques, Photosystème II, Chrome hexavalent, Trinitrotoluène, Fluorométrie PAM et PEA

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Impact of early enteral versus parenteral nutrition on mortality in patients requiring mechanical ventilation and catecholamines: study protocol for a randomized controlled trial (NUTRIREA-2)

BACKGROUND: Nutritional support is crucial to the management of patients receiving invasive mechanical ventilation (IMV) and the most commonly prescribed treatment in intensive care units (ICUs). International guidelines consistently indicate that enteral nutrition (EN) should be preferred over parenteral nutrition (PN) whenever possible and started as early as possible. However, no adequately designed study has evaluated whether a specific nutritional modality is associated with decreased mortality. The primary goal of this trial is to assess the hypothesis that early first-line EN, as compared to early first-line PN, decreases day 28 all-cause mortality in patients receiving IMV and vasoactive drugs for shock. METHODS/DESIGN: The NUTRIREA-2 study is a multicenter, open-label, parallel-group, randomized controlled trial comparing early PN versus early EN in critically ill patients requiring IMV for an expected duration of at least 48 hours, combined with vasoactive drugs, for shock. Patients will be allocated at random to first-line PN for at least 72 hours or to first-line EN. In both groups, nutritional support will be started within 24 hours after IMV initiation. Calorie targets will be 20 to 25 kcal/kg/day during the first week, then 25 to 30 kcal/kg/day thereafter. Patients receiving PN may be switched to EN after at least 72 hours in the event of shock resolution (no vasoactive drugs for 24 consecutive hours and arterial lactic acid level below 2 mmol/L). On day 7, all patients receiving PN and having no contraindications to EN will be switched to EN. In both groups, supplemental PN may be added to EN after day 7 in patients with persistent intolerance to EN and inadequate calorie intake. We plan to recruit 2,854 patients at 44 participating ICUs. DISCUSSION: The NUTRIREA-2 study is the first large randomized controlled trial designed to assess the hypothesis that early EN improves survival compared to early PN in ICU patients. Enrollment started on 22 March 2013 and is expected to end in November 2015. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01802099 (registered 27 February 2013)

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P &lt; 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century