Tolerance of high and low amounts of PLGA microspheres loaded with mineralocorticoid receptor antagonist in retinal target site

Mineralocorticoid receptor (MR)contributes to retinal/choroidal homeostasis. Excess MR activation has been shown to be involved in pathogenesis of central serous chorioretinopathy (CSCR). Systemic administration of MR antagonist (MRA) reduces subretinal fluid and choroidal vasodilation, and improves the visual acuity in CSCR patients. To achieve long term beneficial effects in the eye while avoiding systemic side-effects, we propose the use ofbiodegradable spironolactone-loaded polylactic-co-glycolic acid (PLGA)microspheres (MSs). In this work we have evaluated the ocular tolerance of MSs containing spironolactone in rats’ eyes. As previous step, we have also studied the tolerance of the commercial solution of canrenoate salt, active metabolite of spironolactone. PLGA MSs allowed in vitro sustained release of spironolactone for 30 days. Rat eyes injected with high intravitreous concentration of PLGA MSs (10 mg/mL) unloaded and loaded with spironolactone maintained intact retinal lamination at 1 month. However enhanced glial fibrillary acidic protein immunostaining and activated microglia/macrophages witness retinal stress were observed. ERG also showed impaired photoreceptor function. Intravitreous PLGA MSs concentration of 2 mg/mL unloaded and loaded with spironolactone resulted well tolerated. We observed reduced microglial/macrophage activation in rat retina compared to high concentration of MSs with normal retinal function according to ERG. Spironolactone released from low concentration of MSs was active in the rat retina. Low concentration of spironolactone-loaded PLGA MSs could be a safe therapeutic choice for chorioretinal disorders in which illicit MR activation could be pathogenic

Genome-wide association analyses identify new Brugada syndrome risk loci and highlight a new mechanism of sodium channel regulation in disease susceptibility.

Brugada syndrome (BrS) is a cardiac arrhythmia disorder associated with sudden death in young adults. With the exception of SCN5A, encoding the cardiac sodium channel Na1.5, susceptibility genes remain largely unknown. Here we performed a genome-wide association meta-analysis comprising 2,820 unrelated cases with BrS and 10,001 controls, and identified 21 association signals at 12 loci (10 new). Single nucleotide polymorphism (SNP)-heritability estimates indicate a strong polygenic influence. Polygenic risk score analyses based on the 21 susceptibility variants demonstrate varying cumulative contribution of common risk alleles among different patient subgroups, as well as genetic associations with cardiac electrical traits and disorders in the general population. The predominance of cardiac transcription factor loci indicates that transcriptional regulation is a key feature of BrS pathogenesis. Furthermore, functional studies conducted on MAPRE2, encoding the microtubule plus-end binding protein EB2, point to microtubule-related trafficking effects on Na1.5 expression as a new underlying molecular mechanism. Taken together, these findings broaden our understanding of the genetic architecture of BrS and provide new insights into its molecular underpinnings

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Exploration des déterminants moléculaires impliqués dans la spécificité et la stabilité de l’alternane-saccharase

The alternansucrase (ASR) from Leuconostoc citreum NRRL B-1355 is a glucansucrase belonging to the family 70 of glycoside hydrolases (GH70). This α-transglucosylase uses a cheap and abundant molecule, sucrose, to catalyze the formation of a unique α-glucan polymer made of alternating α-1,6 and α-1,3 linkages in the main chain, called alternan. With a 45°C optimum temperature, ASR is among the most stable glucansucrases to date. To get a deeper insight in ASR determinants involved in linkage specificity, polymerization and stability, we have solved the unliganded 3D structure of this enzyme at 2.8 Å. Coupled to mutagenesis and molecular docking, our results suggest the alternance to be governed by the acceptor positioning in either +2 or +2’ subsite, and the key contributions of Trp675 or Asp772 residue, respectively. Complexes of ASR with various sugar ligands were also obtained and highlighted a site never identified in any other GH70 enzymes. This site is uniquely found in alternansucrase and could act as a bridge between the domain V and the active site facilitating alternan processive elongation. Finally, the construction and characterization of chimera enzymes suggested domain C to be involved in enzyme stability. Overall, our results improved our knowledge on the structure-function relationship of ASR and open new paths for the conception of polymers with controlled structures and physicochemical propertiesL’alternane-saccharase (ASR) de Leuconostoc citreum NRRL B-1355 est une glucane-saccharase appartenant à la famille 70 des glycoside hydrolases (GH70). Cette α-transglucosylase utilise le saccharose, substrat peu coûteux et abondant, pour catalyser la formation d’un polymère d’α-glucane composé de liaisons osidiques α-1,6 et α-1,3 alternées dans la chaîne principale et appelé alternane. Avec une température optimale de 45°C, l’ASR est parmi les glucane-saccharases les plus stables. Afin d’avoir une meilleure compréhension des déterminants de la spécificité de liaison, de la polymérisation et de la plus haute stabilité de l’ASR, nous avons résolu la structure de cette enzyme. Notre étude par mutagénèse dirigée combinée à du docking moléculaire suggère que la spécificité de liaison est contrôlée par le positionnement de l’accepteur dans l’un ou l’autre des sous-sites +2 ou +2’. Des complexes de l’ASR avec différents ligands ont également mis en évidence un site signature de l’enzyme. Ce site est impliqué dans la formation du polymère d’alternane et pourrait servir de pont facilitant l’élongation processive de l’alternane. Enfin, nos travaux préliminaires indiquent que le domaine C pourrait être impliqué dans la stabilité de ces enzymes. Nos résultats ouvrent des nouvelles pistes d’investigation concernant l’étude des relations structure-fonction des glucane-saccharases et la conception de polymères de structure et propriétés physico-chimiques contrôlées

