Evidence of a causal and modifiable relationship between kidney function and circulating trimethylamine N-oxide

The host-microbiota co-metabolite trimethylamine N-oxide (TMAO) is linked to increased cardiovascular risk but how its circulating levels are regulated remains unclear. We applied "explainable" machine learning, univariate, multivariate and mediation analyses of fasting plasma TMAO concentration and a multitude of phenotypes in 1,741 adult Europeans of the MetaCardis study. Here we show that next to age, kidney function is the primary variable predicting circulating TMAO, with microbiota composition and diet playing minor, albeit significant, roles. Mediation analysis suggests a causal relationship between TMAO and kidney function that we corroborate in preclinical models where TMAO exposure increases kidney scarring. Consistent with our findings, patients receiving glucose-lowering drugs with reno-protective properties have significantly lower circulating TMAO when compared to propensity-score matched control individuals. Our analyses uncover a bidirectional relationship between kidney function and TMAO that can potentially be modified by reno-protective anti-diabetic drugs and suggest a clinically actionable intervention for decreasing TMAO-associated excess cardiovascular risk

Imidazole propionate is increased in diabetes and associated with dietary patterns and altered microbial ecology

Microbiota-host-diet interactions contribute to the development of metabolic diseases. Imidazole propionate is a novel microbially produced metabolite from histidine, which impairs glucose metabolism. Here, we show that subjects with prediabetes and diabetes in the MetaCardis cohort from three European countries have elevated serum imidazole propionate levels. Furthermore, imidazole propionate levels were increased in subjects with low bacterial gene richness and Bacteroides 2 enterotype, which have previously been associated with obesity. The Bacteroides 2 enterotype was also associated with increased abundance of the genes involved in imidazole propionate biosynthesis from dietary histidine. Since patients and controls did not differ in their histidine dietary intake, the elevated levels of imidazole propionate in type 2 diabetes likely reflects altered microbial metabolism of histidine, rather than histidine intake per se. Thus the microbiota may contribute to type 2 diabetes by generating imidazole propionate that can modulate host inflammation and metabolism

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Caractérisation de RBcel1: une endoglucanase dotée d'activité transglycosylase

