Structures and Electron Transport Paths in the Four Families of Flavin-Based Electron Bifurcation Enzymes.

Oxidoreductases facilitating electron transfer between molecules are pivotal in metabolic pathways. Flavin-based electron bifurcation (FBEB), a recently discovered energy coupling mechanism in oxidoreductases, enables the reversible division of electron pairs into two acceptors, bridging exergonic and otherwise unfeasible endergonic reactions. This chapter explores the four distinct FBEB complex families and highlights a decade of structural insights into FBEB complexes. In this chapter, we discuss the architecture, electron transfer routes, and conformational changes across all FBEB families, revealing the structural foundation that facilitate these remarkable functions.

Flexible Thermoelectric Wearable Architecture for Wireless Continuous Physiological Monitoring.

Continuous monitoring of physiological signals from the human body is critical in health monitoring, disease diagnosis, and therapeutics. Despite the needs, the existing wearable medical devices rely on either bulky wired systems or battery-powered devices needing frequent recharging. Here, we introduce a wearable, self-powered, thermoelectric flexible system architecture for wireless portable monitoring of physiological signals without recharging batteries. This system harvests an exceptionally high open circuit voltage of 175-180 mV from the human body, powering the wireless wearable bioelectronics to detect electrophysiological signals on the skin continuously. The thermoelectric system shows long-term stability in performance for 7 days with stable power management. Integrating screen printing, laser micromachining, and soft packaging technologies enables a multilayered, soft, wearable device to be mounted on any body part. The demonstration of the self-sustainable wearable system for detecting electromyograms and electrocardiograms captures the potential of the platform technology to offer various opportunities for continuous monitoring of biosignals, remote health monitoring, and automated disease diagnosis.

Mixed waste contamination selects for a mobile genetic element population enriched in multiple heavy metal resistance genes.

Mobile genetic elements (MGEs) like plasmids, viruses, and transposable elements can provide fitness benefits to their hosts for survival in the presence of environmental stressors. Heavy metal resistance genes (HMRGs) are frequently observed on MGEs, suggesting that MGEs may be an important driver of adaptive evolution in environments contaminated with heavy metals. Here, we report the meta-mobilome of the heavy metal-contaminated regions of the Oak Ridge Reservation subsurface. This meta-mobilome was compared with one derived from samples collected from unimpacted regions of the Oak Ridge Reservation subsurface. We assembled 1615 unique circularized DNA elements that we propose to be MGEs. The circular elements from the highly contaminated subsurface were enriched in HMRG clusters relative to those from the nearby unimpacted regions. Additionally, we found that these HMRGs were associated with Gamma and Betaproteobacteria hosts in the contaminated subsurface and potentially facilitate the persistence and dominance of these taxa in this region. Finally, the HMRGs were associated with conjugative elements, suggesting their potential for future lateral transfer. We demonstrate how our understanding of MGE ecology, evolution, and function can be enhanced through the genomic context provided by completed MGE assemblies.

Genomic and environmental controls on Castellaniella biogeography in an anthropogenically disturbed subsurface.

Castellaniella species have been isolated from a variety of mixed-waste environments including the nitrate and multiple metal-contaminated subsurface at the Oak Ridge Reservation (ORR). Previous studies examining microbial community composition and nitrate removal at ORR during biostimulation efforts reported increased abundances of members of the Castellaniella genus concurrent with increased denitrification rates. Thus, we asked how genomic and abiotic factors control the Castellaniella biogeography at the site to understand how these factors may influence nitrate transformation in an anthropogenically impacted setting. We report the isolation and characterization of several Castellaniella strains from the ORR subsurface. Five of these isolates match at 100% identity (at the 16S rRNA gene V4 region) to two Castellaniella amplicon sequence variants (ASVs), ASV1 and ASV2, that have persisted in the ORR subsurface for at least 2 decades. However, ASV2 has consistently higher relative abundance in samples taken from the site and was also the dominant blooming denitrifier population during a prior biostimulation effort. We found that the ASV2 representative strain has greater resistance to mixed metal stress than the ASV1 representative strains. We attribute this resistance, in part, to the large number of unique heavy metal resistance genes identified on a genomic island in the ASV2 representative genome. Additionally, we suggest that the relatively lower fitness of ASV1 may be connected to the loss of the nitrous oxide reductase (nos) operon (and associated nitrous oxide reductase activity) due to the insertion at this genomic locus of a mobile genetic element carrying copper resistance genes. This study demonstrates the value of integrating genomic, environmental, and phenotypic data to characterize the biogeography of key microorganisms in contaminated sites.