Some contributions to the theory of population size dependent bisexual branching processes

International audienc

Bacterial α-Glucan and Branching Sucrases from GH70 Family: Discovery, Structure–Function Relationship Studies and Engineering

International audienceGlucansucrases and branching sucrases are classified in the family 70 of glycoside hydrolases. They are produced by lactic acid bacteria occupying very diverse ecological niches (soil, buccal cavity, sourdough, intestine, dairy products, etc.). Usually secreted by their producer organisms, they are involved in the synthesis of α-glucans from sucrose substrate. They contribute to cell protection while promoting adhesion and colonization of different biotopes. Dextran, an α-1,6 linked linear α-glucan, was the first microbial polysaccharide commercialized for medical applications. Advances in the discovery and characterization of these enzymes have remarkably enriched the available diversity with new catalysts. Research into their molecular mechanisms has highlighted important features governing their peculiarities thus opening up many opportunities for engineering these catalysts to provide new routes for the transformation of sucrose into value-added molecules. This article reviews these different aspects with the ambition to show how they constitute the basis for promising future developments

Physical and Biological Study of Cell Cultures in a Bioreactor:On-line and Off-line Rheological Analyses

Rheological behaviour of culture broth stands as a fundamental parameter in bioprocess performances because it affects simultaneously the heat and mass transfer as well as the flow pattern. On-line measurements of rheological behaviour are hardly compatible with the operating condition with respect to accurate and stringent conditions imposed by cell culture strategy. Our scientific and technical objectives are (i) to develop and identify an experimental device enabling on-line rheometry and (ii) to discuss and compare on-line and off-line measurements. In this aim, a bioreactor was equipped with a derivation loop including a specific on-line rheometric device as well as additional physical and biological measurements (specific density, mass flow rate, electrical conductivity, pH, pO2 and temperature) during microbial cell cultures. In a first time, friction curves of calibrated ducts were established with Newtonian and non-Newtonian shear-thinning fluids. In a second time, axenic cultures with two microorganisms (bacteria and yeast exhibiting different sizes) were investigated in pure oxidative culture in order to produce biomass under high cell concentrations: ~ 40 to 110 gCDW/l for E. coli (bacteria) and ~ 75 to 105 gCDW/l for Y. lipolytica(yeast). Cell broths exhibited Newtonian behaviour for E. coliand shear-thinning behaviour for Y. lipolytica, which were both dependant on biomass concentration. On-line and off-line rheological measurements are consistent for E. coli and Y. lipolytica, but significantly differed. On-line estimated viscosity appears higher than off-line apparent viscosity. Several assumptions in relation with microorganism physiology and metabolism (size, morphology, surface properties, concentration, biological activity) could be formulated in agreement with scientific literature. On-line rheology brings new insight to investigate complex interaction between physical and biological phenomena

Identification of physical and biological interactions in cell cultures in a bioreactor: On-line and off-line rheological characterization

In Proceeding SFGP 2009 (14-16 octobre 2009, Marseille, France) Récents Progrès en Génie des Procédés, N°98, 2009, ISBN: 2-910239-72-1, Ed. SFGP, Paris, France. Abstract : Rheological behaviour of culture broth stands as a fundamental parameter in bioprocess performances because it affects simultaneously heat and mass transfer as well as flow pattern. It is then of first interest to get on-line characterization and to model the rheological behaviour of the fermentation broth relating to the microbial activity (specific kinetics, growth rate, physiology, morphology, cell concentration). In this context, our scientific objectives deals with the identification of the impact of physical properties of complex three-phase broth on bioprocess performances with the development of an experimental platform enabling on-line rheometry measurements during cell cultures. In this way, a bioreactor was equipped with a derivation loop including a specific on-line rheometric device. In a first time, friction curves of calibrated ducts were achieved with Newtonian and non-Newtonian shear-thinning model fluids. In a second time, axenic cultures with two microorganisms of different size (Escherichia coli and Yarrowia lipolytica) were carried out in order to produce high biomass concentrations. The uniqueness of friction curve is confirmed with model fluids, and validates our approach to investigate on-line rheometry of broths. The results obtained with E. coli and Y. lipolytica cultures respectively ranging between ~40-~110gCDW.l-1 and 75-~105gCDW.l-1 are reported. For Y. lipolytica, off-line rheometry demonstrated a shear-thinning behaviour in relation with biomass concentration whereas online viscosity measurements established in laminar flow regime for higher shear rates highlighted a Newtonian plate. For E. coli, on-line and off-line viscosities exhibited the same tendency but strongly differed in term of magnitude. In this case, several assumptions could be formulated to explain this difference: (i) thermal dependency of apparent viscosity, (ii) biological activity, (iii) volume gas fraction (aeration and biological production) in broth (~30-40%v/v) and (iv) shear rates (correlated to flow regime). Impact of different phases on apparent viscosity for high biomass concentration above 110gCDW.l-1 will beinvestigated in close future.Identification of physical and biological interactions in cell cultures in a bioreactor: On-line and off-line rheological characterization. 12. Congrès de la Société Française de Génie des Procédés (SFGP 2009) "Pour relever les défis industriels du XXIème siècle