The role of glycans in biological processes has raised awareness of oligosaccharides and glycoconjugates as important therapeutic targets for a wide range of diseases. Despite the technological advancement over the last decades, the diversity and complexity of these glycans remain a major challenge to their production. In nature, the synthesis of glycans is generally attributed to glycosyltransferases (GTs), which carry out the formation of most glycosidic bonds. Their use on an industrial scale, however, is limited because they are often difficult to produce and require activated sugars as substrates. Although glycoside hydrolases (GHs) are generally associated with the hydrolysis of plant biomass, some of them are also able to catalyze the synthesis of glycosidic bonds from simple saccharides via transglycosylation. The ability of GHs to transglycosylate has aroused interest in glycan synthesis as these enzymes are abundant and cover a wide range of substrate specificity. The overall mechanism of transglycosylation is well known and follows the same reaction scheme as hydrolysis. After a first step called glycosylation, the donor sugar is covalently bound to the enzyme. Transglycosylation occurs when a hydroxyl group of an acceptor sugar is used instead of a water molecule in the deglycosylation step. Most transglycosylating GHs can therefore perform both reactions, but their transglycosylation yield is reduced since the newly formed products are concomitantly hydrolyzed. Although knowledge about transglycosylating GHs is still increasing, there is no unique strategy to direct to transglycosylation yield. Thus, obtaining efficient enzymatic tools for glycan synthesis using GHs remains dependent on a better understanding of the molecular factors controlling the balance between hydrolysis and transglycosylation. This work aims to show such factors through the enzymatic and structural study of RBcel1, a family 5 GH endowed with transglycosylase activity. The main goal of this work is to perform an in-depth study of the catalytic mechanism in RBcel1 via the identification of residues involved in catalysis as well as in substrate binding. Several variants of the enzyme were characterized to understand the roles attributed to different residues of the active site, in both catalysis and transglycosylation. The structural study of these variants allowed to obtain the structure of different reaction intermediates allowing to identify residues involved in the binding of substrate and, potentially, transglycosylation. The results obtained in this work confirm partly some widely known mechanistic elements. They also highlighted new elements in the catalytic mechanism such as the key role of the non-catalytic residue tyrosine 201 in glycosylation and deglycosylation. Furthermore, this study presents a novel method to trap reaction intermediates in the presence of natural substrates while maintaining the catalytic residues. Different elements influencing transglycosylation have been highlighted, such as the size of the acceptor sugar or the reaction medium pH. The latter offers interesting perspectives for orienting the reaction towards transglycosylation since transglycosylation products tend to accumulate at basic pH.La prise de conscience du rôle des glycanes dans les processus biologiques a fait des oligosaccharides et glycoconjugués des cibles thérapeutiques importantes pour un grand nombre de maladies. Malgré les avancées technologiques pour leur synthèse ces dernières décennies, la diversité et la complexité de ces oses font perdurer un défi important envers leur production. Dans la nature, la synthèse des glycanes est généralement attribuée aux glycosyltransférases (GTs), réalisant la formation de la plupart des liaisons glycosidiques. Cependant, leur utilisation à l’échelle industrielle est limitée car elles sont souvent difficiles à produire et nécessitent des oses activés comme substrats. Bien que les glycosides hydrolases (GHs) soient généralement associées à l’hydrolyse de la biomasse végétale, certaines d’entre elles sont également capables de catalyser la synthèse de liaisons glycosidiques à partir de saccharides simples via une activité dite de « transglycosylation ». La capacité des GHs à transglycosyler a suscité un intérêt pour la synthèse de glycanes tant ces enzymes sont abondantes et couvrent une large gamme de spécificités de substrats. Le mécanisme global de la transglycosylation est bien connu et suit le même schéma réactionnel que celui de l’hydrolyse. Après une première étape appelée glycosylation, l’ose donneur est lié de manière covalente à l'enzyme. La transglycosylation se produit lorsqu'un groupe hydroxyle d’un ose accepteur est utilisé au lieu d'une molécule d'eau lors de l'étape de déglycosylation. La plupart des GHs transglycosylantes peuvent donc effectuer les deux réactions, impactant leur rendement de transglycosylation suite à l’hydrolyse sous-jacente des produits nouvellement formés. Bien que les études cherchant à comprendre ce qui, chez certaines enzymes, favorise la transglycosylation se multiplient et apportent de nombreux éclaircissements, elles mettent principalement en évidence qu’il n’existe pas de stratégie unique au sein des GHs permettant d’orienter la réaction en faveur de la transglycosylation. L’obtention d’outils enzymatiques performants pour la synthèse enzymatique à partir de GHs reste donc dépendante de la diversification des connaissances à propos des facteurs moléculaires orientant la réaction vers l’hydrolyse ou la transglycosylation. Ce travail s’inscrit dans cette démarche à travers l’étude enzymatique et structurale de RBcel1, une GH de la famille 5 dotée de l’activité transglycosylase. Le but principal de ce travail est d’effectuer une étude approfondie du mécanisme catalytique chez RBcel1 via l’identification de résidus impliqués dans la catalyse ainsi que dans la liaison au substrat. Plusieurs variants de l’enzyme ont été caractérisés afin de comprendre les rôles attribués à différents résidus du site actif, tant au niveau général de la catalyse qu’au niveau de la transglycosylation. Leur étude structurale a permis d’obtenir la structure de différents intermédiaires de réaction permettant l’identification des résidus impliqués dans la liaison des oses et, potentiellement, la transglycosylation. Les résultats obtenus dans ce travail confortent, en partie, certains éléments mécanistiques largement connus. Ils soulèvent également des éléments nouveaux au niveau du mécanisme catalytique comme le rôle clé du résidu non-catalytique tyrosine 201 dans la glycosylation et la déglycosylation. De plus, ce travail présente une méthode novatrice permettant de piéger des intermédiaires de réaction en présence de substrats naturels tout en maintenant les résidus catalytiques. Différents éléments influençant la transglycosylation ont été soulignés, comme la taille de l’ose accepteur ou le pH du milieu de réaction. Ce dernier point offre d’ailleurs des perspectives intéressantes pour l’orientation de la réaction en faveur de l’hydrolyse étant donné qu’il a mis en évidence une accumulation de produits de transglycosylation à certains pH

BRCA1/2 alterations and reversion mutations in the area of PARP inhibitors in high grade ovarian cancer: state of the art and forthcoming challenges

BRCA1/2 genes are part of homologous recombination (HR) DNA repair pathways in charge of error-free double-strand break (DSB) repair. Loss-of-function mutations of BRCA1/2 genes have been associated for a long time with breast and ovarian cancer hereditary syndrome. Recently, polyadenosine diphosphate–ribose polymerase inhibitors (PARPi) have revolutionized the therapeutic landscape of BRCA1/2-mutated tumors, especially of BRCA1/2 high-grade serous ovarian cancer (HGSC), taking advantage of HR deficiency through the synthetic lethality concept. However, PARPi efficiency differs among patients, and most of them will develop resistance, particularly in the relapse setting. In the current proposal, we aim to review primary and secondary resistance to PARPi in HGSC owing to BRCA1/2 alterations. Of note, as several mechanisms of primary or secondary resistance to PARPi have been described, BRCA1/2 reversion mutations that restore HR pathways are by far the most reported. First, the type and location of the BRCA1/2 primary mutation have been associated with PARPi and platinum-salt sensitivity and impact the probability of the occurrence and the type of secondary reversion mutation. Furthermore, the presence of multiple reversion mutations and the variation of allelic frequency under treatment underline the role of intratumor heterogeneity (ITH) in treatment resistance. Of note, circulating tumor DNA might help us to detect and characterize reversion mutations and ITH to finally refine the treatment strategy. Importantly, forthcoming therapeutic strategies, including combination with antiangiogenics or with targeted therapies, may help us delay and overcome PARPi resistance secondary to BRCA1/2 reversion mutations. Also, progression despite PARPi therapy does not preclude PARPi rechallenge in selected patients