Predictors of germline genetic testing referral and completion in ovarian cancer patients at a Comprehensive Cancer Center.

OBJECTIVES: To identify predictors of referral and completion of germline genetic testing among newly diagnosed ovarian cancer patients, with a focus on geographic social deprivation, oncologist-level practices, and time between diagnosis and completion of testing. METHODS: Clinical and sociodemographic data were abstracted from medical records of patients newly diagnosed with ovarian cancer between 2014 and 2019 in the University of North Carolina Health System. Factors associated with referral for genetic counseling, completion of germline testing, and time between diagnosis and test results were identified using multivariable regression. RESULTS: 307/459 (67%) patients were referred for genetic counseling and 285/459 (62%) completed testing. The predicted probability of test completion was 0.83 (95% CI: 0.77-0.88) for patients with a referral compared to 0.27 (95% CI: 0.18-0.35) for patients without a referral. The predicted probability of referral was 0.75 (95% CI: 0.69-0.82) for patients at the 25th percentile of ZIP code-level Social Deprivation Index (SDI) and 0.67 (0.60-0.74) for patients at the 75th percentile of SDI. Referral varied by oncologist, with predicted probabilities ranging from 0.47 (95% CI: 0.32-0.62) to 0.93 (95% CI: 0.85-1.00) across oncologists. The median time between diagnosis and test results was 137 days (IQR: 55-248 days). This interval decreased by a predicted 24.46 days per year (95% CI: 37.75-11.16). CONCLUSIONS: We report relatively high germline testing and a promising trend in time from diagnosis to results, with variation by oncologist and patient factors. Automated referral, remote genetic counseling and sample collection, reduced out-of-pocket costs, and educational interventions should be explored.

Structural basis for RAD18 regulation by MAGEA4 and its implications for RING ubiquitin ligase binding by MAGE family proteins.

MAGEA4 is a cancer-testis antigen primarily expressed in the testes but aberrantly overexpressed in several cancers. MAGEA4 interacts with the RING ubiquitin ligase RAD18 and activates trans-lesion DNA synthesis (TLS), potentially favouring tumour evolution. Here, we employed NMR and AlphaFold2 (AF) to elucidate the interaction mode between RAD18 and MAGEA4, and reveal that the RAD6-binding domain (R6BD) of RAD18 occupies a groove in the C-terminal winged-helix subdomain of MAGEA4. We found that MAGEA4 partially displaces RAD6 from the RAD18 R6BD and inhibits degradative RAD18 autoubiquitination, which could be countered by a competing peptide of the RAD18 R6BD. AlphaFold2 and cross-linking mass spectrometry (XL-MS) also revealed an evolutionary invariant intramolecular interaction between the catalytic RING and the DNA-binding SAP domains of RAD18, which is essential for PCNA mono-ubiquitination. Using interaction proteomics, we found that another Type-I MAGE, MAGE-C2, interacts with the RING ubiquitin ligase TRIM28 in a manner similar to the MAGEA4/RAD18 complex, suggesting that the MAGEA4 peptide-binding groove also serves as a ligase-binding cleft in other type-I MAGEs. Our data provide new insights into the mechanism and regulation of RAD18-mediated PCNA mono-ubiquitination.

Serum total testosterone is associated with phosphate and calcium excretion in response to oral phosphate loading in healthy middle-aged males.

Androgen receptors are expressed in the kidney and serum testosterone is negatively associated with serum phosphate in males, suggesting a role of testosterone in renal phosphate handling. In this cross-sectional study, we examined the association of serum total and free testosterone with acute phosphate and calcium excretion in males in response to an oral phosphate challenge. Thirty-five healthy adult males with normal baseline testosterone levels consumed a 500 mg phosphorus drink and the urinary excretion of minerals, as well as levels of relevant circulating parameters, were assessed at baseline and hourly for 4 h. Serum total testosterone was positively associated with overall phosphate excretion (r = 0.35, p = 0.04) and calcium excretion (r = 0.44, p = 0.00) in response to the challenge. Serum free testosterone was positively associated with post-challenge calcium excretion (r = 0.34, p = 0.048), but significance was not reached for phosphate excretion (r = 0.31, p = 0.07). Serum total and free testosterone were not associated with parathyroid hormone, fibroblast growth factor-23, or vitamin D-key factors implicated in phosphate and calcium regulation. Overall, higher serum total testosterone levels in healthy middle-aged males are associated with a greater capacity to acutely excrete phosphate and calcium after a single oral phosphate challenge, suggesting potential ramifications of testosterone deficiency related to mineral homeostasis.

