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The levels of the thousands of metabolites in the human plasma metabolome are strongly influenced by an individual’s genetics and the composition of their diet and gut microbiome. Here, by assessing 1,183 plasma metabolites in 1,368 extensively phenotyped individuals from the Lifelines DEEP and Genome of the Netherlands cohorts, we quantified the proportion of inter-individual variation in the plasma metabolome explained by different factors, characterizing 610, 85 and 38 metabolites as dominantly associated with diet, the gut microbiome and genetics, respectively. Moreover, a diet quality score derived from metabolite levels was significantly associated with diet quality, as assessed by a detailed food frequency questionnaire. Through Mendelian randomization and mediation analyses, we revealed putative causal relationships between diet, the gut microbiome and metabolites. For example, Mendelian randomization analyses support a potential causal effect of Eubacterium rectale in decreasing plasma levels of hydrogen sulfite—a toxin that affects cardiovascular function. Lastly, based on analysis of the plasma metabolome of 311 individuals at two time points separated by 4 years, we observed a positive correlation between the stability of metabolite levels and the amount of variance in the levels of that metabolite that could be explained in our analysis. Altogether, characterization of factors that explain inter-individual variation in the plasma metabolome can help design approaches for modulating diet or the gut microbiome to shape a healthy metabolome.

Purpose The major purpose of this study was to detect the changes in gut microbiota composition and inflammatory cytokines production associated with acute and chronic insomnia. This study also evaluated the relationship between gut microbiota changes and increased inflammatory cytokines in insomnia patients. Patients and Methods Outpatients with acute and chronic insomnia (aged 26–55 years; n=20 and 38, respectively) and age/gender-matched healthy controls (n=38) were recruited from a southern China region. Participants’ gut microbiome, plasma cytokines, and self-reported sleep quality and psychopathological symptoms were measured. Results The gut microbiomes of insomnia patients compared with healthy controls were characterized by lower microbial richness and diversity, depletion of anaerobes, and short-chain fatty acid (SCFA)-producing bacteria, and an expansion of potential pathobionts. Lachnospira and Bacteroides were signature bacteria for distinguishing acute insomnia patients from healthy controls, while Faecalibacterium and Blautia were signature bacteria for distinguishing chronic insomnia patients from healthy controls. Acute/chronic insomnia-related signature bacteria also showed correlations with these patients’ self-reported sleep quality and plasma IL-1β. Conclusion These findings suggest that insomnia symptomology, gut microbiota, and inflammation may be interrelated in complex ways. Gut microbiota may serve as an important indicator for auxiliary diagnosis of insomnia and provide possible new therapeutic targets in the field of sleep disorders.

Material properties of the components of magnetorheological (MR) fluids are critical to their control accuracy and service life. The aim of this study was to reveal the effects of temperature on the material properties of MR fluid components. In this paper, a detailed introduction to the components of MR fluids, including main performance indicators and commonly used materials, was presented at first. Then, theoretical analysis and experimental investigation were performed on the temperature-dependent material properties of MR fluid components. These material properties included the magnetization properties of the magnetic particle, as well as the shear viscosity and thermal expansion of the carrier fluid. Experimental results indicated that both the mass magnetization and coercivity of MR particles decreased as the temperature increased and the phenomenon was particularly obvious at high temperatures. Moreover, an increasing temperature could lead to a severe decrease of the shear viscosity and a relatively large thermal expansion of the carrier fluid. Research results from this study may serve to provide a theoretical and an experimental basis for the preparation of MR fluids with high thermal stability.