Nonalcoholic fatty liver disease (NAFLD) is associated with obesity but also found in non-obese individuals. Gut microbiome profiles of 171 Asians with biopsy-proven NAFLD and 31 non-NAFLD controls are analyzed using 16S rRNA sequencing; an independent Western cohort is used for external validation. Subjects are classified into three subgroups according to histological spectra of NAFLD or fibrosis severity. Significant alterations in microbiome diversity are observed according to fibrosis severity in non-obese, but not obese, subjects. Ruminococcaceae and Veillonellaceae are the main microbiota associated with fibrosis severity in non-obese subjects. Furthermore, stool bile acids and propionate are elevated, especially in non-obese subjects with significant fibrosis. Fibrosis-related Ruminococcaceae and Veillonellaceae species undergo metagenome sequencing, and four representative species are administered in three mouse NAFLD models to evaluate their effects on liver damage. This study provides the evidence for the role of the microbiome in the liver fibrosis pathogenesis, especially in non-obese subjects.
We present a capacitor-type device that can generate strong electrostatic field in condensed phase. The device comprises an ice film grown on a cold metal substrate in vacuum, and the film is charged by trapping Cs(+) ions on the ice surface with thermodynamic surface energy. Electric field within the charged film was monitored through measuring the film voltage using a Kelvin work function probe and the vibrational Stark effect of acetonitrile using IR spectroscopy. These measurements show that the electric field can be increased to ∼4 × 10(8) V m(-1), higher than that achievable by conventional metal plate capacitors. In addition, the present device may provide several advantages in studying the effects of electric field on molecules in condensed phase, such as the ability to control the sample composition and structure at molecular scale and the spectroscopic monitoring of the sample under electric field.
The gut microbiomes of human populations worldwide have many core microbial species in common. However, within a species, some strains can show remarkable population specificity. The question is whether such specificity arises from a shared evolutionary history (codiversification) between humans and their microbes. To test for codiversification of host and microbiota, we analyzed paired gut metagenomes and human genomes for 1225 individuals in Europe, Asia, and Africa, including mothers and their children. Between and within countries, a parallel evolutionary history was evident for humans and their gut microbes. Moreover, species displaying the strongest codiversification independently evolved traits characteristic of host dependency, including reduced genomes and oxygen and temperature sensitivity. These findings all point to the importance of understanding the potential role of population-specific microbial strains in microbiome-mediated disease phenotypes.
We investigated the dipolar reorientation of acetone molecules in amorphous solids under the influence of externally applied electric fields in the range of (0−4.3) × 10 8 V· m −1 . The electric field was applied using an ice film capacitor method, and the field strength was estimated from measurements of the film voltage and thickness using a Kelvin probe and the temperature-programed desorption method, respectively. Reorientation of the acetone molecules was monitored with reflection−absorption infrared spectroscopy (RAIRS), which measured the absorbance change of the acetone vibrational bands induced by the applied electric field. The electric field caused a substantial degree of dipolar polarization of the sample. Acetone molecules were reoriented toward the field direction by an average angle of about 31°at an applied field strength of 4.3 × 10 8 V·m −1 , according to analysis of the RAIRS intensity changes using a simple molecular geometry model. While the extent of dipolar polarization of the sample increased with increasing field strength, the sample was not reversibly depolarized with decreasing field strength.Multiple-peak analysis of the ν(CO) spectrum revealed that the molecules in the acetone− water boundary region were more easily rotated compared to those in the bulk.
We studied the Stark effect on the hydroxyl stretching vibration of water molecules in ice under the influence of an external electric field. Electric fields with strengths in the range from 6.4 × 10 7 to 2.3 × 10 8 V·m −1 were applied to an ice sample using the ice film capacitor method. Reflection absorption infrared spectroscopy was used to monitor the field-induced spectral changes of vibrationally decoupled O−H and O−D bands of dilute HOD in D 2 O and H 2 O− ice, respectively. The spectral changes of the hydroxyl bands under applied field were analyzed using a model that simulates the absorption of a collection of Starkshifted oscillators. The analysis shows that the Stark tuning rate of ν(O−D) is 6.4−12 cm −1 /(MV·cm −1 ) at a field strength from 1.8 × 10 8 to 6.4 × 10 7 V·m −1 , and the Stark tuning rate of ν(O−H) is 10−16 cm −1 /(MV·cm −1 ) at a field strength from 2.3 × 10 8 to 9.2 × 10 7 V·m −1 . These values are uniquely large compared to the Stark tuning rates of carbonyl or nitrile vibrations in other frozen molecular solids. Quantum mechanical calculations for the vibrations of isolated water and water clusters show that the vibrational Stark effect increases with the formation of intermolecular hydrogen bonds. This suggests that that the large Stark tuning rate of ice is due to its hydrogen-bonding network, which increases anharmonicity of the potential curve along the O−H bond and the ability to shift the electron density under applied electric field.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.