Environmental stress mediates groundwater microbial community assembly.

Community assembly describes how different ecological processes shape microbial community composition and structure. How environmental factors impact community assembly remains elusive. Here we sampled microbial communities and >200 biogeochemical variables in groundwater at the Oak Ridge Field Research Center, a former nuclear waste disposal site, and developed a theoretical framework to conceptualize the relationships between community assembly processes and environmental stresses. We found that stochastic assembly processes were critical (>60% on average) in shaping community structure, but their relative importance decreased as stress increased. Dispersal limitation and 'drift' related to random birth and death had negative correlations with stresses, whereas the selection processes leading to dissimilar communities increased with stresses, primarily related to pH, cobalt and molybdenum. Assembly mechanisms also varied greatly among different phylogenetic groups. Our findings highlight the importance of microbial dispersal limitation and environmental heterogeneity in ecosystem restoration and management.

Complete genome sequence for the extremely thermophilic bacterium Anaerocellum danielii (DSM:8977).

The complete genome sequence of the extremely thermophilic bacterium Anaerocellum (f. Caldicellulosiruptor) danielii (DSM:8977) is reported here. A. danielii is a fermentative anaerobe and capable of lignocellulose degradation with potential applications in biomass degradation and production of chemicals and fuels from renewable feedstocks.

Correlating Conformational Equilibria with Catalysis in the Electron Bifurcating EtfABCX of Thermotoga maritima.

Electron bifurcation (BF) is an evolutionarily ancient energy coupling mechanism in anaerobes, whose associated enzymatic machinery remains enigmatic. In BF-flavoenzymes, a chemically high-potential electron forms in a thermodynamically favorable fashion by simultaneously dropping the potential of a second electron before its donation to physiological acceptors. The cryo-EM and spectroscopic analyses of the BF-enzyme Fix/EtfABCX from Thermotoga maritima suggest that the BF-site contains a special flavin-adenine dinucleotide and, upon its reduction with NADH, a low-potential electron transfers to ferredoxin and a high-potential electron reduces menaquinone. The transfer of energy from high-energy intermediates must be carefully orchestrated conformationally to avoid equilibration. Herein, anaerobic size exclusion-coupled small-angle X-ray scattering (SEC-SAXS) shows that the Fix/EtfAB heterodimer subcomplex, which houses BF- and electron transfer (ET)-flavins, exists in a conformational equilibrium of compacted and extended states between flavin-binding domains, the abundance of which is impacted by reduction and NAD(H) binding. The conformations identify dynamics associated with the T. maritima enzyme and also recapitulate states identified in static structures of homologous BF-flavoenzymes. Reduction of Fix/EtfABCX's flavins alone is insufficient to elicit domain movements conducive to ET but requires a structural "trigger" induced by NAD(H) binding. Models show that Fix/EtfABCX's superdimer exists in a combination of states with respect to its BF-subcomplexes, suggesting a cooperative mechanism between supermonomers for optimizing catalysis. The correlation of conformational states with pathway steps suggests a structural means with which Fix/EtfABCX may progress through its catalytic cycle. Collectively, these observations provide a structural framework for tracing Fix/EtfABCX's catalysis.

The effects of hydration on the topographical and mechanical properties of corneocytes.

It is well established that the biomechanical properties of the Stratum Corneum (SC) are influenced by both moisture-induced plasticization and the lipid content. This study employs Atomic Force Microscopy to investigate how hydration affects the surface topographical and elasto-viscoplastic characteristics of corneocytes from two anatomical sites. Volar forearm cells underwent swelling when immersed in water with a 50% increase in thickness and volume. Similarly, medial heel cells demonstrated significant swelling in volume, accompanied by increased cell area and reduced cell roughness. Furthermore, as the water activity was increased, they exhibited enhanced compliance, leading to a decreased Young's modulus, hardness, and relaxation times. Moreover, the swollen cells also displayed a greater tolerance to strain before experiencing permanent deformation. Despite the greater predominance of immature cornified envelopes in plantar skin, the comparable Young's modulus of medial heel and forearm corneocytes suggests that cell stiffness primarily relies on the keratin matrix rather than on the cornified envelope. The Young's moduli of the cells in distilled water are similar to those reported for the SC, which suggests that the corneodesmosomes and intercellular lamellae lipids junctions that connect the corneocytes are able to accommodate the mechanical deformations of the SC.

