Fast stress relaxing gellan gum that enhances the microenvironment and secreting function of bone mesenchymal stem cells.

This study shows tunable stress relaxing gellan gum (GG) hydrogel for enhanced cell growth and regenerative medicine. The molecular weight and physical crosslinking density of GG were tuned and characterized with physicochemical analysis and mechanical tests. The result showed that a decrease in the molecular weight of the GG correlated with a decline in the mechanical properties but faster stress relaxing character. We also discovered that human-derived bone marrow stem cells (hBMSC) showed active viability, proliferation, and remodeling in the fast stress relaxing GG hydrogel. In particular, hBMSC showed an enhanced release profile of growth factors and exosomes (Exo) in the fast stress relaxing GG hydrogel. The secretome obtained from hBMSC embedded in hydrogel exhibited similar cytotoxicity and wound healing properties to that of secretome extracted from hBMSC cultured in a tissue culture plate (TCP) a standard culture condition. Thus, this work demonstrates the potential of fast stress relaxing GG hydrogels for medical application.

Association Between Gut Microbiota and Depressive Symptoms: A Cross-Sectional Population-Based Study in South Korea.

OBJECTIVE: This study aimed to investigate the association between gut microbiota and depressive symptoms in a large population cohort of Korean adults. METHODS: Overall, 1238 participants were included in the study. Participants were categorized into depressed or non-depressed groups, based on the depressive symptoms reported on the Center for Epidemiologic Studies Rating Scale for Depression, with a cutoff score of 16, and their fecal microbiota was profiled using 16S ribosomal RNA gene sequencing. Several alpha and beta diversity measures were also estimated. The association between depressive symptoms and gut microbiota was analyzed using generalized linear models. The inferred function of the metagenomes was compared between the two groups. RESULTS: There were no consistent differences in alpha and beta diversity between the depressed and non-depressed groups. However, the continuous measure of depressive symptoms was inversely associated with one of four measures of alpha diversity (Shannon's diversity, p = .021). We also found a substantial difference between the depressed and non-depressed groups in the Bray-Curtis dissimilarity among the four beta diversity indices ( p = .004). Participants whose depressive symptoms exceeded a clinical cutoff score had a lower relative abundance of the genus Faecalibacterium when compared with controls (coefficient = -0.025, q = 0.047). However, the depressed group had a significantly higher abundance of the genus Oscillospira than did the non-depressed group (coefficient = 0.002, q = 0.023). CONCLUSIONS: Our findings contribute to the identification of potential relationships between the gut microbiota and depressive symptoms and provide useful insights for developing microbiota-based interventions for patients with depressive symptoms.

Relation between electrical properties of aerosol-deposited BaTiO3 thin films and their mechanical hardness measured by nano-indentation.

To achieve a high capacitance density for embedded decoupling capacitor applications, the aerosol deposition (AD) process was applied as a thin film deposition process. BaTiO3 films were fabricated on Cu substrates by the AD process at room temperature, and the film thickness was reduced to confirm the limit of the critical minimum thickness for dielectric properties. As a result, the BaTiO3 thin films that were less than 1-µm thick showed unstable electric properties owing to their high leakage currents. Therefore, to overcome this problem, the causes of the high leakage currents were investigated. In this study, it was confirmed that by comparing BaTiO3 thin films on Cu substrates with those on stainless steels (SUS) substrates, macroscopic defects and rough interfaces between films and substrates influence the leakage currents. Moreover, based on the deposition mechanism of the AD process, it was considered that the BaTiO3 thin films on Cu substrates with thicknesses of less than 1 µm are formed with chinks and weak particle-to-particle bonding, giving rise to leakage currents. In order to confirm the relation between the above-mentioned surface morphologies and the dielectric behavior, the hardness of BaTiO3 films on Cu and SUS substrates was investigated by nano-indentation. Consequently, we proposed that the chinks and weak particle-to-particle bonding in the BaTiO3 thin films with thicknesses of less than 0.5 µm on Cu substrates could be the main cause of the high leakage currents.