Comparing hemp composites made with mineral or organic binder on thermal, hygric and mechanical point of view

International audienceThis study investigates the effect of the kind of binder on thermal, hygric and mechanical properties of hemp composites. Three binders are considered: a formulated hydraulic lime based binder, a prompt cement based binder and a peculiar bio-polymer: the Poly-Lactic Acid (PLA). The binder is coupled with hemp shiv to produce biocomposite. For each kind of binder, the specific manufacturing method is presented and discussed.The thermal properties of produced biocomposite are measured with a hot disk method at 23°C, 50%RH. The hygric characterization is based on the measurement of Moisture Buffer Value at 23°C. The mechanical behavior of composite under compression is analyzed.Thermal conductivities range from 0.08 to 0.16 W/(m.K), this allows to use these composites without added insulation layer. Following the classification given in the Nordtest report, the studied materials are very good or excellent hygric regulator. Performances are slightly higher with mineral binders. However, the compressive strength obtained with PLA binder are much higher than the ones with mineral binders

Highlighting the factors governing transglycosylation in the GH5_5 endo-1,4-β-glucanase RBcel1

Transglycosylating glycoside hydrolases (GHs) offer great potential for the enzymatic synthesis of oligosaccharides. Although knowledge is progressing, there is no unique strategy to improve the transglycosylation yield. Obtaining efficient enzymatic tools for glycan synthesis with GHs remains dependent on an improved understanding of the molecular factors governing the balance between hydrolysis and transglycosylation. This enzymatic and structural study of RBcel1, a transglycosylase from the GH5_5 subfamily isolated from an uncultured bacterium, aims to unravel such factors. The size of the acceptor and donor sugars was found to be critical since transglycosylation is efficient with oligosaccharides at least the size of cellotetraose as the donor and cellotriose as the acceptor. The reaction pH is important in driving the balance between hydrolysis and transglycosylation: hydrolysis is favored at pH values below 8, while transglycosylation becomes the major reaction at basic pH. Solving the structures of two RBcel1 variants, RBcel1_E135Q and RBcel1_Y201F, in complex with ligands has brought to light some of the molecular factors behind transglycosylation. The structure of RBcel1_E135Q in complex with cellotriose allowed a +3 subsite to be defined, in accordance with the requirement for cellotriose as a transglycosylation acceptor. The structure of RBcel1_Y201F has been obtained with several transglycosylation intermediates, providing crystallographic evidence of transglycosylation. The catalytic cleft is filled with (i) donors ranging from cellotriose to cellohexaose in the negative subsites and (ii) cellobiose and cellotriose in the positive subsites. Such a structure is particularly relevant since it is the first structure of a GH5 enzyme in complex with transglycosylation products that has been obtained with neither of the catalytic glutamate residues modified.info:eu-repo/semantics/publishe

Glycoside hydrolase family 5: structural snapshots highlighting the involvement of two conserved residues in catalysis

The ability of retaining glycoside hydrolases (GHs) to transglycosylate is inherent to the double-displacement mechanism. Studying reaction intermediates, such as the glycosyl-enzyme intermediate (GEI) and the Michaelis complex, could provide valuable information to better understand the molecular factors governing the catalytic mechanism. Here, the GEI structure of RBcel1, an endo-1,4-β-glucanase of the GH5 family endowed with transglycosylase activity, is reported. It is the first structure of a GH5 enzyme covalently bound to a natural oligosaccharide with the two catalytic glutamate residues present. The structure of the variant RBcel1_E135A in complex with cellotriose is also reported, allowing a description of the entire binding cleft of RBcel1. Taken together, the structures deliver different snapshots of the double-displacement mechanism. The structural analysis revealed a significant movement of the nucleophilic glutamate residue during the reaction. Enzymatic assays indicated that, as expected, the acid/base glutamate residue is crucial for the glycosylation step and partly contributes to deglycosylation. Moreover, a conserved tyrosine residue in the −1 subsite, Tyr201, plays a determinant role in both the glycosylation and deglycosylation steps, since the GEI was trapped in the RBcel1_Y201F variant. The approach used to obtain the GEI presented here could easily be transposed to other retaining GHs in clan GH-A.info:eu-repo/semantics/publishe