Metabolic engineering of Caldicellulosiruptor bescii for 2,3-butanediol production from unpretreated lignocellulosic biomass and metabolic strategies for improving yields and titers.

The platform chemical 2,3-butanediol (2,3-BDO) is used to derive products, such as 1,3-butadiene and methyl ethyl ketone, for the chemical and fuel production industries. Efficient microbial 2,3-BDO production at industrial scales has not been achieved yet for various reasons, including product inhibition to host organisms, mixed stereospecificity in product formation, and dependence on expensive substrates (i.e., glucose). In this study, we explore engineering of a 2,3-BDO pathway in Caldicellulosiruptor bescii, an extremely thermophilic (optimal growth temperature = 78°C) and anaerobic bacterium that can break down crystalline cellulose and hemicellulose into fermentable C5 and C6 sugars. In addition, C. bescii grows on unpretreated plant biomass, such as switchgrass. Biosynthesis of 2,3-BDO involves three steps: two molecules of pyruvate are condensed into acetolactate; acetolactate is decarboxylated to acetoin, and finally, acetoin is reduced to 2,3-BDO. C. bescii natively produces acetoin; therefore, in order to complete the 2,3-BDO biosynthetic pathway, C. bescii was engineered to produce a secondary alcohol dehydrogenase (sADH) to catalyze the final step. Two previously characterized, thermostable sADH enzymes with high affinity for acetoin, one from a bacterium and one from an archaeon, were tested independently. When either sADH was present in C. bescii, the recombinant strains were able to produce up to 2.5-mM 2,3-BDO from crystalline cellulose and xylan and 0.2-mM 2,3-BDO directly from unpretreated switchgrass. This serves as the basis for higher yields and productivities, and to this end, limiting factors and potential genetic targets for further optimization were assessed using the genome-scale metabolic model of C. bescii.IMPORTANCELignocellulosic plant biomass as the substrate for microbial synthesis of 2,3-butanediol is one of the major keys toward cost-effective bio-based production of this chemical at an industrial scale. However, deconstruction of biomass to release the sugars for microbial growth currently requires expensive thermochemical and enzymatic pretreatments. In this study, the thermo-cellulolytic bacterium Caldicellulosiruptor bescii was successfully engineered to produce 2,3-butanediol from cellulose, xylan, and directly from unpretreated switchgrass. Genome-scale metabolic modeling of C. bescii was applied to adjust carbon and redox fluxes to maximize productivity of 2,3-butanediol, thereby revealing bottlenecks that require genetic modifications.

Characterization of the Membrane-Associated Electron-Bifurcating Flavoenzyme EtfABCX from the Hyperthermophilic Bacterium Thermotoga maritima.

Electron bifurcation is an energy-conservation mechanism in which a single enzyme couples an exergonic reaction with an endergonic one. Heterotetrameric EtfABCX drives the reduction of low-potential ferredoxin (E°' ∼ -450 mV) by oxidation of the midpotential NADH (E°' = -320 mV) by simultaneously coupling the reaction to reduction of the high-potential menaquinone (E°' = -74 mV). Electron bifurcation occurs at the NADH-oxidizing bifurcating-flavin adenine dinucleotide (BF-FAD) in EtfA, which has extremely crossed half-potentials and passes the first, high-potential electron to an electron-transferring FAD and via two iron-sulfur clusters eventually to menaquinone. The low-potential electron on the BF-FAD semiquinone simultaneously reduces ferredoxin. We have expressed the genes encodingThermotoga maritimaEtfABCX in E. coli and purified the EtfABCX holoenzyme and the EtfAB subcomplex. The bifurcation activity of EtfABCX was demonstrated by using electron paramagnetic resonance (EPR) to follow accumulation of reduced ferredoxin. To elucidate structural factors that impart the bifurcating ability, EPR and NADH titrations monitored by visible spectroscopy and dye-linked enzyme assays have been employed to characterize four conserved residues, R38, P239, and V242 in EtfA and R140 in EtfB, in the immediate vicinity of the BF-FAD. The R38, P239, and V242 variants showed diminished but still significant bifurcation activity. Despite still being partially reduced by NADH, the R140 variant had no bifurcation activity, and electron transfer to its two [4Fe-4S] clusters was prevented. The role of R140 is discussed in terms of the bifurcation mechanism in EtfABCX and in the other three families of bifurcating enzymes.

Characterisation of superficial corneocyte properties over category I pressure ulcers: Insights into topographical and maturation changes.

BACKGROUND: Pressure ulcers (PUs) are chronic wounds that are detrimental to the quality of life of patients. Despite advances in monitoring skin changes, the structure and function of skin cells over the site of pressure ulcers are not fully understood. OBJECTIVE: The present study aims to evaluate local changes in the properties of superficial corneocytes in category 1 PU sites sampled from a cohort of hospitalised patients. METHODS: Cells were collected from a PU-compromised site and an adjacent control area and their topographical, maturation and mechanical properties were analysed. RESULTS: Corneocytes at the PU-compromised site were characterised by higher levels of immature cornified envelopes (p < 0.001) and greater amounts of desmoglein-1 (corneodesmosomal protein) (p < 0.001) compared to the adjacent control area. The cells at the control site presented the typical ridges-and-valleys topographical features of sacrum corneocytes. By contrast, the PU cells presented circular nano-objects at the cell surface, and, for some patients, the cell topography was deformed. CEs at the PU site were also smaller than at the control site. Although differences were not observed in the mechanical properties of the cells, those of the elderly patients were much softer compared with young subjects. CONCLUSION: This is the first study investigating the changes in corneocyte properties in category I pressure ulcers. Superficial cells at the PU sites showed altered topographical and maturation characteristics. Further studies are required to elucidate if these changes are a consequence of early loss of skin integrity or a result of mechanical and microclimate insults to the skin surface.

Structural basis for the toxicity of Legionella pneumophila effector SidH.

Legionella pneumophila (LP) secretes more than 300 effectors into the host cytosol to facilitate intracellular replication. One of these effectors, SidH, 253 kDa in size with no sequence similarity to proteins of known function is toxic when overexpressed in host cells. SidH is regulated by the LP metaeffector LubX which targets SidH for degradation in a temporal manner during LP infection. The mechanism underlying the toxicity of SidH and its role in LP infection are unknown. Here, we determined the cryo-EM structure of SidH at 2.7 Å revealing a unique alpha helical arrangement with no overall similarity to known protein structures. Surprisingly, purified SidH came bound to a E. coli EF-Tu/t-RNA/GTP ternary complex which could be modeled into the cryo-EM density. Mutation of residues disrupting the SidH-tRNA interface and SidH-EF-Tu interface abolish the toxicity of overexpressed SidH in human cells, a phenotype confirmed in infection of Acanthamoeba castellani. We also present the cryo-EM structure of SidH in complex with a U-box domain containing ubiquitin ligase LubX delineating the mechanism of regulation of SidH. Our data provide the basis for the toxicity of SidH and into its regulation by the metaeffector LubX.

Characterisation of topographical, biomechanical and maturation properties of corneocytes with respect to anatomical location.

BACKGROUND: The Stratum Corneum (SC) is the first barrier of the skin. The properties of individual cells are crucial in understanding how the SC at different anatomical regions maintains a healthy mechanical barrier. The aim of the current study is to present a comprehensive description of the maturation and mechanical properties of superficial corneocytes at different anatomical sites in the nominal dry state. MATERIALS AND METHODS: Corneocytes were collected from five anatomical sites: forearm, cheek, neck, sacrum and medial heel of 10 healthy young participants. The surface topography was analysed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The level of positive-involucrin cornified envelopes (CEs) and desmoglein-1 (Dsg1) were used as indirect measures of immature CEs and corneodesmosomes, respectively. In addition, AFM nanoindentation and stress-relaxation experiments were performed to characterise the mechanical properties. RESULTS: Volar forearm, neck and sacrum corneocytes presented similar topographies (ridges and valleys) and levels of Dsg1 (13-37%). In contrast, cheek cells exhibited circular nano-objects, while medial heel cells were characterized by villi-like structures. Additionally, medial heel samples also showed the greatest level of immature CEs (32-56%, p < 0.001) and Dsg1 (59-78%, p < 0.001). A large degree of inter-subject variability was found for the Young's moduli of the cells (0.19-2.03 GPa), which was correlated with the level of immature CEs at the cheek, neck and sacrum (p < 0.05). CONCLUSION: It is concluded that a comprehensive study of the mechanical and maturation properties of corneocytes may be used to understand the barrier functions of the SC at different anatomical sites.

Are There Any Pleiotropic Benefits of Vitamin D in Patients With Diabetic Kidney Disease? A Systematic Review of Randomized Controlled Trials.

Background: Type 2 diabetes (T2D) and kidney disease are risk factors for vitamin D deficiency. Native forms of vitamin D have a lower risk of hypercalcemia than calcitriol, the active hormone. The enzyme responsible for activating native vitamin D is now known to be expressed throughout the body; therefore, native vitamin D may have clinically relevant effects in many body systems. Objective: The objective of this systematic review was to examine the effect of native vitamin D supplementation on clinical outcomes and surrogate laboratory measures in patients with T2D and diabetic kidney disease (DKD). Design: Systematic review. Setting: Randomized controlled trials (RCTs) conducted in any country. Patients: Adults with T2D and DKD receiving supplementation with any form of native vitamin D (eg, ergocalciferol, cholecalciferol, calcifediol). Measurements: Clinical outcomes and surrogate clinical and laboratory measures reported in each of the trials were included in this review. Methods: The following databases were searched from inception to January 31, 2023: Embase, MEDLINE, Cochrane CENTRAL, Web of Science, ProQuest Dissertations and Theses, and medRxiv. Only RCTs examining supplementation with a native vitamin D form with a control or placebo comparison group were included. We excluded studies reporting only vitamin D status or mineral metabolism parameters, without any other outcomes of clinical relevance or surrogate laboratory measures. Study quality was evaluated using the Cochrane risk-of-bias tool (RoB2). Results were synthesized in summary tables for each type of outcome with the P values from the original studies displayed. Results: Nine publications were included, corresponding to 5 separate RCTs (377 participants total). Mean age ranged from 40 to 63. All trials administered vitamin D3. Intervention groups experienced improvements in vitamin D status and a reduction in proteinuria in 4 of the 5 included RCTs. There was a decrease in low-density lipoprotein and total cholesterol in the 2 trials in which they were measured. Improvements in bone mass, flow-mediated dilation, and inflammation were also reported, but each was only measured in 1 RCT. Effects on glucose metabolism, high-density lipoprotein, triglycerides, blood pressure, oxidative stress, and kidney function were mixed. No serious adverse effects were reported. Limitations: Limitations include the small number of RCTs and lack of information on the use of drugs that affect measured outcomes (eg, proteinuria-lowering renin-angiotensin-aldosterone system inhibitors and lipid-lowering medication) in most studies. Our study is also limited by the absence of a prestudy protocol and registration. Conclusions: Native vitamin D is a safe treatment that improves vitamin D status in patients with DKD. Vitamin D may modify proteinuria and lipid metabolism in DKD, but further well-designed trials that include well-established treatments are necessary. Overall, there is limited evidence for beneficial pleiotropic effects of vitamin D in patients with DKD.

Contexte: Le diabète de type 2 (DT2) et l'insuffisance rénale sont des facteurs de risque pour une carence en vitamine D. Les formes natives de la vitamine D représentent un risque plus faible d'hypercalcémie que le calcitriol, la forme active sur le plan hormonal de la vitamine D. On sait maintenant que l'enzyme responsable de l'activation de la vitamine D peut être exprimée dans tout le corps et donc, que la vitamine D native peut avoir des effets cliniquement significatifs dans de nombreux systèmes de l'organisme. Objectif: Examiner l'effet d'une supplémentation en vitamine D native sur les résultats cliniques et les mesures de laboratoire de substitution de patients atteints de DT2 et de maladie rénale diabétique (MRD). Conception: Revue systématique. Sources: Les essais contrôlés randomisés (ECR) pertinents, sans égard au pays où ils ont été menés. Sujets: Des adultes atteints de DT2 et de MRD recevant une supplémentation de toute forme de vitamine D native (ergocalciférol, cholécalciférol, calcifédiol). Mesures: Les mesures biologiques et cliniques de substitution ainsi que les résultats cliniques rapportés dans chacun des essais inclus. Méthodologie: Une recherche des articles pertinents a été effectuée dans les bases de données Embase, MEDLINE, Cochrane CENTRAL, Web of Science, ProQuest Dissertations and Theses et medRxiv depuis leur création jusqu'au 31 janvier 2023. Seuls les ECR examinant la supplémentation avec une forme native de vitamine D contre un groupe témoin ou un placebo ont été inclus. Nous avons exclu les études ne rapportant que le statut en vitamine D ou les paramètres du métabolisme minéral, sans aucun autre résultat significatif sur le plan clinique ou mesure de laboratoire de substitution. La qualité des études a été évaluée à l'aide de l'outil Cochrane sur le risque de biais (RoB2). Les résultats ont été résumés dans des tableaux récapitulatifs pour chaque type de résultat avec les valeurs de p tirées des essais originaux. Résultats: Neuf publications ont été incluses, lesquelles portaient sur cinq ECR distincts (377 participants au total). L'âge moyen des sujets variait de 40 à 63 ans. De la vitamine D3 avait été administrée dans tous les essais. Dans quatre des cinq ECR inclus, le groupe d'intervention avait connu une amélioration du statut en vitamine D et une réduction de la protéinurie. Une diminution des LDL et du cholestérol total avait été observée dans les deux essais où ces paramètres avaient été mesurés. Des améliorations de la masse osseuse, de la dilatation médiée par le débit et de l'inflammation avaient également été rapportées, mais chacun de ces paramètres n'avait été mesuré que dans un seul ECR. Lorsque rapportés, les effets sur le métabolisme du glucose, les HDL, les triglycérides, la pression artérielle, le stress oxydatif et la fonction rénale étaient mitigés. Aucun effet indésirable grave à la supplémentation n'a été signalé. Limites: Les résultats sont limités par le faible nombre d'ECR inclus et par le manque d'information dans la plupart des études sur l'utilisation de médicaments qui affectent les résultats mesurés (par exemple, les inhibiteurs du SRAA abaissant la protéinurie et les médicaments abaissant le taux de lipides). Aussi, notre étude n'est pas enregistrée et ne comportait pas de protocole pré-étude. Conclusion: La supplémentation en vitamine D native est sûre et elle améliore le statut en vitamine D des patients atteints de MRD. La vitamine D semble modifier la protéinurie et le métabolisme lipidique en contexte de MRD, mais d'autres essais bien conçus et intégrant des traitements bien établis sont nécessaires. Globalement, il existe peu de données probantes sur les effets pléiotropiques bénéfiques de la vitamine D chez les patients atteints de MRD.

Broad-Scale Assessment of Methylmercury in Adult Amphibians.

Mercury (Hg) is a toxic contaminant that has been mobilized and distributed worldwide and is a threat to many wildlife species. Amphibians are facing unprecedented global declines due to many threats including contaminants. While the biphasic life history of many amphibians creates a potential nexus for methylmercury (MeHg) exposure in aquatic habitats and subsequent health effects, the broad-scale distribution of MeHg exposure in amphibians remains unknown. We used nonlethal sampling to assess MeHg bioaccumulation in 3,241 juvenile and adult amphibians during 2017-2021. We sampled 26 populations (14 species) across 11 states in the United States, including several imperiled species that could not have been sampled by traditional lethal methods. We examined whether life history traits of species and whether the concentration of total mercury in sediment or dragonflies could be used as indicators of MeHg bioaccumulation in amphibians. Methylmercury contamination was widespread, with a 33-fold difference in concentrations across sites. Variation among years and clustered subsites was less than variation across sites. Life history characteristics such as size, sex, and whether the amphibian was a frog, toad, newt, or other salamander were the factors most strongly associated with bioaccumulation. Total Hg in dragonflies was a reliable indicator of bioaccumulation of MeHg in amphibians (R2 ≥ 0.67), whereas total Hg in sediment was not (R2 ≤ 0.04). Our study, the largest broad-scale assessment of MeHg bioaccumulation in amphibians, highlights methodological advances that allow for nonlethal sampling of rare species and reveals immense variation among species, life histories, and sites. Our findings can help identify sensitive populations and provide environmentally relevant concentrations for future studies to better quantify the potential threats of MeHg to amphibians.